Key result
Hypoxia and heat-stress significantly reduced mean power output in the middle and end sections of cycling time-trials, whereas negative deceptive feedback improved overall mean power output.
Why the study?
Does manipulation of environmental and feedback factors affect pacing strategy and mean power output in cyclists?
Meta-Analysis (n=351)
Does manipulation of environmental and feedback factors affect pacing strategy and mean power output in cyclists?
Mean Difference: -49.33 (95% CI -76.89–-21.81)
p-value: p=<0.001
Environmental stressors like hypoxia and heat-stress delay exercise regulation before reducing power output, whereas negative deceptive feedback can improve overall cycling performance.
Athletes should adjust pacing for heat/hypoxia exposure; extends meta-analytic evidence on deceptive feedback as a performance modulator.
In search of their optimal performance athletes will alter their pacing strategy according to intrinsic and extrinsic physiological, psychological and environmental factors. However, the effect of some of these variables on pacing and exercise performance remains somewhat unclear. Therefore, the aim of this meta-analysis was to provide an overview as to how manipulation of different extrinsic factors affects pacing strategy and exercise performance. Only self-paced exercise studies that provided control and intervention group(s), reported trial variance for power output, disclosed the type of feedback received or withheld, and where time-trial power output data could be segmented into start, middle and end sections; were included in the meta-analysis. Studies with similar themes were grouped together to determine the mean difference (MD) with 95% confidence intervals (CIs) between control and intervention trials for: hypoxia, hyperoxia, heat-stress, pre-cooling and various forms of feedback. A total of 26 studies with cycling as the exercise modality were included in the meta-analysis. Of these, four studies manipulated oxygen availability, eleven manipulated heat-stress, four implemented pre-cooling interventions and seven studies manipulated various forms of feedback. Mean power output (MPO) was significantly reduced in the middle and end sections (p 0.05). Negative feedback improved overall trial MPO and MPO in the middle section of trials (p 0.05). The available data suggests exercise regulation in hypoxia and heat-stress is delayed in the start section of trials, before significant reductions in MPO occur in the middle and end of the trial. Additionally, negative feedback involving performance deception may afford an upward shift in MPO in the middle section of the trial improving overall performance. Finally, performance improvements can be retained when participants are informed of the deception.
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Davies et al. (2016) conducted a meta-analysis in Cycling performance and pacing strategy (n=351). Environmental and feedback interventions (hypoxia, heat-stress, feedback) vs. Control conditions (normoxia, temperate environment, accurate feedback) was evaluated on Overall mean power output (MPO) in hypoxia vs normoxia (MD -49.33 W, 95% CI -76.89 to -21.81, p=<0.001). Hypoxia and heat-stress significantly reduced mean power output in the middle and end sections of cycling time-trials, whereas negative deceptive feedback improved overall mean power output.
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