# Kinematic alterations after two high-intensity intermittent training protocols in endurance runners

PMID: 31534818
Journal: Journal of Sport and Health Science
Published: 2019-09
Authors: García-Pinillos F, Molina-Molina A, Párraga-Montilla JA, Latorre-Román PA

## Question

Do 10 x 400 m and 40 x 100 m high-intensity intermittent running protocols alter running kinematics in trained endurance runners?

## Summary

Eighteen trained runners completed two demanding interval-running sessions one week apart. Despite high lactate, RPE, and heart-rate responses, the study did not find significant within-session deterioration in the measured running kinematics from the first to the last repetition.

## Population

- Recreationally trained endurance runners.
- Sample size: 18
- Age: 30.9 +/- 11.7 years
- Sex: 16 male, 2 female
- Fitness level: Trained endurance runners
- Health status: No injury history in prior 3 months

## Methodology

- Acute counterbalanced crossover biomechanics study
- Two acute track sessions separated by 7 days
- Outdoor 400 m synthetic track
- Controlled study design.

## Protocol

- 10 x 400 m.
- Modality: Track running.
- Work intervals: 400 m run.
- Recovery: 90-120 s passive standing recovery.
- Sets or repetitions: 10.
- Intensity: Above vVO2max; self-selected hard pace.
- Frequency: single session.
- Program length: single session.
- 40 x 100 m.
- Modality: Track running.
- Work intervals: 100 m run.
- Recovery: 25-30 s passive standing recovery.
- Sets or repetitions: 40.
- Intensity: Above vVO2max; self-selected hard pace.
- Frequency: single session.
- Program length: single session.

## Outcomes

### Kinematics
Status: no clear change
No significant first-to-last repetition kinematic changes occurred within either protocol.

p>=0.05.

### Protocol differences
Status: mixed
The 40 x 100 m protocol was faster and showed different contact, step, hip, knee, and ankle measures.

Reported p values ranged from p<0.001 to p=0.031.

### Foot strike
Status: no clear change
Foot strike pattern did not significantly change within or between protocols.

Between protocols p=0.135; 10 x 400 m p=0.392; 40 x 100 m p=0.317.

## Practical Insights

- In trained runners, acute interval sessions above vVO2max did not cause clear deterioration in measured sagittal-plane kinematics.
- Short 100 m repeats produced faster running and different mechanics than 400 m repeats, even with matched total distance.
- The result should not be used as safety evidence for beginners.

## Limitations

- Small athlete sample with only two women.
- Acute study without injury follow-up.
- Sagittal-plane two-dimensional video was used.
- Only the right leg was analyzed.

## Safety And Adherence

- No adverse events or injuries during the study were reported.
- Participants had no injury history in the previous 3 months and were medically examined annually.
- The authors noted that no general clinical examination was performed by the study.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/31534818/) (pubmed)
- [DOI](https://doi.org/10.1016/j.jshs.2016.11.003) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6742619/) (full text)

## Agent Guidance

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