Table 2. Summary of the biomechanical changes due to knee flexion for barefoot and in-shoe versions of the exercise.
Barefoot Shod
ExtendedKnee FlexedKnee P -value ExtendedKnee FlexedKnee P-value
Kinematic outputs [Degrees] Mean hip adduction angle 4.2 (4.0) 5.7 (4.5) - 5.5 (3.2) 6.5 (3.3) -
Mean hip flexion angle 9.6 (6.7) 28.5 (8.3) NC 8.2 (7.0) 27.3 (7.5) NC
Mean change in hip flexion angle .5 (3.1) -3.8 (4.9) - 1.3 (3.8) -2.8 (5.3) -
Mean knee adduction angle 12.1 (3.1) 10.1 (5.1) - 11.4 (2.3) 9.2 (4.6) -
Mean knee flexion angle -8.7 (7.5) -35.3 (7.7) NC -7.2 (6.5) -33.9 (6.4) NC
Mean change in knee flexion angle 2.6 (4.5) 9.1 (8.5) <.001 -.2 (5.8) 6.4 (8.3) .004
Mean ankle inversion ROM 11.2 (4.0) 11.5 (5.9) - 9.9 (3.8) 9.4 (4.4) -
Mean ankle angle at start -17.7 (4.5) -11.0 (5.9) <.001 17.5 (7.3) -10.4 (7.2) <.001
Mean ankle angle at end 23.5 (6.3) 27.5 (7.3) .001 25.4 (6.2) 30.5 (4.6) <.001
Mean ankle flexion ROM 41.2 (7.4) 38.5 (7.6) - 42.8 (7.8) 40.8 (6.7) -
Inter-segmental moments [Nm/(BW*ht)] Peak hip extension moment .28 (.06) .35 (.11) <.001 .25 (.08) .32 (.11) <.001
Peak hip adduction moment .28 (.06) .35 (.12) .001 .24 (.09) .33 (.12) <.001
Peak knee extension moment .13 (.05) -.04 (.08) <.001 .10 (.06) -.07 (.07) <.001
Peak knee adduction moment .13 (.05) -.04 (.08) <.001 .10 (.06) -.07 (.07) <.001
Peak ankle plantar-flexion moment -.75 (.04) -.72 (.04) <.001 -.76 (.09) -.71 (.08) <.001
Peak ankle inversion moment .09 (.07) .10 (.07) - .05 (.05) .05 (.04) -
Force [BW] Peak Achilles tendon force 3.02 (.50) 2.86 (.48) - 2.76 (.50) 2.51 (.43) -
Muscle activation [% Fmax] Soleus .20 (.06) .19 (.06) - .18 (.05) .16 (.04) -
Gastrocnemius .21 (.07) .17 (.07) - .19 (.06) .17 (.05) -
Note: “start” and “end” refer to the start and end of the exercise, which is determined by peak ankle plantar-flexion and dorsi-flexion respectively and P-values correspond to differences due to knee flexion. NC – Not Compared.