ES was greater for changes in lean body mass following short-term CS, repetitive-bout laboratory-based exercise tasks < or = 30 s (e.g., isometric, isokinetic, and isotonic resistance exercise), and upper-body exercise. CS does not appear to be effective in improving running and swimming performance. There is no evidence in the literature of an effect of gender or training status on ES following CS.

For exercise prescription purposes, it is often assumed that % heart rate reserve (%HRR) provides equivalent intensities to %VO2max. However, a recent study from this laboratory demonstrated that during cycling exercise %HRR is not equivalent to %VO2max, but is instead equivalent to a percentage of the difference between resting and maximal VO2, i.e., % VO2reserve (%VO2R). The current study examined these relationships during treadmill exercise. Fifty adults performed Bruce protocol treadmill tests to exhaustion. For each subject, data obtained at rest, at the end of each stage, and at maximum were used to determine linear regressions of %HRR versus %VO2max, and of %HRR versus %VO2R. For %HRR versus %VO2max the mean intercept and slope were -6.1+/-0.7 and 1.10+/-0.01, respectively, with a mean r of 0.990+/-0.002. For %HRR versus %VO2R, the mean intercept and slope were 1.5+/-0.6 and 1.03+/-0.01, respectively, with a mean r of 0.990+/-0.002. Both regressions differed statistically from the line of identity (i.e., intercept of 0 and slope of 1). However, the regression of %HRR versus %VO2R was significantly closer (P < 0.001 ) to the line of identity than was the regression of %HRR versus %VO2max. We conclude that %HRR should be considered as an indicator of %VO2R, not %VO2max, when prescribing treadmill exercise, as was previously concluded for cycling exercise.

Creatine, a natural nutrient found in animal foods, is alleged to be an effective nutritional ergogenic aid to enhance sport or exercise performance. Research suggests that oral creatine monohydrate supplementation may increase total muscle creatine [TCr], including both free creatine [FCr] and phosphocreatine [PCr]. Some, but not all, studies suggest that creatine supplementation may enhance performance in high-intensity, short-term exercise tasks that are dependent primarily on PCr (i.e., < 30 seconds), particularly laboratory tests involving repeated exercise bouts with limited recovery time between repetitions; additional corroborative research is needed regarding its ergogenic potential in actual field exercise performance tasks dependent on PCr. Creatine supplementation has not consistently been shown to enhance performance in exercise tasks dependent on anaerobic glycolysis, but additional laboratory and field research is merited. Additionally, creatine supplementation has not been shown to enhance performance in exercise tasks dependent on aerobic glycolysis, but additional research is warranted, particularly on the effect of chronic supplementation as an aid to training for improvement in competitive performance. Short-term creatine supplementation appears to increase body mass in males, although the initial increase is most likely water. Chronic creatine supplementation, in conjunction with physical training involving resistance exercise, may increase lean body mass. However, confirmatory research data are needed. Creatine supplementation up to 8 weeks has not been associated with major health risks, but the safety of more prolonged creatine supplementation has not been established. Creatine is currently legal and its use by athletes is not construed as doping.

Objectives-To study the eVects of a supervised, intensive (85% of one repetition maximum (1-RM)) 14 week resistance training programme on lipid profile and body fat percentage in healthy, sedentary, premenopausal women. Subjects-Twenty four women (mean (SD) age 27 (7) years) took part in the study. Subjects were randomly assigned to either a non-exercising control group or a resistance exercise training group. The resistance exercise training group took part in supervised 45-50 minute resistance training sessions (85% of 1-RM), three days a week on non-consecutive days for 14 weeks. The control group did not take part in any structured physical activity. Conclusions-These findings suggest that resistance training has a favourable eVect on lipid profile and body fat percentage in healthy, sedentary, premenopausal women. (Br J Sports Med 1999;33:190-195) Keywords: weight training; cholesterol; women; triglycerides; strength Hyperlipidaemia is a well documented risk factor for cardiovascular disease, and is the leading cause of death in men and women in the United States. Results-Two1 2 Several epidemiological studies have shown that low concentrations of total serum cholesterol and low density lipoprotein (LDL) cholesterol, as well as a normal body fat percentage, are associated with decreased cardiovascular disease morbidity and mortality.3-6 Considerable research has also been devoted to the eVect of exercise on lipid metabolism. Regular physical activity has been shown to improve lipid and glucose metabolism by increasing insulin sensitivity and serum high density lipoprotein (HDL) cholesterol, and decreasing serum LDL cholesterol and triglycerides.6-8 Acute exercise has also been shown to improve lipid profiles.9-13 Therefore, the therapeutic eVect of exercise is a widely recognised strategy to reduce the risk of cardiovascular disease.The eVect of aerobic exercise on serum lipids has been the focus of most study. Favourable changes in triglycerides, LDL and HDL cholesterol have been reported in men after acute aerobic exercise 12-14 and chronic endurance training. 4 The eVect of aerobic exercise on lipid metabolism in women, who have higher HDL cholesterol than men, 15 16 has been less studied. In one study of women no change was seen in HDL cholesterol after aerobic training. 17Many women take part in resistance training, either as a supplement or alternative to aerobic training. High intensity resistance training has been reported to improve body composition and strength, [18][19][20] with no significant change in aerobic capacity.7 8 21 22 The eVect of acute 10 and chronic 22-24 resistance training on lipid metabolism has been studied less than aerobic training, but there are reports of improved lipid profiles in both men and women after high intensity resistance training. [22][23][24] However, there is a dearth of well controlled studies on the eVect of resistance training on lipid metabolism in premenopausal women. Reductions in total and LDL cholesterol have been reported in premenopausal wom...

Interventions should be designed targeting total time spent on the computer, total time watching television, and maternal obesity in child obesity programs.