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Objectives: Males, on average, are bigger and stronger than females. Hormonal differences during puberty are one reason given for this performance advantage. However, not all evidence supports that thesis. Our aim was to further this discussion by measuring early life changes between sexes (when hormones would be similar) in components of muscle function. Methods: Fifty‐one children (29 boys, 22 girls) completed this study. Forearm muscle size and strength were assessed three times with each time point being separated by approximately a year (2021–2023). Results: There was no sex*time interaction for handgrip strength (p = 0.637). There was, however, a time (p < 0.001) and sex (p < 0.001) effect. Strength increased each year and boys were stronger than girls (difference of 1.5 [95% 0.7, 2.3] kg). There was no sex*time interaction for ulnar muscle thickness (p = 0.714) but there was a time (p < 0.001) effect. Muscle size increased each year but there was no evidence of a sex effect (p = 0.12; difference of 0.81 [95% −0.21, 1.8] mm). A strong positive within‐participant correlation between muscle size and strength (r = 0.803 95% CI: [0.72, 0.86], p < 0.0001) was found across time. Conclusion: Muscle size and strength increased together but this increase did not differ based on sex and boys were stronger than girls. Future work is needed to determine the reason for this difference in maximal strength. Any effect was seemingly present at the initial measurement (at the age of 4 years), since muscle size and strength did not change differently between boys and girls over time. [ABSTRACT FROM AUTHOR]

Context: Studies developed the frail elderly handgrip strength (HGS) diagnostic criteria using multiple types of handgrip dynamometers. If different handgrip dynamometers report different values, then this would have the potential to misclassify people into the wrong diagnostic category. Objective: To examine the characteristics of HGS measured by 2 standard handgrip dynamometers and to investigate the influence of hand size on HGS. Setting: University research laboratory. Participants: A total of 87 young and middle-aged adults between the ages of 20 and 60 years participated in this study. Main Outcome Measures: Standard methods of HGS measurements were used for hydraulic and Smedley spring-type dynamometers, although the participants were instructed to maintain an upright standing position in both tests. Results: Test–retest reliability of hydraulic and Smedley dynamometers provided comparable results to that observed with previous studies. However, the difference in HGS between the 2 dynamometers (Hydraulic–Smedley difference) was positively associated (r =.670, P <.001) with the mean of the 2 dynamometers. The participants who had relatively low HGS (at least <35 kg) produced similar HGS values when the 2 dynamometers were compared, whereas persons who had relatively higher HGS (at least >45 kg) produced greater strength values with the hydraulic compared with the Smedley. The hand and palm lengths were weakly correlated (r =.349 and r =.358, respectively, both Ps <.001) with the difference in HGS between the 2 dynamometers. Conclusions: Test–retest reliability of hydraulic and Smedley dynamometers provides comparable results to previous studies. However, the difference in HGS between the 2 dynamometers was positively associated with the mean of the 2 dynamometers. This Hydraulic–Smedley difference would not affect persons who have relatively low HGS (at least <35 kg), while when HGS is relatively high, the comparison between dynamometers should be done with caution. [ABSTRACT FROM AUTHOR]

ABSTRACT Objective Methods Results Conclusion Whether or not an athlete plays with sports equipment in their hands may influence handgrip strength (HGS) changes during development, but longitudinal studies have not confirmed this. This study compared one‐year HGS changes between two sports types (soccer vs. kendo) in children and adolescent athletes.One hundred sixty‐eight young athletes (86 kendo boys and 82 soccer boys) had two HGS measurements separated by 1 year. A 2 (sports) by 2 (timepoints 1 and 2) repeated measures ANOVA was used to determine whether HGS changed differently between sports.There was no evidence for a sport × time interaction in HGS (p = 0.14); however, the mean difference and 95% CI were in the direction of favoring a greater change in kendo athletes [difference of 0.6 (95% CI: −0.2, 1.5) kg]. There was a main effect of time and sport. Kendo athletes had a 4.6 (95% CI: 1.8, 7.5) kg greater HGS than soccer athletes. There was no evidence that the change in HGS between sports depended on the initial age of the athlete (p = 0.205).Using sports equipment during play may positively affect HGS. [ABSTRACT FROM AUTHOR]

The article discusses that resistance training (RT) is a highly popular physical activity that can over time elicit profound improvements in physical function and is thus widely recommended for competitive athletes, prevention and rehabilitation of injury and illness, and healthy aging. It further highlights a range of evidence and theory within four strands to demonstrate that muscle growth, part of the normal physiological adaptation of regular RT.

Accumulating research provides suggestive evidence that acute aerobic exercise may, potentially, enhance episodic memory function post-exercise. Limited research has evaluated whether acute resistance exercise may also enhance episodic memory post-exercise. Furthermore, whether these two exercise modalities have a differential effect on post-exercise episodic memory is relatively unknown. To address these research questions, three experimental studies were conducted (N = 104) among young adults (18–25 years). The experiments implemented acute bouts of aerobic or resistance exercise for 15 min. Episodic memory was comprehensively evaluated post-exercise with a list-learning paradigm and a computerised assessment of what-where-when aspects of episodic memory. Various manipulations (e.g., between vs. within-group) of the study design were implemented across the experiments. Across these three experiments, we failed to find consistent evidence of either type of acute exercise affecting episodic memory performance post-exercise. [ABSTRACT FROM AUTHOR]

Effect sizes provide a universal statistic detailing the magnitude of an effect while removing the influence of the sample size. Effect sizes and statistical tests are closely related with the exception that the effect size illustrates the magnitude of an effect in SD units, whereas the test statistic illustrates the magnitude of effect in SE units. Avoiding statistical jargon, we illustrate why calculations of effect sizes on paired data within the sports and exercise science literature are repeatedly performed incorrectly using the variability of the study sample as opposed to the variability of the actual intervention. Statistics and examples are provided to illustrate why effect sizes are being calculated incorrectly. The calculation of effect sizes when examining paired data supports the results of the test statistic, but only when the effect size calculation is made relative to the variability of the intervention (i.e., the change score SD) because this is what is used for the calculation of the test statistic. Effect size calculations that are made on paired data should be made relative to the SD of the change score because this provides the information of the statistical test while removing the influence of the sample size. After all, we are interested in how variable the intervention is rather than how variable the sample population is. Effect size calculations that are made on pre-test/post-test designs should be calculated as the change score divided by the SD of the change score. [ABSTRACT FROM AUTHOR]

Handheld (HH) Doppler is frequently used for determining the arterial occlusion pressure during blood flow restriction exercises; however, it is unknown whether the blood flow is occluded when the auscultatory signal is no longer present. The purpose of this study was to assess the validity between the HH Doppler and the Doppler ultrasound (US) measurements for determining the arterial occlusion pressure in healthy men. Thirty-five participants underwent 2 arterial occlusion pressure measurements. In the first measure, a pressure cuff (17.5 cm wide) was placed at the most proximal region of the thigh and the pulse of posterior tibial artery was detected using an HH Doppler probe. The cuff was inflated until the auscultatory pulse was no longer detected. After 10 minutes of rest, the procedure was repeated with the Doppler US probe placed on the superficial femoral artery. The cuff was inflated up to the point at which the femoral arterial blood flow was interrupted. The point at which the auscultatory pulse and blood flow were no longer detected was deemed the arterial occlusion pressure. There were no significant differences in arterial occlusion pressure level between the HH Doppler and the Doppler US (133 [±18] vs. 135 [±17] mm Hg, p = 0.168). There was a significant correlation (r = 0.938, p = 0.168), reasonable agreement, and a total error of the estimate of 6.0 mm Hg between measurements. Arterial occlusion pressure level determined by the HH Doppler and the Doppler US was similar, providing evidence that the HH Doppler is a valid and practical method. [ABSTRACT FROM AUTHOR]

