Effect of different forms of high-intensity interval training on VO2max, strength, flexibility, and body fat percentage among middle-aged males

BACKGROUND: High-intensity interval training (HIIT) has become a popular exercise approach due to its potential to elicit significant physiological adaptations. However, limited research has compared the effects of different HIIT modalities on fitness parameters in middle-aged males. This study aimed to determine the effect of different HIIT on VO2max, strength, flexibility, and body fat percentage among middle-aged males. METHODS: Thirty sedentary males aged 40-50 years were randomly assigned to HIIT-Weight Training Circuit (WTC), HIIT-Shuttle Run (SR), or HIIT-Bodyweight Exercise (BWE) groups. Training consisted of 20 sessions over 5 weeks of 4×4 minutes at 90-95% HRmax with 3 minutes recovery at 70% HRmax between intervals. Outcome measures including VO2max, strength, flexibility, and body fat percentage were assessed pre- and postintervention. RESULTS: The result for the Two-Way Mixed ANOVA indicated there was no significant interaction effect between the three training groups. There was no significant main effect for the three training groups, whereas there was a significant effect for the repeated measure time existed. A significant improvement in VO2max, strength, flexibility has been shown between post-test and pre-test for the HIIT-SR, HIIT-WTC, and HIIT-BWE group. Whereas A significant decrease has been shown between post and pretest for all the groups in body fat percentage. CONCLUSIONS: This research findings suggested that different forms of HIIT can elicit differential adaptation in middle-aged males. Incorporating different form of HIIT as HITT-SR, HITT-WTC, and HITT-BWE into exercise program may be an effective way to systematically improve VO2max, strength, flexibility, and body composition in middle-age male population. These findings provide guidance on HIIT prescription according to fitness goals.