The association between healthy lifestyle score with cardiorespiratory fitness and muscle strength

Objective The association of individual behaviours such as diet, tobacco use, body mass index (BMI) and physical activity have been investigated separately in relevance to cardiorespiratory fitness (CRF) and muscle strength. The purpose of this study is to investigate the combined association of the four mentioned lifestyle factors with cardiorespiratory fitness and muscle strength. Methods This cross-sectional study was conducted on 271 Iranian adults, aged 18-70 years. We developed a healthy lifestyle score (HLS) that ranged from 0 to 103 (higher score reflecting better adherence to healthier lifestyle) and included four lifestyle behavioural components (diet, physical activity, smoking and BMI). The relationship between HLS, CRF and muscle strength was determined using linear and non-linear regression analysis. Results HLS score was not significantly associated with VO2max (mL/kg/min) P = .43; VO2max (L min) P = .14; VO2max (LBM) (P = .79) and mean muscle strength (MMS) (kg) (P = .11), muscle strength of right hand (MSR) (kg) (P = .10) and muscle strength of left hand (MSL) (kg) (P = .16) in the unadjusted model. After adjustment for potential confounders, we found a significant association between HLS and Vo2max (L/min), MMS (kg), MSR (kg) and MSL (kg) (P < .001 for all). Also HLS and MMS (r = .06, P = .31), MSR (r = .07, P = .25), MMS (r = .05, P = .39), VO2max (mL/kg/min) (r = .01, P = .77), VO2max (L min) (r = .05, P = .35) and VO2max (LBM) (r = .002, P = .91) have no statistically significant linear relationship. Conclusion Adherence to healthy lifestyle may be associated with increased CRF and muscle strength after adjusting for potential confounding variables.