Changes in balance ability, power output, and stretch-shortening cycle utilisation after two high-intensity intermittent training protocols in endurance runners
Question
How do two equal-volume running HIIT structures acutely affect postural control, vertical jump power, and stretch-shortening-cycle utilization in endurance runners?
Summary
Eighteen recreational endurance runners completed two acute track HIIT workouts with the same 4 km volume: 10 x 400 m with 90 s passive recovery and 40 x 100 m with 30 s passive recovery. The shorter-repeat protocol let runners move faster with lower RPE and no significant changes in jumping, balance, or stretch-shortening-cycle measures, while the 400 m repeat protocol improved CMJ and SJ but worsened postural control.
Methodology
- 18 recreationally trained endurance runners in cross-country season.
- 18 participants.
- Outdoor running.
- Work intervals: 400 m.
- Recovery: 90 s passive standing recovery.
- Intensity: Above vVO2max; 107.17 +/- 2.83% vVO2max on average.
- 4 km high-intensity running plus recovery after 20 min warm-up.
- One acute session.
- Acute field comparison.
- Acute repeated-measures field comparison of two HIIT running protocols
- Vertical jump, Postural control, and Exertion and lactate were tracked.
Outcomes
Jump height
CMJ and SJ improved after 10 x 400 m but did not significantly change after 40 x 100 m.
10 x 400 m CMJ and SJ p<0.05; discussion reports CMJ +5.18% and SJ +6.43%.
Balance
Postural control worsened after 10 x 400 m but not after 40 x 100 m.
10 x 400 m CoP area p=0.006, length p=0.001, velocity p=0.004; 40 x 100 m p=0.812, p=0.220, p=0.364.
SSC
Stretch-shortening-cycle utilization did not significantly change in either protocol.
PSA and RSI p values were non-significant in both protocols.
Intensity
40 x 100 m had faster pace and higher mean HR, while lactate and HRpeak were similar.
Pace and %vVO2max p<0.001; HRmean p<0.001; BLa p=0.670; HRpeak p=0.067.
Insights
- For trained runners, splitting the same 4 km HIIT volume into shorter 100 m repeats may preserve postural control better than 400 m repeats.
- Acute balance measures may be worth monitoring after longer high-intensity running repeats.
Limitations
- Small sample
- Non-randomized protocol order
- Acute field study only
- Intensity was not precisely prescribed beyond above-vVO2max self-paced running
Safety
- No adverse events were reported.
- Participants had no injury in the prior 3 months and were asked to avoid heavy exercise for 72 h before testing.