It is commonly stated that individuals respond differently to exercise even when the same exercise intervention is performed. This has led many researchers to conduct exercise interventions and subsequently categorize individuals into different responder categories to determine what causes individuals to respond differently. Some methods by which differential responders are categorized include percentile ranks, standard deviations from the mean, and cluster analyses. Notably, each of these methods will result in the presence of differential responders even in the absence of an exercise intervention, indicating that individuals may be categorized based on the presence of random error as opposed to true differences in the exercise response. Here we propose a method by which differential responders can be classified after accounting for the presence of random error that is quantified from a time-matched control group. Individuals who exceed random error from the mean response of the intervention group can be confidently labelled as high and low responders. Importantly, the number of differential responders will be proportional to the ratio of variance in the exercise and control groups. We provide easy-to-follow steps and examples to demonstrate how this technique can identify differential responders to exercise. We also detail the flaws in other classification methods by demonstrating the number of differential responders who would have been classified using the same data set. Our hope is that this method will help to avoid misclassifying individuals based on random error and, in turn, increase the replicability of differential responder studies. [ABSTRACT FROM AUTHOR]

The article focuses on an 8-week study conducted on five individuals who did bicep curls in one arm with the other arm serving as a non-exercise control. It found that an increase in strength following 2 weeks of training but no downward shift in electromyography (EMG) amplitude relative to absolute force was observed.

Fat-free body mass (FFM) is a surrogate for skeletal muscle mass and is often used for the normalization of several physiological variables (e.g., oxygen uptake). However, FFM includes non-skeletal muscle components such as the fat-free component of adipose tissue fat cells. As the amount of adipose tissue mass increases, the FFM will also increase and be included in the measurement of FFM. Therefore, FFM may not be an appropriate indicator of muscle mass when targeting individuals with a large amount of body fat. This review aimed (1) to examine the fat-free adipose tissue (FFAT) in adolescents with and without obesity and (2) to investigate the impact of FFAT on peak oxygen uptake (VO2peak) by comparing VO2peak expressed relative to FFM and FFM minus FFAT between adolescents with and without obesity. Calculated FFAT was threefold higher in adolescents with obesity compared to those without obesity (mean ± SD; 6.94 ± 1.40 vs. 2.22 ± 0.58 kg). The VO2peak expressed relative to FFM-FFAT was similar between the two groups (56.5 ± 6.7 vs. 57.4 ± 8.9 ml min−1 kg−1 FFM-FFAT, respectively). On the other hand, VO2peak expressed relative to FFM was approximately 8% different between groups. When normalizing VO2peak by FFM, eliminating the FFAT component from FFM may be needed, especially when comparing groups with different body fat mass. [ABSTRACT FROM AUTHOR]

Objective: Handgrip strength may differ depending on the type of sport played during the developmental period. Youth sports in which athletes hold equipment in their hands may be the most effective for improving handgrip strength. This study aimed to examine the age at which differences in handgrip strength appear by comparing sports that involve gripping (kendo) with those that do not involve gripping (soccer) in young athletes. Methods: Two hundred and twenty‐two male athletes (115 kendo and 107 soccer) between 6 and 15 years old participated in this study. Handgrip strength was measured using a dynamometer, and the average value of both hands was used for analysis. Sports experience was determined when they started practicing each sport. Handgrip strength was compared between sports. Statistical moderation was used to determine if the relationship between sport and handgrip strength depended upon the age of the athlete. Results: Kendo athletes had significantly higher handgrip strength than soccer athletes (4.77 kg [95% CI: 2.34, 7.19]) in the overall sample. We found that the relationship between sport and handgrip strength depended upon the age of the child (sport*age t = −3.6, p =.004). Using the Johnson‐Neyman procedure, we found statistically significant differences between sports from 8.48 years and older. Conclusions: Our results suggest that the type of sport played, that is, whether or not an athlete plays with sports equipment in their hands, may influence the development of handgrip strength during the period of growth, and these sports may contribute to a higher level of handgrip strength in adulthood. [ABSTRACT FROM AUTHOR]

Purpose: The "fat-but-fit" paradigm has been evaluated. However, the duration of overweight/obesity within the "fat-but-fit" paradigm (ie, assessing body mass at more than 1 time point) has not been extensively evaluated, which was this study's purpose.Design: Cross-sectional.Setting: National Health and Nutrition Examination Survey 2003 to 2006.Participants: Ages 36 to 85; N = 3621.Measures: Physical activity assessed via accelerometry. Medical multimorbidity was assessed via physician diagnosis of 13 chronic diseases. Height and body mass were directly measured for current body mass index (BMI), and 10-year prior BMI was calculated using current height and self-reported weight 10 years prior. Six mutually exclusive groups were created: (1) active, normal weight now and 10 years ago; (2) inactive, normal weight now and 10 years ago; (3) active, overweight/obese now but not 10 years ago; (4) active, overweight/obese now and 10 years ago; (5) inactive, overweight/obese now but not 10 years ago; and (6) inactive, overweight/obese now and 10 years ago.Analysis: Logistic regression.Results: Compared to group 1, adjusted odds ratios (ORs) were as follows: group 2: OR = 2.0 ( P = .004), group 3: OR = 1.7 ( P = .004), group 4: OR = 2.5 ( P < .001), group 5: OR = 2.9 ( P < .001), and group 6: OR = 4.8 ( P < .001).Conclusions: All patterns of weight change/duration and activity level altered the odds of medical multimorbidity, suggesting that the duration of overweight/obesity should also be taken into consideration when assessing the "fat-but-fit" paradigm. [ABSTRACT FROM AUTHOR]

Summary: Protein consumption and its association with changes in body composition, muscle function and different strategies to optimize the muscle protein synthetic response have received considerable attention. However, we are not aware of any epidemiological study examining the time‐of‐day consumption (afternoon versus evening) of protein on strength and lean mass. The purpose was to examine the associations between afternoon and evening protein consumption, at different protein thresholds (i.e. 15, 20, 25 and 30 g), in relation to leg lean mass and knee extensor strength in men. Dietary protein consumption was assessed using 24‐h dietary interview format. Knee extensor strength was measured on an isokinetic dynamometer. Leg lean mass was estimated from whole‐body DXA scans. Participants who consumed 20 g, 25 g and 30 g of protein in the evening had greater leg lean mass than those who consumed protein in the afternoon (P<0·05). However, there was no difference in leg lean mass for 15 g of protein consumption in the evening compared to the afternoon (P>0·05). For strength, there were no differences between evening and afternoon consumption of protein for 15 g, 20 g or 25 g (P>0·05); however, those consuming at least 30 g of protein in the evening had greater knee extensor strength compared to those consuming similar amounts in the afternoon (P = 0·05). These findings suggest that evening protein consumption is associated with greater leg lean mass and knee extensor strength when compared to afternoon protein consumption. Based on these findings, we cautiously hypothesize that there may be a circadian rhythm in muscle protein metabolism. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the association between leukocyte telomere length (LTL) and mortality (outcome variable), with consideration by physical activity behaviour. Data from the 1999-2002 National Health and Nutrition Examination Survey were employed (N = 6,611; 20-85 yrs), with follow-up mortality assessment through 31 December 2006. DNA was extracted from whole blood to assess LTL via quantitative polymerase chain reaction. Compared to those in the first LTL tertile, the adjusted hazard ratio for all-cause mortality for those in the 2nd and 3rd LTL tertiles, respectively, was 0.82 (95% CI: 0.60-1.12; P = .22) and 0.76 (95% CI: 0.50-1.14; P = .18). However, after adjustments, LTL tertile 3 (vs. 1) was associated with all-cause mortality (HR = 0.37; 95% CI: 0.14-0.93; P = .03) for those who engaged in moderate-intensity exercise. Similarly, LTL was associated with CVD-specific mortality for those who engaged in moderate-intensity exercise (HR = 0.17; 95% CI: 0.04-0.73; P = .02). Longer telomeres are associated with increased survival, particularly among men and those who are active, underscoring the importance of promotion of physical activity behaviour. [ABSTRACT FROM AUTHOR]

