Upper body has a considerable role in cross-country skiing particularly during double poling (DP), in which strong and fast propulsive actions are exerted entirely through the poles. Our hypothesis was that metabolic rate during DP exercises is determined by the cost of force generation. Furthermore, since DP is far from human legged-locomotion, we hypothesized that the cost of force generation coefficient (K [J•N^-1]) could be more predictive of performance than energetic cost of locomotion (C [J•m^-1•kg^-1]), because of the dimensional meaning of the measurements.

21 skiers performed 3 steady state DP trials at different speeds. Metabolic rate (E'), blood lactate concentration after exercise ([La⁺]), poling time (PT) and average force applied through the poles during a cycle (F_avg) were measured; K and C were calculated for each trial. V'O_2max measured with a maximal DP test was taken as performance parameter.

E' and 1/PT increased significantly with speeds, while F_avg, K and C remained constant. K was negatively related to V'O_2max, while C didn't show correlation with it. K was positively related to [La⁺], at each considered speed.

Since K remained constant across speeds, E' can be considered as cost for generating the force, during double poling exercises. Furthermore, better skiers tend to adopt biomechanical strategies that do not minimize energetic cost of DP, but that allow to exert more force on the poles at the same cost, permitting to reduce upper limbs fatigue.