Strength vs. endurance in myotome assessment-a case for (further studies on) repeated measurements

Myotome testing is often used to detect radiculopathy in patients with low back pain and radiating leg pain. While myotomes are typically assessed by testing the strength of maximum voluntary contraction, some authors suggest endurance should also be assessed, through sustained and/or repeated contractions. Repeated (n = 7) strength tests of the big toe extensor were conducted in two patients with confirmed L5 radiculopathy. Rank-sum tests were conducted for each participant to determine whether their affected leg was weaker. Weakness was observed in both patients with radiculopathy (P1 & P2); however, while weakness was apparent from the first trial in participant P1, it only became detectable after repeated trials in participant P2. Our results suggest that myotome assessment could, in some cases, benefit from repeated strength trials, although further research is needed to confirm the robustness of this conclusion. Additional studies should be conducted in individuals with confirmed radiculopathy to further investigate whether some patients with no immediate weakness show a strength deficit after repeated trials.