Stain use is often associated with an increased likelihood of musculoskeletal complications such as injuries and pain. Consequently, it is plausible to suggest that statin use may indirectly influence lower extremity muscular strength via reduced engagement in muscle-strengthening activities (MSA). However, this has yet to be examined. Therefore, the purpose of this study was to examine whether statin use was associated with muscular strength via engagement in MSA. Data from the 1999-2002 NHANES were used, with 2775 adults (50-85 years) constituting the analytic sample. Statin use was assessed from an interviewer, engagement in MSA (e.g. resistance training) was assessed via survey and lower extremity isokinetic knee extension strength (IKES) was assessed objectively using the Kin Com MP dynamometer. Weighted multivariable linear regression analysis showed no direct association between statin use and IKES (βadjusted = 7·0 newton ∆, P = 0·23). Statin use, however, was associated with a 35% reduced odds of engaging in MSA (ORadjusted = 0·65, P = 0·04), and engaging in MSA was positively associated with IKES (βadjusted = 19·9 newton ∆, P = 0·001). The bootstrap Barron and Kenny mediational analysis indeed demonstrated that statin use was indirectly associated with IKES via MSA (indirect effect coefficient: −0·005; 95% CI: −0·01 to −0·001; P<0·05). Statin use was not directly associated with IKES, but was indirectly associated with IKES via MSA. In conclusion, statin use may decrease muscle force by influencing engagement in MSA. We wish to suggest that a decrease in MSA may be related to an increase in muscle pain associated with statin therapy. [ABSTRACT FROM AUTHOR]

Introduction: This study compares the acute and chronic response of high-load resistance training (HL) to low-load resistance training with low blood flow restriction (LL-BFR) pressure.Methods: Participants completed elbow flexion with either HL or LL-BFR or nonexercise. In the chronic study, participants in the HL and LL-BFR groups were trained for 8 weeks to determine differences in muscle size and strength. The acute study examined the changes in pretesting/posttesting (Pre/Post) torque, muscle swelling, and blood lactate.Results: In the chronic study, similar changes in muscle size and strength were observed for both HL and LL-BFR. In the acute study, Pre/Post changes in the torque, muscle swelling, and blood lactate were similar between HL and LL-BFR.Discussion: Our findings indicate that pressure as low as 50% arterial occlusion can produce similar changes in muscle mass and strength compared with traditional HL. Muscle Nerve 56: E126-E133, 2017. [ABSTRACT FROM AUTHOR]

Background Aerobic exercise and resistance training (RT) are individually associated with positive health outcomes. It has been shown that combining both aerobic and RT exercise may produce greater outcomes than each type alone. Homocysteine has been shown to decrease with aerobic and RT exercise. However, no study has examined the combined effects of both types on homocysteine, which was the purpose of this study. Methods Data from the 2003-2006 NHANES were used. Homocysteine values were obtained from a blood sample. Accelerometer-derived physical activity (PA) was measured using accelerometry, and MSA was measured via a questionnaire. Results Meeting the recommendations for accelerometer-derived PA was associated with lower homocysteine (βadjusted = −0·29; P = 0·04), as was meeting the recommendations for MSA (βadjusted = −0·30; P = 0·028). Compared to those meeting zero recommendations, there was no difference between those meeting 1 and those meeting both ( P = 0·08). Further, higher homocysteine was linked with increased all-cause mortality (HR = 1·47; 95% CI: 1·29-1·69) and CVD-specific mortality (HR = 1·48; 95% CI: 1·20-1·81). Conclusion These results suggest that PA and MSA are associated with lower homocysteine and that there may be a dose-response relationship when combining both forms of exercise, which is an important finding as higher homocysteine is predictive of increased all-cause and CVD-specific mortality. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare exercise with and without different degrees of blood flow restriction ( BFR) on acute changes in muscle thickness ( MTH) and whole blood lactate ( WBL). Forty participants were assigned to Experiment 1, 2 or 3. Each experiment completed protocols differing by pressure, load and/or volume. MTH and WBL were measured pre and postexercise. The acute changes in MTH appear be maximized at 30% one repetition maximum (1 RM) with BFR, although the difference between 20% 1 RM and 30% 1 RM at the lateral site was small (0·1 versus 0·2 cm, P = 0·09). Increasing the exercise load from 20% to 30% 1 RM with BFR produces clear changes in WBL (3·7 versus 5·5 mmol l−1, P<0·001). The acute changes in MTH and WBL for 30% 1 RM in combination with BFR were similar to that observed with 70% 1 RM and 20 and 30% to failure, albeit at a lower exercise volume. These findings may have implications for designing future studies as it suggest that exercise load (to a point) may have a greater influence on acute changes in MTH and metabolic accumulation than the applied relative pressure. [ABSTRACT FROM AUTHOR]

Aim The time-course for changes in muscle size and strength is not well understood, particularly in women. In addition, contributions of muscle size to strength are commonly assessed utilizing a pre-post change score; however, a more appropriate within-subject correlational analysis has never been used. Methods To determine the time-course for thigh muscle size and strength in young (aged 18-25 years) and older (aged 50-65 years) women, and determine the relationship between size and strength after 8 weeks of training carried our three times per week. Results Anterior muscle thickness at the 50% site increased after 1 week of training, and exceeded the measurement error after 2 weeks (mean difference 0.23 cm, 95% CI 0.12-0.34 cm). Anterior muscle thickness at the 70% site increased and exceeded the measurement error after 2 weeks (mean difference 0.30 cm, 95% CI 0.15-0.45 cm). Posterior muscle thickness at the 50% site increased after 1 week of training, and exceeded the measurement error after 2 weeks (mean difference 0.24 cm, 95% CI 0.03-0.44 cm). Posterior muscle thickness at the 70% site increased after 1 week, and exceeded the measurement error after 3 weeks (mean difference 0.21 cm, 95% CI 0.07-0.35 cm). Muscle strength, assessed through one-repetition maximum, increased by 2 weeks in most measurements, and the within-subject variance explained by changes in muscle size ranged between 9% and 35%. Conclusions Muscle growth appeared to occur early into a training program in both young and older women. Furthermore, although a large portion remains unexplained, the variance in muscle strength explained by muscle size is greater than previous studies not utilizing within-subject correlations. Geriatr Gerontol Int 2017; 17: 2000-2007. [ABSTRACT FROM AUTHOR]

