The Study
Effect of 6 weeks of sprint training on growth hormone responses to sprinting
This study is like an experiment where some people did sprint training and others didn't, by random assignment. Then they measured their growth hormone after sprinting. Because it was randomized, we can say the training caused the growth hormone response to be smaller. So we can say 'training causes a smaller growth hormone response'.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
A group of young men did sprint training for 6 weeks. After that, when they sprinted, their body made less growth hormone than before, but they could sprint faster.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 546 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1This means even though training made the men better at sprinting, it reduced the body's hormonal response to exercise, which might affect how the body recovers or adapts.
- 2After training, the highest growth hormone level after sprinting dropped from about 10.3 to 5.8 units (over 40% less).
- 3The total amount of growth hormone released during recovery was 55% lower.
- 4Sprint power improved by 5-6%.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
European Journal of Applied Physiology
Year
2004
Authors
K. Stokes, M. Nevill, P. Cherry, H. Lakomy, G. Hall
Related Content
Claims (6)
In young men, doing short, very fast runs three times a week for six weeks makes the body release much less growth hormone during those runs—less than half of what it used to. At the same time, they actually get a little bit faster at running.
Young men who did six weeks of very intense, short exercise sessions had higher amounts of a waste product called lactate in their blood right after the exercise, but their blood lactate levels dropped faster during rest, showing their bodies improved at clearing this waste product.
Young men who do sprint training three times a week for six weeks get faster and their power output goes up: their peak power increases by 6% and their average power by 5%.
Young men who sprint-trained for six weeks had lower ammonia levels in their blood after exercise. Ammonia is a waste product your muscles make when you work out hard. Levels dropped from about 184 to 139.
Sprint training for six weeks does not change the amount of growth hormone in the blood of young men when they are at rest. This means the training only affects the growth hormone that spikes during exercise, not the normal level.
Doing a short, very fast sprint raises the levels of two important hormones: testosterone and growth hormone. This effect happens right after the sprint.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.