Consequences of repetitive toenail cutting by podiatric physicians on force production, endurance to fatigue, and the electromyogram of the flexor digitorum superficialis muscles.

Background: We hypothesized that the repetitive use of a toenail clipper by podiatric physicians could induce fatigue of the flexor digitorum superficialis (FDS) muscle, reducing the accuracy of toenail cutting.

Methods: We examined the consequences of cutting a plastic sheet, reproducing the resistance of thick toenails, with a podiatric medical clipper on the maximal handgrip force (Fmax) developed by the FDS muscle and an isometric handgrip sustained at 50% of Fmax, during which endurance to fatigue and changes in the power spectra of the surface FDS muscle electromyogram (root mean square and median frequency) were measured. The same participants randomly performed one or five runs of 30 successive cuttings, each on different days.

Results: After the first and fifth cutting runs, Fmax increased, suggesting a post-tetanic potentiation. During the handgrip sustained at 50% of Fmax, we measured a significant reduction in the tension-time index after the first cutting run. Moreover, after the fifth cutting run, the tension-time index decrease was significantly accentuated, and the decrease in FDS muscle median frequency was enhanced. No median frequency decline was measured during the cutting runs.

Conclusions: These results suggest that the efficacy of occupational podiatric medical tasks progressively declines with the repetition of toenail cutting. We propose solutions to remedy this situation.