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Cerebrovascular responses during rowing: Do circadian rhythms explain morning and afternoon performance differences?
Author(s) -
Faull O. K.,
Cotter J. D.,
Lucas S. J. E.
Publication year - 2015
Publication title -
scandinavian journal of medicine and science in sports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.575
H-Index - 115
eISSN - 1600-0838
pISSN - 0905-7188
DOI - 10.1111/sms.12273
Subject(s) - rowing , medicine , morning , cardiology , time trial , middle cerebral artery , circadian rhythm , oxygenation , heart rate , anaerobic exercise , deoxygenated hemoglobin , anesthesia , rating of perceived exertion , physical therapy , blood pressure , hemoglobin , ischemia , archaeology , history
The purpose of this study was to characterize cerebrovascular responses to rowing exercise, investigating whether their diurnal variation might explain performance differences across a day. Twelve male rowers completed incremental rowing exercise and a 2000‐m ergometer time trial at 07:00 h and 16:00 h, 1 week apart, while middle cerebral artery velocity ( MCA v), cerebral (prefrontal), and muscular (vastus lateralis) tissue oxygenation and hemoglobin volume (via near‐infrared spectroscopy), heart rate, and pressure of end‐tidal CO 2 ( P ET CO 2 ) were recorded. MCA v was 20–25% above resting levels (68 ± 12 cm/s) during submaximal and maximal exercise intensities, despite P ET CO 2 being reduced during maximal efforts (down ∼ 0.5–0.8 k P a); thus revealing a different perfusion profile to the inverted‐ U observed in other exercise modes. The afternoon time trial was 3.4 s faster (95% confidence interval 0.9–5.8 s) and mean power output 3.2% higher (337 vs 347 W ; P = 0.04), in conjunction with similar exercise‐induced elevations in MCA v ( P = 0.60) and reductions in cerebral oxygenation ( TOI ) ( P = 0.12). At the muscle, afternoon trials involved similar oxygen extraction ( HH b volume and TOI ) albeit from a relatively lower total H b volume ( P < 0.01). In conclusion, rowing performance was better in the afternoon, but not in conjunction with differences in MCA v or exercise‐induced differences in cerebral oxygenation.