CARDIOVASCULAR RESPONSES TO LOW LEVEL EXERCISES IN MIDDLE-AGED AND ELDERLY HYPERTENSIVE NIGERIANS SEEN AT ILE-IFE

Abstract

Background: Impaired cardiovascular (CVS) responses to exercise had been
associated with worse outcome in subjects with diagnosis of hypertension;
which is the commonest cause of hospitalization, heart failure and sudden
cardiac death in Nigeria. CVS responses to exercise and their determinants, in
both Caucasian and Nigerian subjects had been studied in predominantly young
and middle-aged hypertensive (HT) subjects. Studies on older hypertensive
subjects are scarce especially in Nigeria partly because of the feared potential
dangers of exercising elderly adults on the treadmill. This study was intended to
assess and compare the CVS responses to low level intensity treadmill (LITM)
and six minute walk test (6MWT) exercise in older hypertensive Nigerians (50
74yrs).
Methodology: This is a comparative cross sectional study involving 50 middle
aged (50-59yrs) and 50 elderly (60-74yrs) hypertensives Nigerians, as well as,
50 middle-aged (50-59yrs) and 50 elderly (60-74yrs) normotensives (NT)
subjects that served as controls. They were matched for age, sex, body mass
index and prior habitual physical activity. All subjects underwent LITM, with a
stop target as 70% of their age-predicted maximum heart rate (APMHR) using
Naughton protocol. They also all underwent 6MWT.
Result: All subjects satisfactorily completed the 6MWT. Only 3 (3%) subjects
could not complete the LITM due to fatigue. No subject had any adverse
symptom or sign to necessitate premature stoppage of the test. Maximal heart
rate (MHR) during 6MWT ranged from 72.14±3.58 % to 75.45±3.13 % of
APMHR in both age groups while it was 70% of APMHR during LITM.
MHR was significantly lower in HT than NT subjects during 6MWT in
both age groups (both p<0.001) but only in the elderly arm during LITM
(p=0.025). Peak SBP (both p<0.001) and pressure rate product, PRP (an index
of myocardial oxygen consumption) (both p<0.001) during both modes of
exercise in both age groups were significantly higher in the HT than NT
subjects. These SBP and PRP changes were significantly less when treated HT
subjects were eventually compared with untreated HT subjects during both
modes of exercise(both p<0.001).
Conclusion: Both LITM and 6MWT were comparably well tolerated during
this study without any adverse outcome during both modes of exercise.
Hypertensive subjects CVS response to LITM and 6MWT were both
significantly different from normotensive subjects in both age groups. The
benefit of treatment of hypertensive subjects is further emphasized by the
attenuation of the BP response and PRP in them even at these low levels of
exercises. Average MHR response throughout the 6MWT was consistently
within the recommended range of 70-85% APMHR for adequate submaximal
(low level) intensity exercise. This further suggests that the older hypertensive
Nigerians who may not be able to afford the expensive cost of daily supervised
low intensity treadmill exercise, even if available, can derive comparable CVS
benefits from the simple, safe and cheap regular brisk walking.

CARDIOVASCULAR RESPONSES TO LOW LEVEL EXERCISES IN MIDDLE-AGED AND ELDERLY HYPERTENSIVE NIGERIANS SEEN AT ILE-IFE