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This study examined the accuracy of predicting a free-weight back squat and a bench press one-repetition maximum (1RM) using both 2- and 4-point submaximal average concentric velocity (ACV) methods. Seventeen resistance trained men performed a warm-up and a 1RM test on the squat and bench press with ACV assessed on all repetitions. The ACVs during the warm-up closest to 1.0 and 0.5m.s-1 were used in the 2-point linear regression forecast of the 1RM and the ACVs established at loads closest to 20, 50, 70, and 80% of the 1RM were used in the 4-point 1RM prediction. Repeated measures ANOVA and Bland-Altman and Mountain plots were used to analyze agreement between predicted and actual 1RMs. ANOVA indicated significant differences between the predicted and the actual 1RM for both the 2- and 4-point equations in both exercises (p

Haischer, MH, Cooke, DM, Carzoli, JP, Johnson, TK, Shipherd, AM, Zoeller, RF, Whitehurst, M, and Zourdos, MC. Impact of cognitive measures and sleep on acute squat strength performance and perceptual responses among well-trained men and women. J Strength Cond Res 35(2S): S16-S22, 2021-This study assessed the efficacy of currently used assessments for sleep, anxiety, and stress in predicting 1-repetition maximum (1RM) back squat performance. Fifty-three men (age, 23 ± 3 years; body mass, 86.67 ± 13.93 kg; training age, 6.0 ± 2.5 years; 1RM = 163.5 ± 39.5 kg) and 15 women (age, 21 ± 1.5 years; body mass, 63.34 ± 9.6 kg; training age, 4 ± 1.5 years; 1RM = 81.5 ± 12.5 kg) participated. Subjects completed the Daily Analysis of Life Demands for Athletes (DALDA), the revised Competitive State Anxiety Inventory-2 (CSAI-2R), and Oviedo Sleep Questionnaire (OSQ) to evaluate stress, anxiety, and sleep, respectively. Subjects then completed the perceived self-efficacy (PSE) scale, to predict what loads they were 100, 75, and 50% confident that they could lift for a 1RM; then completed 1RM testing with rating of perceived exertion (RPE) and average concentric velocity (ACV) obtained on each attempt. The performance-dependent variable was calculated by subtracting the PSE responses from the actual 1RM (1RM-PSE difference). Bootstrapping with 1,000 replicate samples was used with linear regression to increased robustness of the statistical analyses, and 95% confidence intervals (CIs) were calculated. Hours of sleep was an inverse predictor of ACV (p = 0.014; 95% CI = 0.046 to-0.011) and a positive predictor of RPE (p = 0.005; 95% CI = 0.068-0.342). Furthermore, the hypersomnia subscale of the OSQ was a negative predictor of 1RM-PSE difference at 50% confidence (p = 0.028; 95% CI = -3.507 to -0.528), and CSAI-2R total score was a negative predictor of RPE at 1RM (p = 0.043; 95% CI = -0.041 to -0.003); however, the DALDA did not exhibit any significant relationships. These data highlight the importance of monitoring anxiety and sleep when assessing readiness for maximal strength performance.

This study examined the time course of recovery following resistance exercise sessions in the back squat, bench press, and deadlift. Twelve well-trained males (age: 24.5 ± 3.8 years, body mass: 84.01 ± 15.44 kg, training age: 7.1 ± 4.2 years) performed 4 sets to failure at 80% of a 1-repetition maximum (1RM) on the squat, bench press, and deadlift in successive weeks. The bench press was always performed in week 2 with the squat and deadlift order counterbalanced between weeks 1 and 3. Indirect muscle damage and performance fatigue was assessed immediately before and after exercise and at 24 h, 48 h, 72 h, and 96 h postexercise. Outcome measures included limb swelling, joint range of motion, delayed onset muscle soreness, average concentric velocity (ACV) at 70% of 1RM, creatine kinase, lactate dehydrogenase, and cell-free DNA (cfDNA). Most measures demonstrated a main time effect (p < 0.05) within conditions; however, no between condition (p > 0.05) differences existed. ACV decreased in the squat condition for up to 72 h (p = 0.02, –8.61%) and in the bench press (p < 0.01, –26.69%) immediately postexercise but did not decline during the deadlift condition (p > 0.05). There was a main time effect for increased cfDNA in the squat (p < 0.01) and bench press (p < 0.05), but not the deadlift (p = 0.153). Further, immediately postexercise increases in cfDNA were directly related (p < 0.05) to changes in ACV in all 3 conditions. These results suggest that the deadlift does not result in greater muscle damage and recovery time than the squat and bench press following volume-type training in well-trained men. Further, acute changes in cfDNA may predict performance during the recovery period.

Purpose: To examine the validity of 2 linear position transducers, the Tendo Weightlifting Analyzer System (TWAS) and Open Barbell System (OBS), compared with a criterion device, the Optotrak Certus 3-dimensional motion-capture system (OC3D). Methods: A total of 25 men (age, 25 [3] y; height, 174.0 [6.7] cm; body mass, 89.0 [14.7] kg; squat 1-repetition maximum [1RM], 175.8 [34.7] kg) with ≥2 y of resistance-training experience completed a back 1RM and 1 set to failure at 70% of 1RM. Average concentric velocity (ACV) and peak concentric velocity (PCV) were recorded by all 3 devices during the final warm-up set, all 1RM attempts, and every repetition during the 70% set. Results: In total, 575 samples were obtained. Bland–Altman plots, mountain plots, a 1-way analysis of variance, SEM, and intraclass correlation coefficients were used to analyze validity. The analysis of variance showed no difference (P = .089) between devices for ACV. However, for PCV, TWAS was significantly different (ie, inaccurate) from OC3D (P P = .001), but OBS was similar (P = .412) to OC3D. For ACV, intraclass correlation coefficients were higher for OBS than for TWAS. Bland–Altman plots showed agreement for ACV for both devices against OC3D but large limits of agreement for PCV for both devices. Mountain plots showed valid ACV for both devices, however, but slightly greater ACV and PCV accuracy with OBS than TWAS. Conclusions: Both devices may provide valid ACV measurements, but some metrics suggest more accurate ACV with OBS vs TWAS. For PCV, neither device is particularly accurate; however, OBS seems to be more accurate than TWAS.

