title: Arterial blood lactate is a useful guide to when rehabilitation should be instigated in COPD.
abstract: OBJECTIVE
  Systemic effects of COPD include skeletal muscle dysfunction; the lactate threshold (LT) is an index of such dysfunction. However, it is not feasible in daily clinical practice to accurately determine the LT in all patients with COPD. There is no simple, practical and non-invasive index for determining the time at which rehabilitation should start. Previous studies have shown that the LT corresponds to the point at which the blood lactate concentration is 0.5 mmol/L above baseline (LTDelta0.5 mmol/L). The aim of the study was to assess the value of LTDelta0.5 mmol/L as an index of selecting candidates for pulmonary rehabilitation in COPD patients.
  
  
  METHODS
  Eighteen male outpatients with COPD were enrolled. Exercise tolerance based on the 12-min walk test and treadmill exercise test, lactate concentrations and activities of daily living before and after individual exercise stress testing were assessed.
  
  
  RESULTS
  There were no significant differences in the 12-min walk distance or metabolic equivalents between patients with and without a 0.5 mmol/L or more increase in lactate from baseline to post-walk test. However, significant differences were observed in activities of daily living, as assessed using Fletcher's scale, between those with and without a 0.5 mmol/L or greater increase in lactate from baseline to post-walk test.
  
  
  CONCLUSIONS
  In daily clinical practice, a 0.5 mmol/L or greater increase in lactate from baseline to post-12-min walk test may be utilized as an index to determine when COPD patients should start rehabilitation, or to assess muscle alterations in the lower extremities in COPD patients undergoing rehabilitation.
authors.affiliation: Nippon Medical School, Chiba Hokusoh Hospital, Respiratory Disease Center, Chiba, Japan. yosuke-t@nms.ac.jp
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Hino
authors.forename: Tetsuyuki
authors.initials: T
authors.lastname: Morikawa
authors.forename: Koichiro
authors.initials: K
authors.lastname: Takeuchi
authors.forename: Kyoichi
authors.initials: K
authors.lastname: Mizuno
authors.forename: Shoji
authors.initials: S
authors.lastname: Kudoh
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D005080:Exercise Test; D017079:Exercise Tolerance; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000503:physiopathology / Q000534:rehabilitation*; D012129:Respiratory Function Tests
chemical_list: D019344:Lactic Acid