Background and Purpose Maximal sprint exercise is known to exert marked and dynamic changes in cerebral blood flow and blood pressure both during and following exercise. However, the effect of maximal sprint exercise on cerebral autoregulation has not been investigated, which forms an important area of investigation given the growing interest surrounding high-intensity exercise and cerebrovascular function. Therefore, the purpose of this study was to investigate the acute effect of maximal sprint exercise on dynamic cerebral autoregulation (dCA) in healthy young adults.
Methods Twenty-one healthy adults (mean ± SD age, height and weight: 22.7 ± 3.1 years, 173.4 ± 8.4 cm and 70.3 ± 10.1 kg, respectively, 13 males, 8 females) volunteered to participate in this study, which involved a single experimental visit. Participants visited the laboratory >2 hours postprandial, having refrained from caffeine, alcohol and vigorous physical activity for 24 hours prior to the visit. dCA was determined using a single sit-to-stand manoeuvre. Following >10 min of seated baseline, participants rapidly (< 3 seconds) stood up and remained standing for 3 minutes. Middle cerebral artery blood velocity (MCAv) was measured using transcranial Doppler ultrasonography, and beat-to-beat blood pressure was measured using finger plethysmography. Participants then completed a maximal, 30 second Wingate test on a cycle ergometer, before repeating the dCA assessment after 25 minutes of seated recovery. Baseline measurements were taken as the last 60 seconds of seated measurements, and the nadir in both MCAv and mean arterial pressure (MAP) were identified as the minimum value during the initial 20 seconds following standing. The fall in MCAv and MAP were expressed in both absolute and relative terms, and dCA was quantified as the percentage fall in MCAv relative to the percentage fall in MAP upon standing (∆%MCAv/∆%MAP). Paired samples t-tests explored the effect of the Wingate test on MCAv, MAP and dCA responses.
Results Baseline MCAv was significantly lower following the Wingate test (59.4 ± 10.4 vs 65.5 ± 11.3 cm.s-1, P<0.01), whilst baseline MAP was unaltered (81.2 ± 10.3 vs 78.7 ± 11.1 mmHg, P=0.44). Upon standing, the fall in MAP was significantly greater following the Wingate test, expressed in both absolute (23.9 ± 6.4 vs 18.4 ± 8.5 mmHg, P=0.01) and relative (29.8 ± 8.3 vs 23.7 ± 11.1%, P=0.01) terms. The relative fall in MCAv from baseline during the sit-to-stand manoeuvre was significantly greater following the Wingate test (23.7 ± 6.2 vs 18.2 ± 8.1%, P=0.02), but not in absolute terms (14.1 ± 4.6 vs 12.0 ± 5.5 cm.s‑1, P=0.16). When expressed relative to each other, dCA was unaltered following exercise (0.9 ± 0.3 vs 0.9 ± 0.6, P=0.75).
Conclusion These findings indicate that maximal sprint exercise significantly impacts the MCAv and MAP responses during a single sit-to-stand manoeuvre. Specifically, the standing-induced fall in both MAP and MCAv are augmented 25 minutes following sprint exercise. Despite this, dynamic cerebral autoregulation remained unaltered in healthy young adults following a Wingate test.