Low-load exercise can increase serum hormones such as growth hormone (GH) concentration in young adults when combined with blood flow restriction (BFR), but it is unclear whether walking with BFR (BFR-walk) can elevate them for older adults. Furthermore, it remained untested whether changes in these purported anabolic hormones contribute to BFR-walk-induced muscle hypertrophy. To examine the relationship between the acute and chronic effects of BFR-walk, seven women (age: 64 ± 2 years) performed treadmill walking with (BFR-walk) and without BFR (CON-walk) at 45% of heart rate reserve for 20 min in a randomized crossover design. During BFR-walk, subjects wore 5-cm cuffs on the proximal part of the upper legs. Blood samples were taken before (PRE), immediately after (POST-1) and 15 min post (POST-2) exercise. There was a main effect of time for GH ( P<0·01) with levels increasing following exercise. In addition, there was a condition and time main effect for insulin; with insulin increasing to a greater degree with BFR at POST-2. Noradrenaline increased across time for both BFR-walk ( P = 0·012) and CON-walk ( P<0·001); but BFR-walk induced greater elevations at POST-1 and POST-2. The change in GH, insulin and noradrenaline was not significantly correlated with BFR-walk-induced muscle hypertrophy. These preliminary results suggest that the BFR-walk-induced elevation in the purported anabolic hormones may not have a large impact on muscle growth. [ABSTRACT FROM AUTHOR]

Purpose: Physical activity (PA) has previously been demonstrated to be inversely related with multimorbidity (having more than one chronic disease); however, it is unknown whether dual participation in both PA and muscle-strengthening activities (MSA) may further reduce the odds of being multimorbid. Therefore, the purpose of our study was to determine the association between multimorbidity and individuals meeting recommended guidelines for both PA and MSA.Design: Nonexperimental.Setting: The 2003-2006 National Health and Nutritional Examination Survey.Subjects: Four thousand five hundred eighty-seven adults aged ≥20 years.Measures: Accelerometry-measured PA, self-reported MSA, and multimorbidity.Analysis: Data were analyzed using multivariable linear and logistic regression.Results: The odds (95% confidence interval) of being multimorbid for those only meeting MSA guidelines, only meeting PA guidelines, and meeting both PA and MSA guidelines (vs. not meeting either), respectively, were .69 (.48, .98; p = .04), .55 (.44, .70; p < .01), and .38 (.27, .53; p < .01).Conclusion: Our findings demonstrate that individuals meeting recommended guidelines for both MSA and PA were less likely to be multimorbid than individuals participating in one or none of these exercise modalities. Determining effective ways to initiate and maintain concurrent adoption of MSA and PA is needed to provide a cost-effective behavioral alternative for reducing the prevalence of multimorbidity. [ABSTRACT FROM AUTHOR]

Background Previous studies have reported the non-homogenous loss of muscle mass (site-specific muscle loss) with ageing, but this relationship to the loss of strength is not totally understood. Purpose To investigate the relationship between maximal dynamic strength and site-specific muscle mass of the thigh and upper arm. Methods Thirty-five recreationally active men were separated into young-aged ( YG, 20-39 years, n = 12), middle-aged ( MG, 40-59 years, n = 13) and old-aged groups ( OG, 60-75 years, n = 10). One-repetition maximum strength (1- RM; leg press, chest press, knee flexion, lat pull-down, and knee extension), muscle thickness ( MTH, anterior and posterior thigh and upper arm) and appendicular lean mass ( aLM) index were obtained from participants. Site-specific thigh MTH ratio was determined by dividing anterior thigh MTH (50% of thigh length) by posterior thigh MTH (50% of thigh length). Results aLM index was not significantly different between age groups, but a significantly smaller site-specific MTH thigh ratio was found in the OG. Collapsed across age groups both site-specific thigh MTH ratio and aLM index were significantly correlated with leg press, knee extension and knee flexion1- RM strength ( r = 0·390-0·699), but not with knee extension: knee flexion ( KE: KF) 1- RM strength ratios ( r = 0·037-0·081). Separated by age groups only aLM index was correlated with KE: KF 1- RM ratio for the OG ( r = 0·780). Conclusions Site-specific thigh MTH ratio may be an important assessment tool in older individuals as it is different among age groups and is significantly related to dynamic maximal strength. However, maximal dynamic strength ratios appear to be less sensitive to differences in site-specific MTH ratios. [ABSTRACT FROM AUTHOR]

Objective: Examine the joint effects of objectively-measured sedentary time and moderate-to-vigorous physical activity (MVPA) on all-cause mortality.Methods: The present study included data from the 2003-2006 National Health & Nutrition Examination Survey, with mortality follow-up data (via National Death Index) through 2011 (N=5575U.S. adults). Sedentary time (activity counts/min between 0 and 99) and MVPA (activity counts/min ≥2020) were objectively measured using the ActiGraph 7164 accelerometer.Results: The median age of the participants was 50yrs; proportion of men was 50.2%; proportion of whites was 53.8%, 18.7% for blacks; median follow-up was 81months; and 511 deaths occurred over the follow-up period. After adjusting for age, gender, race-ethnicity, cotinine, weight status, poverty level, C-reactive protein and comorbid illness (summed score of 0-8 chronic diseases), and for a 1min increase in MVPA and sedentary time, both MVPA (HRadjusted=0.98; 95% CI: 0.96-0.99; P=0.04) and sedentary time (HRadjusted=1.001; 95% CI: 1.0003-1.002; P=0.008) were independently associated with all-cause mortality. Further, MVPA was associated with all-cause mortality among those with greater (above median) sedentary time (HRadjusted=0.95; 95% CI: 0.93-0.97; P<.001). Sedentary time was not associated with all-cause mortality among those engaging in above median levels of MVPA (HRadjusted=0.998; 95% CI: 0.996-1.001; P=.32), but sedentary time was associated with increased mortality risk among those below median levels of MVPA (HR=1.002; 95% CI: 1.001-1.003; P<0.001).Conclusions: Sedentary time and MVPA are independently associated with all-cause mortality. Above median sedentary time levels did not negate the beneficial effects of MVPA on all-cause mortality risk. [ABSTRACT FROM AUTHOR]

Several studies have investigated the relationship between ultrasound-measured muscle thickness ( MT) and individual muscle cross-sectional area ( CSA) and muscle volume ( MV) in extremity and trunk muscles; however, the hamstring muscle has not been studied. The purpose of this study was to examine the relationship between posterior thigh MT by ultrasound and the muscle CSA and MV of the hamstring obtained by magnetic resonance imaging ( MRI). Ten young women aged 20-31 had MT measured by ultrasound at three sites on the medial anterior (50% of thigh length; TL) and posterior (50% and 70% of TL) aspects of the thigh. On the same day, a series of continuous muscle CSA along the thigh was measured by MRI. In each slice, the anatomical CSA of the hamstring (biceps femoris, semitendinosus and semimembranosus) and quadriceps muscle was analysed, and the CSAs at 50% and 70% of TL and maximal CSA of the hamstring ( CSAmax) were determined. MV was calculated by multiplying CSA by slice thickness. A significant correlation was observed between posterior 50% MT and 50% hamstring CSA ( r = 0·848, P = 0·002) and between posterior 70% MT and 70% hamstring CSA ( r = 0·679, P = 0·031). Posterior 50% MT ( r = 0·732, P = 0·016) and 50% MTx TL ( r = 0·873, P = 0·001) were also correlated to hamstring MV. Anterior:posterior 50% thigh MT ratio was correlated to MV ratio of quadriceps and hamstring muscles ( r = 0·803, P = 0·005). Our results suggest that posterior thigh MT reflects hamstring muscle CSA and MV. The anterior:posterior MT ratio may serve as a surrogate for MV ratio of quadriceps and hamstring. [ABSTRACT FROM AUTHOR]

