Among healthy women, Hispanic (Mexican American) ethnicity may be associated with modestly higher levels of adiposity and slightly lower amounts of FFM overall and in the trunk region in particular.

OBJECTIVE: To determine whether plasma leptin and insulin concentrations are related to adiposity-associated elevations in muscle sympathetic nerve activity (MSNA) with age in healthy adult humans. DESIGN: Cross-sectional investigation of young and older adult men. SUBJECTS: Thirty healthy adult men, 16 young (25 AE 1 y, mean AE s.e.) and 14 older (61 AE 1 y). MEASUREMENTSaRESULTS: The older men had higher (P`0.05) levels of body mass, BMI, total fat mass and truncal fat mass (dual energy X-ray absorptiometry) than the young men. MSNA burst frequency (microneurography) was $ 75% higher in the older men (P`0.001). Plasma leptin concentrations were $ 150% higher (P`0.01), whereas plasma insulin concentrations were $ 70% higher (P`0.05) in the older subjects. MSNA was related to both total (r 0.51, P`0.01) and truncal (r 0.56, P`0.01) fat mass. Plasma leptin concentrations were related to total and truncal fat mass (both r 0.83, P`0.001), and to MSNA (r 0.49, P`0.01). Plasma insulin concentrations were related to MSNA (r 0.38, P`0.05). We used partial correlation analyses to assess whether leptin andaor insulin are potential contributors to the relation between body fat and MSNA. Adjusting for the effects of plasma leptin, but not insulin, concentrations eliminated the signi®cant relations between MSNA and total and truncal fat mass. CONCLUSION: Our results: (1) demonstrate a positive relation between MSNA and plasma leptin concentrations in young and older healthy men; and (2) support the concept that circulating leptin concentrations may act as a humoral signal contributing to adiposity-associated elevations in MSNA with age in adult humans.

Hispanic women may undergo greater age-related reductions in physical functional capacity compared with Caucasian women. If so, a greater rate of decline in muscle strength with age could contribute. We tested this hypothesis in 82 healthy sedentary Caucasian (n = 37) and Hispanic (n = 45) adult women aged 21-78 years of similar socioeconomic status. Absolute one-repetition maximum (1-RM) strength of the knee extensors (KE) declined with advancing age in the Caucasian (r = -.55, p < .01) and Hispanic (r = -.45, p < .01) women; the rates of decline were similar in the two groups (-7% to 8% x decade(-1), p = .60). KE strength normalized for thigh fat-free mass (FFM) also declined with age in the Caucasian (r = .52, p < .01) and Hispanic (r = -.41, p < .01) women, the rates of decline being similar (-6% to 7% x decade(-1), p = .66). For all functional performance tasks (10-m walk, stair ascent, stair descent, and chair stand), performance time increased with advancing age (mean of four tasks vs age: Caucasian, r = .64, p < .01; Hispanic, r = .56, p < .01). Absolute and normalized KE 1-RM were inversely related to the mean time for the four performance tasks (r = -.34 to -.58, all p < .01). Normalized KE 1-RM was the best independent predictor of the age-related decline in task performance in both groups. These cross-sectional findings do not support the hypothesis that Hispanic ethnicity per se is associated with a greater decline in KE strength and performance tasks associated with KE strength in healthy women.

We tested the hypothesis that the age-related decline in maximal aerobic capacity, as measured by maximal oxygen uptake (VO(2 max)), is greater in Hispanic than in Caucasian women. We studied 146 healthy sedentary women aged 20-75 yr: 53 Hispanic (primarily of Mexican descent) and 93 Caucasian (non-Hispanic white). The groups did not differ in mean age, body mass, percent body fat, estimated physical activity-related energy expenditure, or education-based socioeconomic status (SES). During maximal exercise, respiratory exchange ratio, rating of perceived exertion, and percent predicted maximal heart rate were similar across age and ethnicity, suggesting equivalent maximum voluntary efforts in all subjects. VO(2 max) (ml x kg(-1) x min(-1)) was inversely related to age (P < 0.01) in Caucasian (r =-0.68) and Hispanic (r = -0.61) women. The absolute rate of decline in VO(2 max) with age was the same in the two groups (-0.31 ml x kg(-1) x min(-1) x yr(-1)). The relative rate of decline (% from age 25 yr) also was similar in the Caucasian (-9.0%) and Hispanic (-9.2%) women. When subjects of all ages were pooled, mean levels of VO(2 max) were similar in the two groups (approximately 28 ml x kg(-1) x min(-1)). These results, the first to our knowledge in Hispanics, indicate that mean levels of VO(2 max), as well as the rate of decline in VO(2 max) with age, are similar in healthy sedentary Hispanic and Caucasian women of similar SES. Thus it does not appear that Hispanic ethnicity per se modulates maximal aerobic capacity in this population.