Effects of Bicycle Ergometer Exercise on Cerebral Blood Flow Velocity and Electroencephalogram Response in Normoxia and Hypoxia

BACKGROUND: The cerebral blood flow velocity (CBFV) has been known to increase in response to acute hypoxia. However, how CBFV might respond to exercise in hypoxic conditions and be associated with electroencephalogram (EEG) remains unclear. The purpose of this study was to evaluate the effect of exercise in hypoxic conditions corresponding to altitudes of 4,000 m on CBFV and EEG. METHODS: In a randomized, double-blind, balanced crossover study, ten healthy volunteers (19.8±0.4 years) were asked to perform the incremental bicycle ergometer exercise twice in hypoxic and control (sea level) conditions with a 1-week interval, respectively. Exercise intensity was set initially at 50 W and increased by 25 W every 2 minutes to 125 W. Acute normobaric hypoxic condition was maintained for 45 minutes using low oxygen gas mixture. CBFV in the middle cerebral artery (MCA) and EEG were measured at rest 5 minutes, rest 15 minutes, immediately after exercise, and 15 minutes recovery using transcranial-Doppler sonography and EEG signal was recorded from 6 scalp sites leading to analysis of alpha and beta wave relative activities. All data were analyzed using two-way repeated-measures analysis of variance and Pearson's correlation. RESULTS: CBFV in the MCA in the hypoxic condition was significantly higher than that in the control condition at rest 5 minutes (83±9 vs. 69±9 cm/s, P<0.01), rest 15 minutes (87±8 vs. 67±7 cm/s, P<0.001), immediately after exercise (112±9 vs. 97±9 cm/s, P<0.01), and 15 minutes recovery (91±11 vs. 74±7 cm/s, P<0.01). However, no significant correlation was found between the changes of CBFV and EEG wave activities. CONCLUSIONS: These results suggest that the drastic change of CBFV observed during exercise with hypoxia might appear independently with EEG wave activities.

Effects of Recumbent Angle during Cycling on Cerebral Blood Flow Velocity and Rate Pressure Product during Exercise and Recovery

BACKGROUND: The cerebral blood flow velocity (CBFV) and rate pressure product (RPP) have been reported to benefit hemodynamics more during exercise in the recumbent position than during that in the upright position. However, it is unclear which angle is of the greatest benefit to hemodynamics during exercise in the recumbent position. This study aimed to evaluate the effect of the recumbent angle on CBFV and RPP during exercise. METHODS: In a balanced crossover study, 15 healthy volunteers (age, 18.7±1.1 years) were asked to perform the bicycle exercise four times in the upright and at recumbent angles of 67° (R), 47°R, and 15°R, with weekly intervals between each condition. The exercise intensity was set initially at 50 W and increased by 25 W every 2 minutes up to 150 W. CBFV in the middle cerebral artery (MCA) was measured using transcranial doppler sonography. All data were analyzed using two-way repeated-measures analysis of variance. RESULTS: CBFV at 15°R was significantly higher than that in the upright position and at 67°R at 10 minutes recovery (69±16 vs. 56±7 and 58±10 cm/s, respectively; P<0.05). The RPP was significantly lower at 67°R, 47°R, and 15°R than in the upright position immediately after exercise (176±23, 177±22, and 173±26, respectively, vs. 241±42 mmHg×beats/min×10⁻²; P<0.001). CONCLUSIONS: At an angle of less than 67°R, exercise increases CBFV and reduces RPP, relative to those during exercise in the upright position. This hemodynamic effect was most prominent at 15°R, where cerebral circulation was further increased in the recovery phase.

Effects of Recumbent Angle during Cycling on Cerebral Blood Flow Velocity and Rate Pressure Product during Exercise and Recovery

BACKGROUND@#The cerebral blood flow velocity (CBFV) and rate pressure product (RPP) have been reported to benefit hemodynamics more during exercise in the recumbent position than during that in the upright position. However, it is unclear which angle is of the greatest benefit to hemodynamics during exercise in the recumbent position. This study aimed to evaluate the effect of the recumbent angle on CBFV and RPP during exercise.@*METHODS@#In a balanced crossover study, 15 healthy volunteers (age, 18.7±1.1 years) were asked to perform the bicycle exercise four times in the upright and at recumbent angles of 67° (R), 47°R, and 15°R, with weekly intervals between each condition. The exercise intensity was set initially at 50 W and increased by 25 W every 2 minutes up to 150 W. CBFV in the middle cerebral artery (MCA) was measured using transcranial doppler sonography. All data were analyzed using two-way repeated-measures analysis of variance.@*RESULTS@#CBFV at 15°R was significantly higher than that in the upright position and at 67°R at 10 minutes recovery (69±16 vs. 56±7 and 58±10 cm/s, respectively; P<0.05). The RPP was significantly lower at 67°R, 47°R, and 15°R than in the upright position immediately after exercise (176±23, 177±22, and 173±26, respectively, vs. 241±42 mmHg×beats/min×10⁻²; P<0.001).@*CONCLUSIONS@#At an angle of less than 67°R, exercise increases CBFV and reduces RPP, relative to those during exercise in the upright position. This hemodynamic effect was most prominent at 15°R, where cerebral circulation was further increased in the recovery phase.

