New Hampshire Musculoskeletal Institute
New Hampshire Musculoskeletal Institute

Monitored Rehab Functional Squat Coordination Test: Reliability, Learning Curve and Eccentric-Concentric Performance Comparisons

Context: Many clinical testing devices operate in open-chain fashion that may not be comparable to real-life activities. The Monitored Rehabilitation Functional Squat System (MRFSS) allows for objective assessment of closed-chain activities, yet to date this system has not been used to answer clinical research questions. It is first necessary to establish reliability and learning curves for MRFSS tests. The MRFSS neuromuscular coordination test could elucidate coordination differences between concentric and eccentric actions. Differences could affect training and/or injury prevention considerations.

Objectives: To determine learning curve and reliability associated with repeated trials of the MRFSS coordination test and to compare tracking accuracy and learning curve during concentric and eccentric test elements.

Design: One group, repeated-measures, intraclass correlation (ICC).

Setting: Outpatient clinic.

Participants: Convenience sample of 20 males (age 24.6±2.8; height 178.5±4.2cm; weight 91.5±14.1kg) with no leg or back conditions, and no central nervous system or uncorrected visual deficits.

Interventions: After providing consent, subjects performed a 5-minute bicycle warm-up then repeated trials of trajectory tracking during two-leg functional squatting (Session 1: 10 trials with 30-second rest intervals; Session 2: 1 trial). While observing real-time results on a monitor, subjects attempted to flex (eccentric) or extend (concentric) the legs to maintain cursor position precisely on the computer-generated path. Resistance was approximately 25% of body weight. Subjects returned after 24-48 hours to perform one trial for reliability analysis. RMANOVAs (pairwise comparisons, Bonferroni correction) were used to quantify learning over Session 1 trials both for overall performance and for eccentric-concentric performance. ICC was used to test reliability between sessions. Paired t-tests were used to compare eccentric and concentric performance over 10 trials (corrected alpha=.005).

Main Outcome Measure: Absolute error (mm; difference between subject’s trajectory and computer path).

Results: All subjects completed both sessions. Significant differences between the first 2 trials and later trials (e.g., Trial 3 mean error=4.3±1.4mm versus Trial 1 mean error=10.7±5.3mm, P<.001) led us to identify Trial 3 as the learning plateau trial. There was no difference in the rate of improvement of eccentric and concentric accuracy over the 10 trials. ICC correlating Trial 3 to Session 2’s reliability trial demonstrated a strong relationship (r=.77, P<.001). Concentric scores were better than eccentric in all trials, with 4 comparisons reaching the corrected significance level (e.g., Trial 6 eccentric error=7.16±2.02mm, concentric error=5.96±1.6mm, P<.001).

Conclusion: The MRFSS Coordination Test had strong reproducibility. Subjects made significant performance gains over the first 2 trials so future studies will incorporate 2 preliminary learning trials. Eccentric and concentric tracking accuracy improved similarly. Concentric tracking may be more accurate, though further research is required to confirm this finding and determine its clinical significance.