title: Electrically induced muscle cramps induce hypertrophy of calf muscles in healthy adults.
abstract: OBJECTIVE
  Skeletal muscles usually cramp at short lengths, where the tension that can be exerted by muscle fibers is low. Since high tension is an important anabolic stimulus, it is questionable if cramps can induce hypertrophy and strength gains. In the present study we investigated if electrically induced cramps (EIMCs) can elicit these adaptations.
  
  
  METHODS
  15 healthy male adults were randomly assigned to an intervention (IG; n=10) and a control group (CG; n=5). The cramp protocol (CP) applied twice a week to one leg of the IG, consisted of 3x6 EIMCs, of 5 s each. Calf muscles of the opposite leg were stimulated equally, but were hindered from cramping by fixating the ankle at 0° plantar flexion (nCP).
  
  
  RESULTS
  After six weeks, the cross sectional area of the triceps surae was similarly increased in both the CP (+9.0±3.4%) and the nCP (+6.8±3.7%). By contrast, force of maximal voluntary contractions, measured at 0° and 30° plantar flexion, increased significantly only in nCP (0°: +8.5±8.8%; 30°: 11.7±13.7%).
  
  
  CONCLUSIONS
  The present data indicate that muscle cramps can induce hypertrophy in calf muscles, though lacking high tension as an important anabolic stimulus.
authors.affiliation: German Sport University Cologne, Institute of Training Science and Sport Informatics, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Behringer
authors.affiliation: German Sport University Cologne, Institute of Training Science and Sport Informatics, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Moser
authors.affiliation: German Sport University Cologne, Institute of Training Science and Sport Informatics, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Montag
authors.affiliation: German Sport University Cologne, Institute of Training Science and Sport Informatics, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
authors.forename: M
authors.initials: M
authors.lastname: McCourt
authors.affiliation: Orthoparc GmbH, The Clinic for Orthopaedics in Cologne, Aachener Straße 1021 B, 50933 Cologne, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Tenner
authors.affiliation: German Sport University Cologne, Institute of Training Science and Sport Informatics, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Mester
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000842:Ankle / Q000502:physiology; D017097:Electric Impedance; D004558:Electric Stimulation / Q000009:adverse effects; D006801:Humans; D006984:Hypertrophy; D007866:Leg / Q000033:anatomy & histology / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009120:Muscle Cramp / Q000503:physiopathology*; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000254:growth & development*