Hamstrings Volumetric Adaptations to a Four-Week Nordic Hamstring Exercise Protocol in Individuals with ACL Reconstruction: A Preliminary Case Series.
Grant E Norte, Amanda M Murray, Justin L Rush and 2 others
PMID 40904716WHAT IT FOUND
Four weeks of Nordic hamstring exercises increased eccentric strength by 11% on average, but muscle volume gains were small (3%) and inconsistent.
Most participants showed some volume increase, yet responses varied widely, suggesting exercise prescription should be individualized rather than standardized.
Key findings
01Eccentric strength increased by a moderate magnitude (11%) after four weeks, with six of seven participants showing gains.
02Total hamstrings muscle volume increased by a trivial-to-moderate magnitude (3.3%) on average, but individual responses ranged from -6.0% to 17.6%.
03Despite strength and volume gains, total hamstrings and semitendinosus volumes remained smaller than normative data after the intervention.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
This was a case series with no control group, so it is impossible to confirm that the changes were caused by the exercise rather than natural recovery or other factors. The sample size was very small (n=7), limiting the generalizability of the findings. Participants had varying times since surgery (5 to 91 months), which may have influenced their capacity for muscle growth. The four-week duration may have been too short to detect significant volumetric changes, as strength improved more consistently than size.
Declared interests
The study was funded by the Great Lakes Athletic Trainers’ Association. The authors declared no conflicts of interest.
The easy way to misread this
Do not assume that four weeks of Nordic hamstring exercises will fully restore muscle volume in ACLR patients. While strength improved for most, volume gains were small and inconsistent, and muscles remained smaller than normal. This is preliminary data, not proof of efficacy for muscle hypertrophy.
Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →