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.
Thirty-nine highly trained XC skiers (26 men and 13 women, age: 22 ± 4 years, V̇O _2max : 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 V̇O _2max test, n = 27; skating graded exercise test to assess the second lactate threshold (LT ₂ ), n = 27; 24-min double poling time trial (24-min DP, n = 25), double poling sprint test (Sprint _DP1 , n = 27), and 1-min self-paced skating sprint test (Sprint _1-min , n = 26) using roller skis on a treadmill, and an upper-body strength test (UB-ST, n = 27) to assess peak power (P _peak ) 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.
V̇O _2max demonstrated good-to-excellent reliability (CV = 1.4%; ICC = 0.99; MDC = 112 mL·min ^-1 ), whereas moderate-to-excellent reliability was found for LT ₂ (CV = 3.1%; ICC = 0.95). Performance during 24-min DP, Sprint _DP1 , and Sprint _1-min showed good-to-excellent reliability (CV = 1.0%-2.3%; ICC = 0.96-0.99). Absolute reliability for UB-ST P _peak was poor (CV = 4.9%-7.8%), while relative reliability was excellent (ICC = 0.93-0.97) across the loads.
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.