Background Interleukin‐15 (IL‐15) is a myokine associated with muscle strength, possibly by attenuating protein breakdown. A variant in the alpha‐receptor (IL‐15Rα 1775 A>C, rs2228059) partially modulates the muscle strength and size response to resistance training. We examined if this polymorphism associated with habitual physical activity among European‐American adults. Methods Men (n = 240, 23.7 ± 0.3 year, body mass index [BMI] 25.3 ± 0.3 kg/m2) and women (n = 292, 23.2 ± 0.3 year, 24.0 ± 0.3 kg/m2) were genotyped. Physical activity phenotypes were derived from the Paffenbarger Physical Activity Questionnaire. Analysis of covariance (ancova) tested log‐transformed differences between the IL‐15Rα genotype and physical activity phenotypes by gender with age and BMI as covariates. Results Men with the IL‐15Rα 1775AA genotype spent more time in light intensity physical activity (39.4 ± 2.4 hr/week) than men with the CC genotype (28.6 ± 2.3 hr/week, (p = .009). Conclusion Further research is needed to confirm our finding and determine the possible mechanisms by which the IL‐15Rα variant modulates light intensity physical activity.

Background The angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism (rs4340) (ACE DIP) accounts for half of the variability in plasma ACE concentrations. ACE has been widely studied for its influence on sports performance; however, research on its influence in physical activity is limited and inconsistent. We examined the influence of the ACE DIP on physical activity among 461 European Americans. Methods Subjects completed the Paffenbarger Physical Activity Questionnaire for weekly walking distance. Multivariate analysis of covariance (MANCOVA) tested log-transformed differences in weekly walking distance among ACE DIP genotypes (II, ID, DD) with gender as a fixed factor, and age and body mass index (BMI) as covariates. Because we found a significant ACE DIPxBMI interaction (P = 0.03), we categorized the sample by normal weight (NW: BMI

Cooke, DM, Haischer, MH, Carzoli, JP, Bazyler, CD, Johnson, TK, Varieur, R, Zoeller, RF, Whitehurst, M, and Zourdos, MC. Body mass and femur length are inversely related to repetitions performed in the back squat in well-trained lifters. J Strength Cond Res 33(3): 890-895, 2019-The purpose of this research note was to examine whether relationships existed between anthropometrics (body mass, body fat percentage [BF%], and femur length) and descriptive characteristics (age and sex) with repetitions performed to failure at 70% of 1 repetition maximum (1RM) in the back squat. Fifty-eight subjects (males = 43, females = 15; age: 23 ± 3 years, training age: 5.5 ± 2.5 years, body mass: 80.65 ± 16.34 kg, BF%: 10.98 ± 3.53%, and femur length: 47.1 ± 2.6 cm) completed a 1RM squat followed by one set to failure at 70% of 1RM. Total repetitions performed at 70% of 1RM were 14 ± 4 (range: 6-26). Bivariate correlations showed significant inverse relationships between body mass (r = -0.352, p = 0.003), BF% (r = -0.278, p = 0.014), and femur length (r = -0.265, p = 0.019), with repetitions performed. No significant relationships existed between age and sex (p > 0.05), with repetitions performed. All these variables entered into a standard multivariate regression. The model R was 0.200, and body mass had the largest influence (p = 0.057) because relative importance analysis demonstrated body mass to contribute to 43.87% of the variance (of the R) in repetitions performed. No other variable was significant or approached significance (p > 0.05). Our results reveal that body mass, BF%, and femur length all are inversely related to repetitions performed at 70% of 1RM in the back squat.

Background and aim Fibroblast growth factor 21 (FGF21) is positively associated with body mass index, potentially as a compensatory mechanism to mediate obesity related metabolic and inflammatory insult due to chronic low-grade elevations of the pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α). Therefore, FGF21 response in obese subjects and the associations with increased pro-inflammatory cytokines, insulin resistance, and energy utilization warrants investigation. Methods and results Twenty four untrained subjects (12 obese and 12 normal-weight) performed 30 min of continuous submaximal aerobic exercise. Following exercise, obese subjects exhibited a blunted FGF21 response to exercise compared to normal-weight subjects as indicated by area-under-the-curves "with respect to increase" (AUCi) analyses ( p = 0.005). Furthermore, while exercise-induced plasma FGF21 was not associated with any inflammatory cytokine (IL-6 and TNF-α) response, FGF21 AUCi was positively correlated with glucose AUCi (r = 0.495, p = 0.014), total relative energy expenditure (r = 0.562, p = 0.004), and relative maximal oxygen consumption (VO 2max ; r = 0.646, p = 0.001) in all subjects. Conclusion Impaired cardiorespiratory fitness may influence the sensitivity of FGF21 response to acute exercise in obese individuals, potentially contributing to the attenuated metabolic response (e.g., glucose) and total exercise energy expenditure. Therefore, exercise training aimed at improving cardiorespiratory fitness and/or body composition may augment cardioprotective properties against obesity-associated CVD through enhanced FGF21 flux.

