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

Abstract

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°/s, 60°/s, and 120°/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°/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.

Effects of poling camber angle on the biomechanics of cross-country sit-skiing

“…Subjects were asked to sit with their lower leg strapped to the seat to simulate the conditions of athletes with disabled lower limb, and then performed three successive 30-s maximal effort tests (poling camber angle at 0°, 15°, 24°, 30°) of DP with 3 min rest between each group and the three consecutive tests. The poling resistance was set at 5% of body weight, which was chosen from several pilot testing and gave skiers the most natural feeling of double-poling 8 .…”

“…Physical tests were performed on an intelligent training and experimenting system of cross-country sit-skiing (Fig. 1 ) 8 . The device can adjust the angle of two rails, which offers non-parallel rails to simulate poling with different camber angles.…”

“…Accumulated evidences have shown that the upper body power (UBP) has an important role in cross-country ski racing, which was further confirmed by statistical analysis from both aerobic energy systems 4 and shorter sprint-type UBP tests 5 . For instance, the factors such as one-repetition maximum (1-RM) strength 6 , lean mass 7 , isokinetic muscle strength 8 , maximum oxygen uptake 9 have been confirmed to be correlated with the skiing or sit-skiing performance. The technical factors such as pole angle [10][11][12] , pacing length [12][13][14] , poling phase 12,15 , body inclination 10 , angular velocities of elbow-and hip-flexion 3 were also found to influence the cross-country skiing.…”

Does the early phase of aging affect the morphology of biceps brachii and torque and total work of elbow flexors in healthy volunteers?

“…The authors pointed out that the performance of many ADL tasks required a high degree of elbow flexion (from 130°up to 150°). Bazzucchi et al (3) observed that older men showed longer isometric endurance time and less absolute torque measured at different angular velocities (15,30,60,90,120, and 150°s -1 ). Regarding the elbow extension torque, a cross-sectional study reported decreases of 20 to 40% and a longitudinal study demonstrated decreases of 1 to 5% in elderly participants compared to young participants (4).…”

“…In addition, muscle strength and performance can be evaluated using the gold standard equipment, the isokinetic dynamometer ( 12 , 13 ). Orthopedic and rheumatology specialists in particular use this device to identify the efficacy of surgery, training, and prevention of muscle or articular lesions ( 14 - 16 ).…”