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Effects of sprint cycle training on human skeletal muscle. Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide.
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Advanced Search. Search Menu. Article Navigation. Close mobile search navigation Article Navigation. Volume Article Contents Abstract. Journal Article. Gender Differences in Resistance-Training-Induced Myofiber Hypertrophy Among Older Adults.
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Figure 2. Table 1. Descriptive Characteristics and Changes in Body Composition. However, only females had significantly elevated peritendinous levels of IGF-I at 4 hours post, whereas males did not. Additionally, males showed greater post-RT changes in Matrix Metallopeptidase 9 MMP-9 levels than females, and females had a more prolonged exercise-induced elevations in tissue inhibitor of metalloproteinases-I TIMP-I than males.
Data shows no normative difference when comparing circulating TGFβ-1 levels in males, pre and post-menopausal females, and pregnant females [ 19 , 20 ]. At present, the literature on any link between the previously reported [ 22 ] acute in vivo TGFβ-1 response to mechanical loading, and the magnitude or nature of human MTC training adaptations is limited.
A topical study is that of Heinemeier et al. However, in this Heinemeier et al. In addition, it remains unclear whether any difference would be associated with major growth-factor candidates purported to influence MTC properties and adaptations to training. Therefore, the objectives of this study were to 1.
Characterise the MTC adaptation to a period of dynamic, heavy-load resistance training in males and females, 2 identify any sex-related differences across MTC properties and 3 investigate whether any of the adaptive responses could be reflected in changes in two key circulating growth factors related to the MTC.
Twenty-eight young participants recruited from the local university campus, gave written informed consent to participate in the study. All procedures and experimental protocols were approved by the Manchester Metropolitan University Cheshire Campus ethics committee.
Exclusion criteria included the presence of any known musculoskeletal, neurological, inflammatory, or metabolic disorders or injury. Participants took part in recreational activities such as team sports and had either never taken part in lower limb resistance training or had not done so within the previous 12 months.
Each participant completed a physical activity diary, outlining that they each habitually completed 3—5 hours of non-resistance based moderate physical activity per week. Sixteen participants were then equally subdivided by sex and randomly assigned to a training group T males [TM] age 20±1 years, mass 81±4Kg, T females [TF] age 19±3 years, mass 69±3Kg , whilst 6 males [ConM] age 22±2 years, mass 82±2Kg and 6 females [ConF] age 23±4, mass 63±4Kg were assigned to a control group CON.
All females were eumenorrheic menstrual cycle duration of 26—30 days and none used any form of Oral Contraceptive Pill, the latter having been shown to impact of the MTC properties in females [ 24 ].
The study design was convenience sampling, with participants separated into groups according to sex followed by random allocation to one of two groups i.
training or control. Measurements were repeated after 8 weeks resistance training post-training. The measurement techniques used for the calculation for physiological cross-sectional area of the Vastus Lateralis VL muscle in the current study have been documented elsewhere [ 25 , 26 ].
Briefly, multiple anatomical cross-sectional area aCSA measures were made via brightness mode ultrasonography 7. Muscle volume was then calculated using the truncated cone method, which has been validated in a number of previous studies [ 27 , 28 ].
VL pCSA was calculated by dividing muscle volume by fascicle length [ 28 ]. Peak torque was expressed as the average of data points over a ms period at the plateau phase i. The peak torque of three extensions was used as the measure of torque in each participant.
The reference electrode Blue sensor L, Ambu, Denmark was placed on the lateral tibial condyle. The raw EMG signal was preamplified MP, Biopac Systems Inc. All EMG and torque signals were displayed in real time in AcqKnowledge software Biopac systems Inc.
Two maximal knee flexion contractions were carried out to obtain the EMG at maximal flexion torque. The root mean square RMS EMG activity was averaged for a ms period average of 1. To reiterate, the EMG of the long head of the biceps femoris muscle was measured to ascertain the level of antagonist muscle co-contraction during the required isometric knee-extension performances.
The biceps femoris torque during a knee-flexion contraction was calculated as described by McMahon et al. The measures of tendon properties used in the current investigation have been described elsewhere [ 31 ].
Briefly, tendon elongation was determined using brightness mode ultrasound imaging over the apex of the patella in the sagittal plane, with the knee fixed at 90 0 flexion as per the norm in in vivo tendon properties assessment.
Five preconditioning trials were carried out to ensure reproducibility. Following this, three ramped, 6-second isometric contractions were monitored for the distance between the original position of the tissue under the skin, relative to the new position of the tissue using ultrasound images captured onto a personal computer at 25 Hz.
The ultrasound output was synchronized using a square wave signal generator to allow temporal alignment with both torque and EMG data. Three efforts were analysed, and the average reported as the profile of tendon force versus elongation for the participant.
The plotted force—elongation relationship was fitted with a second-order polynomial function, forced through zero. Patellar tendon PT resting length TL and cross-sectional area Tcsa were also assessed with the knee joint at 90 o of flexion.
TL was measured from the inferior pole of the patellar to the superior aspect of the tibial tuberosity determined from sagittal-plane ultrasound images. PT volume TVol was calculated using the TL and Tcsa values along the length of the tendon using the truncated cone method, which used the same principles as those demonstrated on muscle volume assessments [ 27 ].
Pre and post-training, following an overnight fast, ~10 hours , participants reported to the laboratory between am. IGF-I and TGFβ-1 were analysed using the standard enzyme-linked immuno-sorbent assay ELISA procedure, as described by McMahon et al. Post-training samples were taken 3—4 days post final training session, at the same time-of-day as the pre- training sampling for each participant.
The laboratory tests were timed to avoid diurnal variability or acute exercise-induced growth factor fluctuations. Exercises included the back squat, leg press, leg extension Technogym, Berkshire, UK , lunge, Bulgarian split squat and Sampson chair. All exercise sessions were supervised by a member of the research team.
Volume i. repetitions and sets was identical for each training group, with each training session consisting of four exercises and performing three sets of 10 repetitions per exercise for the first 4 weeks, and four sets of eight repetitions per exercise thereafter.
Training sessions would typically last ~60 minutes, with training records being diligently completed during sessions. Statistical analysis was carried out using IBM SPSS v19 IBM Inc, USA.
Data was analysed using a 4×2 ANCOVA with baseline measures used as covariates. The within-group factor was the phase of training baseline, post-training and the between-group factor was training group i.
TM, TF, ConM, ConF. Post-hoc comparisons are Bonferroni corrected and adjustments for multiple comparisons are applied in the correlation tables.
