One session of high-intensity interval training (HIIT) every 5 days, improves muscle power but not static balance in lifelong sedentary ageing men: A randomized controlled trial
Question
Does low-frequency HIIT, performed once every 5 days after a conditioning phase, improve peak muscle power, body composition, and static balance in lifelong sedentary ageing men?
Summary
This randomized controlled trial tested a low-frequency cycling HIIT program in sedentary men aged 56-65 years. After a 6-week supervised conditioning phase, the intervention group performed one HIIT session every 5 days for 6 weeks, while controls stayed inactive. The low-frequency HIIT phase improved peak cycling power and lean mass and reduced body fat, but it did not improve static balance; no participants were lost to follow-up and no adverse events were recorded.
Methodology
- Thirty-three lifelong sedentary but otherwise healthy men aged 56-65 years, randomized to intervention or inactive control.
- 33 participants.
- Wattbike cycle ergometer.
- Work intervals: 6 x 30-second sprints.
- Recovery: 3-minute active recovery between sprints.
- Intensity: First 3 sessions at 40% PPO, final 6 at 50% PPO.
- 5-minute warm-up plus intervals and recoveries; full duration about 23 minutes before any cool-down.
- Once every 5 days.
- 6 weeks HIIT after 6 weeks conditioning.
- Randomized controlled trial with 2:1 allocation to intervention or inactive control and three measurement phases.
- Peak power output, Body composition, Static balance, and Safety and adherence were tracked.
Outcomes
Peak power output
Low-frequency HIIT significantly increased absolute and relative peak power output in the intervention group.
Interaction p < 0.01; phase C 831.1 +/- 170.6 W intervention vs 657.3 +/- 133.1 W control.
Body composition
Intervention showed reduced total body fat and increased lean body mass after HIIT.
Lean body mass interaction p < 0.01; total body fat decreased within intervention between phases A-B and B-C, p < 0.05.
Static balance
No measure of static balance improved after conditioning or HIIT.
No phase, group, or interaction effects, p > 0.05.
Safety/adherence
Feasibility was high with no loss to follow-up and no recorded adverse events.
100% completed phases A, B, and C.
Insights
- Older sedentary men may benefit from longer recovery between HIIT sessions.
- A conditioning phase before HIIT can be important for safety and adherence.
- Stationary cycling power work should not be assumed to improve balance.
Limitations
- Male-only sample.
- Young-old age range only.
- Conditioning phase makes attribution less clean.
- No long-term follow-up.
- Static balance assessment may not have been challenging enough.
Safety
- No participants were lost to follow-up.
- No adverse events were recorded during conditioning or low-frequency HIIT.
- Medical clearance and conditioning preceded high-intensity training.