title: Bimodal recovery of quadriceps muscle force within 24 hours after sprint cycling for 30 seconds.
abstract: The aim of the study was to investigate the manifestation of potentiation and fatigue as well as the coexistence of these phenomena at different muscle lengths during a 24-hour period after a sprint cycling for 30 s.
  
  
  METHODS
  Twelve healthy untrained men (mean age 23.6+/-1.7 years) took part in the experiment. The contractility of quadriceps muscle was studied before (Initial) and 2, 5, 30, 60 min and 24 h after exercise via the electrically evoked contractions at 1, 15, 50 Hz and maximal voluntary contractions at short and long muscle length.
  
  
  RESULTS
  1) In early, fast-recovery phase (within the first 5 min), muscle force evoked by electrical stimulation of 1, 15, 50 Hz was restored at short muscle length, conversely at long length (Initial vs. 5 min: 15 Hz and 50 Hz, both P<0.05), whereas maximal voluntary contraction force was still suppressed at both muscle lengths; 2) in the second phase (from 5 min to 30-60 min), muscle force decreased at low- and high-frequency stimulations and was more expressed at low-frequency stimulation and at short muscle length than that at long length, but the maximum voluntary contraction force recovered to initial; 3) in long-lasting phase (within 24 hours), 15 Hz force was still suppressed at both muscle lengths.
  
  
  CONCLUSIONS
  A bimodal recovery of contractility of the quadriceps following sprint cycling for 30 s is determined by the concomitant complex interaction of mechanisms enhancing (potentiation) and suppressing (fatigue) contractile potential of the muscle.
authors.affiliation: Department of Applied Physiology and Health Education, Lithuanian Academy of Physical Education, Kaunas, Lithuania. a.skurvydas@lkka.lt
authors.forename: Albertas
authors.initials: A
authors.lastname: Skurvydas
authors.forename: Nerijus
authors.initials: N
authors.lastname: Masiulis
authors.forename: Danguole
authors.initials: D
authors.lastname: Satkunskiene
authors.forename: Aleksas
authors.initials: A
authors.lastname: Stanislovaitis
authors.forename: Gedminas
authors.initials: G
authors.lastname: Mamkus
authors.forename: Sigitas
authors.initials: S
authors.lastname: Kamandulis
authors.forename: Vilma
authors.initials: V
authors.lastname: Dudoniene
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001642:Bicycling / Q000502:physiology*; D004558:Electric Stimulation; D005080:Exercise Test / Q000379:methods; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D013997:Time Factors