title: Muscle Fatigue When Swimming Intermittently Above and Below Critical Speed.
abstract: OBJECTIVE
  To examine muscle fatigue of the shoulder internal rotators alongside swimming biomechanics during long-duration submaximal swimming sets performed in 2 different speed domains.
  
  
  METHODS
  Eight trained swimmers (mean ± SD 20.5 ± 0.9 y, 173 ± 10 cm, 71.3 ± 10.0 kg) raced over 3 distances (200-, 400-, 800-m races) for determination of critical speed (CS; slope of the distance-time relationship). After a familiarization with muscle isokinetic testing, they subsequently randomly performed 2 constant-speed efforts (6 × 5-min blocks, 2.5-min recovery) 5% above (T105) and 5% below CS (T95) with maximal voluntary contractions recorded between swimming blocks.
  
  
  RESULTS
  Capillary blood lactate concentration ([La]), rating of perceived exertion (RPE), peak torque, stroke length, and stroke rate were maintained throughout T95 (P < .05). [La], RPE, and stroke rate increased alongside concomitant decreases in maximal torque and stroke length during T105 (P < .05) with incapacity of the swimmers to maintain the pace for longer than ~20 min. For T105, changes in maximal torque (35.0 ± 14.9 to 25.8 ± 12.1 Nm) and stroke length (2.66 ± 0.36 to 2.23 ± 0.24 m/cycle) were significantly correlated (r = .47, P < .05).
  
  
  CONCLUSIONS
  While both muscle fatigue (shoulder internal rotators) and task failure occur when swimming at a pace greater than CS, the 2.5-min recovery period during the sub-CS set possibly alleviated the development of muscle fatigue for the pace to be sustainable for 6 × 5 min at 95% of CS. A causal relationship between reduction in stroke length and loss of muscle strength should be considered very cautiously in swimming.
authors.affiliation: Sport, Exercise Science And Medicine (SESAME), University of Brighton, Eastbourne, UK.
authors.forename: Jeanne
authors.initials: J
authors.lastname: Dekerle
authors.forename: James
authors.initials: J
authors.lastname: Paterson
mesh_terms: D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology; D012785:Shoulder Joint / Q000502:physiology*; D013550:Swimming / Q000502:physiology*; D019415:Torque; D055815:Young Adult
chemical_list: D019344:Lactic Acid