Genome-wide association studies have identified thousands of variants that are associated with numerous phenotypes. One such variant, rs13266634, a non-synonymous single nucleotide polymorphism in the solute carrier family 30 (zinc transporter) member eight gene, is associated with a 53% increase in risk of developing type 2 diabetes. We hypothesized that individuals with the protective allele against type 2 diabetes would show a positive response to short-term (acute) and long-term (chronic) resistance exercise. Therefore, two cohorts of young adults: the Eccentric Muscle Damage Cohort (EMD; n = 156) and the Functional Single Nucleotide Polymorphisms Associated with Muscle Size and Strength Study (FAMuSS; n = 874) were tested for association of the rs13266634 variant with measures of skeletal muscle response to resistance exercise. Our results were sexually dimorphic in both cohorts. Men in the in the EMD study with two copies of the protective allele showed less post-exercise bout strength loss, less soreness, and lower creatine kinase values. In addition, men in the FAMuSS study, homozygous for the protective allele, showed higher pre-exercise strength and larger arm skeletal muscle volume but did not show a significant difference in skeletal muscle hypertrophy or strength with resistance training.

The overarching aim of this study was to compare volume-equated high-repetition daily undulating periodization (DUPHR) versus a low-repetition daily undulating periodization (DUPLR) program for muscle performance. Sixteen college-aged (23 ± 3 years) resistance-trained males were counterbalanced into 2 groups: (i) DUPHR (n = 8), with a weekly training order of 12 repetitions (Day 1), 10 repetitions (Day 2), and 8 repetitions (Day 3); and (ii) DUPLR (n = 8), with a weekly training order of 6 repetitions (Day 1), 4 repetitions (Day 2), and 2 repetitions (Day 3). Both groups trained 3 times/week for 8 weeks on nonconsecutive days, with pre- and post-training testing during weeks 1 and 8. Participants performed only squat and bench press exercises each session. Changes in one-repetition maximum (1RM) strength, muscle thickness (MT), and muscular endurance (ME) were assessed. Both groups significantly increased 1RM strength for both squat and bench press (p < 0.01), and no group differences existed (p > 0.05). Similarly, both groups experienced significant increases in chest, lateral quadriceps distal, and anterior quadriceps MT (p < 0.05), but no change was present in either group for lateral quadriceps mid MT (p < 0.05). No group differences were discovered for changes in MT (p > 0.05). ME did not significantly change in the squat or bench press for either group (p > 0.05); however, for squat ME, a moderate effect size was observed for DUPHR (0.57) versus a trivial effect size for DUPLR (0.17). Our findings suggest that in previously trained males, training volume is a significant contributor to strength and hypertrophy adaptations, which occur independently of specific repetition ranges.

Background: Prostate cancer is the most common form of non-dermatologic cancer and the second leading cause of cancer deaths in the United States. Survival rate for the advanced disease still remains low, so current research is aimed at alternative or adjuvant treatments that will target components of the signal pathways in the progression of carcinogenesis with little or no cytotoxicity. In this study we investigated the effect of genistein on expression levels of genes involved in the immune response pathways. The mechanism of genistein-induced cell death was also investigated. The chemosensitivity of the LNCaP prostate cancer cells to genistein was investigated using ATP and MTS assays, and a caspase binding assay was used to determine apoptosis induction. Several molecular targets/genes were determined using cDNA microarray and RT-PCR analysis. Results: The overall data revealed that genistein induces cell death in a time- and dose-dependent manner, and regulates expression levels of several genes involved in carcinogenesis and immunity including MHC genes that are involved in immune recognition of cells and the DefB1 and the HLA membrane receptor genes involved in immunogenicity. Conclusion: The results of the study indicate that genistein inhibits carcinogenesis of LNCaP prostate cancer growth via regulation of the identified specific targets/pathways in immunogenicity/immune response. The results thus provide significant insight into the roles that genistein could play in immune response to prostate cancer proliferation and potential role in immunotherapy and/or adjuvant therapeutic regimen.

Recently, a genome-wide association study (GWAS) that identified eight single-nucleotide polymorphisms (SNPs) associated with BMI highlighted a possible neuronal influence on the development of obesity. We hypothesized these SNPs would govern the response of BMI and subcutaneous fat to resistance training in young individuals (age = 24 years). We genotyped the eight GWAS-identified SNPs in the article by Willer et al. in a cohort (n = 796) that undertook a 12-week resistance-training program. Females with a copy of the rare allele (C) for rs17782313 (MC4R) had significantly higher BMIs (CC/CT: n = 174; 24.70 ± 0.33 kg/m2, TT: n = 278; 23.41 ± 0.26 kg/m2, P = 0.002), and the SNP explained 1.9% of overall variation in BMI. Males with a copy of the rare allele (T) for rs6548238 (TMEM18) had lower amounts of subcutaneous fat pretraining (CT/TT: n = 65; 156,534 ± 7,415 mm3, CC: n = 136; 177,825 ± 5,139 mm3, P = 0.019) and males with a copy of the rare allele (A) for rs9939609 (FTO) lost a significant amount of subcutaneous fat with exercise (AT/AA: n = 83; −798.35 ± 2,624.30 mm3, TT: n = 47; 9,435.23 ± 3,494.44 mm3, P = 0.021). Females with a copy of the G allele for a missense variant in the SH2B1 (rs7498665) was associated with less change of subcutaneous fat volume with exercise (AG/GG: n = 191; 9,813 ± 2,250 mm3 vs. AA: n = 126; 770 ± 2,772 mm3; P = 0.011). These data support the original finding that there is an association between measures of obesity and a variant near the MC4R gene and extends these results to a younger population and implicates FTO, TMEM18, and SH2B1 polymorphisms in subcutaneous fat regulation.