The application of blood flow restriction (BFR) with low load exercise has been shown to produce favorable muscle and vascular adaptations. Given the potential clinical utility of BFR, it is important to characterize the ratings of perceived exertion (RPE) and discomfort across a variety of relative pressures as the individual's perceptual response may ultimately dictate whether a participant continues with this modality of exercise. Fourteen participants completed 3 days of exercise. Conditions included unilateral elbow flexion with six pressures ranging from 40% to 90% arterial occlusion at 30% of their one repetition maximum (1RM). Differences in RPE (6: no exertion at all, 20: maximal exertion) were found across conditions for set 2 (range of 13–15), 3 (range of 15–16), and 4 (range of 15–17). Following Bonferroni adjustments, none were significant. Differences in discomfort (0: no discomfort at all; 10: maximum discomfort) were found across conditions for set 1 (range of 2–3), 2 (range of 3.2–5), 3 (range of 4–6.5), and 4 (range of 5–7). Post-hoc analyses only found differences within set 3. Although it is presently unknown if higher pressures are required for optimal adaption of tissues other than skeletal muscle, our results suggest that the perceptual rating during exercise is unlikely to be a limiting factor in the application of higher pressures. [ABSTRACT FROM AUTHOR]

Background: Physical activity has been shown to attenuate the association between overweight/obesity and mortality. Much less is known, however, on how the duration of overweight/obesity potentially alters this association, which was the purpose of this study.Methods: The 1999-2006 NHANES was used and 11,057 adults (ages 36-85) were evaluated. Eight mutually exclusive groups were created: (1) physically active, normal weight now and 10years ago; (2) physically inactive, normal weight now and 10years ago; (3) physically active, overweight/obese now but normal weight 10years ago; (4) physically inactive, normal weight now but overweight/obese 10years ago; (5) physically active, overweight/obese now but normal weight 10years ago; (6) physically inactive, overweight/obese now but normal weight 10years ago; (7) physically active, overweight/obese now and 10years ago; and (8) physically inactive, overweight/obese now and 10years ago.Results: After adjustments, only those individuals that were inactive were at a significantly increased risk for all-cause mortality independent of overweight/obesity status (Groups 2, 4, 6, 8).Conclusion: In alignment with the Exercise is Medicine initiative®, our results provide support for clinicians to perform routine assessments of physical activity, and to further promote physical activity among all individuals regardless of body mass status. [ABSTRACT FROM AUTHOR]

Recent work has found that older adults with obesity and systemic inflammation have associated metabolic dysfunction but do not have associated lower lean mass or strength. However, this lean mass estimate may be inflated with obesity, given that 15 % of adipose tissue is composed of fat-free tissue. The primary purpose of this study was to investigate, in a nationally representative sample of adults, whether obese adults with chronic systemic inflammation (unhealthy) have differences in lean mass, muscle strength, and insulin resistance when compared to normal weight individuals without elevated levels of systemic inflammation (healthy). A secondary objective was to determine whether these potential differences were moderated by physical activity and to determine if these groups had a differential risk for all-cause mortality. Our findings suggests that the unhealthy group was associated with higher upper body lean mass (β = 823; 95 % confidence interval (CI) 637–1010; P < 0.001), lower body lean mass (β = 2724; 95 % CI 2291–3158; P < 0.001), and strength (β = 34.6; 95 % CI 13.5–55.7; P = 0.003) compared to the healthy group despite having systemic inflammation and correcting for fat-free adipose tissue. However, the unhealthy group was associated with insulin resistance (odds ratio (OR) = 16.1; 95 % CI 2.7–96.1; P = 0.005) although this finding was attenuated in those physically active (OR = 8.5; 95 % CI 2.43–30.15; P = 0.003). Despite this metabolic dysfunction, there was no difference in all-cause mortality risk between groups (hazard ratio (HR) = 1.16 (95 % CI 0.69–1.96; P = 0.54)) suggesting that higher amounts of lean mass and strength may be protective of premature mortality. [ABSTRACT FROM AUTHOR]

Objective: Participating in muscle-strengthening activities (MSA) has been shown to reduce the risks associated with many individual chronic diseases; however, the impact of MSA on multimorbidity remains unexplored. Therefore, the purpose of this study was to determine the association between MSA and multimorbidity.Methods: Data from the 2003-2006 NHANES were used including 4587 adults (≥20 years old). Participation in MSA was defined as self-reported involvement within the last 30 days. Multimorbidity was deemed as having ≥2 of the 14 chronic diseases.Results: After adjustments (including accelerometry-assessed physical activity), individuals participating in MSA had a 26% reduced odds of having multimorbidity (OR=0.74; 95% CI: 0.62-0.88; p=0.001) and each 2 day/week increase in MSA was associated with an 8% reduced odds of being multimorbid (OR=0.92; 95% CI: 0.84-1.00; p=0.05).Conclusion: Independent of accelerometry-assessed physical activity, the participation in MSA may reduce the odds of being multimorbid, with evidence of a dose-response relationship. [ABSTRACT FROM AUTHOR]

Introduction: Short leukocyte telomere length (LTL) has become a hallmark characteristic of aging. Some, but not all, evidence suggests that physical activity (PA) may play an important role in attenuating age-related diseases and may provide a protective effect for telomeres. The purpose of this study was to examine the association between PA and LTL in a national sample of US adults from the National Health and Nutrition Examination Survey. Methods: National Health and Nutrition Examination Survey data from 1999 to 2002 (n = 6503; 20-84 yr) were used. Four self-report questions related to movement-based behaviors (MBB) were assessed. The four MBB included whether individuals participated in moderate-intensity PA, vigorous-intensity PA, walking/cycling for transportation, and muscle-strengthening activities. An MBB index variable was created by summing the number of MBB an individual engaged in (range, 0-4). Results: A clear dose-response relation was observed between MBB and LTL; across the LTL tertiles, respectively, the mean numbers of MBB were 1.18, 1.44, and 1.54 (Ptrend < 0.001). After adjustments (including age) and compared with those engaging in 0 MBB, those engaging in 1, 2, 3, and 4 MBB, respectively, had a 3% (P = 0.84), 24% (P = 0.02), 29% (P = 0.04), and 52% (P = 0.004) reduced odds of being in the lowest (vs highest) tertile of LTL; MBB was not associated with being in the middle (vs highest) tertile of LTL. Conclusions: Greater engagement in MBB was associated with reduced odds of being in the lowest LTL tertile. [ABSTRACT FROM AUTHOR]

