Moderate intensity exercise of a non-structured nature seems to facilitate most of the disease prevention goals and health promoting benefits. With new guidelines promoting a less intense and more time-efficient approach to regular physical activity, it is hoped that an upward trend in the physical activity patterns, and specifically children at risk for chronic disease, will develop in the near future.
Abstract:The purpose of this study was to investigate the time course of hypertrophic adaptations in both the upper arm and trunk muscles following high-intensity bench press training. Seven previously untrained young men (aged 25±3 years) performed free-weight bench press training 3 days (Monday, Wednesday and friday) per week for 24 weeks. Training intensity and volume were set at 75% of one repetition maximum (1-RM) and 30 repetitions (3 sets of 10 repetitions, with 2−3 min of rest between sets), respectively. Muscle thickness (MTH) was measured using B-mode ultrasound at three sites: the biceps and triceps brachii and the pectoralis major. Measurements were taken a week prior to the start of training, before the training session on every Monday and 3 days after the final training session. Pairwise comparisons from baseline revealed that pectoralis major MTH significantly increased after week-1 (p=0.002), triceps MTH increased after week-5 (p=0.001) and 1-RM strength increased after week-3 (p=0.001) while no changes were observed in the biceps MTH from baseline. Significant muscle hypertrophy was observed earlier in the chest compared to that of the triceps. Our results indicate that the time course of the muscle hypertrophic response differs between the upper arm and chest.
The purpose of this study was to compare the prevalence of severe sarcopenia detected by total skeletal muscle mass (SM) index and of site-specific thigh sarcopenia for differing age groups in men and women. Japanese nonobese men and women aged 20 to 85 (n=1,994, 55 % women) had muscle thickness (MTH) measured by ultrasound at six sites on the anterior and posterior aspects of the body. SM was estimated from ultrasound-derived prediction equations. Site-specific thigh sarcopenia was calculated using ultrasoundmeasured MTH at the anterior and posterior aspects of the thigh (MTH ratio, anterior 50 %/posterior 50 % thigh MTH (A50/P50 MTH)). Sarcopenia was defined as a SM index (SM divided by height 2 ) of >2 standard deviations (SD) below the mean for young adults. Sitespecific thigh sarcopenia was defined as a ratio of A50/P50 MTH of >2 SD below the mean for young adults. Age was inversely correlated to SM index and A50/P50 MTH in men (r=−0.480 and r=−0.522) and women (r=−0.243 and r=−0.516). The prevalence rate of sarcopenia was less than 3 % for women under the age of 60, 7 % for ages 60-69, and 24 % for ages 70-80. In men, the prevalence rate of sarcopenia was less than 7 % under the age of 50, 18 % for ages 50-59, 33 % for ages 60-69, and 47 % for ages 70-85. Compared to the sarcopenia estimated by SM index, there was a higher prevalence of site-specific thigh sarcopenia observed in both sexes. These results suggest that site-specific thigh sarcopenia appears before it is able to be detected at the whole body level.
The aim of this review was to highlight research that has focused on examining expressions of peak oxygen uptake (VO2peak) in children and youth, with special reference to allometric scaling. VO2peak is considered the highest VO2 during an increasing workload treadmill or bicycle ergometer test until volitional termination. We have reviewed scholarly works identified from PubMed, One Search, EBSCOhost and Google Scholar that examined VO2peak in absolute units (L·min(-1)), relative units [body mass, fat-free mass (FFM)], and allometric expressions [mass, height, lean body mass (LBM) or LBM of the legs raised to a power function] through July 2015. Often, the objective of measuring VO2peak is to evaluate cardiorespiratory function and fitness level. Since body size (body mass and height) frequently vary greatly in children and youth, expressing VO2peak in dimensionless units is often inappropriate for comparative or explanatory purposes. Consequently, expressing VO2peak in allometric units has gained increased research attention over the past 2 decades. In our review, scaling mass was the most frequent variable employed, with coefficients ranging from approximately 0.30 to over 1.0. The wide variance is probably due to several factors, including mass, height, LBM, sex, age, physical training, and small sample size. In summary, we recommend that since skeletal muscle is paramount for human locomotion, an allometric expression of VO2peak relative to LBM is the best expression of VO2peak in children and youth.
LOFTIN, MARK, MELINDA SOTHERN, LAURA TROSCLAIR, ANN O'HANLON, JAMES MILLER, AND JOHN UDALL. Scaling VO 2 peak in obese and non-obese girls. Obes Res. 2001;9:290 -296. Objective: The conventional ratio method (milliliters O 2 per mass) typically is used to express VO 2 peak. The goal of the current study was to compare VO 2 peak of obese girls with normal-weight girls by ratio and allometric scaling methods. Research Methods and Procedures: We compared VO 2 peak by ratio and allometric methods in 46 obese and 47 normal-weight girls. Indirect calorimetry was used to measure VO 2 peak during either treadmill running or walking. Regression analysis was used to determine coefficients for mass and stature for each group with ANOVA used to compare data between groups. Results: The obese girls were taller and had higher values of body fatness (p Յ 0.05). Absolute VO 2 peak (liters per minute) was similar between groups; however VO 2 peak relative to mass was 50% lower (p Յ 0.05) in the obese girls. When VO 2 peak (milliliters per minute per kilogram) and mass were correlated, r ϭ Ϫ0.48 was found in the obese group. Allometric scaling of logarithmic transformed stature and mass reduced this to r ϭ Ϫ0.002, thus eliminating the bias associated with the ratio method. Adjusting VO 2 peak allometrically scaled for mass, stature, and the combination of mass and stature reduced the difference between groups from 50% (ratio method) to 10% to 11% (p Յ 0.05) with higher values found in the normal-weight girls. Discussion: These results demonstrate the bias associated with the ratio method when comparing VO 2 peak in obese girls with VO 2 peak in normal-weight girls. Allometric scaling eliminated the bias and thus may reflect a truer comparative response.
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