Emerging data have revealed a negative association between adiposity and muscle quality (MQ). There is a lack of research to examine this interaction among young, healthy individuals, and to evaluate the contribution of adiposity to adaptation after resistance exercise (RE).The purpose of this investigation was to examine the influence of subcutaneous adipose tissue (SAT) on muscle function among non-obese individuals before and after RE.Analyses included 634 non-obese (body mass index30 kg m(-2)) subjects (253 males, 381 females; age=23.3 ± 5.2 years). SAT and muscle mass (magnetic resonance imaging-derived SAT and biceps muscle volume), isometric and dynamic biceps strength, and MQ (strength/muscle volume), were analyzed at baseline and after 12 weeks of unilateral RE.At baseline, SAT was independently associated with lower MQ for males (β=-0.55; P0.01) and females (β=-0.45; P0.01), controlling for body mass and age. Adaptation to RE revealed a significant negative association between SAT and changes for strength capacity (β=-0.13; p=0.03) and MQ (β=-0.14; P0.01) among males. No attenuation was identified among females. Post-intervention SAT remained a negative predictor of MQ for males and females (β=-0.47; P0.01).The findings reveal that SAT is a negative predictor of MQ among non-obese, healthy adults, and that after 12 weeks of progressive RE this association was not ameliorated. Data suggest that SAT exerts a weak, negative influence on the adaptive response to strength and MQ among males.

Baseline muscle size and muscle adaptation to exercise are traits with high variability across individuals. Recent research has implicated several chemokines and their receptors in the pathogenesis of many conditions that are influenced by inflammatory processes, including muscle damage and repair. One specific chemokine, chemokine (C-C motif) ligand 2 (CCL2), is expressed by macrophages and muscle satellite cells, increases expression dramatically following muscle damage, and increases expression further with repeated bouts of exercise, suggesting that CCL2 plays a key role in muscle adaptation. The present study hypothesizes that genetic variations in CCL2 and its receptor ( CCR2) may help explain muscle trait variability. College-aged subjects [ n = 874, Functional Single-Nucleotide Polymorphisms Associated With Muscle Size and Strength (FAMUSS) cohort] underwent a 12-wk supervised strength-training program for the upper arm muscles. Muscle size (via MR imaging) and elbow flexion strength (1 repetition maximum and isometric) measurements were taken before and after training. The study participants were then genotyped for 11 genetic variants in CCL2 and five variants in CCR2. Variants in the CCL2 and CCR2 genes show strong associations with several pretraining muscle strength traits, indicating that inflammatory genes in skeletal muscle contribute to the polygenic system that determines muscle phenotypes. These associations extend across both sexes, and several of these genetic variants have been shown to influence gene regulation.

Converging lines of evidence suggest that AKT1 is a major mediator of the responses to insulin, insulin-like growth factor 1 (IGF1), and glucose. AKT1 also plays a key role in the regulation of both muscle cell hypertrophy and atrophy. We hypothesized that AKT1 variants may play a role in the endophenotypes that make up metabolic syndrome. We studied a 12-kb region including the first exon of the AKT1 gene for association with metabolic syndrome-related phenotypes in four study populations [FAMUSS cohort (n = 574; age 23.7 ± 5.7 years), Strong Heart Study (SHS) (n = 2,134; age 55.5 ± 7.9 years), Dynamics of Health, Aging and Body Composition (Health ABC) (n = 3,075; age 73.6 ± 2.9 years), and Studies of a Targeted Risk Reduction Intervention through Defined Exercise (STRRIDE) (n = 175; age 40–65 years)]. We identified a three SNP haplotype that we call H1, which represents the ancestral alleles at the three loci and H2, which represents the derived alleles at the three loci. In young adult European Americans (FAMUSS), H1 was associated with higher fasting glucose levels in females. In middle age Native Americans (SHS), H1 carriers showed higher fasting insulin and HOMA in males, and higher BMI in females. In older African-American and European American subjects (Health ABC) H1 carriers showed a higher incidence of metabolic syndrome. Homozygotes for the H1 haplotype showed about twice the risk of metabolic syndrome in both males and females (p

Studies exploring the relationship between physical activity, fitness, and cognitive function vary across the lifespan in terms of both their number and the apparent strength of the associations. Studies of children are relatively few in number but generally show a positive association between physical activity and cognitive function. Studies of younger adults are even more scarce; findings are equivocal and do not support the hypothesis that greater physical activity or fitness benefits cognitive function. Studies of older adults suggest that greater physical activity and fitness may improve or at least maintain cognitive function. Increasing physical activity may improve cognitive function, especially executive function in elderly persons. A veritable handful of studies suggest that long-term strength training may have cognitive benefits for elderly persons. Regular exercise and greater aerobic fitness are associated with greater brain volume, improved neurophysiological responses to stimuli as measured by electroencephalography (EEG), and higher levels of growth factors that promote growth of brain tissue, neurogenesis, and angiogenesis. However, the findings are not unequivocal (EEG), often based on animal studies (growth factors), and the physiological significance is not well understood. Therefore, while promising, much work remains to validate these findings in humans and to determine their physiological significance for brain health and function. Current evidence does not support the cardiovascular fitness hypothesis and suggests that the neural activity during exercise itself may initiate changes in the brain, independent of the nature of the exercise. More studies are needed to establish a causal relationship, not merely associations, between exercise and cognitive function. These studies need to better quantify physical activity. Likewise, more work is needed to determine the mechanisms by which exercise alters brain function.