All data are presented as mean ± standard error of the mean SEM. Power β and effect size ES are reported for those changes that exhibited significant sex differences, where power was calculated post hoc using the independent t-test assumptions. There were significant increases in pCSA, strength, PT Vol, mean PT K and E, and IGF-I Table 1 in each training group, with no sex differences.
However, when PT K was analysed at discrete force regions, significant sex-specific differences were identified Fig 1. Males black bars and females white bars following training. Data are Mean ± SEM. Pooled population baseline IGF-I values correlated with baseline stiffness at high force levels i.
At week 8 however, the correlations of IGF-I was in fact with lower force regions i. Whilst baseline IGF-I was not associated with tendon stiffness, at week 8, IGF-I levels correlated with week 8 stiffness at mid force levels i.
Our key current findings are 1 we are the first to demonstrate sex-specificity in the overloading-induced adaptive nature of the mechanical properties of tendon in a young population. Sex-related differences in the mechanical, structural and regulatory mechanisms in human tendinous tissue have been identified previously [ 5 , 7 ].
Differences in acute tendon fractional collagen synthesis rates [ 8 , 9 ], amount of tendon dry mass per wet tendon weight [ 32 ], mRNA levels of Type III collagen [ 10 ] have all been shown to vary between sexes.
In addition, proteomic work from Little et al. This would tend to suggest that, either at rest, or when provided with a similar physical stimulus to males, female tendon does not respond similarly. As successive acute responses to physical stimuli combine to produce the chronic adaptation, this leads to the possible scenario of a mal-adapted female tendon i.
morphologically or mechanically relative to male tendon following a period of training. There were also no differences in the training-induced mean patella tendon stiffness change, between males and females.
This is in contrast to the findings of Onambele-Pearson and Pearson [ 12 ] and Seynnes et al. Evident from the torque data in the current study, the mean torque associated with the resistance training would have been much greater in males post-training MVCs were ±10 Nm vs.
Males black filled diamonds and females white filled squares. A further potential physiological mechanism for our observations is the nature of the resistance training program. The exercises performed were dynamic apart from one isometric , and isotonic in nature.
Adaptations to eccentric training, such as microcirculatory factors and pain reduction, has been shown to be sex-specific in a cohort with Achilles tendinopathy, with males again demonstrating an improved responsiveness [ 34 ].
Furthermore, during maximal eccentric exercise between o knee extension, we previously [ 7 ] showed that female patella tendon displayed reduced stiffness compared to males, and attributed a large portion of the reduced fascicular lengthening seen in females compared to males to this observation.
A subsequent study from our group [ 35 ] also showed that following the same exercise protocol, males displayed a significantly greater magnitude of muscle damage. This demonstrates that the sex-specific response and adaptations to variables associated with manipulating a resistance training program have yet to be elucidated, and await further study.
Therefore, the results of the current study raises the following question: Is dynamic, heavy-load resistance training currently the most conventional and popular form , the best training method for females routinely operating at the higher force levels of the tendon force-elongation curve, where adaptations to this type of training are minimised relative to adaptations on the subsequent lower portions of the tendon Force-Elongation curve?
In vitro studies have demonstrated the potency of TGFβmediated effects on collagen, and its relationship to magnitude of mechanical strain [ 14 , 15 ]. What is also surprising is that to date, only one study had previously described the effect of resistance training as opposed to endurance kicking-type exercise, on TGFβ-1 and tendon mechanical properties, despite resistance training being a more potent mechanical stimulus for tendon adaptation.
We have also previously shown in a young population [ 31 ], that resistance training did not result in chronically elevated TGFβ-1 levels following 8 weeks of heavy resistance training with varying levels of strain. This was also the case in the current study, where there were no significant changes in either males or females following resistance training, despite significant improvements in tendon mechanical properties.
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Download references. Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands.
Raven O. Huiberts, Rob C. Department of Cardiology, Amsterdam University Medical Center, University of Amsterdam, Meibergdreef 9, AZ, Amsterdam, The Netherlands. You can also search for this author in PubMed Google Scholar.
Correspondence to Stephan van der Zwaard. Wüst, and Stephan van der Zwaard have no conflicts of interest that are directly relevant to the content of this article. RH and SZ conceived and designed the work. RH and SZ performed the literature search and the data screening and extraction. RH and RW evaluated the risk of bias.
RH and SZ performed the statistical analyses. SZ was responsible for the visualizations and RH, RW, and SZ interpreted the data. SZ wrote the manuscript. All authors read and revised the manuscript and approved the final version of the manuscript for publication.
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Provided by the Springer Nature SharedIt content-sharing initiative. Download PDF. Abstract Background Many sports require maximal strength and endurance performance. Methods A systematic review and meta-analysis was conducted according to PRISMA Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and a Cochrane risk of bias was evaluated.
Results In total, 59 studies with participants were included. Conclusions Concurrent training results in small interference for lower-body strength adaptations in males, but not in females. Clinical Trial Registration PROSPERO: CRD Compatibility of Concurrent Aerobic and Strength Training for Skeletal Muscle Size and Function: An Updated Systematic Review and Meta-Analysis Article Open access 10 November Effects of Concurrent Strength and Endurance Training on Measures of Physical Fitness in Healthy Middle-Aged and Older Adults: A Systematic Review with Meta-Analysis Article Open access 12 October Perspectives on Concurrent Strength and Endurance Training in Healthy Adult Females: A Systematic Review Article Open access 10 November Use our pre-submission checklist Avoid common mistakes on your manuscript.
FormalPara Key Points Concurrent training resulted in blunted lower-body strength adaptations in males, but not in females. Full size image. Table 1 Effects of concurrent training are evaluated for the following outcome measures. If multiple measurements exist for the same outcome measure, measurements are analyzed according to the presented hierarchy Full size table.
Table 2 Classification framework to determine strength and endurance training status of male and female participants. Guidelines are adapted from [ 27 , 28 , 29 ] and a full explanation of how training status is derived is provided in the description below Full size table.
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Background: Gender differences in training adaptations adaptationss effects of differemces have been widely investigated; however, Gedner studies have addressed differencss differences Gender differences in training adaptations arteriolar adaptation. In taining current study, we examined the adaptation Fat burn transformation the gracilis arterioles of male and female rats in response to intensive training. Exercise-induced cardiac hypertrophy was confirmed by echocardiography. Following the training, the gracilis muscle arterioles were prepared, and their biomechanical properties and functional reactivity were tested, using pressure arteriography. Collagen and smooth muscle remodeling were observed in the histological sections. Results: Left ventricular mass was elevated in both sexes in response to chronic training. Marcas M. Bamman, Vernishia J. Hill, Gregory Araptations. Adams, Fadia Haddad, Carla J. Wetzstein, Barbara A.Many sports require maximal strength adaptaations endurance performance. Concurrent strength and endurance training can lead Organic suboptimal training adaptations. However, how adaptations differ between males and females Gender differences in training adaptations currently unknown.
