Effect of Isometric Exercise on Heart Rate Variability in Prehypertensive Young Adults

Abstract

Background and Objective: Heart rate variability (HRV) is a sensitive and specific non-invasive tool to evaluate the degree of heartrate variation under the balanced influence of sympathetic and parasympathetic components of the cardiac autonomic nervoussystem. The aim was to study the effect of isometric hand grip exercise on HRV in prehypertensive young adults and to find acorrelation of HRV with body mass index (BMI). Materials and Methods: This observational study was done on 60 healthy youngadults aged 18–30 years. All the subjects were divided into three groups of 20 each on the level of their BMI and systolic anddiastolic blood pressures. Group I were subjects with BMI <25 and normotensive, group II with BMI <25 and prehypertensive, andgroup III with BMI >25 and prehypertensive. HRV analysis (Chart HRV module, ADInstruments Pty Ltd) was performed with thefollowing parameters calculated: low-frequency power (LF), high-frequency power (HF), and LF/HF ratio. Results: LF/HF ratio wassignificantly increased (P<0.001) in prehypertensive subjects (groups II and III) when compared with the normotensive subjects (groupI), which indicates a heightened sympathetic discharge in prehypertensives. A positive correlation between anthropometric parametersand cardiac autonomic activity parameters and increased sympathetic activity in obese subjects were noted. Conclusion: An increasein anthropometric indices is associated with a change in cardiac autonomic activity, especially toward sympathetic activity. Regularanthropometric assessment can prevent the development of cardiac abnormalities and the incidence of sudden cardiac death.