Previous studies have reported associations of polymorphisms in the IGF1 gene with phenotypes of body composition (BC). The purpose of this study was to identify phenotypes of BC and physical function that were associated with the IGF1 promoter polymorphism (rs35767, −C1245T). Subjects from the Health, Aging, and Body Composition Study, white males and females (n = 925/836) and black males and females (533/705) aged 70–79 years were genotyped for the polymorphism. Phenotypes of muscle size and function, bone mineral density, and BC were analyzed for associations with this polymorphism. To validate and compare these findings, a cohort of young (mean age = 24.6, SD = 5.9) white men and women (n = 173/296) with similar phenotypic measurements were genotyped. An association with BC was identified in elderly females when significant covariates (physical activity, age, smoking status, body mass index) were included. White women with C/C genotype had 3% more trunk fat and 2% more total fat than those with C/T (P

The present study examined associations between the ciliary neurotrophic factor (CNTF) 1357 G → A polymorphism and the muscle strength response to a unilateral, upper arm resistance-training (RT) program among healthy, young adults. Subjects were 754 Caucasian men (40%) and women (60%) who were genotyped and performed a training program of the nondominant (trained) arm with the dominant (untrained) arm as a comparison. Peak elbow flexor strength was measured with one repetition maximum, isometric strength with maximum voluntary contraction, and bicep cross-sectional area with MRI in the trained and untrained arms before and after training. Women with the CNTF GG genotype gained more absolute isometric strength, as measured by MVC (6.5 ± 0.3 vs. 5.2 ± 0.5 kg), than carriers of the CNTF A1357 allele in the trained arm pre- to posttraining ( P < 0.05). No significant associations were seen in men. Women with the CNTF GG genotype gained more absolute dynamic (1.0 ± 0.1 vs. 0.6 ± 0.1 kg) and allometric (0.022 ± 0.0 vs. 0.015 ± 0.0 kg/kg−0.67) strength, as measured by 1 RM, than carriers of the CNTF A1357 allele in the untrained arm pre- to posttraining ( P < 0.05). No significant associations were seen in men. No significant associations, as measured by cross-sectional area, were seen in men or women. The CNTF 1357 G → A polymorphism explains only a small portion of the variability in the muscle strength response to training in women.

The purpose of this study was to assess the association of age with muscle mass and strength in a group of young adults before and after 12 weeks of progressive resistance training. Eight hundred twenty-six young males and females (age 24.34 +/- 5.69 yr, range 18-39 yr) completed a strictly supervised 12-week unilateral resistance training program of the nondominant arm. Isometric (maximal voluntary contraction [MVC]) and dynamic strength (1 repetition maximum [1RM]) of the elbow flexors and cross-sectional area (CSA) of the biceps-brachii using magnetic resonance imaging (MRI) scans were measured before and after training. Pearson correlation coefficients were calculated for size and strength variables and age. In addition, the cohort was divided into groups according to decade of life and differences assessed by analysis of variance. Age correlated significantly and positively with all pretraining measures of muscle size and strength (CSA: r = 0.191, p < 0.001; MVC: r = 0.109, p = 0.002; 1RM: r = 0.109, p = 0.002). Age was not related to the training-induced changes in CSA or MVC but was negatively associated with the change in 1RM (r = -0.217, p < 0.001). The study indicates that age does have a significant positive relationship with muscle size and strength in untrained young adults. Although age was negatively associated with improvements in 1RM, the effect of age was small relative to the improvements induced through resistance training, thus suggesting age does not limit response to training in any practical way during early adulthood.

Cancer is the second leading cause of death in the United States, accounting for 1 in 4 deaths annually. It has been estimated that one third of all cancer deaths are related to overweight/ obesity, physical inactivity, and poor diet. Epidemiological studies have shown that regular physical activity reduces the risk for some types of cancer as well as postdiagnosis mortality. In studies examining the relation between regular physical activity and the risk of breast cancer, women who were the most physically active reduced their risk by at least 20%. Higher levels of recreational physical activity especially demonstrated greater risk reduction. Meta-analyses suggest that greater physical activity, especially leisure-time physical activity, may reduce the risk of colon cancer by 20% or more in men and women. Physical activity did not demonstrate an association with the risk for cancer of the rectum in either gender. Most studies report an inverse relation between physical activity level and risk for endometrial cancer. Although the estimates of risk reduction vary greatly across studies, the average reported risk reduction was about 30%. The benefit of regular physical activity in the prevention of prostate cancer is not as clear as with other types of cancer. There is some evidence, however, that physical activity may be protective of the more aggressive forms of the disease. Further research is needed to better quantify the specific components of physical activity required to reduce the risk for different cancers.

