M. Zimny, B. Carino, K. Tice, B. Wallace, R.S. McCulloch

Gonzaga University, Spokane, WA

PURPOSE: This study investigated whether upper limb muscle recruitment patterns are optimized in experienced rock climbers (RC) as compared to weight lifters (WL). It was hypothesized that, between RC and WL, there would be significant variance in relative contribution of arm musculature during pull-down exercises with rock-climbing grips. METHODS: Subjects included 16 males (7 RC, 9 WL), ages 18-25 years, with body mass (BM) 79.9±6.1 kg, height 179.5±3.3 cm and fat free mass (FFM) of 69.7±3.3 kg (all values reported as mean±SD). EMG electrodes were placed on the biceps brachii, triceps brachii, upper trapezius, anterior deltoid, latissimus dorsi, pectoralis major, and flexor digitorum superficialis on the dominant side. Subjects stood on a force plate in a wooden framework fitted with three separate grips; a slope grip (large climbing grip that required subjects to palm a rounded surface), a crimp grip (climbing grip that allowed finger tips to pull down on a small ledge), and a bar grip (standard pull-up bar). Each subject performed a 7-second, one-arm pull down with the grip height adjusted so that the subject’s arm and shoulder were flexed 90°, keeping the upper arm parallel to the ground. Subjects completed three trials for each grip condition in a randomized order. EMG (normalized to max voluntary contractions; MVC) and force plate data were collected in order to compare muscle activation and lift-off force between grips and between groups in order to see if RC were able to generate more force using different muscle activity as hypothesized. A 2-by-3 repeated measures ANOVA analysis was performed on data measured by the force plate and the normalized muscle activation measured by the EMG between the climbers group and the weight lifters. RESULTS: There were no significant differences between RC and WL for EMG muscle activation. There was a significant difference between the slope (17.6 ± 16.2 %MVC) & crimp (9.6 ± 11.7 %MVC; p=0.023), crimp & bar (32.4 ± 36.5 %MVC; p=0.011) grips for the biceps brachii. RC lifted significantly more %BM than WL for each grip, with the following %BM results: bar grip; RC (73.90 ± 12.26%) and WL (55.1 ± 12.63%) (p=0.01), slope; RC (59.92 ±9.89%) and WL (37.44 ± 6.16%) (p<0.01), and crimp; RC (38.76 ± 6.54%) and WL (28.92 ± 6.64%) (p=0.01). CONCLUSION: While muscle activation did not appear to vary significantly between subject groups, bicep EMG results suggest grip type may influence neural patterns in recruitment. The force plate data shows that rock climbers are more effective at generating lift force in a climbing position. Our findings suggest that activation of other muscles besides those measured may be responsible for the higher RC forces.

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