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In this study, we assessed age-related changes in indoor 16.1-km cycling time-trial performance in 40 competitive male cyclists aged 25-63 years. Participants completed two tests: (1) a maximal ramped Kingcycle ergometer test, with maximal ramped minute power (RMPmax, W) recorded as the highest mean external power during any 60 s and maximal heart rate (HRmax, beats min(-1)) as the highest value during the test; and (2) an indoor Kingcycle 16.1-km time-trial with mean external power output (W), heart rate (beats min(-1)), and pedal cadence (rev min(-1)) recorded throughout the event. Results revealed age-related declines (P < 0.05) in absolute and relative time-trial external power output [(24 W (7.0%) per decade], heart rate [7 beats min(-1) (3.87%) per decade], and cadence [3 rev min(-1) (3.1%) per decade]. No relationships (P > 0.05) were observed for mean power output and heart rate recorded during the time-trial versus age when expressed relative to maximal ramped minute power and maximal heart rate respectively. Strong relationships (P < 0.05) were observed for maximal ramped minute power and time-trial power (r= 0.95) and for maximal heart rate and time-trial heart rate (r= 0.95). Our results show that indoor 16.1-km time-trial performance declines with age but relative exercise intensity (%RMPmax and %HRmax) does not change.

This study was designed to investigate the effect of exercise intensity on insulin resistance by comparing moderate- and high-intensity interventions of equal energy cost. Maximum oxygen consumption (VO(2max)), insulin, glucose and triglycerides were measured in 64 sedentary men before random allocation to a non-exercise control group, a moderate-intensity exercise group (three 400-kcal sessions per week at 60% of VO(2max)) or a high-intensity exercise group (three 400-kcal sessions per week at 80% of VO(2max)). An insulin sensitivity score was derived from fasting concentrations of insulin and triglycerides, and insulin resistance was assessed using the homeostasis model assessment of insulin resistance (HOMA-IR). Data were available for 36 men who finished the study. After 24 weeks, insulin concentration decreased by 2.54+/-4.09 and 2.37+/-3.35 mU l(-1), insulin sensitivity score increased by 0.91+/-1.52 and 0.79+/-1.37, and HOMA-IR decreased by -0.6+/-0.8 and -0.5+/-0.8 in the moderate- and high-intensity exercise groups, respectively. When data from the exercise groups were combined, one-way analysis of variance with one-tailed post hoc comparisons indicated that these changes were significantly greater than those observed in the control group (all P<0.05). Twenty-four week changes in insulin concentration, insulin sensitivity score and HOMA-IR were not significantly different between the exercise groups. These data suggest that exercise training is accompanied by a significant reduction in insulin resistance, as indicated by well-validated surrogate measures. These data also suggest that moderate-intensity exercise is as effective as high-intensity exercise when 400 kcal are expended per session.

This study was designed to investigate the effect of exercise intensity on cardiorespiratory fitness and coronary heart disease risk factors. Maximum oxygen consumption (Vo(2 max)), lipid, lipoprotein, and fibrinogen concentrations were measured in 64 previously sedentary men before random allocation to a nonexercise control group, a moderate-intensity exercise group (three 400-kcal sessions per week at 60% of Vo(2 max)), or a high-intensity exercise group (three 400-kcal sessions per week at 80% of Vo(2 max)). Subjects were instructed to maintain their normal dietary habits, and training heart rates were represcribed after monthly fitness tests. Forty-two men finished the study. After 24 wk, Vo(2 max) increased by 0.38 +/- 0.14 l/min in the moderate-intensity group and by 0.55 +/- 0.27 l/min in the high-intensity group. Repeated-measures analysis of variance identified a significant interaction between monthly Vo(2 max) score and exercise group (F = 3.37, P < 0.05), indicating that Vo(2 max) responded differently to moderate- and high-intensity exercise. Trend analysis showed that total cholesterol, low-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol, and fibrinogen concentrations changed favorably across control, moderate-intensity, and high-intensity groups. However, significant changes in total cholesterol (-0.55 +/- 0.81 mmol/l), low-density lipoprotein cholesterol (-0.52 +/- 0.80 mmol/l), and non-high-density lipoprotein cholesterol (-0.54 +/- 0.86 mmol/l) were only observed in the high-intensity group (all P < 0.05 vs. controls). These data suggest that high-intensity training is more effective in improving cardiorespiratory fitness than moderate-intensity training of equal energy cost. These data also suggest that changes in coronary heart disease risk factors are influenced by exercise intensity.

This study was designed to investigate the effect of exercise intensity on insulin resistance by comparing moderate- and high-intensity interventions of equal energy cost. Maximum oxygen consumption ( VO2max), insulin, glucose and triglycerides were measured in 64 sedentary men before random allocation to a non-exercise control group, a moderate-intensity exercise group (three 400-kcal sessions per week at 60% of VO2max) or a high-intensity exercise group (three 400-kcal sessions per week at 80% of VO2max). An insulin sensitivity score was derived from fasting concentrations of insulin and triglycerides, and insulin resistance was assessed using the homeostasis model assessment of insulin resistance (HOMA-IR). Data were available for 36 men who finished the study. After 24 weeks, insulin concentration decreased by 2.54±4.09 and 2.37±3.35 mU l−1, insulin sensitivity score increased by 0.91±1.52 and 0.79±1.37, and HOMA-IR decreased by −0.6±0.8 and −0.5±0.8 in the moderate- and high-intensity exercise groups, respectively. When data from the exercise groups were combined, one-way analysis of variance with one-tailed post hoc comparisons indicated that these changes were significantly greater than those observed in the control group (all P<0.05). Twenty-four week changes in insulin concentration, insulin sensitivity score and HOMA-IR were not significantly different between the exercise groups. These data suggest that exercise training is accompanied by a significant reduction in insulin resistance, as indicated by well-validated surrogate measures. These data also suggest that moderate-intensity exercise is as effective as high-intensity exercise when 400 kcal are expended per session. [ABSTRACT FROM AUTHOR]

In this study, we assessed the agreement between the powers recorded during a 30 s upper-body Wingate test using three different methods. Fifty-six men completed a single test on a Monark 814E mechanically braked ergometer fitted with a Schoberer Rad Messtechnik (SRM) powermeter. A commercial software package (Wingate test kit version 2.21, Cranlea, UK) was used to calculate conventional and corrected (with accelerative forces) values of power based on a resistive load (5% body mass) and flywheel velocity. The SRM calculated powers based on torque (measured at the crank arm) and crank rate. Values for peak 1 and 5 s power and mean 30 s power were measured. No significant differences ( P  >0.05) were found between the three methods for 30 s power values. However, the corrected values for peak 1 and 5 s power were 36 and 23% higher ( P  <0.05) respectively than those for the conventional method, and 27 and 16% higher ( P  <0.05) respectively than those for the SRM method. The conventional and SRM values for peak 1 and 5 s power were similar ( P  >0.05). Power values recorded using each method were influenced by sample time ( P  <0.05). Our results suggest that these three measures of power are similar when sampled over 30 s, but discrepancies occur when the sample time is reduced to either 1 or 5 s. [ABSTRACT FROM AUTHOR]