KOSTEK, M. A., T. J. ANGELOPOULOS, P. M. CLARKSON, P. M. GORDON, N. M. MOYNA, P. S. VISICH, R. F. ZOELLER, T. B. PRICE, R. L. SEIP, P. D. THOMPSON, J. M. DEVANEY, H. GORDISH-DRESSMAN, E. P. HOFFMAN, and L. S. PESCATELLO. Myostatin and Follistatin Polymorphisms Interact with Muscle Phenotypes and Ethnicity. Med. Sci. Sports Exerc., Vol. 41, No. 5, pp. 1063–1071, 2009. Purpose: We examined associations among myostatin (MSTN) 2379 A 9 G and 163 G 9 A and follistatin (FST) j5003 A 9 T and j833 G 9 T single nucleotide polymorphisms (SNP) on the muscle size and the strength response to resistance training (RT). Methods: Subjects (n = 645, age = 24.1 T 0.2 yr, body mass index [BMI] = 24.2 T 0.2 kgIm j2 ) self-disclosed themselves as Caucasian (78.9%), African American (3.6%), Asian (8.4%), Hispanic (5.0%), or Other (4.2%). They were genotyped for MSTN 2379 A 9 G( n = 645), MSTN 163 G 9 A( n = 639), FST j5003 A 9 T( n = 580), and FST j833 G 9 T( n = 603). We assessed dynamic (one repetition maximum [1RM]) and isometric (maximum voluntary contraction [MVC]) muscle strength and size (crosssectional area [CSA]) of the elbow flexors before and after 12 wk of unilateral upper-arm RT. Repeated-measures ANCOVA tested associations among genetic variants and muscle phenotypes with age and BMI as covariates. Results: Baseline MVC was greater among African Americans who were carriers of the MSTN G 2379 allele (AG/GG, n = 15) than the A2379A homozygotes (n = 8; 64.2 T 6.8 vs 49.8 T 8.7 kg). African Americans who were carriers of the FST T j5003 allele (n = 12) had greater baseline 1RM (11.9 T 0.7 vs 8.8 T 0.5 kg) and CSA (24.4 T 1.3 vs 19.1 T 1.2 cm 2 ) than African Americans with the A-5003A genotype (n = 14; P G 0.05). No MSTN or FST genotype and muscle phenotype associations were found among the other ethnic groups (P Q 0.05). Conclusion: MSTN 2379 A 9 G and FST j5003 A 9 T were associated with baseline muscle strength and size among African Americans only. These ethnic-specific associations are hypothesis generating and should be confirmed in a larger sample of African Americans.

The prevalence of cardiovascular disease (CVD), obesity, diabetes mellitus, hypertension, and physical inactivity is significantly higher in African Americans. The higher prevalence of these important risk factors is thought to be largely responsible for the higher CVD mortality rate in blacks. Limited evidence suggests that the aerobic power of African Americans may be inherently lower than that of whites. This apparent deficiency may be explained, in part, by differences in muscle oxidative capacity but is poorly understood. Studies have shown a lower prevalence of overweight/obesity, the metabolic syndrome, and insulin resistance with higher levels of physical activity/fitness. Training studies have shown that increasing physical activity and/or fitness positively affects metabolic risk factors, body composition, and insulin sensitivity. The few studies of African Americans suggest that they respond to exercise training in a manner similar to whites. Controlling blood pressure of hypertensive blacks at levels comparable with that of whites could result in more than 7000 fewer deaths from CVD. Physical fitness has been shown to be negatively associated with blood pressure in African Americans, but results from interventional studies have been equivocal. Some evidence suggests that increased physical activity and/or fitness may reduce the blood pressure response to submaximal exercise and other stressors in African Americans. Blacks have higher levels of high-density lipoprotein cholesterol (HDL-C) and lower levels of total cholesterol, triglycerides, and small dense low-density lipoprotein particles. Studies suggest that the blood lipid response to exercise training is similar between African Americans and whites. There may be an intensity threshold of 75% of age-predicted maximal heart rate to elicit significant changes in HDL-C. More research is needed to explore the association between physical activity/fitness and CVD risk factors in this population.

Both cross-sectional and longitudinal data suggest that the age-associated decline in VO2max is greater in men when expressed in absolute terms such as L or mL· min—1. When expressed in relative terms (ie, percentage decline per decade), the apparent gender difference disappears. Cross-sectional studies report a slower rate of decline than longitudinal studies, probably due to selection bias. The impact of physical activity on the rate of decline in aerobic power with age is not entirely clear. Meta-analyses of cross-sectional studies did not find increased levels of physical activity to be associated with lower rates of decline in VO2max. Longitudinal studies suggest that regular vigorous exercise can slow the rate of decline in VO2max by as much as 50%, but the reduction or cessation of training with advancing age may result in a misleading acceleration in that decline. The most consistent finding in cross-sectional and longitudinal studies is a strong association between the age-associated declines in maximal heart rate and VO2max, but physical activity has little, if any, impact on maximal heart rate. Aerobic exercise training of sufficient intensity can increase aerobic power in both men and women, but the mechanisms may be different, with men demonstrating a greater improvement in factors related to stroke volume and cardiac output, whereas the adaptations in women appear to be more dependent on increased oxygen extraction by skeletal muscle.

The purposes of this study were to (1) derive and test allometric scaling models of biceps isometric strength using body mass (BM) and muscle cross-sectional area (CSA) as the scaling variables, (2) assess the influence of body mass index (BMI) by separating the cohort by BMI (normal25 kg/m(2) vs. overweight/obeseor =25 kg/m(2)) and repeating step 1, and (3) assess the effect of BMI on isometric strength allometrically adjusted for differences in CSA by comparing scaled strength between normal weight versus overweight/obese women. The participants were 183 women (18-39 years old) who reported no strength training in the prior year. Isometric strength and CSA of the biceps were assessed on the non-dominant arm. The CSA allometric model met all statistical criteria and produced a scaling exponent of 0.44. The BM model did not meet these criteria until the entire cohort was separated by BMI. The scaling exponents for normal weight and overweight/obese women were 1.48 and 0.35, respectively. These data suggest that BMI exerted an influence on the relationship between BM and allometrically scaled isometric strength and may be explained by previous studies demonstrating greater contribution of fat mass (FM) versus fat-free mass (FFM) to BMI in overweight/obese women. As such, allometric scaling models of isometric strength, especially in populations that are heterogeneous with regard to body composition, must be carefully tested and examined across the range of BMI. Isometric strength relative to CSA was not significantly different between groups. However, allometrically scaled strength, using CSA as the criterion variable, was significantly greater in overweight/obese women compared to those of normal weight. These data suggest that isometric strength in women is not completely determined by CSA and other factors such as intramuscular fat and muscle fiber type may be confounding or contributing factors.

