Immune system response to isometric handgrip exercise and effects of duration and intensity of the exercise protocol on selected immune system parameters in prehypertensives.

Background: Recent studies have shown that physical exercise significantly modulates immunocyte dynamics and possibly plays a significant role on immune function. This study examined the responses of some selected immune system parameters to isometric handgrip exercise and identified possible effects of intensity and duration of the exercise protocols.

Methods: One hundred and ninety-two (N=192) sedentary pre-hypertensive subjects, aged between 30-50 years were recruited into the study. They were randomly distributed into three groups of 64 subjects each. A detailed explanation and a demonstration of the exercise protocol were given to the subjects and they were asked to report at the Exercise Physiology unit of the Physiotherapy department, Federal Medical Centre, Asaba, Delta State at 4.00 pm daily for the exercise practice. The training session for each day took place between the hours of 4.00 pm and 8.00 pm daily (FMC/ASB/A81.VOL.XII/101). The subjects performed a 24 consecutive day's isometric handgrip exercise at 30% Maximum Voluntary Contraction (MVC). At the end of the 24 days, group one (GP1) discontinued with the exercise protocol, while group two (GP2) and group three (GP3) continued with the exercise protocol for another 24 consecutive days nevertheless GP3 performed at an increased intensity of 50% MVC. The clinical trial was registered with Nigeria Clinical Trial Registry, Federal Ministry of Health, Abuja Nigeriawith Trial No: 1216582 (https://www.nctr.nhrec.net/viewTrials.php?TID=1216582).

Results: At the end of the study, the result shows thatthe number of CD4 cells and CD4/CD8 ratio significantly (P<0.05) increased while the CD8 cell decreased in GP2 and GP3. It was further shown that increase in duration produced a more significant change compared to an increase in intensity of the isometric effort.

Conclusion: The study established that isometric handgrip exercise alters the circulating levels of the immune system parameters which could have positive beneficial effects on the prehypertensive individuals as the number of CD4 cells and CD4/CD8 ratio increased especially when practiced over a longer duration.