Biomechanical determinants of oxygen extraction during cross‐country skiing

<jats:p>To determine the relationship of muscle activation, force production, and cycle characteristics to <jats:styled-content style="fixed-case"><jats:roman>O<jats:sub>2</jats:sub></jats:roman></jats:styled-content> extraction during high‐ and lower‐intensity double poling (<jats:styled-content style="fixed-case">DP</jats:styled-content>), nine well‐trained male cross‐country skiers performed <jats:styled-content style="fixed-case">DP</jats:styled-content> on a treadmill for 3 min at 90% <jats:styled-content style="fixed-case"><jats:roman>VO<jats:sub>2peak</jats:sub></jats:roman></jats:styled-content> followed by 6 min at 70%. During the final minute at each workload, arterial, femoral, and subclavian venous blood were collected for determination of partial pressure of <jats:styled-content style="fixed-case"><jats:roman>O<jats:sub>2</jats:sub></jats:roman></jats:styled-content>, partial pressure of <jats:styled-content style="fixed-case"><jats:roman>CO<jats:sub>2</jats:sub></jats:roman></jats:styled-content>, <jats:styled-content style="fixed-case">pH</jats:styled-content>, and lactate. Electromyography (<jats:styled-content style="fixed-case">EMG</jats:styled-content>) was recorded from six upper and lower body muscles, leg and pole forces were measured, and cardiorespiratory variables were monitored continuously. <jats:styled-content style="fixed-case"><jats:roman>O<jats:sub>2</jats:sub></jats:roman></jats:styled-content> extraction was associated with time point of peak pole force (<jats:styled-content style="fixed-case">PF<jats:sub>peak</jats:sub></jats:styled-content>), duration of recovery, <jats:styled-content style="fixed-case">EMG</jats:styled-content> activity, and lower body use. Arm <jats:styled-content style="fixed-case"><jats:roman>O<jats:sub>2</jats:sub></jats:roman></jats:styled-content> extraction was lower than in the legs at both intensities (<jats:italic><jats:styled-content style="fixed-case">P</jats:styled-content></jats:italic> < 0.001) and was reduced to a lesser extent upon decreasing the workload (<jats:italic><jats:styled-content style="fixed-case">P</jats:styled-content></jats:italic> < 0.05). Arm root‐mean‐square <jats:styled-content style="fixed-case">EMG</jats:styled-content> was higher during the poling phase and entire cycle compared with the legs (<jats:italic><jats:styled-content style="fixed-case">P</jats:styled-content></jats:italic> < 0.001). Blood lactate was higher in the subclavian than in femoral vein and artery (<jats:italic><jats:styled-content style="fixed-case">P</jats:styled-content></jats:italic> < 0.001) and independent of intensity. <jats:styled-content style="fixed-case"><jats:roman>O<jats:sub>2</jats:sub></jats:roman></jats:styled-content> extraction was correlated to low muscle activation, later <jats:styled-content style="fixed-case">PF<jats:sub>peak</jats:sub></jats:styled-content>, prolonged poling time, and extensive dynamic lower body use. Cycle rate and recovery time were associated with <jats:styled-content style="fixed-case"><jats:roman>O<jats:sub>2</jats:sub></jats:roman></jats:styled-content> extraction during high‐intensity exercise only.</jats:p>