Upper limb isokinetic muscle strength predicts the performance in cross-country sit-skiing

The double poling (DP) technique in cross-country sit-skiing is primarily considered as an upper-body exercise. The upper limb muscle strength and motion economy are important factors accounting for DP performance in cross-country sit-skiing. The present study investigates how upper limb muscle strength predicts DP performance in cross-country sit-skiing. A total of 19 female non-disabled college students (age 23.2 +/- 0.8 years, BMI 20.4 +/- 2.2) performed 30-s and 3-min DP performance tests using a sit-skiing ergometer. Isokinetic muscle strength of the shoulder and elbow extensor were measured at the angular velocity of 30 degrees/s, 60 degrees/s, and 120 degrees/s with an ISOMED2000 isokinetic system. A medium correlation was found between DP output power and isokinetic upper limb muscle strength (shoulder strength at all speeds, r = 0.39-0.74, p <= 0.1). Multiple regression analyses which were employed to predict power production in the 30-s and 3-min tests showed that shoulder extension strength at 60 degrees/s accounted for 34% of the variation in the 30-s test, and 40% of the variance in the 3-min test. Muscle strength and biomechanical analysis of DP process indicated that upper limb extensor muscle strength and muscle coordination were important factors for the power output generation in sit-skiing DP. These results may use to guide special physical fitness training for paralympic cross-country sit-skiing.

Automated summary

The study found a moderate correlation between upper limb muscle strength and DP output power, with the shoulder extension strength at 60 degrees/s showing a higher correlation. Multiple regression analysis indicated that shoulder extension strength at 60 degrees/s explained 34% and 40% of the variance in the 30-s and 3-min tests respectively.