Factors influencing exercise capacity during submaximal exercise in male and female adults / Nur Syazni Abd Razak

This study aimed to 1) compare the anthropometric, body composition, level of physical activity (PA), fatigue (rating of perceived exertion [RPE]) and aerobic fitness (VChmax) between males and females; 2) investigate the relationship between the anthropometric, body composition, PA, fatigue, and VChmax in males and females; 3) determine factors that influence fatigue and VChmax during submaximal exercise in males and females; 4) identify the ability of the interest independent variable in predicting VChmax, providing an estimate cut-off value that corresponds to the best trade-off between sensitivity and specificity of the possible predictive variable in males and females. A cross-sectional study was conducted among young adults aged 18 to 40 years old in a public university. The anthropometric (weight, height, body mass index [BMI], waist circumference [WC], waist-to-hip ratio [WHR], and waist-to-height ratio [WHtR]), body composition (fat and muscle mass percentages), level of PA, fatigue and VChmax were measured. Height was measured by using a fixed stadiometer; weight, BMI, fat, and muscle mass percentages were calculated by using a bioimpedance analysis. A tape measure was used to measure the waist and hip circumferences and the International Physical Activity Questionnaire (IPAQ) was utilized to assess the PA. To assess fatigue and VChmax, a Borg's 6-20 scale and Astrand-Rhyming nomogram were used, respectively, during the cycle ergometer exercise test. Data were analysed via Mests, Pearson's correlations, stepwise linear regression models, and receiver operating characteristic (ROC) analyses. The results showed that weight, height, WC, WHR, WHtR, fat percentage, muscle mass, and PA were significantly different between males and females (ALL, p > 0.05). In males, WC (r=-0.571), fat percentage (r = -0.532), weight (r=-0.521), muscle mass (r = 0.516), WHtR (r=-0.516), WHR (r=-0.487) and BMI (r=-0.47) were significantly correlated with VChmax (all, p<0.05). Among females, fat percentage (r = -0.601), WC (r=-0.581), weight (r=-0.571), muscle mass (r = 0.549), WHtR (r=-0.545), BMI (r=-0.545), WHR (r=-0.473) and height (r=-0.287) were significantly correlated with VChmax (all, p<0.05). Moreover, WC and fat percentage were the significant predictors of VChmax in males and females, respectively. In sub-analyses, WC was demonstrated as a superior determinant to predict the VChmax in both genders. The ROC analyses of WC showed 0.786 for males and 0.831 females. The ROC analyses also produced a new cut-off values of WC in prediction of cardiovascular disease risk which were 83.75 cm and 81.25 cm in males and females, respectively. As a conclusion, this study presented that the anthropometric, body composition, and PA were significantly different between males and females. The anthropometric and body composition were strongly correlated with aerobic fitness in both genders. WC was demonstrated to be a stronger predictor to predict V02max in both males and females. An awareness of the importance of monitoring WC among general population and health professionals should be addressed to combat the rising prevalence of cardiovascular diseases.