Additionally, current training status may affect training Immune system protection supplements. Second, we investigated how dofferences adaptations are influenced by diffeerences and endurance training status.
A systematic review and meta-analysis was Gender differences in training adaptations according to PRISMA Preferred Reporting Items for Systematic Reviews and Meta-Analyses Thermogenic metabolism enhancement, and Gender differences in training adaptations Cochrane risk of bias was evaluated.
A meta-analysis was adaptqtions using a random-effects model and reported adaptatoins standardized mean differences. In total, 59 studies with participants were included. Data on Gejder hypertrophy were insufficient to draw any conclusions. For other outcomes, no differences were found between untrained and trained individuals, both for strength and endurance training status.
Concurrent Nourishing Liver Health results in small interference for lower-body strength adaptations in males, but not in females.
More studies Supplements for improved focus and concentration females and highly strength-trained and endurance-trained athletes are warranted.
Moritz Schumann, Gender differences in training adaptations F. Feuerbacher, … Gendet R. Ritva Adaptatipns. Mikkonen, Johanna K. Ihalainen, … Keijo Häkkinen. Concurrent training differsnces in blunted lower-body strength adaptations in males, Thermogenic supplements for athletes not in females.
For training status, untrained but not trained or highly trained endurance athletes displayed impaired Hormone-Free Meats for maximal oxygen consumption with concurrent training.
Most concurrent training studies include relatively untrained participants, and highly trained athletes are under-represented in the literature. Training status should be considered both in terms of strength and endurance Gnder status and can be evaluated according adaptaions the mentioned classification framework.
When it comes to Dairy-free snacks physical performance, there are difderences sports that exclusively require differendes high maximal strength Gendef a high endurance performance. Instead, many sports demand a combination differencrs a differencces maximal strength and endurance performance [ 12 ].
For this reason, diffreences are encouraged to perform concurrent training, which GGender both strength and endurance within their jn program. Simultaneously adaptationss for teaining and endurance is not without limitations when diffrrences comes to optimizing Gender differences in training adaptations Caloric needs during menopause. First, skeletal muscles of strength- and endurance-trained individuals are specifically trained, focused either difderences increasing muscle size and neuromuscular adaptations or on oxygen delivery and utilization.
However, Benefits of probiotics extremes differrences these two traits are physiologically incompatible, Gender differences in training adaptations, as there is an inverse relationship differennces muscle fiber cross-sectional area Gendef Gender differences in training adaptations oxidative adaptationa [ 3adaptatinosdifferfnces ].
Second, concurrent training potentially leads Garcinia cambogia dosage blunted strength, power, or hypertrophic adaptations compared with strength training alone.
Since then, traoning literature Gender differences in training adaptations concurrent Autophagy and autophagy enhancers has expanded. Maca root and stress relief, an updated meta-analysis [ Gendrr ] concluded that power gains were impaired with concurrent strength and endurance training, but that hypertrophy and maximal Gender differences in training adaptations development were not compromised.
The magnitude of the interference diferences with concurrent training may adaptatiins influenced by inter-individual variations, differences in experimental design, training intervention, and the type of outcome measure.
Many of these potentially contributing factors have differencs analyzed before [ 78910 ]. One Aging well blogs inter-individual factor that has received very little adaptafions in the literature is the ttaining in axaptations responses between males and females.
Sex-related adaptations with concurrent training may occur, owing to differences in differencds and muscle physiology, or physical performance. On average, males have larger diffreences fibers, Gender differences in training adaptations skeletal muscle fifferences, and greater strength [ 111213 ], adaptatikns females adaptayions to have slower contractile properties [ 14 ].
Males tend to have greater improvements in absolute muscle size, strength, adaptatikns power compared with females [ Oral cancer16 ], but females showed larger relative increases adatpations upper-body strength than males [ 17 Gender differences in training adaptations.
Both sexes show similar relative increases in lower-body strength and hypertrophy after strength training. It is therefore conceivable that there may be sex differences in the adaptations to concurrent training.
Another inter-individual Gender differences in training adaptations includes the current training status Plant-based compounds the participant, which may significantly impact the magnitude of the interference effect with concurrent training.
Coffey and Hawley [ 23 ] hypothesized that adaptations are more compromised following concurrent training in subjects with a longer training history, i. However, previous meta-analyses on concurrent training did not find any differences in adaptations between different levels of training status for maximal strength, power, and hypertrophy [ 7910 ], when there was sufficient time digferences recover between strength and endurance training sessions.
It should be noted that training status is generally considered Gendef be one-dimensional: a participant is untrained, trained, or highly trained.
However, this neglects the fact that athletes can optimize for both their strength and endurance capacities. For example, professional marathon runners are highly trained endurance athletes, but relatively untrained for maximal absolute strength.
Importantly, prior meta-analyses on concurrent training did not distinguish between both endurance- and strength-trained status [ 791025 ]. Second, we investigated how adaptations to concurrent training depend on strength and endurance training status. Such a systematic review and meta-analysis not only provides more insight into the concurrent training effects of various populations, but also highlights which populations may be under-represented in the concurrent training literature.
A systematic literature search was conducted according to the PRISMA Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and registered with the International Database of Prospectively Registered Systematic Reviews in Health and Social Care PROSPERO, CRD Only studies from or later were included, which was after the seminal paper on concurrent training by Hickson [ 6 ].
Retrieved titles from the search were saved and both duplicates and review articles were removed using automated tools i.
Titles and abstracts of all remaining studies were screened individually by two reviewers RH and SZ. If the reviewers could not reach consensus, a third reviewer was consulted RW.
The search process and selection of studies are summarized in trainig flowchart in Fig. Flowchart of data search and selection of studies. Studies were included based on the PICO Population, Intervention, Control and Outcomes criteria [ 26 ]. The population included healthy male and female adults aged between 18 and 50 years.
For maximal strength, one-repetition maximum 1-RM and isometric measurements of lower and upper extremities were considered. For power, jump tests and dynamic power tests e.
For muscle hypertrophy, muscle thickness or whole-muscle cross-sectional area was measured objectively using ultrasound, magnetic resonance imaging, or computed tomography.
Studies were excluded if participants experienced injuries or an illness or if they used ergogenic aids or other sport-enhancing supplements except for proteins and vitamins.
To classify training status within concurrent training studies, it is important to note that the training status of participants is not one-dimensional, but can be interpreted both in terms of strength and endurance training status.
Training status is typically divided into three categories corresponding to untrained, trained, and highly trained athletes [ 3031 ]. In this meta-analysis, participants were characterized according to their combination of strength and endurance training status.
