title: Muscle cramp susceptibility increases following a volitionally induced muscle cramp.
abstract: BACKGROUND
  Muscle cramping may increase peripheral nervous system excitability. It is unknown if, and how long, cramp susceptibility is affected by previous cramping. We tested whether volitionally induced muscle cramps (VIMCs) lowered cramp threshold frequency (TFc) and how long TFcwas affected post-VIMC.
  
  
  METHODS
  Fifteen cramp-prone participants volitionally induced a flexor hallucis brevis (FHB) cramp on 4 separate days. FHB TFcwas measured before VIMC (i.e., baseline) and 5, 30, and 60 min post-VIMC. VIMC electromyography (EMG) amplitude, VIMC duration, and perceived VIMC intensity were measured to ensure consistency of VIMC between days.
  
  
  RESULTS
  VIMC EMG amplitude, duration, and perceived intensity were similar between days (P > 0.05). VIMC lowered TFc; baseline TFc(18 ± 6 Hz) was higher than 5-min (14 ± 6 Hz), 30-min (14 ± 5 Hz), and 60-min TFc(14 ± 5 Hz; P < 0.05).
  
  
  CONCLUSIONS
  Acute VIMCs increase cramp susceptibility. Clinicians should apply treatments for at least 60 min postcramp to decrease the probability of cramp recurrence. Muscle Nerve 56: E95-E99, 2017.
authors.affiliation: Central Michigan University, School of Rehabilitation and Medical Sciences, 1208 Health Professions Building, Mount Pleasant, Michigan, USA.
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Miller
authors.affiliation: Central Michigan University, School of Rehabilitation and Medical Sciences, 1208 Health Professions Building, Mount Pleasant, Michigan, USA.
authors.forename: Blaine C
authors.initials: BC
authors.lastname: Long
authors.affiliation: School of Health Sciences, Mount Pleasant, Michigan, USA.
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Edwards
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D004198:Disease Susceptibility / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D009120:Muscle Cramp / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology*; D058748:Pain Perception / Q000502:physiology*; D055815:Young Adult
keywords: electrical stimulation; electromyography; flexor hallucis brevis; pain; recurrence; threshold frequency