This study was undertaken to determine whether or not elastic compression stockings (ECS) can be used in elderly sportsmen to increase performance and leg pain recovery between two maximal exercises. For 2 weeks, 12 trained elderly cyclists, 63 (3) years old, performed two 5-min maximal exercises, Plim1 and Plim2, separated by an 80-min recovery period, twice a week with a 2-day rest interval. During the 80-min recovery period, they randomly wore or did not wear grip-top ECS Ganzoni-Sigvaris. ECS exerted a 44 hPa pressure at the ankle. Blood lactate concentrations, hematocrit, and plasma volume were measured after a 60-min rest and every 20 min during recovery. Leg sensations were assessed with a questionnaire. The decrease in maximal power between Plim1 and Plim2 was lower when wearing the ECS during the 80-min recovery period; when expressed as a percentage of Plim1, the difference reached 2.1 (1.4)%, P < 0.01. Between the two exercises, blood lactate concentrations and hematocrit were significantly decreased when wearing ECS. The increase in plasma volume was not significant. The 12 cyclists stated that wearing the ECS had a positive effect on their leg pain. Ten of the cyclists thought that it could have influenced their performance. However, no relationship was found between the gain in performance and the leg pain sensation. It was concluded that wearing ECS during an 80-min recovery period significantly increased subsequent performance. This was associated with a reduction in lactate and hematocrit.

This study was undertaken to determine whether the loss of muscle protein mass during aging could be explained by a reduced sensitivity of muscle protein synthesis to feeding and exercise. Male Wistar rats aged 12 and 24 mo were exercised by treadmill running for 4 mo. Protein synthesis was measured by the flooding dose method in tibialis anterior, soleus, and liver of conscious rested, trained rats and age-matched controls in the postprandial or in the postabsorptive state. No marked change with age could be detected in basal muscle protein synthesis. In contrast, protein synthesis was stimulated in adult but not in old rats by feeding in tibialis anterior and by exercise in soleus. In liver, protein synthesis was not modified by age but was stimulated by feeding and by exercise, which improved the response to feeding. We conclude that the impact of nutrition on muscle protein synthesis is blunted in old age, which could contribute to the age-related loss of nutrition-sensitive muscle proteins.

The effects of endurance training on the skeletal muscle of rats have been studied at sea level and simulated high altitude (4,000 m). Male Wistar rats were randomly assigned to one of four groups: exercise at sea level, exercise at simulated high altitude, sedentary at sea level, and sedentary at high altitude (n = 8 in each group). Training consisted of swimming for 1 h/day in water at 36 degrees C for 14 wk. Training and exposure to a high-altitude environment produced a decrease in body weight (P less than 0.001). There was a significant linear correlation between muscle mass and body weight in the animals of all groups (r = 0.89, P less than 0.001). High-altitude training enhanced the percentage of type IIa fibers in the extensor digitorum longus muscle (EDL, P less than 0.05) and deep portions of the plantaris muscle (dPLA, P less than 0.01). High-altitude training also increased the percentage of type IIab fibers in fast-twitch muscles. These muscles showed marked metabolic adaptations: training increased the activity levels of enzymes involved in the citric acid cycle (citrate synthase, CS) and the beta-oxidation of fatty acids (3 hydroxyacyl CoA dehydrogenase, HAD). This increase occurred mainly at high altitude (36 and 31% for HAD in EDL and PLA muscles; 24 and 31% for CS in EDL and PLA muscles). Training increased the activity of enzymes involved in glucose phosphorylation (hexokinase). High-altitude training decreased lactate dehydrogenase activity. Endurance training performed at high altitude and sea level increased the isozyme 1-to-total lactate dehydrogenase activity ratio to the same extent.(ABSTRACT TRUNCATED AT 250 WORDS)

Twenty-five competitive wrestlers restricted their caloric intake (28 kcal.kg-1.day-1) for 19 days, using a hypocaloric control (hC, n = 6), hypocaloric high-protein (hHP, n = 7), hypocaloric high-branched-chain amino acid (hBCAA, n = 6), hypocaloric low-protein (hLP, n = 6) diet to determine the effects of caloric restriction on body composition and performances versus control diet (C, n = 6). Anthropometric parameters (weight, percent body fat) and adipose tissue (AT) distribution measured by magnetic resonance imaging (MRI) obtained before and after diet, were compared. A significant highest body weight loss (-4 kg, p < 0.05) and decrease in the percent of body fat (-17.3%, p < 0.05) were observed for subjects of the hBCAA group. Subjects of the hBCAA group exhibited a significant reduction (-34.4%, p < 0.05) in abdominal visceral adipose tissue (VAT). There was no change in aerobic (VO2max) (p > 0.75) and anaerobic capacities (Wingate test) (p > 0.81), and in muscular strength (p > 0.82). We conclude that under our experimental conditions, the combination of moderate energy restriction and BCAA supplementation induced significant and preferential losses of VAT, and allowed maintainance of a high level of performance.

. Metabolic and vascular support for the role of myoglobin in humans: a multiparametric NMR study. Am J Physiol Regul Integr Comp Physiol 287: R1441-R1449, 2004 doi:10.1152/ajpregu.00242.2004In human muscle the role of myoglobin (Mb) and its relationship to factors such as muscle perfusion and metabolic capacity are not well understood. We utilized nuclear magnetic resonance (NMR) to simultaneously study the Mb concentration ([Mb]), perfusion, and metabolic characteristics in calf muscles of athletes trained long term for either sprint or endurance running after plantar flexion exercise and cuff ischemia. The acquisitions for 1 H assessment of Mb desaturation and concentration, arterial spin labeling measurement of muscle perfusion, and 31 P spectroscopy to monitor high-energy phosphate metabolites were interleaved in a 4-T magnet. The endurance-trained runners had a significantly elevated [Mb] (0.28 Ϯ 0.06 vs. 0.20 Ϯ 0.03 mmol/kg). The time constant of creatine rephosphorylation (PCr), an indicator of oxidative capacity, was both shorter in the endurance-trained group (34 Ϯ 6 vs. 64 Ϯ 20 s) and negatively correlated with [Mb] across all subjects (r ϭ 0.58). The time to reach maximal perfusion after cuff release was also both shorter in the endurance-trained group (306 Ϯ 74 vs. 560 Ϯ 240 s) and negatively correlated with [Mb] (r ϭ 0.56). Finally, Mb reoxygenation rate tended to be higher in the endurance-trained group and was positively correlated with PCr (r ϭ 0.75). In summary, these NMR data reveal that [Mb] is increased in human muscle with a high oxidative capacity and a highly responsive vasculature, and the rate at which Mb resaturates is well correlated with the rephosphorylation rate of Cr, each of which support a teleological role for Mb in O 2 transport within highly oxidative human skeletal muscle.