Incline dependence of the power-duration relationship in cross-country skiing

The findings demonstrate that in cross-country skiing, both <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup><mml:mrow><mml:mi>W</mml:mi></mml:mrow> <mml:mrow><mml:mo>'</mml:mo></mml:mrow> </mml:msup> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub><mml:mrow><mml:mi>P</mml:mi></mml:mrow> <mml:mrow><mml:mi>a</mml:mi> <mml:mi>n</mml:mi></mml:mrow> </mml:msub> </mml:mrow> </mml:math> are highly incline-dependent, showing markedly higher values at steeper gradients. Moreover, the variability observed in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>C</mml:mi> <mml:mi>P</mml:mi></mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup><mml:mrow><mml:mi>W</mml:mi></mml:mrow> <mml:mrow><mml:mo>'</mml:mo></mml:mrow> </mml:msup> </mml:mrow> </mml:math> across inclines exceeded the typical sensitivity of these parameters to external factors reported in cycling. A large proportion of the incline-related changes in model parameters could be explained by accounting for the estimated variations in gross efficiency across speeds and inclines. However, the persistence of a significant difference in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup><mml:mrow><mml:mi>W</mml:mi></mml:mrow> <mml:mrow><mml:mo>'</mml:mo></mml:mrow> </mml:msup> </mml:mrow> </mml:math> even when expressed in terms of estimated metabolic power at steeper inclines suggests the involvement of additional physiological mechanisms, potentially a larger amount of recruited muscle mass due to differences in muscle fiber recruitment between conditions.