Introduction: The aim of the present study was to compare between effects of 8 weeks of high-intensity interval training (HIT) based on heart rate (HR-based) or Speed (Speed-based) on aerobic power and heart rate variability (HRV) in young active girls.
Methods: 25 girls physical education students from Shokrani school of Isfahan voluntary participated in this study. The subjects were divided into Speed-based (Number: 13; Age: 17.3 ± 0.6 yrs, Weight: 60.1 ± 7.7 kg, Height: 166.1 ± 6.0 cm) or HR-based (Number: 12; Age: 17.1 ± 0.2 yrs, Weight: 59.9 ± 3.8 kg, Height: 165.2 ± 2.6 cm) groups. Subjects underwent the 30-15 Intermittent Fitness Test (30-15IFT) before and after 8 weeks of HIT, to measure the maximal performance (VIFT) and estimate maximal oxygen uptake (VO2max) as aerobic power indices. Resting HRV was also recorded in the first and last weeks. Dependent t-test and analyses of covariate (ANCOVA) with the significant level of P<0.05, were used in statistical analyses.
Results: 8 weeks of HIT with both methods elicited significant increases in VO2max and VIFT (P<0.05). HRV showed a significant increase only in HR-based group (P<0.05). In between-group analyses, just HRV elicited a more significant improvement in HR-based method (P<0.05).
Conclusions: It seems, that both HIT intensity controlling methods are effective in improving aerobic power but eliciting changes in HRV needs implementing HR-based approach.