title: Muscle damage and soreness after endurance exercise of the elbow flexors.
abstract: OBJECTIVE
  This study investigated changes in indirect markers of muscle damage after endurance exercise of the elbow flexors and compared the changes with those after maximal eccentric actions (Max-ECC) of the elbow flexors.
  
  
  METHODS
  Eighteen male students rhythmically lifted (1 s) and lowered (1 s) a light dumbbell (1.1-1.8 kg: 9% of MIF) in 60-180 degrees of elbow joint angle for 2 h (2-h Ex). Maximal isometric force (MIF), relaxed (RANG) and flexed elbow joint angles (FANG), upper-arm circumference (CIR), muscle soreness (SOR), B-mode ultrasound (US), and plasma creatine kinase (CK) activity were assessed before and immediately after, and up to 96 h after exercise.
  
  
  RESULTS
  All measures were altered significantly (P < 0.05) after 2-h Ex in a similar time course to Max-ECC; however, changes in RANG, FANG, CIR, US, and CK (peak: 356 +/- 121 IU.L-1) were significantly (P < 0.05) smaller compared with those after Max-ECC. SOR developed immediately after 2-h Ex and peaked 24-48 h after exercise. MIF dropped to 44.1% of the preexercise level, which was significantly (P < 0.05) lower than that after Max-ECC (58.1%), immediately postexercise. MIF recovered to 79.8% at 24 h, and 97.8% at 96 h postexercise, which was a significantly (P < 0.05) faster recovery compared with that of Max-ECC (73.1% at 96 h).
  
  
  CONCLUSIONS
  These results showed low-intensity continuous muscle contractions (3600 times) resulted in muscle damage; however, the magnitude of the muscle damage was less severe, and the recovery was faster compared with 12 maximal eccentric muscle actions.
authors.affiliation: Exercise and Sports Science, Graduate School of Integrated Science, Yokohama City University, Japan. nosaka@yokohama-cu.ac.jp
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nosaka
authors.forename: Mike
authors.initials: M
authors.lastname: Newton
authors.forename: Paul
authors.initials: P
authors.lastname: Sacco
mesh_terms: D000293:Adolescent; D000328:Adult; D001132:Arm / Q000033:anatomy & histology; D015415:Biomarkers / Q000097:blood; D003402:Creatine Kinase / Q000097:blood; D004550:Elbow / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000503:physiopathology*; D010146:Pain / Q000503:physiopathology*; D010807:Physical Endurance / Q000502:physiology*; D014463:Ultrasonography; D014891:Weight Lifting / Q000502:physiology
chemical_list: D015415:Biomarkers; D019344:Lactic Acid; D003402:Creatine Kinase