title: Mechanical efficiency of treadmill running exercise: effect of anaerobic-energy contribution at various speeds.
abstract: OBJECTIVE
  Mechanical efficiency (ME) describes the ratio between mechanical (PMECH) and metabolic (PMET) power. The purpose of the study was to include an estimation of anaerobic energy expenditure (AnE) into the quantification of PMET using the accumulated oxygen deficit (AOD) and to examine its effect on the value of ME in treadmill running at submaximal, maximal, and supramaximal running speeds.
  
  
  METHODS
  Participants (N = 11) underwent a graded maximal exercise test to determine velocity at peak oxygen uptake (vVO2peak). On 4 separate occasions, subjects ran for 6 min at speeds corresponding to 50%, 70%, 90%, and 110% of vVO2peak. During each testing session, PMET was measured from pulmonary oxygen uptake (VO2p) using open-circuit spirometry and was quantified in 2 ways: from VO2p and an estimate of AnE (from the AOD method) and from VO2p only. PMECH was determined from kinematic analyses.
  
  
  RESULTS
  ME at 50%, 70%, 90%, and 110% of vVO2peak was 59.9% ± 11.9%, 55.4% ± 12.2%, 51.5% ± 6.8%, and 52.9% ± 7.5%, respectively, when AnE was included in the calculation of PMET. The exclusion of AnE yielded significantly greater values of ME at all speeds: 62.9% ± 11.4%, 62.4% ± 12.6%, 55.1% ± 6.2%, and 64.2% ± 8.4%; P = .001 (for 50%, 70%, 90%, and 110% of vVO2peak, respectively).
  
  
  CONCLUSIONS
  The data suggest that an estimate of AnE should be considered in the computation of PMET when determining ME of treadmill running, as its exclusion leads to overestimations of ME values.
authors.affiliation: School of Human Kinetics, Laurentian University, Sudbury, ON, Canada.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Keir
authors.forename: Raphaël
authors.initials: R
authors.lastname: Zory
authors.forename: Céline
authors.initials: C
authors.lastname: Boudreau-Larivière
authors.forename: Olivier
authors.initials: O
authors.lastname: Serresse
mesh_terms: D000293:Adolescent; D000328:Adult; D015308:Anaerobic Threshold; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D001696:Biomechanical Phenomena; D004734:Energy Metabolism; D005080:Exercise Test; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D012123:Pulmonary Ventilation; D012420:Running; D013147:Spirometry; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D019344:Lactic Acid; D010100:Oxygen