Richard L. Carpenter

Moderate exercise-induced energy expenditure does not alter leptin levels in sedentary obese men.

Objective:The purpose of the study was to determine whether exercise-induced increases in energy expenditure (EE) alter circulating leptin levels in obese individuals. Design:Participants were randomized to an exercise intervention group (n = 8) or nonexercising control (n = 7). Setting:All data were collected on an outpatient basis at the exercise physiology laboratory at the University of Central Florida. Patients:Fifteen healthy obese males (24.9 ± 1.4 years old, body mass index 33.4 ± 0.7 kg · m−2). Interventions:Members of the intervention group underwent a single exercise session of moderate intensity (58.4 ± 1.3% of VO2max) for 60 minutes. Main Outcome Measurements:Postexercise, 24 hour postexercise, and 48 hour postexercise levels of leptin, insulin, and ghrelin. Results:The exercise session elicited an EE of 567 ± 25 Kcal. No significant main effect or time-by-group interactions for leptin or ghrelin were observed immediately after the exercise bout or in the days following the intervention. Conclusions:These preliminary data suggest that a bout of acute exercise of moderate intensity and duration does not affect leptin concentration. It is possible that a higher level of EE is required to elicit substantial changes.

Association of Age with Muscle Size and Strength Before and After Short-Term Resistance Training in Young Adults

Lowndes, J, Carpenter, RL, Zoeller, RF, Seip, RL, Moyna, NM, Price, TB, Clarkson, PM, Gordon, PM, Pescatello, LS, Visich, PS, Devaney, JM, Gordish-Dressman, H, Hoffman, EP, Thompson, PD, and Angelopoulos, TJ. Association of age with muscle size and strength before and after short-term resistance training in young adults. J Strength Cond Res 23(7): 1915-1920, 2009-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.