Factors influencing short duration, high-intensity endurance cycling

[摘要] ENGLISH ABSTRACT:A 5 km cycling time trial (TT) demands high, sustained muscle power output andsubstantial oxidative and glycolytic energy delivery. The aims of this study were to firstlyuse the novel approach of using Peak Sustained Power Output (PSPO) as a predictor ofcycling performance for variable fixed-workload testing and 5 km time trialing andwhether oral creatine supplementation would affect 5 km time trial performance andmetabolism. The effect of oral creatine supplementation with 20 g/day for 7 days on 5 kmtime trial performance and metabolism after a random-variable workload protocol(stochastic test) was investigated in a single-blind placebo controlled study. Thirteentrained male cyclists volunteered for the study that was approved by the University ofStellenbosch Research Ethics Committee. We hypothesized that Cr supplementationwould affect time trial performance as well as the appearance of breakdown products ofadenine nucleotides in the plasma. Baseline: the subjects' peak power output wasmeasured and they underwent a baseline stochastic test followed immediately by a 5 kmtime trial (STI) and on a different day, a single 5 km time trial test (Tl) was undertaken.Study 1: In the following week the subjects repeated the stochastic test with 5 km timetrial (ST2) and on a different day a 5 km time trial (T2). During T2 blood samples weretaken at regular intervals as well as during recovery. A muscle biopsy was taken after T2in the recovered state. The major performance predictors were the 5-km time trials (TTland TT2) with a coefficient of variation between the thirteen trained male cyclists of0.6%. The 5 km time trials in the fatigued state (STI and ST2) had a coefficient ofvariation of 0.7%. Results: There was a significant difference between 5 km TTperformed fresh and 5km TT performed fatigued (P=0.0001). The decrement in timeranged between 1.0 sec to 38.0 sec. The relationship between two different high intensityendurance performance tests: PSPO and 5 km TT (TT mean) had a correlation ofr=-0.79P

[发布机构] Stellenbosch University