Background No study has applied the “fat-but-fit” paradigm with respect to muscular strength as an index of fitness, despite muscular strength being independently associated with functional ability and mortality. Purpose To examine the relationship between lower extremity muscular strength, C-reactive protein (CRP), and all-cause mortality among normal weight, overweight and obese individuals. Methods Data from the 1999–2002 NHANES were used (N = 2740 adults; ≥ 50 years). CRP values were obtained from a blood sample. Lower body isokinetic knee extensor strength (IKES) was assessed using a Kin Kom MP isokinetic dynamometer. Participant data was linked to death certificate data from the National Death Index to ascertain all-cause mortality status. Participants were classified, based on body mass index (BMI) and strength as: normal weight and unfit (< 75th IKES percentile); overweight and unfit; obese and unfit: normal weight and fit (≥ 75th IKES percentile); overweight and fit; and obese and fit. Results Independent of physical activity and other confounders, compared to those who were normal weight and unfit, unfit overweight (β = .14, p = 0.009), unfit obese (β = .33, p < 0.001), and obese and fit (β = .17, p = 0.008) participants, had higher CRP levels. However, there was no difference in CRP levels between normal weight and unfit participants and overweight and fit participants (β = 0.04, p = 0.35). Compared to normal weight unfit adults, overweight fit (HR = 0.28; 95% CI: 0.11–0.70; p = 0.008) adults had a lower hazard rate for all-cause mortality. Conclusions These finding suggest that increased lower body strength, independent of physical activity, may reduce premature all-cause mortality and attenuate systemic inflammation among overweight adults. [ABSTRACT FROM AUTHOR]

The aim was to compare exercise with and without different degrees of blood-flow restriction on perceived exertion (RPE) and discomfort. Participants were assigned to Experiment 1, 2, or 3. Each completed protocols differing by pressure, load, and/or volume. RPE and discomfort were taken before and after each set. For pressure and RPE, the 20% one repetition maximum (1RM) blood-flow restriction conditions were affected by increasing the pressure from 40% to 50% blood-flow restriction (~12 vs. ~14). This did not appear to happen within the 30% 1RM blood-flow restriction conditions or the higher pressures in the 20% 1RM conditions. The similar RPE between 20% and 30% 1RM to failure was expected given both were to failure. For discomfort, ratings were primarily affected by load at the lowest pressure. Increasing pressure to 50% blood-flow restriction increased discomfort at 20% 1RM (~2.6 vs. ~4). There was a further increase when increasing to 60% blood-flow restriction (~4 vs. ~4.8). The high-load condition had the lowest discomfort, while ratings were highest with 20% 1RM to failure. In conclusion, exercise with blood-flow restriction does not appear to augment the perceptual response observed with low-load exercise to failure. [ABSTRACT FROM PUBLISHER]

The purpose of this study was to determine the muscular adaptations to low-load resistance training performed to fatigue with and without blood flow restriction ( BFR). Middle-aged (42-62 years) men ( n = 12) and women ( n = 6) completed 18 sessions of unilateral knee extensor resistance training to volitional fatigue over 6 weeks. One limb trained under BFR, and the contralateral limb trained without BFR [free flow ( FF)]. Before and after the training, measures of anterior and lateral quadriceps muscle thickness ( MTh), strength, power and endurance were assessed on each limb. The total exercise training volume was significantly greater for the FF limb compared with the BFR limb ( P<0·001). Anterior quadriceps thickness and muscle function increased following the training in each limb with no differences between limbs. Lateral quadriceps MTh increased significantly more ( P<0·05) in the limb trained under BFR ( BFR: 3·50 ± 0·61 to 3·67 ± 0·62 cm; FF: 3·49 ± 0·73 to 3·56 ± 0·70 cm). Low-load resistance training to volitional fatigue both with and without BFR is viable options for improving muscle function in middle-aged individuals. However, BFR enhanced the hypertrophic effect of low-load training and reduced the volume of exercise needed to elicit increases in muscle function. [ABSTRACT FROM AUTHOR]

ABSTRACT Introduction An unresolved question in resistance training combined with blood flow restriction (BFR) is what percentage of estimated arterial occlusion pressure provides the most robust acute muscular response. Methods Forty participants were assigned to Experiments 1, 2, or 3. Each experiment completed exercise protocols differing by pressure, exercise load, and/or volume. Torque was measured pre- and postexercise, and muscle activation was measured pre- and during each set. Results Pressure and load did not affect torque greatly. Muscle activation increased in all conditions ( P < 0.05) and was higher with 30% 1RM compared with 20% 1RM. Pressure appeared to increase muscle activation from 40% to 50% arterial occlusion [66% vs. 87% maximal voluntary contraction (30% 1RM)] but was not further increased with higher pressure. Conclusion Different levels of BFR may alter the acute muscular response to a degree, although higher pressures do not appear to augment these changes. Muscle Nerve 51:713-721, 2015 [ABSTRACT FROM AUTHOR]

To test the validity of published equations, 79 Caucasian adults (40 men and 39 women) aged 50–78 y had muscle thickness (MT) measured by ultrasound at nine sites of the body. Fat-free mass (FFM), lean soft tissue mass (LM) and total muscle mass (TMM) were estimated from MT using equations previously published in the literature. Appendicular LM (aLM) was estimated using dual-energy X-ray absorptiometry (DXA) and this method served as the reference criterion. There were strong correlations (range r = 0.85–0.94) between DXA-derived aLM and estimated FFM, leg LM or TMM. Total error between DXA-derived aLM and TMM (∼2 kg) was lower compared with the three other selected equations (6–10 kg). A Bland-Altman plot revealed that there was no systematic bias between aLM and TMM; however, the other three equations included systematic error. Our results suggest that an ultrasound equation for TMM is appropriate and useful for evaluating skeletal muscle mass in the body. [ABSTRACT FROM AUTHOR]

We investigated the effects of 3 weeks of detraining on muscle cross-sectional area ( CSA) and one-repetition maximum strength (1- RM) in young men who had previously participated in 6 weeks (3 days week−1) of bench press training [blood flow restricted low-intensity ( LI- BFR; n = 10, 20% 1- RM) or high-intensity ( HI; n = 7, 75% 1- RM)]. Bench press 1- RM and muscle CSA of triceps brachii ( TB) and pectoralis major ( PM) were evaluated before (pre) and after training period (post) as well as after detraining period (detraining). Bench press 1- RM was higher at both post and detraining than at pre for LI- BFR ( P<0·01) and the HI ( P<0·01). TB and PM muscle CSA were higher at both post and detraining than at pre for the HI group ( P<0·01), while the LI- BFR group only increased ( P<0·01) at post. Relative dynamic strength (1- RM divided by TB muscle CSA) was higher at both post and detraining than at pre for the HI group ( P<0·01), while the LI- BFR group only increased ( P<0·01) at detraining. In conclusion, increased muscle strength following 6 weeks of training with LI- BFR as well as HI was well preserved at 3 weeks of detraining. HI-induced muscle strength appears to be dependent upon both neural adaptations and muscle hypertrophy with training and detraining. On the other hand, LI- BFR-induced muscle strength appears to be related primarily to muscle hypertrophy with training and to neural adaptations with detraining. [ABSTRACT FROM AUTHOR]

