# Aerobic and Anaerobic Fitness according to High-Intensity Interval Training Frequency in Youth Soccer Players in the Last Stage of Rehabilitation

PMID: 36497647
Journal: International journal of environmental research and public health
Published: 2022 Nov 23
Authors: Yan S, Kim Y, Choi Y

## Question

In youth male soccer players at the last stage of rehabilitation, does low-frequency HIIT improve aerobic and anaerobic fitness compared with a higher-frequency HIIT schedule?

## Summary

This short rehabilitation study compared low-frequency and high-frequency HIIT in 54 male high-school soccer players who were in the last stage of return-to-play rehabilitation. Both two sessions per week and five sessions per week improved VO2peak, graded treadmill exercise duration, anaerobic power, and knee strength over 4 weeks. The higher-frequency group generally improved more, but the lower-frequency schedule still produced meaningful fitness gains for athletes who could not attend rehabilitation frequently.

## Population

- Fifty-four male high-school soccer players in the last stage of rehabilitation after sports injuries.
- Sample size: 54
- Sex: Male only
- Fitness level: Youth soccer players returning to play after detraining/injury.
- Health status: Recovered enough for late-stage rehabilitation with restored range of motion and strength and almost no pain.

## Methodology

- Non-randomized comparative intervention based on participants' attendance circumstances, with pre/post testing over 4 weeks.
- 4 weeks.
- Rehabilitation center with treadmill, cycle ergometer, and isokinetic testing.
- Controlled study design.

## Protocol

- Low-frequency HIIT.
- Modality: Cycle ergometer and treadmill.
- Work intervals: 10-second acceleration plus 10-20 seconds at target intensity.
- Recovery: 120 seconds between sets and 3 minutes between bouts.
- Sets or repetitions: 3 sets in each of 3 bouts for cycle, then same structure on treadmill.
- Intensity: 85-100% HRmax.
- Session duration: 50-60 minutes total recovery and training time.
- Frequency: 2 sessions per week.
- Program length: 4 weeks.
- Progression: None reported.
- High-frequency HIIT.
- Modality: Cycle ergometer and treadmill.
- Work intervals: Same interval structure as LFG.
- Recovery: Same recoveries as LFG.
- Sets or repetitions: Same as LFG.
- Intensity: 85-100% HRmax.
- Session duration: 50-60 minutes total recovery and training time.
- Frequency: 5 sessions per week.
- Program length: 4 weeks.
- Progression: None reported.

## Outcomes

### Aerobic fitness
Status: improved
Both groups improved GXT variables, including VO2peak; HFG had higher post-test VO2peak and exercise duration.

Post VO2peak LFG 56.4 vs HFG 57.1 mL/kg/min, p = 0.035; exercise duration p = 0.041.

### Anaerobic power
Status: improved
Both groups improved early Wingate set performance, while HFG improved more in later repeated-sprint performance.

Post Wingate 5-set peak power LFG 606.3 vs HFG 629.3 W, p = 0.039.

### Knee strength
Status: mixed
Both groups improved 60 and 180 degrees/second knee strength/power, but 240 degrees/second muscular endurance improved only in HFG.

Post 240 degrees/second LFG 68.5 vs HFG 70.2 J, p = 0.010.

### Body composition
Status: no clear change
Neither group significantly changed muscle mass or body fat.

p > 0.05.

## Practical Insights

- Two weekly supervised HIIT sessions may be useful in late-stage youth athlete rehabilitation when attendance barriers exist.
- Higher frequency may produce stronger repeated anaerobic and muscular-endurance adaptations.
- Return-to-play HIIT should be supervised and recovery-aware.

## Limitations

- Non-random frequency assignment.
- Male soccer players only.
- Late-stage rehabilitation sample only.
- No long-term follow-up.
- No dietary management.
- Potential insufficient recovery in HFG.

## Safety And Adherence

- No intervention adverse events were reported.
- Participants were screened by specialists before enrolment.
- The authors caution against overload from frequent or long-term HIIT in growing adolescents.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/36497647/) (pubmed)
- [DOI](https://doi.org/10.3390/ijerph192315573) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9735649/) (full text)

## Agent Guidance

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