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. Author manuscript; available in PMC: 2008 Oct 1.
Published in final edited form as: Osteoarthritis Cartilage. 2007 May 31;15(10):1134–1140. doi: 10.1016/j.joca.2007.03.024

Figure 1.

Figure 1

Figure 1

Figure 1

Figure 1A: Surface Representation of the Motor Unit Action Potential (S-MUAP) Area by Kellgren & Lawrence Grade and %Effort More advanced radiographic OA was associated with activation of smaller MUs (S-MUAP area) at lower effort levels that increased less as % effort increased compared to lower KL grades (P<0.0001), taking into account the observed effort-related increase in S-MUAP area.

Figure 1B: Firing rate (mFR) by KL Grade and %Effort mFR increased as %effort increased (P< 0.001), but comparably across all KL grades (interactive effect P > 0.05).

Figure 1C: Motor unit recruitment index (MURI) by KL grade and %Effort The estimated number of active motor units (MURI) also increased progressively as %effort increased (P<0.001), but did so comparably across all KL Grades (interactive effect P > 0.05).