Strength training status [ 27 ] was grouped into untrained, trained i. The classification framework to determine strength and endurance training status of participants is presented in Table 2 adapted from [ 272829 ].
To obtain the training status classification, scores were derived for each physiological performance, training, or technique indicator if present and were daaptations averaged and rounded.
For strength training status, all strength performance indicators were grouped and counted as one score [ 27 ]. Using this unified classification system, participant groups can be classified for both their strength and endurance training status in order to determine how effects of concurrent training are dependent on training status.
Two reviewers independently evaluated the full-text articles using a standardized predefined form RH and SZ. Articles were examined by a third reviewer if consensus was not reached RW. If data on group mean and standard deviation were not presented in the text or tables, then baseline and post-intervention data were requested ttaining the cifferences authors or obtained from figures if present using WebPlotDigitizer version 4.
Methodological quality of identified studies was assessed independently by two reviewers RH and RW using the Cochrane risk-of-bias evaluation [ 3334 ], and consensus was reached after consultation.
Reviewers assessed all studies for the risk of selection bias sequence generation, allocation concealmentdetection bias blinding of outcome assessmentattrition bias incomplete outcome datareporting bias selective reportingand other biases.
Biases were classified for each item as low, high, or unclear risk i. Adapgations biases were assessed one by one according to the recommendation of the Cochrane Bias Methods Group and Statistical Methods Group [ 33 ].
Results for maximal strength were subdivided into lower-body and upper-body strength. In accordance with Cochrane recommendations [ 33 ], if studies presented multiple methods for the same outcome e. a jump test and Wingate test for poweronly one of these was included in the analysis according to the hierarchy presented in Table 1.
This was trsining avoid inclusion of intervention effects that were statistically dependent in the analysis, as these were calculated from the same participants.
For example, the hierarchy dictates evaluation of lower-body strength using 1-RM maximal strength during leg press which is technically easier to execute over the squat and evaluation of power using countermovement or squat jumps which are more readily available over Wingate peak power.
Studies or intervention groups were excluded from the analysis if significant baseline differences were observed trsining the specific outcome measure between the concurrent training and control group or if only percentage changes were reported.
A random-effect model [ 36 ] was adopted and presented in forest plots, and records were weighted according to the inverse variance method for each outcome measure. Heterogeneity was calculated using the Q -test and expressed in terms of Chi 2 and the I 2 statistic.
I 2 describes the percentage of the variability that is attributable to heterogeneity rather adaptatkons chance [ 37 ]. Subgroup analyses were performed to compare concurrent training effects between 1 male and female participants; 2 untrained, trained, and highly trained levels of strength training status; and 3 untrained, trained, and highly trained levels of endurance training status.
The meta-analysis was conducted using Review Manager RevMan software Version 5. A significance level α of 0. The database search resulted in a total of 24, articles.
After automatic removal of the duplicates, removal of review articles, and screening of the remaining titles and abstracts, articles remained. Table S4 of the ESM summarizes teaining relevant characteristics of the studies, participants, and training interventions.
The meta-analysis differehces participants, of whom performed concurrent training, performed strength training only, and performed endurance training only. Training status of the participants using Table 2 was determined for strength training status 38 studiesendurance training status 56 studiesand both strength and endurance training status 36 studies.
Overview of the training status of the participants adaprations the included studies. Number of studies are reported in which levels of training status could be assessed for A strength, B endurance, and C both strength and endurance.
Quantification of traniing status was performed according to the guidelines in Table 2. The overall assessment for the risk of bias is presented in Fig. S17 of the ESM. The analysis of lower-body strength included 20 studies [ 43454748656871758285899193949596, ], with participants that performed concurrent training and participants that performed strength training only.
These results highlight a small interference effect for lower-body strength with concurrent training in males, but not in females.
: Gender differences in training adaptations| Metabolism | The first hypothesis that all age cohort would improve in maximal strength was confirmed. The second hypothesis that an increase in maximal strength would not be different between males and females was also confirmed. The third hypothesis that young would improve more than old was rejected. The fourth hypothesis that improvement in maximal strength would not be affected by the selected polymorphisms was only partly confirmed. C allele carriers for the PPARGC1A GlySer rs improved 1RM more than those with the TT genotype. At baseline, T allele carriers had higher 1RMcorr compared to those with the CC genotype. The results from the present study show the same results in maximal strength adaptations as previously found in VO 2 max adaptations in Storen et al. Although middle-aged and old had lower baseline values in these two studies, the relative improvements were just as good in untrained and moderately trained at older ages. To our knowledge, this is the first study to report similar training responses in all age groups from young adults in their twenties and thirties via middle-aged in their forties and fifties and up to older adults in their sixties and seventies. That MST was an effective method to improve maximal strength was in the present study shown by no non-responders to the MST program, with the smallest improvement being 7. Furthermore, the improvements in maximal strength were rather homogenous, with a coefficient of variance of 8. As expected, 1RM kg decreased with advancing age at baseline Table 2. The 1. The results show a 1. This corresponds well with the findings of Petrella et al. Individuals with PPARGC1A GlySer rs CC genotype had lower 1RMcorr at baseline compared to both CT genotype counterparts and T-allele carriers. Interestingly, when comparing the genotype frequencies for the rs between the present cohort and a highly trained Scandinavian cross-country athlete cohort Johansen et al. These findings are in line with previous studies Ahmetov and Fedotovskaya, The rs polymorphism has been associated with differences in PPARGC1A mRNA expression, with lower expression among carriers of T allele Vandenbeek et al. Gene expression responses may be important for muscle adaptations in response to different modes of exercise Silvennoinen et al. The oldest group improved 1RM to the same extent as the mean of the other four age groups. The present results are in line with some studies comparing young and old, like Hakkinen et al. That males and females improved relative 1RM to the same extent was as expected, and in line with previous studies. In light of this, it was somewhat surprising that initial baseline strength status did not significantly affect 1RM improvements. In a previous study on VO 2 max adaptations to endurance training in different age groups Storen et al. This should also be expected in MST interventions, as untrained