Integrative Physiological and Biomechanical Aspects in Competitive Cross-country Skiing

METHODS: DP was examined in three studies (A-C), involving roller skiing on a treadmill. In study A (n=6), the subjects performed 10 min of DP at ~74% of their VO2max. Catheters were inserted in a. and v. femoralis, v. subclavia and right atrium to measure a-v O2 difference at systemic level as well as over the arms and legs. Blood flow in arms and legs was measured by constant-infusion thermodilution and cardiac output was calculated using the Fick principle. Moreover, lactate kinetics was examined using tracer technique. Study B and C were performed with the same group of skiers (n=11). Study B was a biomechanical analysis with the skiers DP at 85% of their maximal DP velocity (Vmax). Electromyography (EMG) was performed on upper and lower body muscles and movement in the elbow, hip, knee and ankle joints were analysed using goniometry. In Study C the skiers performed two incremental DP tests with or without locking the knee and ankle joints (DPLOCKED and DPFREE) at 85% of their Vmax during DPFREE. Peak oxygen uptake (VO2peak), heart rate and blood lactate concentration were determined. 2-D video analysis and measurements of pole and plantar forces were performed in both study B and C. Statistical significance was set to P<0.05.