2003 Volume 2 Issue 1 Pages 49-57
Cardiovagal function declines with increasing age. We tested the hypothesis that age-related delay in cardiovagal reactivation is associated with age and habitual physical activity after cessation of exercise, and that is related to rapid cessation of central command in children and adults.
Cardiovagal reactivation was examined in 22 healthy children (8-9 yrs) and 98 adults (young group, 19-39 yrs; middle-aged group, 40-59 yrs; old group, 60-79 yrs) who were classified as either ‘sedentary’ or ‘habitual physical activity’, by using sequence analysis of the time constant of recovery heart rate (HRTC) and decay rate for 5 sec (HRDR) immediately after cessation of moderate pedaling exercise.
HRTC was progressively slower with increasing age. HRTC of the habitual physical activity and sedentary groups within age groups were different (young group, 37 ± 5.5 sec vs 57 ± 11.1 sec; middle-age group, 46 ± 11.5 sec vs 85 ± 28.4 sec; old group, 56 ± 15 sec vs 108 ± 37 sec; all p<0.05). HRTC in children were markedly faster than in the young habitual physical activity group (child group, 30 ± 5.1 sec; young group, 37 ± 5.5 sec; p<0.05). However, HRDR became progressively slower with increasing age. HRDR for the habitual physical activity and sedentary groups did not vary within age groups (young group, -1.67 ± 0.84 sec vs - 1.27 ± 0.69 sec; middle-age group, -1.3 ± 0.35 sec vs - 0.98 ± 0.34 sec; old group, -1.09 ± 0.62 sec vs - 1.08 ± 0.38 sec), but HRTC in the sedentary subjects decreased more slowly than in the habitual physical activity subjects. HRDR between the child group and both the middle-aged group and the old group were different in both habitual physical activity and sedentary subjects (p<0.05).
Our data demonstrate that HRTC in habitual physical activity subjects is well preserved with increasing age, while HRTC in sedentary subjects appears to be prolonged. These results suggest that habitual physical activity could be very useful for the maintenance of central cardiac regulation, such as central command and/or cardiovagal baroreflex sensitivity, and that decreased HRTC could be neuroautonomic control that helps to protect old subjects from cardiac diseases.