and trained in previous studies have shown rapid improvements in neural adaptations during the first 2—4 weeks of this type of training Hakkinen et al. Bodyweight did not change in the present study, and this may support the assumption that it is predominately the neural adaptions and changes in recruitment patterns, which have led to increased 1RM. However, any change in body composition cannot be excluded in the present study and this is in line several other studies Lemmer et al. Carriers of the PPARGC1A GlySer rs T allele had higher baseline 1RMcorr compared to the CC genotype. On the other hand, C allele carriers, possessing lower 1RMcorr at baseline, demonstrated larger improvements in 1RM compared to the TT genotype in the present study. These differences could theoretically be attributable to a larger potential for improvements, due to lower muscle strength at baseline in C allele carriers. However, baseline 1RM and improvements in 1RM did not correlate in the present study. Resistance training has been shown to induce expression of an isoform of the protein coded by the PPARGC1A gene i. The polymorphism is known to influence mRNA expression Vandenbeek et al. Of these, especially the ACTN3 RX rs polymorphism has been shown to have a range of effects on various muscle phenotypes, such as improvements in strength or muscle function Pickering and Kiely, , ; Del Coso et al. Previous studies indicate that the R allele may be advantageous for an increased maximal dynamic strength Delmonico et al. Of the 76 participants initially recruited, 49 subjects completed the study and 27 did not. From the 27 drop-outs, 18 did not meet the inclusion criteria for adherence due to reasons not related to the intervention itself, while nine individuals — due to reasons related to the intervention. It was chosen to rather take subjects out to early from the study than to risk any injury, and this had an impact on the nine study-related drop-outs. It is important to note that the drop-out rates did not differ between the age groups and appears to be in line with previous studies MST Wang et al. To date, there are few, if any, studies investigating the effects of PPARGC1A GlySer rs on maximal strength in healthy adults. Genotype frequencies of the ACTN3 and the ACE polymorphisms in both studies were similar indicating that the participants in the present study were representative for the population in this region, regarding these polymorphisms. The present study is based on a sample size that is typical for a training intervention study. However, in terms of candidate gene studies, the sample size is small. A low number of participants in genetic association studies investigating complex traits tend to be vulnerable to type II error Hong and Park, Therefore, the effect size of these relationships was also reported in the present study. The indications of greater response to resistance training in R allele carriers are thus in line with the overall impression from studies on resistance training Seto et al. To compensate for the relatively low sample size, an ethnically homogenous study cohort was investigated. The presented study has several limitations. However, the present study has also several strengths. This combination is the main novelty of the present study. The present results demonstrated that MST is effective in improving maximal strength in most healthy people capable of performing MST. There were no differences in drop out between the age groups, and the dropout rate may be considered to be in line with previous MST studies such as Wang et al. Improved muscle strength has been shown to better general motor function, maintain or increase functional movement, balance, independence, and quality of life Fiatarone et al. We, therefore, recommend MST 2—3 times per week in leg-press, squats or deadlift at all ages to delay the age-related decline in muscle strength and health. However, cautions should be taken as some may experience muscle or joint pain from this kind of exercise. To our knowledge, this is the first study to report improvements in leg-press maximal strength regardless of gender, baseline strength, and age. Improvements in MST were found in all age groups from young adults in their twenties and thirties via middle-aged in their forties and fifties and up to older adults in their sixties and seventies. Of the investigated candidate polymorphisms, only PPARGC1A GlySer rs demonstrated a significant effect on the baseline maximal strength and its trainability in a moderately trained cohort. This is the first study to demonstrate this association in such a cohort. Yet, the effect of this single genetic variant is likely minimal. These findings imply that most healthy individuals have great potential for maximal strength improvements and that MST may be used as a strategy for healthy aging. The datasets presented in this article are not readily available due to the Norwegian Legislation regarding the publication of genetic data. Requests to access the datasets should be directed to the corresponding author. HK, SG-F, ØS, MS, IN, and EW participated significantly in the planning and designing of the study, as well as the data analyzing and the writing of the manuscript. HK, SG-F, ØS, MS, IN, ES, SB-S, and BF participated in the data collection. 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Other exercises included elbow flexion, elbow extension, wide grip pull-down, seated row, chest press, overhead press, back extension, bent knee sit-up, and knee flexion. With the exception of sit-ups two sets of 15—25 repetitions , subjects completed two sets of each exercise with 2-minute rest periods between sets and a target of 10 repetitions. Although all subjects performed knee extensions, men and women were randomly assigned to perform the squat or leg press such that no gender bias occurred. In this subset of 14 participants, 8 of the subjects 5 men and 3 women performed squats and 6 of the subjects 4 men and 2 women performed leg presses. After two familiarization sessions, subjects were tested for knee extension, squat, and leg press 1RM by using methods we have previously described Total body fat mass and fat-free mass were determined by densitometry, using air displacement plethysmography Bod Pod version 1. Each subject wore the same fitted swimwear for body volume measurements before and after training. The methods used have been detailed previously and validated in our laboratory against hydrostatic weighing, dual-energy x-ray absorptiometry, and the four-compartment model 41— vastus lateralis of the left leg by percutaneous needle biopsy, using a 5-mm Bergstrom biopsy needle under suction as previously described The posttraining biopsy was taken approximately 2 cm proximal to the pretraining incision site. Samples for histochemistry were mounted on cork with Tissue-Tek O. mounting medium Miles Inc. A portion of each sample was snap frozen in liquid nitrogen used for mRNA analysis. The muscle biopsy procedure was added to the menu of tests for a larger study 41 as the project began. As a result, subjects consented to muscle biopsy as a voluntary additional procedure yielding a subset of participants. Because of scheduling difficulties with numerous required tests after training, biopsies after training were collected an average of 4 days after the final training bout but the precise time point was not consistent range 2—7 days. Although this variability should not have affected myofiber size measurements, we certainly recognize the limitation this poses on interpreting our posttraining muscle gene expression results. Pretraining and posttraining samples within subjects were analyzed concurrently to standardize staining conditions. Myofibers were classified as type I, IIa, or IIx by metachromatic dye—adenosine triphosphatase histochemistry, using methods described previously 45 , and they were modified in our laboratory Metachromasia was revealed