Marc Bonnefoy

Leg extensor power and dehydroepiandrosterone sulfate, insulin-like growth factor-I and testosterone in healthy active elderly people

Abstract We examined the association between quadriceps muscle function and serum levels of dehydroepiandrosterone sulphate (DHEAS), insulin-like growth factor I (IGF-I) and testosterone in a group of healthy elderly people. Fifty-three independent, community-dwelling elderly subjects (26 men and 27 women) aged from 66 to 84 years volunteered to participate in the study. Physical activity (PA) was evaluated by a questionnaire. Quadriceps maximal muscle power (W˙max) and optimal shortening velocity (vopt) were measured on a friction-loaded non-isokinetic cycle ergometer. The W˙max is expressed in relation to body mass (W˙max/kg, W · kg−1), and in relation to the mass of the two quadriceps muscles (W˙max/Quadr, W · kgQuadr−1). In women, when adjusted for age, anthropometric measurements and PA indices, IGF-I correlated significantly with W˙max/kg (partial correlation: r=0.59; P=0.001), W˙max/Quadr (r=0.58; P=0.002) and vopt (r=0.53; P=0.004), whereas DHEAS was correlated significantly with W˙max/kg (r=0.54; P=0.003) and W˙max/Quadr (r=0.58; P=0.002). No such correlation was found in men. These findings indicate that in healthy elderly women lower values for quadriceps muscle W˙max and vopt are related, independently of age, anthropometric measurements and PA indices, to lower circulating levels of DHEAS and IGF-I.

Peak anaerobic power in elderly men

Abstract The relationship of maximal anaerobic power (Pmax) of the quadriceps muscle and corresponding optimal shortening velocity (vopt) with age, habitual physical activity (PA) and maximal oxygen consumption (V˙O2max) were assessed in 37 healthy older [71.1 (SD 3.8) years] men and compared to those of 16 young [22.7 (SD 3.4) years] men. The PA was evaluated using a questionnaire. The Pmax and vopt were measured on a friction loaded non-isokinetic cycle ergometer. The Pmax was expressed relative to body mass –Pmax · kg−1, and relative to the mass of the two quadriceps muscles –Pmax· kgquad−1. The decline of Pmax· kg−1 from youth to advanced age (8.3% per decade) was greater than the decrease in quadriceps muscle mass (3.8% per decade), in Pmax· kgquad−1 (5.9% per decade) and in vopt (4.3% per decade). In the older men, a negative relationship of Pmax· kg−1 (r = −0.33) and Pmax· kgquad−1 (r = −0.44) with age was found. Ergometer measurements were not correlated with PA activity indices or V˙O2max, while V˙O2max was positively associated with PA. In a multiple stepwise regression analysis age was the only variable that contributed significantly to Pmax· kg−1 and Pmax· kgquad−1 variances. Our findings indicated that in these healthy elderly men, unlike the fall in V˙O2max, habitual PA did not attenuate the decline in Pmax of the quadriceps muscle with age. This finding was different from a previously described relationship in older women and would suggest sex differences in determining Pmax in healthy older subjects.

Relationship of physical activity and fitness to lipid and lipoprotein (a) in elderly subjects.

PURPOSE To determine, both by a cross-sectional and longitudinal study design, the relationship of maximal oxygen consumption (VO2max) and physical activity (PA) to blood lipids and lipoprotein(a) [Lp(a)] in a population of healthy and weight-stable elderly volunteers aged 66-84 yr. METHODS In a cross-sectional study in 52 subjects (23 men and 29 women), all independent variables (age, anthropometric, VO2max, and PA indices) were used in a multiple stepwise regression analysis to select variables influencing lipid and lipoprotein parameters. In a prospective nonintervention study, 38 subjects (17 men and 21 women) were reexamined after 6 months. RESULTS In a cross-sectional study, sports activity index contributed significantly to total cholesterol (TC), low density lipoprotein (LDL) cholesterol (LDL-C), TC/high density lipoprotein (HDL) cholesterol (HDL-C) ratio, and LDL-C/HDL-C ratio variance in men, whereas VO2max accounted for 23% variance of apolipoprotein A-I in women. In a prospective study, there was no indication that any measured variable was correlated with absolute or relative changes in PA indices in the total group or when analyzed by gender. CONCLUSIONS These data confirm that favorable relationship between PA/fitness and blood lipid profile is visible in elderly people but spontaneous changes in habitual PA are not a sufficient stimulus to alter serum lipid and lipoprotein levels in this population. Furthermore, there is no direct association between Lp(a) levels and PA, fitness, or body composition in the elderly men and women.

Intramyocellular lipid variations in active older men: relationship with aerobic fitness

Intramyocellular lipid (IMCL) variations in older men are poorly explored. In young adults, IMCL can be influenced by both diet and exercise interventions; this flexibility is related to aerobic fitness. We evaluated in active older adults the influence of maximal aerobic capacity on short‐term diet and exercise‐induced variations in IMCL stores.