Will motor skill- and/or strength training affect technique, work economy and time performance in cross-country poling? Competitive cross-country skiers (age 16- 30) will perform a 10 weeks training intervention. They will be randomized in one of the following three groups: poling specific motor skill training 3 times per week in addition to their regular training, maximal strength training 3 times per week in addition to their regular training and a control group who only perform their regular training. Pre- and post intervention, all participants will perform tests in VO2max (running), VO2max (poling), work economy (poling), video and inertial measurement unit (IMU) analyzes of poling technique, time performance test (poling), motor skill tests and maximal strength tests.

Motor Skill- and Maximal Strength Training; Importance for Technique, Work Economy and Time Performance in Cross Country Poling Purpose The relative use of poling in classic cross-country skiing has increased over the last years. (Danielsen et al 2015). As a result of this poling performance has become increasingly important for over all classic cross-country skiing performance. Poling performance with best possible technical skills, implying high velocity with a least possible energy cost (C) should thus be beneficial. Previous research (Østerås et al 2002) has shown improved work economy in poling after maximal strength training (MST). To the investigators knowledge, the effect of motor skill training (MOT) on C has not previously been investigated. In this study MOT and MST will therefore be investigated (in two different groups of cross-country skiers), how they may affect poling technique, C, lactate threshold (LT) and poling performance. The results from this study may give further insight and knowledge in scientific based training practice.

The purpose of this study is thus to investigate if:

1. MOT results in technical changes in poling?
2. MST results in technical changes in poling?
3. MOT improves C in poling?
4. MST improves C in poling?
5. changes in 1-4 improves time performance in poling?

In order to investigate this, competitive cross-country skiers (age 16- 30) will perform a 10 weeks training intervention. They will be randomized in one of the following three groups: poling specific motor skill training (10-12 x 3 repetitions maximum, RM) in specific designed cross country exercises 3 times per week in addition to their regular training. Further, maximal strength training in squat, dead lift, bench press, bench pull and pull down (2-5 x 3 repetitions RM) 3 times per week in addition to their regular training and a control group who only perform their regular training. Pre- and post intervention, all participants will perform tests in VO2max (running), VO2max (poling), work economy (poling), video and IMU analyzes of poling technique, time performance test (poling), motor skill tests and maximal strength tests.

Inclusion Criteria:

• healthy, competitive cross country athletes 16-30 years old

Exclusion Criteria:

• contraindications to maximal strength training and strength and endurance testing

planned published in a peer reviewed journal