Effect of Sustained Isometric and Isotonic Exercises on Blood Pressure and Heart Rate Variability – A Comparative Study

Introduction: Isometric exercises are contractions of a particular muscle which doesn’t noticeably change length and the affected joint doesn’t move [1]. Isotonic exercises involve contracting muscle shortens against a constant weight, as when lifting as weight [2,3]. These two different types of exercise have profound changes in the body affecting the respiratory and cardiovascular systems [4]. Studies comparing the effectiveness of isotonic and isometric exercises on blood pressure and heart rate variability (HRV) were scanty [5].

Objective: The present study planned to investigate and compare the efficacy of isometric as well as isotonic exercises on changes in blood pressure, heart rate and HRV.

Materials and methods: 10 normal healthy subjects in the age group 17-20 years of both genders participated in the study. All the subjects were assessed under three different conditions: Resting state, After isotonic exercises (20 repetitions of straight leg raise) and After isometric exercises 2 mins of sustained abdominal exercises). After each procedure, blood pressure and heart rate variability were calculated.

Results: Isometric exercises cause reduction of systolic and diastolic blood pressure, mean arterial pressure while pulse rate increases significantly. Isotonic exercises increase the systolic and diastolic blood pressure and mean arterial pressure significantly. The result is statistically significant with p<0.050.

Conclusion: Thus it can be concluded an innovative finding that isometric exercise causes profound decline in blood pressure and increased heart rate variability thus showing a negative impact on cardiovascular health. So it can be concluded that isotonic exercise improves the circulation and supports the cardiovascular system and strengthens the muscle, improves bone density and boosts cardiac function