Effects of high-intensity interval training on executive functions and IGF-1 levels in sedentary young women: a randomized controlled trial
Question
Does online HIIT, with or without an added daily-step goal, improve salivary IGF-1 and executive functions in sedentary young women compared with control?
Summary
This randomized trial tested 12 weeks of online HIIT, HIIT plus a 10,000-steps/day physical activity goal, or control in sedentary young women. The study did not find clear group-by-time effects showing that HIIT specifically improved salivary IGF-1 or executive function. Some cognitive scores improved over time, but the pattern was not specific to the intervention groups, so practice effects or outside factors remain plausible.
Methodology
- Sedentary young women.
- 77 participants.
- Bodyweight/cardio online HIIT.
- Work intervals: 30 s exercise.
- Recovery: 30 s rest.
- Intensity: RPE 8 progressing to 9-10 on CR10.
- About 40 min.
- 3 sessions/week.
- 12 weeks.
- Three-arm randomized controlled trial with blinded assessors/data analysts and 12-week follow-up after training stopped.
- Salivary IGF-1, and Executive function were tracked.
Outcomes
IGF-1
No statistically significant group, time, or interaction effect for salivary IGF-1.
Reported p values > .40.
Executive function
Some measures improved over time, but not with consistent group-by-time effects attributable to HIIT.
Digit Span Backward time p < .001 but interaction p = .286; Digit Span Total interaction p = .081.
Insights
- 30/30 online HIIT is implementable, but this trial does not justify strong cognition or IGF-1 claims.
- Daily activity goals may be paired with structured HIIT, but evidence here is trend-level.
Limitations
- Attrition from 77 to 58 analyzed.
- Healthy young women only.
- Practice effects in cognitive testing.
- Surrogate biomarker outcome.
- No detailed adverse-event reporting.
- Online supervision and no objective neurobiological measures.
Safety
- No adverse-event details were reported.