Test–Retest Reliability of Knee Proprioceptive Force Sense Assessed Using a Pressure Biofeedback Unit in Male Soccer Players

Abstract

The aim of this study was to determine the test–retest reliability, measurement error and agreement of a pressure biofeedback-based knee proprioceptive force sense (KPFS) assessment in healthy competitive male soccer players. The study employed a methodological test–retest reliability design. A total of 64 male soccer players actively competing at amateur or semi-professional levels participated in this study. KPFS was assessed as the mean of three trials per session with a pressure biofeedback unit (PBU) using an ipsilateral force reproduction protocol. Test–retest reliability over a seven-day interval was evaluated using a two-way random-effects, absolute agreement, single-measure ICC model [ICC(2,1)]. Standard Error of Measurement (SEM) and Minimal Detectable Change (MDC95) were computed to determine measurement precision and clinical responsiveness. Agreement and systematic bias were evaluated using Bland–Altman analysis. The mean KPFS error was 4.88 ± 2.73 mmHg at the initial test and 4.98 ± 2.51 mmHg at the retest (mean difference: −0.10 ± 1.03 mmHg). The protocol demonstrated excellent test–retest reliability with an ICC(2,1) of 0.924 (95% CI: 0.888–0.965). SEM and MDC95 values were 0.72 mmHg and 2.01 mmHg, respectively. Bland–Altman analysis confirmed minimal systematic bias with acceptable limits of agreement between −2.12 and 1.91 mmHg. PBU-based KPFS assessment demonstrates high test–retest reliability and temporal stability in male soccer players. Given its portability, cost-effectiveness, low measurement error and clinical feasibility, this protocol provides a viable tool for objective proprioceptive screening in male soccer players within sports rehabilitation and field-based settings.