Effects of High-Intensity Interval Training Protocols on Liver Enzymes and Wellness in Women

Rengers TA, Orr SC, Marks CRC, Hew-Butler T, Choi MD, Butcher SJ, Drignei D, Brown EC

Question

Do rowing HIIT and multimodal resistance-based HIIT differ in effects on liver enzymes, cardiometabolic risk factors, and psychosocial outcomes in healthy young women without obesity?

Summary

Sixteen recreationally active women without obesity completed 12 weeks of group HIIT using either rowing or a multimodal resistance/conditioning format. Rowing HIIT reduced ALT and AST more than multimodal HIIT, whole-group perceived wellness improved, and other cardiometabolic markers did not clearly change.

Methodology

Recreationally active females without obesity who were not in a regular training program.
16 participants.
Rowing ergometer or heavy resistance/conditioning circuit.
Work intervals: 60 seconds maximum-intensity work.
Recovery: 3 minutes rest.
Intensity: >90% age-estimated maximum heart rate; mean achieved 90.8% R-HIIT and 89.6% MM-HIIT.
60 minutes including warm-up/instruction and cool-down.
3 sessions/week.
12 weeks.
Parallel-group randomized trial comparing two supervised HIIT modalities
ALT, AST, Wellness, and Cardiometabolic markers were tracked.

Outcomes

ALT

R-HIIT had significantly lower postintervention ALT than MM-HIIT after adjustment; paired tests showed ALT decreased in R-HIIT.

Mean difference 13.16, p=0.013, partial eta squared=0.44, 95% CI 3.40 to 22.92.

Improved

AST

R-HIIT had significantly lower postintervention AST than MM-HIIT after adjustment.

Mean difference 10.79, p=0.024, partial eta squared=0.38, 95% CI 1.67 to 19.90.

Improved

Wellness

Perceived wellness improved for the whole group, with a significant within-group increase in MM-HIIT, but no between-group difference.

Whole group 14.72 +/- 2.6 to 16.89 +/- 2.76, p=0.002.

Improved

Other cardiometabolic markers

Resting heart rate, blood pressure, glucose, lipids, BMI, waist circumference, and waist-to-height ratio showed no significant changes.

No significant changes reported.

No clear change

Insights

In this small sample, rowing HIIT was more favorable than multimodal resistance HIIT for liver enzymes.
Group HIIT with modeling and encouragement may support perceived wellness.
Heavy multimodal HIIT needs coaching and equipment.

Limitations

Small sample
No no-exercise control group
Unblinded assessors
Healthy baseline values reduced room for cardiometabolic improvement
Groups were not energy-expenditure matched

Safety

Two participants dropped out from R-HIIT; one due to an unexpected commitment and one due to a concussion outside the study.
No intervention-related adverse events were reported.