title: Energetics of walking in patients with peripheral arterial disease: a proposed functional evaluation protocol.
abstract: The energy cost of walking (at 3.2 km x h(-1)) per unit distance (J x kg(-1) x m(-1)) at gradients of 0%, +7%, and +12% and during a progressive test (2% increase in gradient every 2 min), as well as the overall (aerobic plus anaerobic) net cumulative energy consumption and the corresponding maximal exercise duration were assessed in 19 patients with peripheral arterial disease (PAD) and in 13 moderately active control subjects. With a 0% gradient, the energy cost of walking was approximately 40% greater in patients with PAD than in controls (2.93+/-0.52 and 2.13+/-0.33 J x kg(-1) x m(-1) respectively; P <0.01). In contrast, at gradients of +7% and +12%, the energy cost of walking was similar in the two groups (+7%: PAD, 4.15+/-0.74 J x kg(-1) x m(-1); controls, 4.18+/-0.54 J x kg(-1) x m(-1); +12%: PAD, 5.59+/-1.03 J x kg(-1) x m(-1); controls, 5.64+/-0.75 J x kg(-1) x m(-1)). In patients with PAD, maximal exercise duration with gradients of 0%, +7% and +12% was 449+/-254, 322+/-200 and 229+/-150 s respectively, whereas the net cumulative energy consumption at fatigue was almost constant at approximately 1100 J x kg(-1) for all gradients. The greater energy cost of walking in PAD patients compared with controls in level, but not uphill, walking is interpreted as being mainly the consequence of an altered mechanical locomotory pattern, and not of lower metabolic efficiency. For a wide range of loads, net cumulative energy consumption appears to be independent of maximal exercise duration, a finding that provides a practical criterion for assessing the degree of functional impairment of patients with PAD on metabolic grounds.
authors.affiliation: Muscle Physiology and Proteome Section, I.B.F.M.-Consiglio Nazionale delle Ricerche, L.I.T.A., v. F. lli Cervi 93, I-20090 Segrate, Italy. claudio.marconi@ibfm.cnr.it
authors.forename: Claudio
authors.initials: C
authors.lastname: Marconi
authors.forename: Guido
authors.initials: G
authors.lastname: Ferretti
authors.forename: Sara
authors.initials: S
authors.lastname: Anchisi
authors.forename: Maria
authors.initials: M
authors.lastname: Catalano
authors.forename: Giovanni
authors.initials: G
authors.lastname: Scandale
authors.forename: Antonio
authors.initials: A
authors.lastname: Antico
authors.forename: Gianluca
authors.initials: G
authors.lastname: Iob
authors.forename: Flavio
authors.initials: F
authors.lastname: Peinetti
authors.forename: Paolo
authors.initials: P
authors.lastname: Cerretelli
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D004185:Disability Evaluation; D004734:Energy Metabolism; D005080:Exercise Test / Q000379:methods; D005221:Fatigue / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D016491:Peripheral Vascular Diseases / Q000378:metabolism* / Q000534:rehabilitation; D013997:Time Factors; D016138:Walking / Q000502:physiology*