title: Consequences of repetitive toenail cutting by podiatric physicians on force production, endurance to fatigue, and the electromyogram of the flexor digitorum superficialis muscles.
abstract: 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.
authors.forename: Bruno
authors.initials: B
authors.lastname: Vie
authors.forename: Remy
authors.initials: R
authors.lastname: Loffredo
authors.forename: Farid
authors.initials: F
authors.lastname: Sanahdji
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Weber
authors.forename: Yves
authors.initials: Y
authors.lastname: Jammes
mesh_terms: D004576:Electromyography; D006804:Ergonomics; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D008954:Models, Biological; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009262:Nails; D011032:Podiatry / Q000295:instrumentation; D055815:Young Adult