Cardiorespiratory response to dynamic and static leg pless

Introduction

Comparative study on leg press between static and dynamic mode has been rarely conducted. The purpose of this research is to examine the difference in cardiorespiratory response between dynamic and static exercise when a leg press is performed with one leg or two legs and the weight load remains the same.

Methods

Seven participants (20-21yrs) were recruited for this experiment. They have done eight modes of leg press characterized following two elements: the unilateral or bilateral condition and the exercise intensity, 20% of maximal voluntary contraction (20%MVC) or 40% of maximal voluntary contraction (40%MVC). The duration of the dynamic exercise and the static exercise loaded 20%MVC was six minutes, and the static exercise with 40%MVC was three minutes. Minute ventilation (VE), oxygen uptake (VO2), heart rate (HR), respiratory exchange ratio (RER), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured in an environmental chamber.

Results

The dynamic leg press exercise loaded 20% and 40 %MVC were performed in the steady state while no steady state appeared during the static leg press at even 20%MVC. Results indicate that oxygen uptake in the static exercises was significantly lower than in the dynamic ones, but HR was not lower. Also, SBP and DBP in the static exercise were significantly higher than those in the dynamic exercise. Rate pressure product didn’t appear to be different at the first minute between the dynamic and the static exercises, but they became remarkably different by the 3rd minute.

Discussion / Conclusions
From this comparison between the dynamic and static exercises, it is suggested that static exercise is likely to induce greater circulatory response while dynamic exercise tends to bring about greater respiratory response. This seemingly attributes to the tendency that static muscle contraction limits the blood flow to the active muscles.

References

[1]. Gonzalez-Camarena R, et al. (2000). Med Sci Sports Eexerc 32: 1719-1728
[2]. Ogita F, et al (2000). Med Sci Sports Exerc 32:1737-1742.
[3]. Sadamoto T, et al (1983). Eur Appl Physiol 51: 395-408.