Context: Blood flow restriction (BFR) increases muscle size and strength when combined with low loads, but various methods are used to produce this stimulus. It is unclear how using elastic knee wraps can impact acute muscular responses compared with using nylon cuffs, where the pressure can be standardized. Objective: Investigate how elastic knee wraps compare with nylon cuffs and high-load (HL)/low-load (LL) resistance exercise. Design: A randomized cross-over experimental design using 6 conditions combined with unilateral knee extension. Setting: Human Performance Laboratory. Participants: A total of 9 healthy participants (males = 7 and females = 2) and had an average age of 22 (4) years. Intervention: LL (30% of 1-repetition maximum [1-RM]), HL (70% 1-RM), BFR at 40% of arterial occlusion pressure (BFR-LOW), BFR at 80% of arterial occlusion pressure (BFR-HIGH), elastic knee wraps stretched by 2 in (PRACTICAL-LOW), and elastic knee wraps stretched to a new length equivalent to 85% of thigh circumference (PRACTICAL-HIGH). BFR and practical conditions used 30% 1-RM. Main Outcome Measures: Muscle thickness, maximum voluntary isometric contraction, and electromyography amplitude. Bayesian statistics evaluated differences in changes between conditions using the Bayes factor (BF10), and median and 95% credible intervals were reported from the posterior distribution. Results: Total repetitions completed were greater for BFR-LOW versus PRACTICAL-HIGH (BF10 = 3.2, 48.6 vs 44 repetitions) and greater for PRACTICAL-LOW versus BFR-HIGH (BF10 = 717, 51.8 vs 36.3 repetitions). Greater decreases in changes in maximum voluntary isometric contraction were found in PRACTICAL-HIGH versus HL (BF10 = 1035, -103 N) and LL (BF10 = 45, -66 N). No differences in changes in muscle thickness were found between LL versus PRACTICAL-LOW/PRACTICAL-HIGH conditions (BF10 = 0.32). Greater changes in electromyography amplitude were also found for BFR-LOW versus PRACTICAL-HIGH condition (BF10 = 6.13, ~12%), but no differences were noted between the other BFR conditions. Conclusions: Overall, elastic knee wraps produce a more fatiguing stimulus than LL or HL conditions and might be used as an alternative to pneumatic cuffs that are traditionally used for BFR exercise. [ABSTRACT FROM AUTHOR]

Free play in kindergarten can be roughly divided into fine and gross motor activities, but the effects of these activities on improving handgrip strength are unknown. Therefore, we aimed to compare one-year changes in handgrip strength and forearm flexor muscle size in children separated by preferred play in a kindergarten. One hundred and eleven children were recruited from a local kindergarten. They underwent handgrip strength and forearm muscle thickness measurements, and 95 (49 boys and 46 girls) underwent a second measurement one year after the first measurement. Class teachers assessed the physical activity of everyone in their class after the second measurement. Using three evaluation scores by the class teachers, we divided children into three groups based on the children's preference to play in kindergarten (fine movement vs. gross motor movement). Handgrip strength did not change differently between groups across one year. However, children who liked active playing outside (i.e., gross motor activity) were stronger than others. Furthermore, children who like playing outside observed greater changes than the other groups in the ulna (right hand) and radius muscle thickness (left hand), suggesting that changes in forearm muscle size might be incongruent with changes in handgrip strength among the three activity groups. [ABSTRACT FROM AUTHOR]

Objectives: The factors involved in changes in grip strength (GS) during growth/development are not well known. Findings from cross‐sectional studies have indicated that digit lengths are associated with physical fitness, including GS. This study aimed to investigate the association of changes in GS over 1 year and the second (2D) and fourth (4D) digit lengths in young children using the 4D as a covariate. Methods: One hundred and three young children (54 boys and 49 girls) performed maximum voluntary GS and ultrasound‐measured forearm muscle thickness measurements in the right hand. All participants completed the first measurement and underwent a second measurement 1 year after the first one. The 2D and 4D were taken on the palmar surface of the outstretched right hand at the second measurement. Results: The 2D was inversely associated with the change in GS (B = −2.1, p = 0.023) adjusted for all covariates. Girls had numerically lower adjusted changes in grip strength, although this was not statistically significant [−0.61 (−1.2, 0.02) kg]. When sex was removed from the model, the 2D remained inversely associated with the change in GS (B = −2.39, p = 0.011). Finally, when only adjusting for the 4D, the 2D was inversely associated with the change in GS (B = −3.07, p = 0.004). Conclusion: This study documented the association between changes in GS over 1 year and digit lengths in young children. The difference in children's digit length needs to be recognized as a factor involved in weak GS in children. [ABSTRACT FROM AUTHOR]

When health professionals measure the fitness levels of clients, body composition is usually estimated. In field settings, body composition is commonly estimated with skinfolds or bioelectrical impedance analysis. Recently, a portable ultrasound device has been manufactured to estimate what percentage of body mass is composed of adipose tissue ( AT%). A reported advantage of using ultrasound is that inter- and intrarater variations may be minimized when compared with the skinfold technique. Therefore, the purpose of this pilot study was twofold; 1) to determine the validity of a portable ultrasound device compared with skinfolds and 2) determine the reliability of the portable ultrasound device. Participants had their measurements taken in the following order: urine specific gravity, body mass, height, skinfolds and ultrasound determined. Participants had their urine specific gravity and ultrasound determined AT% estimates measured again 48 h later. The current pilot study found that the ultrasound was not a valid estimate of AT% when compared with the skinfold estimate ( TE > 4%). In addition, the 1-site estimate from the ultrasound was more reliable than the 3-site estimate of AT%. These data are of importance to practitioners because it demonstrates that while the ultrasound is not a valid estimate compared with skinfolds, the 1-site estimate may be able to track changes in AT% over time, making the ultrasound an option for assessing changes in body composition. [ABSTRACT FROM AUTHOR]

Hypertension is a risk factor for heart disease, and chronic exercise is recognized as a method for reducing resting blood pressure. Recent studies report that while exercise may benefit the majority of the population, the blood pressure adaptation is not always uniform; some individuals have an adverse blood pressure response to chronic aerobic exercise programmes. The purpose of this study was to examine the individual changes in resting blood pressure in response to exercise training regimens aimed at increasing muscle mass and strength. We have also included exercise (resistance and aerobic) in combination with blood flow restriction ( BFR). Of 74 individuals, 11% had an increased risk, 16% had a decreased risk and 73% had no change in risk classification following exercise. The statistical analysis found that the group that decreased risk with exercise tended to have higher baseline levels of blood pressure. However, there were little baseline differences between the group that increased risk or the group that had no change in risk, suggesting that starting values may not necessarily determine who will see a beneficial response. In conclusion, the blood pressure adaptation to resistance training and exercise with BFR is not homogeneous with some participants increasing, decreasing or staying in the same risk category following an exercise intervention. These are important findings as they would not have been noted or discussed when looking only at the group means. Future research may identify molecular predictors so that individuals at risk for adverse events can be identified prior to exercise. [ABSTRACT FROM AUTHOR]

When health professionals measure the fitness levels of clients, body composition is usually estimated. In practice, the reliability of the measurement may be more important than the actual validity, as reliability determines how much change is needed to be considered meaningful. Therefore, the purpose of this study was to determine the reliability of two bioelectrical impedance analysis ( BIA) devices (in athlete and non-athlete mode) and compare that to 3-site skinfold ( SKF) readings. Twenty-one college students attended the laboratory on two occasions and had their measurements taken in the following order: body mass, height, SKF, Tanita body fat-350 ( BF-350) and Omron HBF-306C. There were no significant pairwise differences between Visit 1 and Visit 2 for any of the estimates ( P>0·05). The Pearson product correlations ranged from r = 0·933 for HBF-350 in the athlete mode (A) to r = 0·994 for SKF. The ICC's ranged from 0·93 for HBF-350(A) to 0·992 for SKF, and the MD's ranged from 1·8% for SKF to 5·1% for BF-350(A). The current study found that SKF and HBF-306C(A) were the most reliable (<2%) methods of estimating BF%, with the other methods ( BF-350, BF-350(A), HBF-306C) producing minimal differences greater than 2%. In conclusion, the SKF method presented with the best reliability because of its low minimal difference, suggesting this method may be the best field method to track changes over time if you have an experienced tester. However, if technical error is a concern, the practitioner may use the HBF-306C(A) because it had a minimal difference value comparable to SKF. [ABSTRACT FROM AUTHOR]

