Intra-Session Reliability of Eccentric Countermovement Jump Kinetics in Individuals Six Months After Anterior Cruciate Ligament Reconstruction.
Gwendal Kersante, Karine Langlois, Ayrton Moiroux-Sahraoui and 3 others
Eccentric peak force and eccentric impulse from a countermovement jump are reliable within a single session in patients six months after ACL reconstruction.
Eccentric rate of force development is not reliable, with the highest trial-to-trial variation of the three measures.
Key findings
1Eccentric peak force and eccentric impulse showed good intra-session reliability, with ICC values of 0.87 to 0.89 on the operated limb and 0.84 to 0.89 on the non-operated limb.
2Eccentric rate of force development showed only moderate reliability (ICC 0.62 on the operated limb, 0.71 on the non-operated limb) and the highest variability, with coefficients of variation of 39.81% and 30.83%.
3The operated limb produced lower values across all three eccentric variables: peak force 631.71 N versus 745.48 N, impulse 119.56 N·s versus 141.25 N·s, and rate of force development 1055.76 N·s⁻¹ versus 1352.32 N·s⁻¹.
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How it was doneWhat they foundWhat it means for PTs
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What it does not show
Retrospective design: the researchers could not control for fatigue, pain, or psychological state on the day of testing, and they acknowledge this may have inflated variability, especially for rate of force development. Only within-session reliability was tested. There is no inter-session data, no minimal detectable change value, and no link to clinical outcomes, so you cannot yet use these numbers to decide whether a patient has improved between visits. The jump was bilateral and symmetrical (hands on hips), which the authors note may mask compensatory strategies that would show up in a unilateral or sport-specific task. Only eccentric-phase variables were examined; concentric force, jump height, and rate of force relaxation were not reported. Participants were excluded if they had any concomitant meniscal or ligament injury, so the findings may not generalise to the more complex post-surgical patients you see in practice. Single time point (six months post-surgery) at a single clinic, with all surgeries performed by three surgeons using one protocol.
Declared interests
The authors declare no competing interests and state the research received no specific grant from any public, commercial, or not-for-profit funding body.
The easy way to misread this
Do not read the good reliability of eccentric peak force and eccentric impulse as evidence they can detect meaningful recovery changes over time. This study only tested consistency within one session, not whether scores shift as a patient improves, and the authors state plainly that reliability does not establish sensitivity to functional recovery or return-to-sport readiness.
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 →