Rat walking tracks do not reflect maximal muscle force capacity

The relationship between walking-track measurements and maximum force gener ation in reinnervated rat hindlimb muscles was assessed. A rat model was de signed to result in a broad range of recoveries of both muscle force and wa lking-track measurements after unilateral sciatic nerve injury and reconstr uction. Three months following sciatic nerve injury, maximal force in the e xtensor digitorum longus (EDL) muscle ranged from 1325 to 3666 mN, and maxi mal specific forces ranged from 137.5 to 359.4 kNm(-2). In the same animals , functional intermediate toe spread factor (FIS) ranged from -0.03 to -0.7 8. Neither the correlation coefficient between EDL muscle maximal force and FIS (r = 0.4) nor that between EDL maximal specific force and FIS (r = -0. 2) were statistically significant. The lack of correlation between muscle m aximal force values and walking-track measurements suggests that these neur omuscular tests are assessing different factors.