Serum leptin levels are associated with bone mass in nonobese women

Both serum leptin and bone mineral density are positively correlated with body fat, generating the hypothesis that leptin may be a systemic and/or local regulator of bone mass. We investigated 214 healthy, nonobese Australian women aged 20-91 yr. Bone mineral content, projected bone area, and body fat mass were measured by dual energy x-ray absorptiometry and fasting serum leptin levels by RIA. Associations between bone mineral content (adjusted for age, body weight, body fat mass, and bone area) and the natural logarithm of serum leptin concentrations were analyzed by multiple regression techniques. There was a significant positive association at the lateral spine, two proximal femur sites (Ward's triangle and trochanter), and whole body (partial r² = 0.019 to 0.036; all P < 0.05). Similar trends were observed at the femoral neck and posterior-anterior-spine. With bone mineral density the dependent variable (adjusted for age, body weight, and body fat mass), the association with the natural logarithm of leptin remained significant at the lateral spine (partial r² = 0.030; P = 0.011), was of borderline significance at the proximal femur sites (partial r² = 0.012 to 0.017; P = 0.058 to 0.120), and was not significant at the other sites. Our results demonstrate an association between serum leptin levels and bone mass consistent with the hypothesis that circulating leptin may play a role in regulating bone mass.

Psychological responses to acute resistance exercise in men and women who are obese

The purpose of the study was to investigate the psychological response to the very first session of resistance exercise on positive well-being (PWB), psychological distress (PD), and perception of fatigue in untrained men and women who are obese. Forty-five (male = 22, female = 23) untrained, middle-aged volunteers (mean ± SEM, 51.0 ± 1.0; range, 40-69 years) participated in the study. Participants were divided into 4 groups according to sex and obesity level (i.e., men who are obese, men who are nonobese, women who are obese, women who are nonobese). The threshold for obesity was defined as waist circumference ≥94 cm for men and 80 cm for women. Measures included body composition, aerobic power, muscle strength, and quality of life (Short Form 36, SF-36). Before and after resistance exercise, participants completed the Subjective Exercise Experience Scale (SEES). Paired sample t-tests were used to assess changes in SEES scores within group pre- and post-exercise and repeated-measures analysis of variance were used to assess changes in SEES scores between groups. Exercise increased the perception of PWB in both women who are obese and nonobese, without changes in PD or fatigue. In women, the change in PWB after exercise was negatively correlated with most scales of the SF-36, particularly with the mental health dimension (r = -0.55, p < 0.01). No significant changes in PWB, PD, or fatigue were found in men who are obese. Acute resistance exercise improved PWB in women who are obese and nonobese and those with lower self-perceived quality of life scores at the start improved the most. In addition, resistance exercise did not increase feelings of distress in either women or men who are obese.