Showing papers on "Interval training published in 1991"

Uniqueness of interval and continuous training at the same maintained exercise intensity.

Abstract: The present study sought to evaluate the inconsistencies previously observed regarding the predominance of continuous or interval training for improving fitness. The experimental design initially equated and subsequently maintained the same relative exercise intensity by both groups throughout the program. Twelve subjects were equally divided into continuous (CT, exercise at 50% maximal work) or interval (IT, 30 s work, 30 s rest at 100% maximal work) training groups that cycled 30 min day−1, 3 days week−1, for 8 weeks. Following training, aerobic power (VO2max), exercising work rates, and peak power output were all higher (9–16%) after IT than after CT (5–7%). Vastus lateralis muscle citrate synthase activity increased 25% after CT but not after IT. A consistent increase in adenylate kinase activity (25%) was observed only after IT. During continuous cycling testing the CT group had reduced blood lactate (1ab) levels and respiratory quotient at both the same absolute and relative (70% VO2max) work rates after training, while the IT group displayed similar changes only at the same absolute work rates. By contrast, both groups responded similarly during intermittent cycling testing with lower 1ab concentrations seen only at absolute work rates. These results show that, of the two types of training programs currently employed, IT produces higher increases in VO2max and in maximal exercise capacity. Nevertheless, CT is more effective at increasing muscle oxidative capacity and delaying the accumulation of 1ab during continuous exercise.

Dietary carbohydrate, muscle glycogen, and power output during rowing training

Abstract: The belief that high-carbohydrate diets enhance training capacity (mean power output) has been extrapolated from studies that have varied dietary carbohydrate over a few days and measured muscle glycogen but did not assess power output during training. We hypothesized that a high-carbohydrate (HI) diet (10 g.kg body mass-1.day-1) would promote greater muscle glycogen content and greater mean power output during training than a moderate-carbohydrate (MOD) diet (5 g.kg body mass-1.day-1) over 4 wk of intense twice-daily rowing training. Dietary protein intake was 2 g.kg body mass-1.day-1, and fat intake was adjusted to maintain body mass. Twelve male and 10 female collegiate rowers were randomly assigned to the treatment groups. Training was 40 min at 70% peak O2 consumption (VO2) (A.M.) and either three 2,500-m time trials to assess power output or interval training at 70-90% peak VO2 (P.M.). Mean daily training was 65 min at 70% peak VO2 and 38 min at greater than or equal to 90% peak VO2. Mean muscle glycogen content increased 65% in the HI group (P less than 0.05) but remained constant at 119 mmol/kg in the MOD group over the 4 wk. Mean power output in time trials increased 10.7 and 1.6% after 4 wk in the HI and MOD groups, respectively (P less than 0.05). We conclude that a diet with 10 g carbohydrate.kg body mass-1.day-1 promotes greater muscle glycogen content and greater power output during training than a diet containing 5 g carbohydrate.kg body mass-1.day-1 over 4 wk of intense twice-daily rowing training.(ABSTRACT TRUNCATED AT 250 WORDS)

Monitoring exercise stress by changes in metabolic and hormonal responses over a 24-h period.

Abstract: Metabolic and endocrine responses of 14 subjects of varying levels of fitness to an intensive anaerobic interval training session were assessed before exercise and at 2 h, 4 h, 8 h and 24 h postexercise. The endocrine response of the same subjects to a control day, where they were required not to exercise, was also assessed and compared with the values obtained on the interval training day. Uric acid, urea, and creatine phosphokinase concentrations still remained elevated above pre-exercise values 24 h postexercise. Lactate, creatinine, testosterone and cortisol concentrations were significantly elevated above pre-exercise values immediately postexercise but these had reversed by 2 h postexercise. Over the remainder of the recovery period testosterone concentrations remained significantly lower than values measured at similar times on the control day. This was shown to be due directly to a change in testosterone as sex hormone binding globulin concentration remained constant throughout the recovery period. The data indicate that when comparisons of data were made to control (rest) days, imbalances in homeostasis, due to intensive training, are not totally reversed within the next 24-h. The data also demonstrate that the parameters measured undergo the same variations in subjects with a wide range of physical fitness, indicating that these parameters could be used to monitor exercise stress and recovery in athletes of a wide range of abilities. The more acute responses to exercise could be mistaken for overtraining if insufficient recovery time were not permitted between the final exercise session and taking blood samples, further emphasising the need to be able to recognise the difference between the fatigue associated with acute exercise and a state of chronic fatigue that may result from too little regeneration time within the training programme.

The Effect of Downhill Running Training on 200m and 2000m Running Performance

Abstract: Downhill running as a method of training for improved running performance is an option which has rarely been explored. The purpose of this study was to explore the idea that downhill interval training may be an effective form of improving efficiency and thus, performance time, in 200m and 2000m level running by producing increases in both stride length (SL) and stride frequency (SF). To test this hypothesis, twelve fit male subjects were divided into two training groups, downhill (0) and level (l), matched on the basis of a 2000m time trial performance and V02max. The dependant variables of time, SL and SF for both 200m and 2000m time trials were measured before and after a six week training program which consisted of an 8x300m interval session run twice per week. The L and D groups performed these intervals, on a grass surface, with a level and a 3.8% downhill grade, respectively. No significant improvements in performance or differences between the two groups were found for either criterion distance on any of the variables. Significant correlations, however, were found between increases in both SL and SF and decreases in both run times between preand post-training tests for both groups. Increases in SF were significantly correlated (r=0.918, p<0.01) with improvements in 2000m run time in the D group. SF was also found to significantly correlate with 200m time, as was both SL and SF with 2000m run time. It was concluded that neither the D or L training program implemented in this study yielded significant improvements in 200m or 2000m run times.• However, the results did imply that increasing both SL and SF may be factors in improving running performance. • In addition, the results suggest that downhill running may be beneficial for enhancing middle distance (2000m) running performance, particularly in increasing SF. iii