Effects of high-intensity interval training on lean mass, strength, and power of the lower limbs in healthy old and young people
Question
Does 12 weeks of stationary-bike HIIT improve lower-limb lean mass, maximal strength, rate of force development, and muscle power in healthy young and older men?
Summary
This small uncontrolled study tested 12 weeks of stationary-bike HIIT in physically inactive healthy young and older men. Both age groups completed all 36 sessions, and the authors reported increases in lower-limb lean mass, knee-extension strength, early rate of force development, and sit-to-stand power. Because there was no non-exercising control group and only 9 men per age group, results should be treated as suggestive rather than definitive.
Methodology
- Healthy physically inactive young and older men with BMI 18.5-30 kg/m2.
- 18 participants.
- Stationary bicycle.
- Work intervals: 1 minute at 90% HRmax.
- Recovery: 2 minutes inactive rest.
- Intensity: 90% of maximum HR from reference testing.
- 30-minute interval block; training warm-up/cool-down not reported.
- 3 sessions/week.
- 12 weeks.
- Two-group pre-post intervention study nested in a larger HIIT project; no non-training control group.
- Lower-limb lean mass, Knee-extension maximal strength, Rate of force development, and Sit-to-stand muscle power were tracked.
Outcomes
Lower-limb lean mass
Non-dominant limb lean mass increased over time in both groups, without a time-by-group interaction.
NDL time effect p=0.014; DL interaction p=0.335, NDL interaction p=0.294.
Maximal strength
Dominant-limb maximal strength increased over time, with no time-by-group interaction.
DL time effect p=0.022; interactions were not significant.
Rate of force development
RFD 0-50 ms improved in the non-dominant limb; other RFD intervals did not show broad improvement.
NDL RFD 0-50 ms time effect p=0.021; all time-by-group interactions p>0.05.
Sit-to-stand power
Sit-to-stand power increased in both groups, with a larger relative increase in older adults.
Time effect p=0.02; no time-by-group interaction p=0.425; young +12.1%, older +34.7% described in discussion.
Insights
- Stationary-bike HIIT may be a tolerable supervised option for inactive older men who pass screening.
- Muscle-power outcomes can improve alongside cycling HIIT, but causal claims are weak without a control group.
- Lower-limb asymmetry may persist after bilateral cycling and deserves monitoring in older users.
Limitations
- Small sample size.
- No randomization or control group.
- All participants were men.
- Order of strength testing was not randomized.
- Adverse events were not reported in detail.
Safety
- Participants were screened for cardiorespiratory and musculoskeletal contraindications.
- All sessions were supervised with continuous HR monitoring.
- The article did not report adverse events.