An All-Out Test to Determine Finger Flexor Critical Force in Rock Climbers.

PURPOSE: The fatigue resistance of the finger flexors is known to be a key determinant of climbing performance. This study set out to establish the association between the single all-out assessment of finger flexor critical force (ff-CF) and the impulse above CF (W') on climbing performance (self-reported sport and boulder climbing ability). METHODS: A total of 129 subjects completed an assessment of dominant arm ff-CF, comprised of a series of rhythmic isometric maximum voluntary contractions (CF defined as mean end-test force [in kilograms]; W' impulse above CF [in kilogram second]). RESULTS: The ff-CF protocol resulted in the same force decay to a plateau seen in previous isometric critical torque and critical force tests. Linear regression analysis, adjusting for sex, revealed that CF percentage of body mass explained 61% of sport and 26% of bouldering performance and W' per kilogram body mass explained 7% sport and 34% bouldering performance. A combined model of CF as a percentage of body mass and W' per kilogram body mass, after adjustment for sex differences, was able to explain 66% of sport climbing and 44% of bouldering performance. CONCLUSIONS: The results illustrate the relevance of the CF threshold in describing the fatigue resistance of the finger flexors of rock climbers. Given ff-CF ability to describe a considerable proportion of variance in sport climbing and bouldering ability, the authors expect it to become a common test used by coaches for understanding exercise tolerance and for determining optimal training prescription.

The Determination of Finger-Flexor Critical Force in Rock Climbers.

Purpose: To determine if the mathematical model used for the estimation of critical force (CF) and the energy store component W' are applicable to intermittent isometric muscle actions of the finger flexors of rock climbers, using a multisession test. As a secondary aim, the agreement of estimates of CF and W' from a single-session test was also determined. The CF was defined as the slope coefficient, and W' was the intercept of the linear relationship between total "isometric work" (Wlim) and time to exhaustion (Tlim). Methods: Subjects performed 3 (separated by either 20 min or >24 h) tests to failure using intermittent isometric finger-flexor contractions at 45%, 60%, and 80% of their maximum voluntary contraction. Results: Force plotted against Tlim displayed a hyperbolic relationship; correlation coefficients of the parameter estimates from the work-time CF model were consistently very high (R2 > .94). Climbers' mean CF was 425.7 (82.8) N (41.0% [6.2%] maximum voluntary contraction) and W' was 30,882 (11,820) N·s. Good agreement was found between the single-session and multisession protocol for CF (intraclass correlation coefficient [ICC3,1] = .900; 95% confidence interval, .616-.979), but not for W' (ICC3,1 = .768; 95% confidence interval, .190-.949). Conclusions: The results demonstrated the sensitivity of a simple test for the determination of CF and W', using equipment readily available in most climbing gyms. Although further work is still necessary, the test of CF described is of value for understanding exercise tolerance and to determine optimal training prescription to monitor improvements in the performance of the finger flexors.