A protective effect of exercise against interpersonal stress-induced cardiovascular reactivity in youth
Lambiase, Maya Jung
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Background. Empirical evidence suggests an association between blood pressure reactivity to psychological stress in childhood and hypertension in adulthood. Acute aerobic exercise dampens blood pressure reactivity to subsequent stress in adults. The purpose of this study was to determine if a bout of interval exercise reduces cardiovascular reactivity to an interpersonal stressor in children. Research design. Twenty-two children (n = 11 boys, n = 11 girls), ages 8-12 completed a control television-speech protocol and an experimental interval exercise-speech protocol. The order of test days was counterbalanced across children. Heart rate, blood pressure and perceived stress measures were collected at baseline, after watching television or exercising for 25 minutes (post-television or post-exercise), after reading for 20 minutes (post-read), and then after preparing (post-speech preparation) and giving a speech (post-speech). Salivary α-amylase concentrations were measured at baseline, post-speech preparation and post-speech as a marker of sympathetic tone. Children wore an accelerometer for 7 days to assess usual physical activity. Results. Diastolic (DBP) and mean arterial pressures (MAP) increased (p ≤ 0.001) when giving a speech on both the television and exercise days; however, the slope of the increase was greater (p ≤ 0.006) when children watched television than when they exercised. Salivary a-amylase concentrations were lower (p ≤ 0.05) when giving a speech after exercising than when giving a speech after watching television. The changes in DBP (ρ = 0.51, p ≤ 0.02) and MAP (ρ = 0.44, p ≤ 0.05) were correlated with the change in α-amylase from baseline to post- speech on the exercise day. Children's usual activity level was inversely correlated with the change in DBP (ρ = -0.47, p ≤ 0.03) and the change in MAP (ρ = -0.47, p ≤ 0.03) from baseline to post-speech on the exercise day. Conclusion. An acute bout of interval exercise can attenuate stress-induced blood pressure responses and dampened sympathetic output may be one mechanism whereby exercise attenuates stress-induced cardiovascular reactivity as indexed by reduced α-amylase. Frequent exercise may help to reduce the risk of hypertension and cardiovascular disease in adulthood by reducing stress-induced cardiovascular reactivity.