Associations of Markerless Motion-Based Physical Function Test Performance with Running Gait Kinetics: Application for Therapeutic Monitoring.
Katherine Tansky, Ryan M Nixon, Matthew Martenson and 3 others
Simple jump and hop tests done with a markerless camera system tracked running ground reaction forces moderately to strongly (r up to 0.882) in 62 runners.
But the study measured correlation only — no one was followed for injury, and loading-rate correlations were weaker.
Key findings
1Peak ground reaction forces from the three functional tests (single-leg jump, lateral bound, multihop) correlated moderately to strongly with peak GRF measured during running on an instrumented treadmill (r = 0.641 to 0.882, all p < 0.001).
2Correlations with running vertical average loading rate (VALR) were weaker and less consistent: only the single-leg jump GRFs reached moderate (r = 0.634 to 0.742, p < 0.001); lateral bound distance was fair (r = 0.518); multihop and lateral bound GRFs did not reach significance.
3The markerless functional screen took 8 minutes with one staff member, compared with 36 minutes and three staff members for the instrumented treadmill assessment.
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What it does not show
No follow-up: the study did not track whether any runner went on to be injured, so the correlations cannot be read as predictive of injury risk. Cross-sectional design at a single site: the runners were a convenience sample from one university lab, all seeking gait-improvement services, which may over-represent motivated, injury-conscious individuals and limit generalisability. Sampling-rate mismatch: the markerless system recorded at 60 fps while the treadmill sampled at 1,200 Hz, which the authors note may limit the temporal resolution and accuracy of the markerless force estimates. Only three functional tests were evaluated; the authors acknowledge that other tests available in the system (e.g., step-down) might have shown different or stronger correlations. The study evaluates a specific commercial product (DARI® Motion); results may not generalise to other markerless systems.
Declared interests
Authors report no conflicts of interest. Funded by the University of Florida. The study evaluates the DARI® Motion system (DARI® Motion Inc., Overland Park, KS), a commercial product, but no financial relationship with that company is declared.
The easy way to misread this
Do not read the moderate-to-strong GRF correlations as evidence that the markerless functional tests predict running injury or that they can replace instrumented treadmill gait analysis for clinical decision-making. The study is cross-sectional with no injury follow-up, and the loading-rate (VALR) correlations — the measure the authors cite as more consistently associated with running injuries — were weaker and inconsistent across the three tests. A correlation of 0.88 between two force measurements in 62 runners does not establish that one predicts the other over time or that either predicts who will get hurt.
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 →