Test–retest reliability of ski-specific aerobic, sprint, and neuromuscular performance tests in highly trained cross-country skiers

Abstract

Purpose: Laboratory tests are commonly performed by cross-country (XC) skiers due to the challenges of obtaining reliable performance indicators on snow. However, only a few studies have reported reliability data for ski-specific test protocols. Therefore, this study examined the test–retest reliability of ski-specific aerobic, sprint, and neuromuscular performance tests. Methods: Thirty-nine highly trained XC skiers (26 men and 13 women, age: 22 ± 4 years, V̇O2max: 70.1 ± 4.5 and 58.8 ± 4.4 mL·kg−1·min−1, respectively) performed two test trials within 6 days of a diagonal V̇O2max test, n = 27; skating graded exercise test to assess the second lactate threshold (LT2), n = 27; 24-min double poling time trial (24-min DP, n = 25), double poling sprint test (SprintDP1, n = 27), and 1-min self-paced skating sprint test (Sprint1-min, n = 26) using roller skis on a treadmill, and an upper-body strength test (UB-ST, n = 27) to assess peak power (Ppeak) with light, medium, and heavy loads. For each test, the coefficient of variation (CV), intraclass correlation coefficient (ICC), and minimal detectable change (MDC) were calculated. Results: V̇O2max demonstrated good-to-excellent reliability (CV = 1.4%; ICC = 0.99; MDC = 112 mL·min−1), whereas moderate-to-excellent reliability was found for LT2 (CV = 3.1%; ICC = 0.95). Performance during 24-min DP, SprintDP1, and Sprint1-min showed good-to-excellent reliability (CV = 1.0%–2.3%; ICC = 0.96–0.99). Absolute reliability for UB-ST Ppeak was poor (CV = 4.9%–7.8%), while relative reliability was excellent (ICC = 0.93–0.97) across the loads. Conclusion: In highly trained XC skiers, sport-specific aerobic and sprint performance tests demonstrated high test–retest reliability, while neuromuscular performance for the upper body was less reliable. Using the presented protocols, practitioners can assess within- and between-season changes in relevant performance indicators.