title: Exercise responses in patients with chronically high creatine kinase levels.
abstract: Elevated serum creatine kinase (CK) is often taken to reflect muscle disease, but many individuals have elevated CK without a specific diagnosis. How elevated CK reflects muscle metabolism during exercise is not known.
  
  
  
  Participants (46 men, 48 women) underwent incremental exercise testing to assess aerobic performance, cardiovascular response, and ventilatory response. Serum lactate, ammonia, and CK were measured at rest, 4 minutes into exercise, and 2 minutes into recovery.
  
  
  
  High-CK and control subjects demonstrated similar aerobic capacities and cardiovascular responses to incremental exercise. Those with CK ≥ 300 U/L exhibited significantly higher lactate and ammonia levels after maximal exercise, together with increased ventilatory responses, whereas those with CK ≥200 U/L but ≤ 300 U/L did not.
  
  
  
  We recommend measurement of lactate and ammonia profiles during a maximal incremental exercise protocol to help identify patients who warrant muscle biopsy to rule out myopathy. Muscle Nerve 56: 264-270, 2017.
authors.affiliation: UCLA Exercise Physiology Research Laboratory, Department of Medicine, David Geffen School of Medicine, University of California, 10833 Le Conte Avenue, 37-131 CHS, Los Angeles, 90095, USA.|Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, USA.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Cooper
authors.affiliation: UCLA Exercise Physiology Research Laboratory, Department of Medicine, David Geffen School of Medicine, University of California, 10833 Le Conte Avenue, 37-131 CHS, Los Angeles, 90095, USA.|Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, USA.
authors.forename: Brett A
authors.initials: BA
authors.lastname: Dolezal
authors.affiliation: UCLA Exercise Physiology Research Laboratory, Department of Medicine, David Geffen School of Medicine, University of California, 10833 Le Conte Avenue, 37-131 CHS, Los Angeles, 90095, USA.|Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, USA.
authors.forename: Eric V
authors.initials: EV
authors.lastname: Neufeld
authors.affiliation: Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, USA.
authors.forename: Perry
authors.initials: P
authors.lastname: Shieh
authors.affiliation: Cambridge University Sports & Exercise Medicine Unit, Addenbrooke's Hospital, Cambridge, England.
authors.forename: John R
authors.initials: JR
authors.lastname: Jenner
authors.affiliation: Queen's University, Belfast, Northern Ireland, UK.
authors.forename: Marshall
authors.initials: M
authors.lastname: Riley
mesh_terms: D000328:Adult; D000641:Ammonia / Q000097:blood; D002908:Chronic Disease; D003402:Creatine Kinase / Q000097:blood*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism; D009135:Muscular Diseases / Q000097:blood* / Q000503:physiopathology*; D010101:Oxygen Consumption; D011659:Pulmonary Gas Exchange; D012189:Retrospective Studies
chemical_list: D019344:Lactic Acid; D000641:Ammonia; D003402:Creatine Kinase
keywords: ammonia; creatine kinase; exercise testing; lactate; myopathy