# Adding High-Intensity Interval Training to Classical Resistance Training Does Not Impede the Recovery from Inactivity-Induced Leg Muscle Weakness

PMID: 36670879
Journal: Antioxidants (Basel, Switzerland)
Published: 2022 Dec 22
Authors: Venckunas T, Brazaitis M, Snieckus A, Mickevicius M, Eimantas N, Subocius A, Mickeviciene D, Westerblad H, Kamandulis S

## Question

Does adding all-out cycling HIIT to resistance training affect recovery from inactivity-induced leg muscle weakness after 3 weeks of unloading?

## Summary

Sixteen recreationally active young men completed 3 weeks of dominant-leg unloading and were then randomized to 3 weeks of resistance training alone or resistance training plus all-out cycling HIIT. Adding eight cycling HIIT sessions did not impair recovery of muscle thickness or maximal voluntary contraction torque, and cycling power improved across the HIIT sessions.

## Population

- 16 healthy recreationally active young men after 3 weeks of dominant-leg unloading.
- Sample size: 16
- Age: Ctrl 25.0 +/- 1.6 years; HIIT 26.9 +/- 2.2 years
- Sex: Men only
- Fitness level: Moderately active, no structured training or competitive sport
- Health status: Healthy; chronic disease and lower-limb injury excluded

## Methodology

- Randomized post-unloading training comparison
- 3 weeks unloading plus 3 weeks training
- Supervised laboratory and gym-based intervention
- Randomized and controlled study design.

## Protocol

- Resistance plus all-out cycling HIIT.
- Modality: Stationary cycling plus machine resistance training.
- Work intervals: 30 s.
- Recovery: 4 min.
- Sets or repetitions: 4 bouts week 1, 5 bouts week 2, 6 bouts week 3.
- Intensity: All-out cycling at 0.75 Nm/kg body weight.
- Session duration: Resistance workout about 40 min; HIIT bout block about 14-23 min depending on 4-6 bouts plus setup.
- Frequency: HIIT on non-resistance days during 3-week training; resistance 3 days/week.
- Program length: 3 weeks.
- Progression: Bout count increased weekly.
- Resistance training only.
- Modality: Machine resistance training.
- Sets or repetitions: Three sets each of leg press, knee extension, and hamstring curl.
- Intensity: Dominant leg sets to failure within 8-12 reps.
- Session duration: About 40 min.
- Frequency: 3 sessions/week.
- Program length: 3 weeks.
- Progression: Resistance adjusted to maintain 8-12 reps to failure.

## Outcomes

### MVC torque
Status: improved
MVC torque fell after unloading and fully recovered after training in both groups, with no group difference.

About 11% decrease after unloading; no significant group difference at any time.

### Muscle thickness
Status: improved
Muscle thickness fell after unloading and recovered after training in both groups.

About 6% decrease after unloading; no group difference.

### Cycling power
Status: improved
HIIT cycling power increased across the eight sessions.

+5.1 +/- 1.7% by session 2 and +9.1 +/- 3.0% by last session versus session 1.

## Practical Insights

- All-out cycling HIIT can be progressed from 4 to 6 bouts over 3 weeks when separated from resistance days.
- This is not enough evidence to prescribe HIIT after disuse without screening or supervision.

## Limitations

- Small sample
- Men only
- Short intervention
- Artificial unloading model
- No adverse-event reporting
- Some missing reliable MVC data

## Safety And Adherence

- No adverse events or injuries were reported.
- 20 Hz torque reduction after training suggested residual low-frequency force depression despite 48 h rest.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/36670879/) (pubmed)
- [DOI](https://doi.org/10.3390/antiox12010016) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9854626/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.