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Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
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Chronobiological Effects on Mountain Biking Performance.

António Silveira1, Francisco Alves2, Ana M Teixeira1

  • 1Research Center for Sport and Physical Activity (CIDAF), Faculty of Sports Science, University of Coimbra, 3004-531 Coimbra, Portugal.

International Journal of Environmental Research and Public Health
|September 9, 2020
PubMed
Summary
This summary is machine-generated.

Time of day does not significantly impact most physiological and mechanical variables during a mountain bike time trial. Performance metrics like heart rate and power output show strong morning-to-afternoon correlations.

Keywords:
MTBcircadian rhythmcyclingheart ratemechanical power

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Area of Science:

  • Sports Science
  • Exercise Physiology
  • Chronobiology

Background:

  • Understanding chronobiology's influence on athletic performance is crucial for optimizing training and competition.
  • Mountain biking (MTB) time trials involve complex physiological and mechanical demands.
  • Previous research has explored diurnal variations in various sports, but specific data for MTB time trials is limited.

Purpose of the Study:

  • To investigate the impact of time of day (morning vs. afternoon) on key variables during a mountain bike (MTB) time trial.
  • To analyze chronobiological influences on mechanical, kinematic, and physiological responses in elite MTB athletes.
  • To determine if diurnal variations affect performance metrics in a maximal MTB time trial setting.

Main Methods:

  • Sixteen male MTB athletes performed two 20-minute maximal time trial protocols.
  • One protocol was conducted in the morning, and the second in the afternoon on separate occasions.
  • Key variables including pedaling cadence, heart rate, and power output were measured and analyzed.

Main Results:

  • No significant differences were observed in most physiological and mechanical variables between morning and afternoon trials.
  • Pedaling cadence (stroke rate) was significantly higher in the morning protocol (85.06 ± 7.58 rpm) compared to the afternoon (82.63 ± 7.41 rpm).
  • Strong positive correlations were found between morning and afternoon measurements for heart rate, power output, and cadence.

Conclusions:

  • The time of day generally does not influence the physiological and mechanical outcomes of a maximal MTB time trial.
  • While pedaling cadence showed a slight diurnal variation, overall performance indicators remained consistent.
  • These findings suggest that athletes can expect similar internal and external loads regardless of whether the time trial is performed in the morning or afternoon.