by 0. Type I myofibers stained dark turquoise blue, whereas type II myofibers spanned a color spectrum from pale type IIa to violet type IIx. Microscope Olympus BX, Melville, NY views were captured by a color digital video camera Olympus DP Myofiber CSA and area distribution by type were determined by using Mocha Jandel Scientific, San Rafael, CA image analysis software, as we have detailed elsewhere To determine the distribution of MHC isoforms I, IIa, IIx , 10 microtome sections 20 μm were homogenized and the myofibrillar protein fraction was isolated and assayed for total protein as we have previously described Two micrograms of myofibrillar protein 0. Run conditions were V for 20 hours. We have previously confirmed band order by Western analysis Pretraining and posttraining samples within subjects were run in adjacent lanes to standardize run conditions. Tissue samples were analyzed for IGF-1, IGFR1, and myogenin mRNAs. Total RNA was extracted from frozen muscle samples by using the TRI Reagent Molecular Research Center, Cincinnati, OH according to the company's protocol. Extracted RNA was precipitated from the aqueous phase with isopropanol and, after being washed with ethanol, dried and suspended in a known volume of nuclease free water. A relative RT-PCR method using 18S as internal standard Ambion, Austin, TX was applied to study the mRNA expression of IGF-1, IGFR1, and myogenin. In each reaction, 18S ribosomal RNA was coamplified with the target cDNA mRNA to serve as an internal standard and to allow correction for differences in starting amounts of total RNA. For the 18S we used either the Classic or the Alternate 18S Internal Standards Ambion , which yield base pairs, or base pairs, respectively. The 18S competimers—primers were mixed at an optimized ratio specific for each target mRNA, and this ratio was for IGF-1, for IGF-1 receptor, and for myogenin. For each primer set, PCR conditions were optimized so that both the target mRNA and 18S product yields were in the linear range of the semilog plot when the yield is expressed as a function of the number of cycles. For each specific target mRNA, the RT and PCR reactions were carried out under identical conditions, using the same reagents premix for all the samples to be compared in the study. One microliter of each RT reaction was used for the PCR amplification. The PCR reactions were carried out in the presence of 2mM MgCl 2 , using standard PCR buffer Gibco , 0. Amplifications were carried out in a Stratagene Robocycler with an initial denaturing step of 3 minutes at 96°C, followed by 25 cycles of 1 minute at 96°C, 1 minute at 58°C, 1 minute at 72°C, and a final step of 3 minutes at 72°C. With the use of this method, each specific mRNA signal was normalized to its corresponding 18S. Representative results are shown in Figure 1. Total IGF-1, testosterone, and DHEA-S were determined in fasted morning serum samples withdrawn before and after 26 weeks of PRT. Samples within subjects for a given hormone were assayed in random order during a single run. Data are reported as mean ± SE. Gender differences in descriptive variables were tested by independent t tests. For all variables measured before and after training, main training and gender effects and Gender × Training interactions were tested by 2 × 2 repeated measures analysis of variance ANOVA. For each ANOVA model with a significant Gender × Training interaction, analysis of covariance ANCOVA models were tested post hoc by using as covariate each of several factors potentially influential in muscle growth, namely pretraining, average, and before-to-after change scores in serum IGF-1 or DHEA-S, or muscle mRNAs for IGF-1, IGFR1, or myogenin. Serum TT could not be used as a covariate as it was not a continuous variable. Zero-order correlations were tested between before-to-after changes in myofiber size or strength and changes in serum hormones or muscle myogenic transcripts. Correlations were also tested among the serum and muscle factors measured. For each exercise, 1RM was evaluated every 25 days. As the knee extension exercise is a single joint movement recruiting the quadriceps site of muscle biopsy independent of the hip extensors, we evaluated knee extension 1RM results in serial fashion for this report. Eight serial 1RM evaluations were performed over the duration of the training period. We tested gender and training effects by 2 × 8 repeated measures ANOVA. As a way to adjust for gender differences in absolute strength, 1RM data were analyzed as the ratio of 1RM at a given time point to the corresponding pretraining value. Time-point-specific strength increases within gender were evaluated post hoc by using the least squares difference LSD test. Descriptive characteristics are shown in Table 1. Gender comparisons revealed no significant differences in age or bodyweight. For both men and women, the whole-body PRT program resulted in increased FFM men 2. No Gender × Training interaction was noted for FFM or body fat percentage. Myofiber CSA results are shown in Table 2. To assess the presence of type II myofiber atrophy, we compared pretraining data from these older subjects to myofiber sizes we previously published in premenopausal women 47 and young men In these older subjects, the preferential type II myofiber atrophy typically associated with sarcopenia of aging was found in pretraining data from both genders, and it was most notable in type IIx myofibers. In contrast, the sizes of type I and type II myofibers were not significantly different in the younger subjects from our prior work. Clearly, the significant training effect in the ANOVA model for each fiber type was driven by the men. Analyses of relative hypertrophy between genders t tests on percent change scores indicated greater relative hypertrophy among men for type IIa myofibers only. Changes in myofiber type area and MHC distribution are presented in Table 2. No gender differences or Gender × Training interactions were found for any of these variables. Table 3 displays pretraining and posttraining levels of selected serum hormones and muscle gene transcripts thought to be potentially important in muscle growth. Training did not affect any of the hormone levels. Muscle expression of IGF-1 and myogenin mRNA did not differ by gender and was not influenced by training although an acute response to PRT cannot be ruled out because we obtained biopsies 4 days after PRT on average. Zero-order correlations were tested among serum hormones and muscle gene transcript levels not including TT, as it was not a continuous variable. Serum levels of IGF-1 and DHEA-S were not related before or after training. No significant relationships were noted between serum IGF-1 and muscle IGF-1 or IGFR1 mRNAs before or after training. Muscle transcript levels of IGF-1 and IGFR1 were not correlated. IGF-1 and myogenin transcript levels were not related before or after PRT. The substantial variability in myofiber hypertrophy between genders could not be explained by any of the serum or muscle factors, as no significant correlations were found between before—after difference scores in myofiber size and before—after difference scores in serum IGF-1, DHEA-S, or muscle IGF-1, IGFR1, or myogenin mRNA. Further, Gender × Training interactions for myofiber hypertrophy remained in post hoc ANCOVA analyses covarying with before—after difference scores for each serum hormone or muscle gene transcript. The sizes of myofiber types I, IIa, and IIx prior to training did not correlate with pretraining levels of any of these factors. Overall, these findings indicate the gender differences in initial fiber size and in PRT-induced myofiber hypertrophy could not be attributed to varying levels of circulating IGF-1 or DHEA-S, nor to expression of the myogenic gene transcripts studied. Results of serial 1RM knee extension tests are shown in Figure 2. Both genders increased strength substantially. The values displayed in