High-intensity interval training (HIIT) has become a popular training regimen in team sports, but its specific effects on physiological adaptations remain a topic of research. A recent systematic review and meta-analysis aimed to clarify these effects by analyzing data from 46 studies involving 1204 athletes.
The analysis found that HIIT significantly improved several key performance metrics compared to regular sport-specific training. The results indicated a positive effect on maximal oxygen uptake (VO2max) with a standardized mean difference (g) of 0.76 (95% CI [0.61, 0.92]). Additionally, improvements were observed in maximal aerobic power (g = 0.43, 95% CI [0.04, 0.82]), ventilatory threshold (g = 0.70, 95% CI [0.53, 0.88]), Yo-Yo intermittent recovery test performance (g = 1.02, 95% CI [0.76, 1.28]), and 30-s Wingate peak (g = 0.91, 95% CI [0.67, 1.16]) and mean power (g = 0.70, 95% CI [0.39, 1.01]).
Interestingly, the effects of HIIT on body composition were generally unclear, suggesting that while HIIT can enhance performance metrics, its impact on body composition may be limited.
Further analysis through multivariable meta-regression did not reveal significant differences in the effects of HIIT based on sex or training level. However, longer training durations were associated with greater improvements in VO2max. Exploratory analyses suggested that athletes could expect increases in VO2max of approximately 2.56 mL·kg-1·min-1 after about 5 weeks of HIIT and 5.11 mL·kg-1·min-1 after approximately 10 weeks.
Moreover, shorter recovery times between repetitions were linked to greater VO2max improvements, although other program variables were estimated with less precision. The findings underscore the effectiveness of incorporating HIIT into regular training regimens for enhancing both aerobic and anaerobic performance in trained team-sport athletes.
What this study does not show
This study does not establish a direct causal relationship between HIIT and improved body composition outcomes among athletes.
Evidence scorecard
- Analytic validity: established
- Clinical validity: established
- Clinical utility: partial
The evidence class for this meta-analysis is human_meta_analysis, indicating a robust analysis of existing human studies.