Cardiovascular disease is the number one killer of women in the United States. It is estimated that 36.6% of women older than age 20 have some form of cardiovascular disease. In 2004, an estimated 459 100 women died from cardiovascular disease, more than 10 times the number of women who died from breast cancer that same year. Regular physical activity of moderate intensity, such as brisk walking, reduces the risk of cardiovascular disease and mortality in women. The benefits of more vigorous exercise are not clear, but the apparent lack of a dose-response relationship between exercise intensity and cardiovascular benefit may be the result of the design of many epidemiologic and interventional studies. Studies examining the benefits of greater cardiorespiratory fitness for women are limited, but the data suggest that they are similar to that of men. Women may require greater caloric expenditure than men for weight reduction, but this issue may be confounded by other variables such as caloric intake and spontaneous physical activity. The risk of cardiovascular disease associated with type 2 diabetes is much greater in women than in men. Regular physical activity and greater cardiorespiratory fitness are associated with a lower incidence and prevalence of type 2 diabetes in women. Greater cardiorespiratory fitness has also been found to be protective of the metabolic syndrome, but the benefit of physical activity is unclear. Limited evidence suggests that moderate-intensity activities can lower systolic blood pressure in women. There is a pressing need for more research into the health benefits of regular physical activity in women.

Metabolic syndrome is a global public health problem identified as a seminal cause of cardiovascular disease and type 2 diabetes. The syndrome is characterized by the clustering of cardiovascular risk factors, including insulin resistance, central obesity, hypertension, and atherogenic dyslipidemia. Currently there are 5 working medical society definitions of metabolic syndrome. However, the majority of recent research focusing on metabolic syndrome has relied on the National Cholesterol Education Program (NCEP) definition because of its clinical utility. Studies of the association between physical activity and prevalence of metabolic syndrome using National Health And Nutrition Examination Survey (NHANES) data generally found the association to be reduced or attenuated by other lifestyle factors and is generally weaker in females. Other studies tracking physical activity over longer periods have generally found a stronger association between regular physical activity and lower prevalence or incidence of metabolic syndrome. Interventional studies are limited but suggest that regular exercise reduces the incidence of metabolic syndrome. The amount and intensity of physical activity required to prevent or reverse metabolic syndrome has yet to be definitely determined. Evidence suggests that regular, moderate-intensity physical activity may be preventive of metabolic syndrome and that activity of greater intensity may carry greater benefit. Greater cardiorespiratory fitness has demonstrated an even stronger negative association with metabolic syndrome. Strength training is recommended as an adjunct to regular aerobic exercise but is not the primary form of activity to prevent or manage metabolic syndrome.

The purpose of this study was to validate the percentage of body fat (%BF) values estimated from the BOD POD (BP) with those obtained from hydrostatic weighing (HW) in athletic American high school boys. Additionally, the %BF values measured via near-infrared interactance (NIR), bioelectrical impedance (BIA), and skinfold (SF) were compared to HW to determine the validity of these measures. Thirty white boys (mean age +/- SD = 15.8 +/- 1.0 years) who where currently participating in organized sports volunteered to have their %BF estimated. Measurements were obtained from NIR, BP, BIA, and SF in random order and concluded with HW. The findings from the present study indicated that the NIR and BIA instruments produced significant (P0.008) constant error (CE) and total error (TE) values that were too large to be of practical value (TE4.0%BF). The BP produced a significantly (P0.008) higher CE with acceptable TE values compared to HW, but compared to all three SF estimations, the BP TE values were higher. Two of the SF equations were nonsignificant (P0.008) and had the lowest TE values compared to HW. These data suggest that the BP can produce acceptable body fat measures for athletic white boys but is not superior to estimates made by the SF equations used in this study.

Glucocorticoid receptor (NR3C1) polymorphisms associate with obesity, muscle strength, and cortisol sensitivity. We examined associations among four NR3C1 polymorphisms and the muscle response to resistance training (RT). European-American adults (n = 602, 23.8±0.4yr) completed a 12 week unilateral arm RT program. Maximum voluntary contraction (MVC) assessed isometric strength (kg) and MRI assessed biceps size (cm2) pre- and post-resistance training. Subjects were genotyped for NR3C1 -2722G>A, -1887G>A, -1017T>C, and +363A>G. Men carrying the -2722G allele gained less relative MVC (17.3±1.2vs33.5±6.1%) (p = 0.010) than AA homozygotes; men with -1887GG gained greater relative MVC than A allele carriers (19.6±1.4vs13.2±2.3%) (p = 0.016). Women carrying the -1017T allele gained greater relative size (18.7±0.5vs16.1±0.9%) (p = 0.016) than CC homozygotes. We found sex-specific NR3C1 associations with the muscle strength and size response to RT. Future studies should investigate whether these associations are partially explained by cortisol’s actions in muscle tissue as they interact with sex differences in cortisol production.

The prevalence of overweight and obesity is increasing at an epidemic rate. Increased adiposity, especially central or visceral adiposity, is predictive of cardiovascular disease/coronary heart disease, metabolic syndrome, and type 2 diabetes mellitus. The increased risk for cardiovascular disease/coronary heart disease and metabolic abnormalities associated with abdominal obesity may be mediated, at least in part, by increased systemic inflammation. Greater physical activity and/or fitness may reduce inflammation associated with greater visceral adiposity. Increased adiposity and low levels of physical activity and/or fitness are risk factors for atherosclerotic disease and type 2 diabetes, as well as the increased mortality associated with them. Increased physical activity/fitness reduces disease and mortality risk regardless of body mass index but does not completely abrogate the risks associated with obesity. Both moderate to vigorous physical activity and weight loss independently reduce the risk for type 2 diabetes and improve glucose/insulin metabolism via di ferent mechanisms. Physical activity on the order of 2500 to 2800 kcal/wk may be necessary to prevent weight gain or maintain weight loss. Strength training is recommended as an adjunct to regular aerobic exercise but not as the primary mode of exercise for weight loss. Individuals are strongly encouraged to engage in regular physical activity because of the known health benefits, regardless of whether that activity results in weight loss.