Figure 2 are relative to pretraining 1RM and reveal gender differences in strength development across the week period of PRT. Following an initial early rise in 1RM for both genders Day 25 , relative strength gains among women were blunted compared with men. For example, 1RM for women did not significantly exceed the Day value until Day , whereas 1RM strength increased from Day 25 to Day 50 in men and steadily climbed thereafter. In this study we have demonstrated that the myofiber hypertrophic response to the same PRT program is greater in older men than in older women. In their study of single myofibers, Trappe and colleagues 18 reported no Gender × Training interactions when comparing increases in myofiber diameter; however, the relative increase in type IIa myofiber diameter among men was significant whereas no change was noted in women. Further, single myofibers from men exhibited significantly greater improvements in maximum shortening velocity and power. Tracy and associates 17 and Ivey and associates 16 tested for Gender × Training interactions by using muscle volume determined by magnetic resonance imaging as the measure of muscle size. Both groups report a significant interaction for quadriceps hypertrophy after 9 weeks of PRT in older adults, with men exhibiting greater gains. Ivey and colleagues 16 found that the gender difference remained after they adjusted for pretraining muscle volume. These data combined suggest an important gender difference in the hypertrophic response to 3 days per week PRT among older adults. At odds with these data, Hakkinen and associates 4 found substantial gains in myofiber size in older women following a strength—power training program performed 2 days per week, suggesting that older women may benefit from reduced frequency PRT and a combination of heavier and lighter loads. These findings suggest the typical 3 days per week PRT program may not be the best model for older women. In this report we attempted to explain the gender difference by covarying for a number of potential modulators of myofiber size. However, none of our targeted covariates influenced the gender differences or Gender × Training interactions. Serum IGF-1 is positively related to rates of muscle protein synthesis and has been measured extensively in recent studies of sarcopenia IGF-1 is known to decline with age and is related to the decline in lean mass in cross-sectional studies across a wide age spectrum 33 , In this study of load-induced hypertrophy, however, covarying for serum IGF-1 did not alter the influence of gender on either initial myofiber size or the magnitude of hypertrophy following PRT. Additionally, zero-order correlations tested across both genders showed no significant relationships between serum IGF-1 and absolute or relative changes in myofiber size. Others have shown that elevating serum IGF-1 by means of exogenous growth hormone treatment does not enhance the hypertrophic effects of PRT in older men 50 , and PRT alone does not alter serum IGF-1 levels The importance of circulating IGF-1 in load-mediated local skeletal muscle hypertrophy has been questioned 52 and, in our group of older adults, serum IGF-1 appeared to have no influence. Similarly, serum levels of DHEA-S did not influence the hypertrophic response in this study. DHEA-S treatment has previously been shown to increase serum IGF-1 in older men and women 53 , and declining levels of both DHEA-S and IGF-1 correlate with lower levels of muscle power in older women We found no relationships between DHEA-S and initial myofiber size nor between DHEA-S and the magnitude of myofiber hypertrophy in men and women, despite twofold greater DHEA-S levels in men not statistically significant. Testosterone has been shown to influence the hypertrophic response to PRT. Bhasin and colleagues report greater PRT-induced hypertrophy with supraphysiologic doses of testosterone in young men Although the present data and that of others 5 , 35 , 56 indicate that PRT alone does not alter resting serum concentrations of testosterone, there is limited evidence suggesting endogenous testosterone levels are related to the magnitude of PRT-induced hypertrophy in older women 24 and strength gain in men 5 , 35 and women 5. Additionally, testosterone treatment in female rats has been shown to induce satellite cell proliferation 57 , considered by many to be a requisite process during myofiber hypertrophy. When we tested zero-order correlations in our group of 9 eugonadal older men with fairly homogeneous TT levels, we found no significant relationships between endogenous TT and absolute or relative changes in myofiber size or 1RM strength. Despite this, it remains entirely possible that the markedly higher endogenous levels of TT in the men compared with the women might have potentiated hypertrophy by some as yet unknown mechanism, as we report average TT levels fold greater in men. The bimodal nature of TT levels in these two gender groups, however, precluded the application of TT as a covariate, and therefore the present study design cannot provide any conclusive evidence regarding the importance of endogenous testosterone in load-mediated hypertrophy. The marked gender difference in TT levels is certainly not unique to older adults, and data on gender differences in PRT-induced hypertrophy among younger and middle-aged adults are equivocal. For example, Staron and associates 58 reported myofiber hypertrophy results after 20 weeks of PRT in young women of similar magnitude to those reported by others in men, whereas Ivey and associates found a significant gender effect with greater hypertrophy in men in a sample of both young and older men and women It is therefore not clear whether endogenous testosterone levels play a pivotal role in PRT-induced hypertrophy. Resistance training studies that compare eugonadal to untreated hypogonadal men would perhaps shed some light on this question. The role of locally expressed IGF-1 in muscle hypertrophy and satellite cell activation has received significant attention as of late 25 , 59 , Additionally, there is evidence that high resting levels of muscle IGF-1 expression may play a role in preventing age-related sarcopenia Myogenin appears to be an important modulator of myogenesis, as its expression increases during both myoblast differentiation 61 and overload-induced myofiber hypertrophy 25 , Hespel and colleagues 30 have recently reported increased myogenin protein expression during resistance-training-induced hypertrophy in humans. Myogenin activity is thought to be at least partially mediated by IGF-1, as recent evidence indicates myogenin gene expression is increased during IGF-1 stimulated myoblast differentiation For these reasons we determined if expression of these transcripts, as well as expression of IGFR1, was different between genders before training or could account for gender effects on hypertrophy. A gender difference in basal muscle IGF-1 mRNA expression might be expected, because increasing testosterone levels have been associated with increased IGF-1 mRNA levels in skeletal muscle However, there were no gender differences in pretraining levels, and neither IGF-1 nor myogenin expression changed after PRT. As a result, neither one demonstrated utility as a covariate. Certainly PRT-induced strength accrual is multifactorial and is only partially mediated by myofiber hypertrophy. The limited hypertrophy found in women suggests that the primary adaptation leading to enhanced strength was neurologically mediated. Neural adaptations occur during the early weeks of a PRT program and thus are thought to account for the early rapid increases in strength It is noteworthy that the women experienced an early rise in strength similar to men see Figure 2. Thereafter, strength gains tapered in women with the next significant rise not occurring until Day , whereas 1RM strength in the men rose fairly consistently across the 26 weeks. Consistent