Author(s): WAGNER, C., SANDBAKK, Ø., SCHIEMANN, S., KEINER, M., Institution: LEUPHANA UNIVERSITY LÜNEBURG, Country: GERMANY, Abstract-ID: 2648

INTRODUCTION:
In cross-country skiing, poling-dominant techniques such as double poling (DP) and G3 skating amplify performance differences. Previous regression analyses, including preliminary work from our laboratory, have identified fat-free mass (FFM) as the strongest predictor of DP performance, alongside maximal strength and aerobic power. Despite this, resistance-training interventions in Nordic skiing have predominantly focused on neural adaptations rather than morphological adaptations. The present study aimed to compare the effects of two upper-body resistance training modalities on maximal strength, FFM, and their influence on power output during DP ergometry and aerobic power.
METHODS:
41 youth Nordic skiers (f = 23, m = 18, age: 17.3 ± 2.0 years, VO2max: 65.7 ± 9.3 mL·kg-1·min-1) were allocated to IG1 (4-12 repetition maximum), IG2 (15-20 repetition maximum), or a control group maintaining habitual training. Intervention groups performed upper-body resistance training (4 times 5 sets per session, twice weekly). Outcome measures included one-repetition maximum (1RM), FFM, 3-min seated DP ergometer power output (DPP3min), peak oxygen uptake during DP ergometry (VO2peak) and maximal oxygen uptake (VO2max) during treadmill running. VO2peak during DP and G3 roller-ski time trials was also assessed. Intervention effects were analyzed using 3x2 repeated-measures ANOVA with Scheffé post hoc testing. Associations between changes in physiological variables and performance were examined using correlation analyses.
RESULTS:
Significant group x time interactions (p<0.01) for 1RM (ƞ2= 0.49), FFM (ƞ2= 0.36), DP3min (ƞ2= 0.37), and VO2peak during DP (ƞ2= 0.32). IG1 showed superior improvements in 1RM (g = 0.6-0.91), FFM (g= 0.61) and VO2peak during DP roller-ski time trails (g= 0.49) compared to IG2. No interaction effects were observed for VO2peak during G3 or treadmill VO2max. Changes in DP3min and VO2peak during DP were significantly correlated with increases in FFM (r= 0.52-0.66) and 1RM (0.56-0.6).
CONCLUSION:
Increases in FFM appear central to improvements in maximal strength and VO2peak during DP, independent of resistance training modality. These findings support the importance of absolute upper-body strength and muscle mass for performance in poling-dominant techniques in youth Nordic skiers. The improvements in DP-specific VO2peak without concomitant changes in whole-body VO2max are consistent with modality-specific, likely peripheral adaptations. From a practical perspective, structured and progressive upper-body resistance training appears essential during adolescence, to enhance long-term performance development in Nordic skiing.