Mechanical energetics and dynamics of uphill double-poling on roller-skis at different incline-speed combinations.

The considerable larger amount of negative PT+L during poling at INC5 than at INC12 indicate that the legs and trunk generate more power than 'necessary' during the swing phase and thus must absorb more energy during the poling phase. This larger surplus of PT+L at INC5 seems necessary for positioning the body and poles so that high Parm generation can occur in a short time. At INC12, less Parm is generated, probably due to less advantageous working conditions for the arms, related to body and pole positioning. These incline differences seem linked to shorter swing and longer poling times during steep uphill DP, which are due to the increased influence of gravity and slower speed at steep inclines.