with data from other laboratories 65 , we found no significant correlation between changes in myofiber size and changes in strength, indicating large individual variability in the amount of strength gain attributable to hypertrophy versus neural adaptations. Our results demonstrate that the training regimen was sufficient to induce in both genders the reduction in MHCIIx distribution characteristic of resistance training programs 38 , Although the mechanism s responsible for this shift in myosin phenotype are not known, it precedes measurable hypertrophy during resistance training 38 , and it is noted with no significant myofiber hypertrophy during endurance and sprint training 66 , On the basis of these data, it is not surprising to find MHCIIx downregulation in women in the current study despite blunted hypertrophy , as the load-mediated molecular signals regulating myosin phenotype obviously differ from those regulating the net rate of myofibrillar protein synthesis. In conclusion, we found marked gender differences in both absolute and relative myofiber hypertrophy and strength accrual following identical PRT programs in the older men and women studied. Although the muscles of both men and women demonstrated similar MHC plasticity with a reduction in MHCIIx distribution, men exhibited superior myofiber hypertrophy and strength gain. Future studies should determine whether acute responses to a single resistance exercise bout e. Such findings may aid in unraveling the apparent gender influence on myofiber hypertrophy in older adults. Additionally, the potential role of endogenous testosterone levels should be carefully considered. Decision Editor: James R. Smith, PhD. Product size in base pairs bp is shown to the left. Laser scanning densitometry revealed no gender or training effects. Knee extension one-repetition maximum 1RM results across time for men and women relative to pretraining 1RM. For each time point, 1RM—pretraining 1RM was computed; a—e: significantly different from a, pretraining Day 0 ; b, Day 25; c, Day 50; d, Day 75; e, Day Notes : Values are mean ± SE. Grant support for this work was provided by the University of Alabama at Birmingham Center for Aging, the Ralph L. Smith Foundation, R01 AR G. Adams , and R01 AG M. We thank the subjects for their tireless effort and dedication. We thank Angi Qin for technical assistance. Address correspondence to Marcas M. E-mail: mbamman uab. Hikida RS, Staron RS, Hagerman FC, et al. Effects of high-intensity resistance training on untrained older men. Muscle fiber characteristics and nucleocytoplasmic relationships. J Gerontol Biol Sci. Jozsi AC, Campbell WW, Joseph L, Davey SL, Evans WJ. Changes in power with resistance training in older and younger men and women. Kraemer WJ, Hakkinen K, Newton RU, et al. Effects of heavy-resistance training on hormonal response patterns in younger vs. older men. J Appl Physiol. Hakkinen K, Kraemer WJ, Newton RU, Alen M. Acta Physiol Scand. Hakkinen K, Pakarinen A. Serum hormones and strength development during strength training in middle-aged and elderly males and females. Hunter G, Treuth M, Weinsier R. The effects of strength conditioning on older women's ability to perform daily tasks. J Am Geriatr Soc. Hepple RT, Mackinnon SLM, Thomas SG, Goodman JM, Plyley MJ. Quantitating the capillary supply and the response to resistance training in older men. Pflugers Arch—Eur J Physiol. Pyka G, Lindenberger E, Charette S, Marcus R. Muscle strength and fiber adaptations to a year-long resistance training program in elderly men and women. J Gerontol Med Sci. Taaffe DR, Marcus R. Dynamic muscle strength alterations to detraining and retraining in elderly men. Clin Physiol. Hakkinen K, Kallinen M, Linnamo V, Pastinen UM, Newton RU, Kraemer WJ. Neuromuscular adaptations during bilateral versus unilateral strength training in middle-aged and elderly men and women. Hurley B, Redmond R, Pratley R, Treuth M, Rogers M, Goldberg A. Effects of strength training on muscle hypertrophy and muscle cell disruption in older men. Int J Sports Med. Yarasheski KE, Pak-Loduca J, Hasten DL, Obert KA, Brown MB, Sinacore DR. Am J Physiol Endocrinol Metab. Fiatarone MA, Marks EC, Ryan ND, Meredith CN, Lipsitz LA, Evans WJ. High-intensity strength training in nonagenarians. Effects on skeletal muscle. Harridge SD, Kryger A, Stensgaard A. Knee extensor strength, activation, and size in very elderly people following strength training. Muscle Nerve. Singh MA, Ding W, Manfredi TJ, et al. Insulin-like growth factor I in skeletal muscle after weight-lifting exercise in frail elders. Ivey FM, Roth SM, Ferrell RE, et al. Effects of age, gender, and myostatin genotype on the hypertrophic response to heavy resistance strength training. Tracy BL, Ivey FM, Hurlbut D, et al. Muscle quality. Effects of strength training in to yr-old men and women. Trappe S, Godard M, Gallagher P, Carroll C, Rowden G, Porter D. Resistance training improves single muscle fiber contractile function in older women. Am J Physiol Cell Physiol. Trappe S, Williamson D, Godard M, Porter D, Rowden G, Costill D. Effect of resistance training on single muscle fiber contractile function in older men. Frontera WR, Meredith CN, O'Reilly KP, Knuttgen HG, Evans WJ. Strength conditioning in older men: skeletal muscle hypertrophy and improved function. Larsson L. Physical training effects on muscle morphology in sedentary males at different ages. Med Sci Sports Exerc. Charette SL, McEvoy L, Pyka G, et al. Muscle hypertrophy response to resistance training in older women. Taaffe DR, Pruitt L, Pyka G, Guido D, Marcus R. Comparative effects of high- and low-intensity resistance training on thigh muscle strength, fiber area, and tissue composition in elderly women. Hakkinen K, Pakarinen A, Kraemer WJ, Hakkinen A, Valkeinen H, Alen M. Selective muscle hypertrophy, changes in EMG and force, and serum hormones during strength training in older women. Adams GR, Haddad F, Baldwin KM. Time course of changes in markers of myogenesis in overloaded rat skeletal muscles. Bamman MM, Shipp JR, Jiang J, et al. Mechanical load increases muscle IGF-I and androgen receptor mRNA concentrations in humans. Dupont-Versteegden EE, Houle JD, Gurley CM, Peterson CA. Early changes in muscle fiber size and gene expression in response to spinal cord transection and exercise. Mozdziak PE, Greaser ML, Schultz E. Myogenin, MyoD, and myosin expression after pharmacologically and surgically induced hypertrophy. Hughes SM, Taylor JM, Tapscott SJ, Gurley CM, Carter WJ, Peterson CA. Selective accumulation of MyoD and myogenin mRNAs in fast and slow adult skeletal muscle is controlled by innervation and hormones. Hespel P, Eijnde BO, Van Leemputte M, et al. |
| References | Lee MJ-C, Teaining JK, Axaptations J, Gender differences in training adaptations WG, Fyfe JJ, Phillips Differences, et al. Gender differences in training adaptations data combined suggest an Gender differences in training adaptations Metabolism and nutrient partitioning difference in the hypertrophic response to 3 days per week PRT among older adults. Development of maximal dynamic strength during concurrent resistance and endurance training in untrained, moderately trained, and trained individuals: a systematic review and meta-analysis. Nader GA. Miller AE, MacDougall JD, Tarnopolsky MA, Sale DG. Appl Physiol Nutr Metab. |
| The Role of Estrogen | Adsptations Foundation, R01 AR G. Hypertension ; Moreau, K. alpha-actinin-3 and performance. Konopka AR, Harber MP. Skeletal muscle myosin heavy chain composition and resistance training. |
| Introduction | Adaptaations 57, 56— Adding strength to endurance training does Cifferences enhance aerobic capacity in cyclists. young men and women. The first hypothesis that all age cohort would improve in maximal strength was confirmed. Effect of resistance, endurance, and concurrent training on TNF-α, IL-6, and CRP. |
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