Background: Modern rock climbers stress the importance of hand-to-rock contact strength as a factor for success in competitive sport climbing events, however, the degree of handgrip fatigue that occurs during difficult climbing and the time course of recovery from fatigue have not been previously described. The purpose of this study was to characterize the nature of handgrip fatigue that results from difficult continuous climbing until a fall occurs.
Methods: Eleven expert-level rock climbers (age = 28.7 +/- 4.5 years) volunteered to climb continuous laps over a pre-set competition-type route on an indoor modular climbing wall until a fall occurred. The route difficulty (YDS rating of 5.12 a) was near the limit of each subject's "on-sight" lead climbing ability and placed an emphasis on physically difficult movements. "On-sight" refers to a climbing style where the climber ascends the route on the first try without falls and without prior viewing or information about the route. Practice was allowed to enable each subject to master the individual technical movements of the route. Fingertip blood samples were obtained 10 min pre-climb, at post-climb, and at 5-, 10-, and 20-min recovery and analyzed for lactate. Maximum handgrip force in Newtons was determined via dynamometry for each hand and averaged for pre-climb, post-climb, and 5-, 10-, and 20-min recovery periods. Right handgrip endurance, defined as the time that the dominant hand handgrip force could be sustained above 70 percent of handgrip strength, was determined pre-climb, post-climb, and at 20-min recovery.
Results: Mean climbing time during testing was 12.9 +/- 8.5 min for 2.8 +/- 2.2 laps over the route. Data among measurement times were analyzed using a repeated measures ANOVA with Newman-Keuls post hoc tests. Handgrip strength decreased by 22 percent and handgrip endurance decreased by 57 percent from pre-climb to post-climb and both remained depressed after 20 minutes of resting recovery. The pre-climb blood lactate of 1.4 +/- 0.8 mmol.l-1 significantly increased to 6.1 +/- 1.4 mmol.l-1 at post-climb and remained elevated (2.3 +/- 0.8 mmol.l-1) at 20-min recovery. Percent decreases in handgrip strength were significantly correlated with climbing time (R = 0.70), number of laps completed (R = 0.70), and blood lactate (R = 0.76). Percent decreases in handgrip endurance were significantly correlated with climbing time (R = 0.70) and number of laps completed (R = 0.80), but not with blood lactate (R = 0.56).
Conclusions: It was concluded that handgrip strength and handgrip endurance decrease with continuous difficult rock climbing and remain depressed after 20 minutes of resting recovery. It also appears that handgrip strength recovers at a faster rate than handgrip endurance.