Effects of Bicycle Ergometer Exercise on Cerebral Blood Flow Velocity and Electroencephalogram Response in Normoxia and Hypoxia

BACKGROUND@#The cerebral blood flow velocity (CBFV) has been known to increase in response to acute hypoxia. However, how CBFV might respond to exercise in hypoxic conditions and be associated with electroencephalogram (EEG) remains unclear. The purpose of this study was to evaluate the effect of exercise in hypoxic conditions corresponding to altitudes of 4,000 m on CBFV and EEG.@*METHODS@#In a randomized, double-blind, balanced crossover study, ten healthy volunteers (19.8±0.4 years) were asked to perform the incremental bicycle ergometer exercise twice in hypoxic and control (sea level) conditions with a 1-week interval, respectively. Exercise intensity was set initially at 50 W and increased by 25 W every 2 minutes to 125 W. Acute normobaric hypoxic condition was maintained for 45 minutes using low oxygen gas mixture. CBFV in the middle cerebral artery (MCA) and EEG were measured at rest 5 minutes, rest 15 minutes, immediately after exercise, and 15 minutes recovery using transcranial-Doppler sonography and EEG signal was recorded from 6 scalp sites leading to analysis of alpha and beta wave relative activities. All data were analyzed using two-way repeated-measures analysis of variance and Pearson's correlation.@*RESULTS@#CBFV in the MCA in the hypoxic condition was significantly higher than that in the control condition at rest 5 minutes (83±9 vs. 69±9 cm/s, P<0.01), rest 15 minutes (87±8 vs. 67±7 cm/s, P<0.001), immediately after exercise (112±9 vs. 97±9 cm/s, P<0.01), and 15 minutes recovery (91±11 vs. 74±7 cm/s, P<0.01). However, no significant correlation was found between the changes of CBFV and EEG wave activities.@*CONCLUSIONS@#These results suggest that the drastic change of CBFV observed during exercise with hypoxia might appear independently with EEG wave activities.

Effects of Recumbent Bicycle Exercise on Cardiac Autonomic Responses and Hemodynamics Variables in Patients with Atrial Fibrillation

BACKGROUND@#The purpose of this study is to investigate the safety and efficiency of recumbent bicycle ergometer exercise by observing heart rate variability (HRV) and hemodynamic variables in patients with atrial fibrillation.@*METHODS@#In a balanced crossover study, 13 patients with atrial fibrillation (mean age, 62.2±5.3 years) were asked to perform a bicycle exercise twice, once in the upright position and once in the recumbent position at an angle of 30°, with a 1-week interval between both. The exercise intensity was set initially at 10 W and increased by 15 W every 2 minutes up to 70 W. HRV and hemodynamic variables were measured. All data were analyzed using one-way repeated-measures analysis of variance.@*RESULTS@#Low-frequency normalization in HRV was increased with no intergroup differences immediately after exercise. The rate pressure product was significantly lower in the recumbent than in the upright position right after exercise (104.8±14.3 vs. 151.8±51.4 mmHg×beats/min×10⁻², P < 0.01).@*CONCLUSIONS@#Recumbent exercise improves the safety and efficiency of cardiac rehabilitation for atrial fibrillation patients by reducing myocardial workload without compromising the activation of the autonomic nervous system that regulates cardiac activity.

Effects of Recumbent Bicycle Exercise on Cardiac Autonomic Responses and Hemodynamics Variables in Patients with Atrial Fibrillation

BACKGROUND: The purpose of this study is to investigate the safety and efficiency of recumbent bicycle ergometer exercise by observing heart rate variability (HRV) and hemodynamic variables in patients with atrial fibrillation.METHODS: In a balanced crossover study, 13 patients with atrial fibrillation (mean age, 62.2±5.3 years) were asked to perform a bicycle exercise twice, once in the upright position and once in the recumbent position at an angle of 30°, with a 1-week interval between both. The exercise intensity was set initially at 10 W and increased by 15 W every 2 minutes up to 70 W. HRV and hemodynamic variables were measured. All data were analyzed using one-way repeated-measures analysis of variance.RESULTS: Low-frequency normalization in HRV was increased with no intergroup differences immediately after exercise. The rate pressure product was significantly lower in the recumbent than in the upright position right after exercise (104.8±14.3 vs. 151.8±51.4 mmHg×beats/min×10⁻², P < 0.01).CONCLUSIONS: Recumbent exercise improves the safety and efficiency of cardiac rehabilitation for atrial fibrillation patients by reducing myocardial workload without compromising the activation of the autonomic nervous system that regulates cardiac activity.