Autonomic recovery from peak arm exercise in fit and unfit individuals with paraplegia.
BACKGROUND
Altered autonomic cardiovascular control in persons with paraplegia may reflect peripheral sympathetic denervation caused by the injury or deconditioning due to skeletal muscle paralysis. Parameters of autonomic cardiovascular control may be improved in fit persons with paraplegia similar to effects reported in the noninjured population.


OBJECTIVE
To determine differences in resting and recovery HR and cardiac autonomic control in fit and unfit individuals with paraplegia.


METHODS
Eighteen healthy males with paraplegia below T6 were studied; nine participated in aerobic exercise conditioning (fit: >or=30 min.d, >or=3 d.wk, >or=6 months), and nine were sedentary (unfit). Analysis of heart rate variability (HRV) was used to determine spectral power (ln transformed) in the high- (lnHF) and low-frequency (lnLF) bandwidths, and the LF/HF ratio was calculated. Data were collected at baseline (BL) and at 2, 10, 30, 60, and 90 min of recovery from peak arm cycle ergometry.


RESULTS
The relative intensity achieved on the peak exercise test was comparable between the groups (i.e., 88% peak predicted HR). However, peak watts (P<0.001) and oxygen consumption (P<0.01) were higher in the fit compared with the unfit group (56 and 51%, respectively). Recovery lnHF was increased (P<0.05), and recovery lnLF (P<0.01) and LF/HF (P<0.05) were reduced in the fit compared with the unfit group. Mean recovery autonomic activity was not different from BL in the fit group. In the unfit group, mean recovery lnHF was reduced, and mean recovery lnLF and LF/HF remained elevated above BL.


CONCLUSIONS
These data suggest that fit individuals with paraplegia have improved cardiac autonomic control during the postexercise recovery period compared with their unfit counterparts.
Wecht
Jill M
JM
VA RR&D Service Center of Excellence, Bronx 10468, and Department of Medicine, Mount Sinai School of Medicine, New York, NY, USA. jm.wecht@med.va.gov
Marsico
Robert
R
Weir
Joseph P
JP
Spungen
Ann M
AM
Bauman
William A
WA
De Meersman
Ronald E
RE
D000328:Adult; D001132:Arm; D002302:Cardiac Output / Q000502:physiology; D005080:Exercise Test; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010264:Paraplegia; D010809:Physical Fitness / Q000502:physiology*; D012146:Rest; D014481:United States