Blood Pressure and Heart Rate Responses in Young Nigerian Women during Passive and Zero-Resistance Active Exercise Tests Compared to Non-Obese Control

Aim: To compare blood pressure (BP) and heart rate (HR) responses to passive and unloaded active leg movements and the neural control mechanisms between obese young female adults and their non-obese control.

Study Design: A case control study.

Place and Duration of Study: Department of Human Physiology, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria, between July 2015 to January 2016.

Methodology: Thirty normotensive young women were randomly selected for this study and assigned into two groups- obese (n =15) and non-obese (n =15). Subjects performed a sub-maximal ergometer exercise test. Each group performed separate bouts of 5-minutes passive and unloaded active cycling exercises. BP and HR were recorded at baseline and during the two exercise conditions. All statistics were done using SPSS (version 25). Comparative analyses were done using independent sample t-test (for normally distributed data) or Mann Whitney-U (for abnormally distributed data) or a two-way analysis of variance (ANOVA).

Results: The obese women indicated significantly (p < 0.05) higher HR, systolic BP, diastolic BP, mean arterial pressure (MAP), and rate pressure product (RPP) compared with the non-obese control at baseline, during passive and unloaded active exercise conditions. The magnitude of increase (Δ) in BP from baseline to passive leg movement and ΔHR elicited from passive to unloaded active movement showed no significant differences between the two groups.

Conclusions: The higher mean BP and HR observed in the obese women, at baseline, during passive and unloaded active cycle movements were attributed to poor cardio-respiratory fitness and greater myocardial metabolic demand imposed by excessive adipose tissue. The lack of significant differences in ΔBPbaseline-passive exercise and ΔHRpassive-active, between the two groups, suggests that both mechanoreceptors and central neural command played limited roles in increased BP and HR drive during low-intensity dynamic exercise tests.