Changes in Inspiratory and Expiratory Flow Rates with Sustained Hand Grip and their Correlation with Fat Free Mass Index in Healthy Young Adults

Introduction: Aerobic exercises which are isotonic in nature have been proved to be beneficial in a number of cardiovascular and lifestyle diseases. But the effect of isometric exercises on cardiovascular and respiratory system is not fully evaluated. Existing literature on effect of isometric exercise on respiratory flow parameters are scanty and needs to be studied. Further, the impact of muscle mass on respiratory flow parameters need to be evaluated. Aim: To investigate the change in respiratory flow parameters (Peak Inspiratory Flow (PIF), Maximal Inspiratory Flow (MIF) 50, Peak Expiratory Flow (PEF), Maximum Expiratory Flow (MEF) 25-75, MEF 25, MEF 50 and MEF 75) in response to Sustained hand grip exercise and to find out any correlation between these flow parameters and Fat Free Mass Index (FFMI). Materials and Methods: A cross-sectional study was conducted at Department of Physiology, MKCG Medical College, Berhampur University, Odisha between October 2011 and August 2014. A total of 150 healthy volunteers aged between 17 to 25 years were included in the study. Anthropometric measurements were recorded using standardised instruments. Body fat percentage was measured by Bioelectric Impedance Analysis technique and then Fat Free Mass (FFM) and FFMI were calculated using standard formulae. Respiratory Flow parameters were assessed using Flow handy Spirometer as per the American Thoracic Society/European Respiratory Society (ATS/ERS) guidelines. Sustained hand grip exercise was performed with Physilab Grip Dynamometer. IBM SPSS Statistics Version 24.0, was used for statistical analysis. Paired sample t-test was used to compare lung volumes at baseline and after 3 minutes of sustained hand grip exercise. The p-value <0.05 was considered statistically significant. Karl Pearson Correlation coefficient was used to study the linear relationship between FFMI and various inspiratory and expiratory flow rates. Results: The mean values of all respiratory flow parameters under study decreased at 3 minutes of sustained hand grip exercise as compared to baseline values. This change was statistically significant for PEF (p-value 0.012), MEF 25-75 (p-value 0.041), MEF 50 (p-value 0.001), MEF 75 (p-value 0.012) and MIF50 (p-value 0.004) (p<0.05). All the flow rates studied except MEF 25 showed significant positive correlation with FFMI (r-values between 0.231 to 0.380, p<0.05) but the strength of association was low. Conclusion: There was a statistically significant reduction in both inspiratory and expiratory flow parameters with isometric sustained hand grip exercise. So, isometric exercises should be avoided in patients with obstructive airway diseases. But muscle mass should be improved for better ventilation as authors observed a positive correlation between FFMI and respiratory flow rates.