Search

Many athletes seek to optimize body composition to fit the physical demands of their sport. American football requires a unique combination of size, speed, and power. The purpose of the current study was to evaluate longitudinal changes in body composition in Division I collegiate football players. For 57 players (mean ± SD, age = 19.5 ± 0.9 years, height = 186.9 ± 5.7 cm, weight = 107.7 ± 19.1 kg), body composition was assessed via dual-energy x-ray absorptiometry in the off-season (March- Pre), end of off-season (May), mid-July (Pre-Season), and the following March (March-Post). Outcome variables included weight, body fat percentage (BF%), fat mass, lean mass (LM), android and gynoid (GYN) fat, bone mineral content (BMC), and bone mineral density (BMD). For a subset of athletes (n = 13 out of 57), changes over a 4-year playing career were evaluated with measurements taken every March. Throughout a single year, favorable changes were observed for BF% (Δ = -1.3 ± 2.5%), LM (Δ = 2.8 ± 2.8 kg), GYN (A = -1.5 ± 3.0%), BMC (Δ = 0.06 ± 0.14 kg), and BMD (Δ = 0.015 ± 0.027 g⋅cm-2, all p ≤ 0.05). Across 4 years, weight increased significantly (Δ = 6.6 ± 4.1 kg) and favorable changes were observed for LM (Δ = 4.3 ± 3.0 kg), BMC (Δ = 0.1 8 ± 0.1 7 kg), and BMD (Δ = 0.033 ± 0.039 g⋅-2, all p ≤ 0.05). Similar patterns in body composition changes were observed for linemen and non-linemen. Results indicate that well-trained collegiate football players at high levels of competition can achieve favorable changes in body composition, even late in the career, which may confer benefits for performance and injury prevention. [ABSTRACT FROM AUTHOR]

The article offers information whether effects of increasing and decreasing exercise levels are symmetric in weight gain and weight loss. According to the author, changes in adiposity are compared with the running distances at baseline and follow-up in men and women whose reported exercise increased or decreased during the 7.7 years of follow up. He emphasized that due to the reductions of weekly exercise in men and women, weight gain may not be reversed by resuming prior activity. Moreover, men's exercise threshold for symmetric weight change with changing exercise levels has been agreed by the IOM guidelines.

The article presents a prospective study which examines the hypothesis that long-term maintenance of vigorous activity, particularly running, attenuates age-related weight gain. The subjects of the study were 6,119 male and 2,221 female runners whose running distances changed after years. Based on the follow-up survey of these individuals, both sexes increased their body weight and waist circumference as their running intervals changed over time. According to the authors, both men and women gained less weight relative to the level of their vigorous activity.

Introduction/Purpose: Data from vigorously active women (runners) suggested that declines in adiposity with weekly running distance were nonlinear and dependent on whether the women are relatively lean or fat. The purpose of the current study is to assess the cross-sectional relationship between the amount of moderate-intensity physical activity (walking distance) and indicators of adiposity. Methods: Cross-sectional analyses (i.e., quadratic polynomial regression, regression for percentiles of adiposity) of body mass index (BMI), body circumferences, and bra cup sizes in 27,596 women. Results: The estimated percent reductions between walking 40-50 km·wk-1 and < 10 km·wk-1 were greatest for BMI, intermediate for waist circumference and cup size, and least for hip and chest circumferences. The relationships of walking distance to SMI and body circumferences were all nonlinear (convex). In addition, the inverse relationship between weekly walking distance and adiposity was greatest at the highest percentile of BMI, body circumferences, and cup size, and least at the lowest percentiles. Thus, the decline in adiposity per kilometer per week increment in walking distance was greatest in overweight mostly sedentary women and least in lean active women. The decline in SMI per kilometer per week of exercise was greater in the walkers than previously reported for runners. However, based on the relationships between walking distance and percentiles of the BMI distribution reported here, we show that the majority of this difference is attributable to the leanness of the runners and greater fatness of the walker. Conclusion: These data suggest that in women the greatest benefit of walking may be among the most obese and that at higher weekly distances the declines in weight associated with walking diminish. Whether these relationships are causal remains to be determined. [ABSTRACT FROM AUTHOR]