Reliability and validity of test concepts for the cross-country skiing sprint

Purpose: This study was conducted, first, to develop a test concept for the new cross-country (XC) skiing sprint and to check test reliability and validity, and, secondly, to test the hypothesis that short-duration maximal speed in double poling (DP) predicts DP sprint performance over race distance (1000-1500 m). Methods: A total of 31 elite XC skiers performed test-retest of a 50-m DP sprint test (DP50m) and a subgroup (N = 17) performed test-retest of a DP sprint speed test (DPVmax) and a 1000-m DP sprint test (DP1000m), both on a treadmill. Additionally, 17 subjects performed all three tests to check validity, whereas six subjects performed an additional 1000-m DP field test. All tests were performed on roller skis. Results: The DP50m, DPVmax, and DP1000m were reliable (r = 0.78-0.99 P < 0.001, CV = 0.79-6.18). The 50-m time (t(50)) and maximal velocity (V-max50) of DP50m correlated to the maximal velocity (V-max) in the DP1000m-test (r = -0.90; r = 0.86; P < 0.001), and time in the DPfield-teSt (t(field)) correlated (r = 0.96, P < 0.01) to time in the DP1000m-test (t(1000)), showing validity of all treadmill tests. t(50), V-max50, V-max, and fatigue index (FI) correlated to t(1000) (r = 0.87-, r = -0.85; r = -0.95; r = 0.86, P < 0.001). Conclusions: Cross-country skiing DP sprint tests appear reliable, valid, and standardizable. The relationship of maximal DP speed on DP sprint performance over race distance suggests (a) to integrate short-time sprint tests as predictors for XC sprint skiing performance, and (b) to reconsider the role of XC skiing specific speed training as an additional instrument to improve XC skiing sprint performance.