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The impact of a passive warm-up on power output

Introduction

Field-based team sports, such as field hockey, rugby union, rugby league and soccer are hugely popular sports worldwide. The majority of athletes incorporate some form of warm-up into all practice and competition situations, little however is understood about the advantages of this action. A number of alternative warm-ups have been suggested in recent years. Many team games involve repeated sprints of short duration, interspersed with periods of low intensity recovery. During the course of a field hockey or soccer match it has been recorded that a sprint or high intensity run occurs once every 30 s (Duthie et al., 2003; Reilly and Gilbourne, 2003).  These sprints tend to be short in duration (<4 seconds). Therefore it was decided that there would be large practical implications for games players if a study was completed to determine the effects of warm-up on repetitive sprints. The aim of this study is to determine the effects of a passive warm-up on repeated sprint performance.

Statistical analysis
Data will be checked for normal distribution and Sphericity (Mauchley's correction). Two-way analysis of variance (ANOVA) for repeated measures will be used to determine differences between trials for PPO, MPO, peak pedal revolutions, O2 uptake and heart rate (HR).  Where a significant difference is found a post-hoc Tukey test will be used.  A paired t-test will be used to analyse percentage decline in PPO and MPO and temperature data.  Pearson product moment correlation will be used to determine any relationships present. Significance will be determined as P<0.05. The results will be presented as the mean ± standard error (SE).

Limitations
There are a few limitations to this study.  The major limitation is that the training status of the subjects is unknown.  Therefore, no indication of the proportion of type I and type II fibres is able to be inferred from the type of activity completed by the subjects. The different fibre types work at different contractile speeds and show different velocity-power relationships.  This will have large implications on the magnitude of the PPO at the given pedal rate velocity (Bogdanis et al. 1998; Sargeant, 1994). It is not possible to obtain values for muscle lactate as a muscle biopsy is too intrusive, so blood lactate values will be taken instead. Although this does give a good indication of the conditions prevailing it does not give an accurate measure of muscle lactate level or muscle pH values which would give a clearer indication of the metabolic pathways occurring.  Temperature will be gauged using a measure of aural body temperature.  More distinct evidence of the effect of a passive warm-up would be provided if muscle temperature could be measured as the heating provided is aimed at heating solely the working muscle.

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