TY - JOUR
T1 - Aerobic exercise training improves orthostatic tolerance in aging humans
AU - Xu, Diqun
AU - Wang, Hong
AU - Chen, Shande
AU - Ross, Sarah
AU - Liu, Howe
AU - Olivencia-Yurvati, Albert
AU - Raven, Peter B.
AU - Shi, Xiangrong
N1 - Publisher Copyright:
Copyright © 2016 by the American College of Sports Medicine.
PY - 2017
Y1 - 2017
N2 - Purpose: This study was designed to test the hypothesis that aerobic exercise training of the elderly will increase aerobic fitness without compromising orthostatic tolerance (OT). Methods: Eight healthy sedentary volunteers (67.0 ± 1.7 yr old, four women) participated in 1 yr of endurance exercise training (stationary bicycle and/or treadmill) program at the individuals' 65%-75% of HRpeak. Peak O2 uptake (VO2peak) and HRpeak were determined by a maximal exercise stress test using a bicycle ergometer. Carotid baroreceptor reflex (CBR) control of HR and mean arterial pressure (MAP) were assessed by a neck pressure-neck suction protocol. Each subject's maximal gain (Gmax), or sensitivity, of the CBR function curves were derived from fitting their reflex HR and MAP responses to the corresponding neck pressure-neck suction stimuli using a logistic function curve. The subjects' OT was assessed using lower-body negative pressure (LBNP) graded to -50 mm Hg; the sum of the product of LBNP intensity and time (mm Hg min-1) was calculated as the cumulative stress index. Results: Training increased VO2peak (before vs after: 22.8 ± 0.92 vs 27.9 ± 1.33 mL min-1 kg-1, P < 0.01) and HRpeak (154 ± 4 vs 159 ± 3 bpm, P < 0.02) and decreased resting HR (65 ± 5 vs 59 ± 5 bpm, P < 0.02) and MAP (99 ± 2 vs 87 ± 2 mm Hg, P < 0.05). CBR stimulus-response curves identified a leftward shift with an increase in CBR-HR Gmax (from -0.13 ± 0.02 to -0.27 ± 0.04 bpm mm Hg-1, P = 0.01). Cumulative stress index was increased from 767 ± 68 mm Hg min-1 pretraining to 946 ± 44 mm Hg min-1 posttraining (P < 0.05). Conclusion: Aerobic exercise training improved the aerobic fitness and OT in elderly subjects. An improved OT is likely associated with an enhanced CBR function that has been reset to better maintain cerebral perfusion and cerebral tissue oxygenation during LBNP.
AB - Purpose: This study was designed to test the hypothesis that aerobic exercise training of the elderly will increase aerobic fitness without compromising orthostatic tolerance (OT). Methods: Eight healthy sedentary volunteers (67.0 ± 1.7 yr old, four women) participated in 1 yr of endurance exercise training (stationary bicycle and/or treadmill) program at the individuals' 65%-75% of HRpeak. Peak O2 uptake (VO2peak) and HRpeak were determined by a maximal exercise stress test using a bicycle ergometer. Carotid baroreceptor reflex (CBR) control of HR and mean arterial pressure (MAP) were assessed by a neck pressure-neck suction protocol. Each subject's maximal gain (Gmax), or sensitivity, of the CBR function curves were derived from fitting their reflex HR and MAP responses to the corresponding neck pressure-neck suction stimuli using a logistic function curve. The subjects' OT was assessed using lower-body negative pressure (LBNP) graded to -50 mm Hg; the sum of the product of LBNP intensity and time (mm Hg min-1) was calculated as the cumulative stress index. Results: Training increased VO2peak (before vs after: 22.8 ± 0.92 vs 27.9 ± 1.33 mL min-1 kg-1, P < 0.01) and HRpeak (154 ± 4 vs 159 ± 3 bpm, P < 0.02) and decreased resting HR (65 ± 5 vs 59 ± 5 bpm, P < 0.02) and MAP (99 ± 2 vs 87 ± 2 mm Hg, P < 0.05). CBR stimulus-response curves identified a leftward shift with an increase in CBR-HR Gmax (from -0.13 ± 0.02 to -0.27 ± 0.04 bpm mm Hg-1, P = 0.01). Cumulative stress index was increased from 767 ± 68 mm Hg min-1 pretraining to 946 ± 44 mm Hg min-1 posttraining (P < 0.05). Conclusion: Aerobic exercise training improved the aerobic fitness and OT in elderly subjects. An improved OT is likely associated with an enhanced CBR function that has been reset to better maintain cerebral perfusion and cerebral tissue oxygenation during LBNP.
KW - Carotid arterial baroreflex
KW - Cerebral tissue oxygenation
KW - Lower-body negative pressure
KW - Peak o uptake
KW - Presyncope
UR - http://www.scopus.com/inward/record.url?scp=84994613455&partnerID=8YFLogxK
U2 - 10.1249/MSS.0000000000001153
DO - 10.1249/MSS.0000000000001153
M3 - Article
C2 - 27824693
AN - SCOPUS:84994613455
SN - 0195-9131
VL - 49
SP - 728
EP - 735
JO - Medicine and Science in Sports and Exercise
JF - Medicine and Science in Sports and Exercise
IS - 4
ER -