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Cerebrovascular responses during rowing: Do circadian rhythms explain morning and afternoon performance differences?
O K Faull1,2, J D Cotter1, S J E Lucas3,4
1School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand.
Scandinavian Journal of Medicine & Science in Sports
|June 20, 2014
Summary
Rowing performance is better in the afternoon, with faster times and higher power output. However, this improvement is not linked to changes in middle cerebral artery velocity (MCAv) or cerebral oxygenation during exercise.
Area of Science:
- Exercise Physiology
- Sports Science
- Neurovascular Coupling
Background:
- Athletic performance can exhibit diurnal variations, potentially influenced by physiological factors.
- Understanding cerebrovascular responses during exercise is crucial for optimizing training and performance.
Purpose of the Study:
- To characterize cerebrovascular responses to rowing exercise.
- To investigate if diurnal variations in these responses explain performance differences throughout the day.
Main Methods:
- Twelve male rowers underwent incremental rowing and a 2000-m time trial at 07:00h and 16:00h.
- Measurements included middle cerebral artery velocity (MCAv), cerebral and muscular tissue oxygenation, hemoglobin volume, heart rate, and PET CO2 using near-infrared spectroscopy.
Main Results:
- Afternoon time trials were faster (3.4s) with higher mean power output (3.2%).
- Exercise increased MCAv by 20-25% and reduced cerebral oxygenation, with no significant diurnal difference in these responses.
- Muscle oxygen extraction was similar, but total hemoglobin volume was lower in the afternoon.
Conclusions:
- Rowing performance is enhanced in the afternoon compared to the morning.
- This performance improvement is not explained by differences in MCAv or exercise-induced changes in cerebral oxygenation.
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