More than 18 million people in the United States are estimated to have type 2 diabetes mellitus (T2DM). The prevalence of coronary heart disease has been estimated to be as high as 55% in adult diabetics, and cardiovascular disease (CVD) is responsible for at least two thirds of deaths in persons with T2DM. The metabolic syndrome, a clustering of interrelated risk factors, is predictive of T2DM and CVD and prevalent in the T2DM population. Increased aerobic fitness and/or physical activity (3 hours per week moderate activity and/or 1 hour per week vigorous activity) have been demonstrated to be protective of metabolic syndrome. Regular moderate to vigorous physical activity (150 minutes per week moderate activity and/or 90 minutes per week vigorous activity) has been shown to reduce the risk of developing T2DM, even in high-risk individuals. Sedentary behaviors such as television watching are associated with increased risk for T2DM independent of diet and physical activity levels. Glycemic control is related more to exercise intensity than volume. Exercise should be performed at least 3 days per week, with no more than 2 days between exercise bouts. Long-term weight loss may require 7 hours per week of moderate to vigorous exercise. Strength training, alone or in combination with regular aerobic exercise, has been shown to improve glycemic control, hypertension, and other T2DM-related risk factors. Unless specifically contraindicated, strength training is safe for persons with T2DM. The American Diabetes Association now recommends 150 minutes per week of moderate activity and/or 90 minutes per week of vigorous aerobic activity and strength training 3 days per week as part of a program to prevent or manage T2DM. Guidelines for preparticipation screening and consideration for specific conditions are also presented.

Apolipoprotein B (apoB) concentration and age are independently associated with an increased risk for cardiovascular disease. Age is also associated with increased apoB concentration. The purpose of this study was to determine the effects of exercise on apoB and examine the association between age and lipoproteins. Forty-one sedentary individuals exercised for 6 months, four times/week for 40 min between 60 and 85% of their maximal heart rate. Lipids were determined three times: before training, 24 and 72 h after the last training session. Exercise did not alter apoB (1.2+/-0.05 g/l vs. 1.2+/-0.05 g/l; P0.05), or other lipids or lipoproteins. When participants were sequestered by baseline low density lipoprotein cholesterol (LDLc), total cholesterol (TC) was decreased at 24 h post (6.3+/-0.2 mmol/l vs. 6.0+/-0.2 mmol/l, P0.05) and LDLc after 24 and 48 h post (4.3+/-0.1 mg/dl vs. 3.9+/-0.1 and 4.1+/-0.2 mg/dl, P0.05) in the high LDLc group. In the low LDLc group both TC (4.4+/-0.2 mmol/l vs. 4.6+/-0.2 and 4.6+/-0.2 mmol/l, P0.05) and LDLc (2.6+/-0.1 mmol/l vs. 2.8+/-0.1 and 2.8+/-0.2 mmol/l, P0.05) were elevated at 24 h and remained elevated at 72 h post compared to baseline. Age does not affect apoB or lipoproteins in response to exercise. Individuals with high baseline LDLc experienced acute reduction in TC and LDLc produced by each exercise session.

Depression and anxiety are major public health problems and have been shown to be associated with increased risk for cardiovascular disease. The prevalence and incidence of depression and anxiety are lower in those who are regularly active. Regular physical activity has also been shown to reduce symptoms of depression and anxiety in those who already suffer from these disorders. Depression and anxiety may increase the risk for cardiovascular disease by a number of mechanisms, including hypertension and reduced vascular function, autonomic nervous system dysfunction, and increased platelet activity and aggregation. Regular physical activity has been demonstrated to lower blood pressure and improve nitric oxide— mediated vascular function, increase heart rate variability and baroreflex sensitivity, increase fibrinolysis, and, possibly, decrease platelet activity. Little or no work has been done to determine the optimal amount or intensity of exercise to prevent or reduce the symptoms of depression and anxiety. Based on the limited data available, a physical activity routine consistent with the 1996 Surgeon General's Report on Physical Activity and Health is appropriate—specifically, at least 30 minutes of moderate-intensity activity on most days, if not every day, of the week. Little evidence supports a dose-response relation between physical activity and depression or any of the physiological mechanisms discussed here. This is not to say that there is no such relationship but, rather, that well-controlled studies are lacking. Studies on anxiety, especially, are lacking. This includes the link with cardiovascular disease, physiological mechanisms, and the effects of regular physical activity.

More than half of all Americans do not engage in regular physical activity of even moderate intensity, with nearly 1 in 4 reporting no leisure-time physical activity. Despite the well-known benefits of regular exercise, fewer than half of physicians counsel their patients on increasing physical activity. Aerobic exercise of a minimum intensity of only 30% to 40% of heart rate reserve is sufficient to improve cardiovascular fitness in most individuals, with a goal of gradually progressing to 60% to 80% heart rate reserve. Exercise duration and frequency are also gradually increased to maximize cardiovascular stimulus. The goal is a minimum weekly energy expenditure of 1000 kcal per week, and 2000 kcal per week or more may be needed for weight loss and/or management. Strength training 2 to 3 days per week is recommended as an adjunct to regular aerobic exercise, especially for those with impaired glucose/insulin metabolism. It is safe for most elderly individuals to follow these guidelines, including strength training, as long as appropriate precautions are taken.