title: Metabolic and muscle damage profiles of concentric versus repeated eccentric cycling.
abstract: OBJECTIVE
  Eccentric cycling is an exercise modality that could elicit multiple health benefits with low metabolic cost, but unaccustomed performance results in significant muscle damage. It is not known whether muscle damage is attenuated when eccentric cycling is repeated; thus, this study compared metabolic and muscle damage responses to concentric (CONC) and two consecutive eccentric (ECC1 and ECC2) cycling bouts.
  
  
  METHODS
  Ten men (28 ± 8 yr) performed each cycling bout for 30 min at 60% of the maximal concentric power output at 60 rpm, with 2 wk between bouts. HR, oxygen consumption (V˙O2), blood lactate (BLa), RPE, and muscle activity (EMG) data were collected during cycling. Maximal voluntary isometric knee extensor (MVC) strength, squat (SJ), countermovement jump (CMJ) height, muscle soreness indicators, and plasma creatine kinase (CK) activity were measured before, immediately after, and 1-4 d after exercise.
  
  
  RESULTS
  Average HR, V˙O2, BLa, and RPE were lower (P < 0.05) during ECC1 than CONC, and EMG amplitude was also lower during ECC1 than CONC. Decreases in MVC, CMJ, and SJ and the increase in muscle soreness were greater (P x0003C; 0.05) after ECC1 than CONC. Increases in creatine kinase were minimal after all bouts. When comparing ECC1 and ECC2, HR and BLa were lower (P < 0.05) during ECC2 than ECC1, and decreases in MVC, CMJ, and SJ and the increase in muscle soreness were greater (P < 0.05) after ECC1 than ECC2. After ECC2, MVC, CMJ, and SJ did not change and no muscle soreness was developed.
  
  
  CONCLUSIONS
  Eccentric cycling was less metabolically demanding than concentric cycling, and HR and BLa were further reduced during ECC2. Muscle damage is minimal after ECC2 and should not influence the choice to undertake eccentric cycling training.
authors.affiliation: School of Exercise and Health Sciences, Edith Cowan University, Joondalup, WA, Australia. l.penailillo@ecu.edu.au
authors.forename: Luis
authors.initials: L
authors.lastname: Peñailillo
authors.forename: Anthony
authors.initials: A
authors.lastname: Blazevich
authors.forename: Hideo
authors.initials: H
authors.lastname: Numazawa
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nosaka
mesh_terms: D000328:Adult; D001642:Bicycling / Q000293:injuries* / Q000502:physiology*; D003402:Creatine Kinase / Q000097:blood; D004576:Electromyography; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009068:Movement / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000473:pathology* / Q000503:physiopathology*; D063806:Myalgia / Q000097:blood / Q000209:etiology / Q000503:physiopathology; D010101:Oxygen Consumption; D055815:Young Adult
chemical_list: D019344:Lactic Acid; D003402:Creatine Kinase