Although chronic exercise is generally believed to improve the lipidemic profile, it is not clear whether this is due to exercise training or to other determinants such as the usually low body fat of athletes. The aim of the present study was to compare the lipidemic profile of young lean athletes and non-athletes matched for percentage body fat. Fourteen endurance athletes and fourteen sedentary men participated in the study. Participants provided two blood samples at the beginning and end of a 7-d period, during which they recorded physical activity and food intake. Athletes had significantly higher energy expenditure and energy intake but not significantly different macronutrient composition of their diet from non-athletes. No significant differences were found in serum triacylglycerol, total cholesterol, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol concentrations between groups. These data suggest that athletes and non-athletes with similar body fat do not differ in their lipidemic profiles.
Anatoli Petridou, Despina Lazaridou and Vassilis Mougios
Andreas Apostolidis, Vassilis Mougios, Ilias Smilios, Johanna Rodosthenous and Marios Hadjicharalambous
Purpose: Inconsistent results among studies examining the effects of caffeine on exercise performance are potentially due to interindividual variability in biological responses to caffeine ingestion. The aims, therefore, of the present study were to identify high and low caffeine responders and compare the influence of caffeine on exercise performance and biological responses between groups during a simulated soccer-game protocol on treadmill. Methods: Well-trained soccer players were distinguished as high (n = 11) and low (n = 9) caffeine responders based on resting blood pressure, plasma glycerol, nonesterified fatty acid, and epinephrine responses to caffeine. Participants underwent 2 simulated soccer-game protocols on a treadmill after caffeine (6 mg·kg−1) or placebo ingestion. Exercise performance and several biological responses were evaluated. Results: Exercise performance did not differ between the high and low responders to caffeine (P > .05). However, time to fatigue (high, caffeine: 797  s vs placebo: 487  s; low, caffeine: 625  s vs placebo 447  s) and countermovement jump (high, caffeine: 42.1 [5.5] cm vs placebo: 40.5 [5.7] cm; low, caffeine: 41.0 [3.8] cm vs placebo: 38.8 [4.6] cm) improved with caffeine relative to placebo (P < .001). Rating of perceived exertion was lower (P < .001) in high (13.4 [2.3]) than in low responders (14.3 [2.4]) with caffeine ingestion. Conclusions: Caffeine improved aerobic endurance and neuromuscular performance in well-trained soccer players regardless of their responsiveness to caffeine at rest. Since no changes in substrate utilization were found with caffeine supplementation, performance improvements could be attributed to positive effects on the central nervous system and/or neuromuscular function, although the precise mechanism remains unclear.