Introduction Elastic band ( EB) training is a common form of resistance training used by the elderly, individuals with joint problems or those recovering from injury. EB training performed at low intensities by these populations may have little effect on muscle hypertrophy. However, when combined with blood flow restriction ( BFR), low-intensity EB resistance training may result in muscle hypertrophy. Methods Postmenopausal women (61 ± 5 years) were assigned to a moderate-to-high-intensity EB group ( MH, n = 8) or a low-intensity EB group combined with BFR ( LI- BFR, n = 6). Each group performed seated chest press, seated row and seated shoulder press with EB three times a week for eight weeks. EB colours progressed in each group by having participants maintain a rating of 7-9 on the OMNI Resistance for active muscle ( OMNI- RES AM) scale (0-10) throughout training. In the LI- BFR group, BFR pressure progressed during the first 4 weeks of training (80-120 mmHg), after which EB colours were progressed. Results 1-repetition maximum increased for chest press ( P = 0·01), shoulder press ( P = 0·02) and seated row ( P = 0·01), but no differences were found between groups. Only pectoralis major muscle thickness in the upper body increased ( P = 0·04). A trend was found for an increase in total bone-free lean body mass ( P = 0·055). Conclusions The main findings of this study were that moderate-to-high-intensity EB training and low-intensity EB training with BFR resulted in similar increases in strength, total bone-free lean body mass and muscle thickness. [ABSTRACT FROM AUTHOR]

The purpose was to investigate the acute effects of blood flow restriction ( BFR) on arterial and venous hemodynamic parameters. Nine participants completed a 10-min time control (resting condition) and then a lower body BFR protocol. The protocol was five, 5-min bouts of restrictive cuff inflation with 3-min of deflation between each bout. The pressure was set relative to each individual's thigh circumference. There were no significant differences between resting and BFR conditions for blood pressure or wave reflection. There was, however, a significant decrease in venous compliance and maximal venous outflow following BFR. Acute BFR with pressures relative to thigh circumference does not result in acute changes in blood pressure or wave reflection. There is, however, an acute decrease in venous compliance and maximal venous outflow, the significance of which is currently unknown. These results suggest that an acute BFR protocol affects venous but not arterial hemodynamics. [ABSTRACT FROM AUTHOR]

We investigated the acute and chronic effects of low-intensity concentric or eccentric resistance training with blood flow restriction (BFR) on muscle size and strength. Ten young men performed 30% of concentric one repetition maximal dumbbell curl exercise (four sets, total 75 reps) 3 days/week for 6 weeks. One arm was randomly chosen for concentric BFR (CON-BFR) exercise only and the other arm performed eccentric BFR (ECC-BFR) exercise only at the same exercise load. During the exercise session, iEMG for biceps brachii muscles increased progressively during CON-BFR, which was greater (p,0.05) than that of the ECC-BFR. Immediately after the exercise, muscle thickness (MTH) of the elbow flexors acutely increased (p,0.01) with both CON-BFR and ECC-BFR, but was greater with CON-BFR (11.7%) (p,0.01) than ECC-BFR (3.9%) at 10-cm above the elbow joint. Following 6-weeks of training, MRI-measured muscle cross-sectional area (CSA) at 10-cm position and mid-upper arm (12.0% and 10.6%, respectively) as well as muscle volume (12.5%) of the elbow flexors were increased (p,0.01) with CON-BFR. Increases in muscle CSA and volume were lower in ECC-BFR (5.1%, 0.8% and 2.9%, respectively) than in the CON-BFR and only muscle CSA at 10-cm position increased significantly (p,0.05) after the training. Maximal voluntary isometric strength of elbow flexors was increased (p,0.05) in CON-BFR (8.6%), but not in ECC (3.8%). These results suggest that CON-BFR training leads to pronounced acute changes in muscle size, an index of muscle cell swelling, the response to which may be an important factor for promoting muscle hypertrophy with BFR resistance training. [ABSTRACT FROM AUTHOR]

Although evidence for high-intensity resistance training-induced muscle hypertrophy has accumulated over the last several decades, the basic concept of the training can be traced back to ancient Greece: Milo of Croton lifted a bull-calf daily until it was fully grown, which would be known today as progressive overload. Now, in the 21st century, different types of training are being tested and studied, such as low-intensity exercise combined with arterial as well as venous blood flow restriction ( BFR) to/from the working muscles. Because BFR training requires the use of a cuff that is placed at the proximal ends of the arms and/or legs, the BFR is only applicable to limb muscles. Consequently, most previous BFR training studies have focused on the physiological adaptations of BFR limb muscles. Muscle adaptations in non- BFR muscles of the hip and trunk are lesser known. Recent studies that have reported both limb and trunk muscle adaptations following BFR exercise training suggest that low-intensity (20-30% of 1 RM) resistance training combined with BFR elicits muscle hypertrophy in both BFR limb and non- BFR muscles. However, the combination of leg muscle BFR with walk training elicits muscle hypertrophy only in the BFR leg muscles. In contrast to resistance exercise with BFR, the exercise intensity may be too low during BFR walk training to cause muscle hypertrophy in the non- BFR gluteus maximus and other trunk muscles. Other mechanisms including hypoxia, local and systemic growth factors and muscle cell swelling may also potentially affect the hypertrophic response of non- BFR muscles to BFR resistance exercise. [ABSTRACT FROM AUTHOR]

Objectives: Exercise to failure results in similar muscle protein synthesis responses, independent of intensity. However, low-intensity exercise likely requires more time under tension and those with injuries may be incapable of sustaining the mechanical stress to reach failure. Design: The purpose was to determine whether elastic knee wraps (KW) provide a stimulus to decrease time under tension and overall volume of work while maintaining a similar level of metabolic stress. Methods: Thirteen healthy subjects participated in a randomized crossover study consisting of three trials. The first determined 1 repetition maximum (1RM) on the bilateral leg extension. Subjects were then assigned to a blood flow restriction (BFR) or control (CON) group. After trial 2, subjects crossed over to the opposite trial. KW were placed around the thigh of each leg during BFR. Leg extensions were completed at 30% 1RM until failure. Whole blood lactate (WBL) was taken pre-, post-, and 3 and 5 min postexercise. Heart rate (HR) was measured before, following the first and second sets, and 3 and 5 min postexercise. Results: This study found KW provide a BFR stimulus allowing failure to occur sooner with similar metabolic stress postreperfusion. There were no differences in HR at any time point. Conclusions: These results may benefit populations that cannot sustain the mechanical stress of high-intensity exercise or low-intensity exercise that requires a longer sustained time under tension. [ABSTRACT FROM AUTHOR]

The article reports on research conducted to investigate the effect endurance, strength and power training had on muscle fiber type shifting and to analyze the effects of various forms of exercise had on type I and type II interconversions. Researchers found that a shift from type II to type I fibers may occur under longer duration, higher volume endurance type events.

Historically, collegiate wrestlers have been associated with utilizing rapid weight loss methods to reach a desired weight class. Following three deaths in 1997, the National Collegiate Athletic Association (NCAA) implemented a program which prevents wrestlers from wrestling below a minimum weight (MW) of 5% body fat. Although numerous studies have investigated adolescent wrestlers, few have investigated collegiate wrestlers using the methods outlined by the NCAA. The purpose of this review paper is to outline potential problems with the current NCAA protocol as well as critique studies investigating the validity of methods to assess MW. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]