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Metabolic cost, mechanical work, and efficiency during walking in young and older men
Author(s) -
Mian O. S.,
Thom J. M.,
Ardigò L. P.,
Narici M. V.,
Minetti A. E.
Publication year - 2006
Publication title -
acta physiologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.591
H-Index - 116
eISSN - 1748-1716
pISSN - 1748-1708
DOI - 10.1111/j.1748-1716.2006.01522.x
Subject(s) - treadmill , antagonist , thigh , preferred walking speed , medicine , mechanical energy , gait , work (physics) , energy cost , electromyography , physical medicine and rehabilitation , physical therapy , cardiology , anatomy , physics , receptor , architectural engineering , power (physics) , quantum mechanics , engineering , thermodynamics
Aim: To investigate mechanical work, efficiency, and antagonist muscle co‐activation with a view to better understand the cause of the elevated metabolic cost of walking ( C W ) in older adults. Methods: Metabolic, mechanical and electromyographic measurements were made as healthy young (YOU; n = 12, age = 27 ± 3 years) and older (OLD; n = 20, age = 74 ± 3 years) men of equivalent body mass and leg length walked on a treadmill at four speeds (ranging from 0.83 to 1.67 m s −1 ). Results: Net (above resting) C W , determined by indirect calorimetry was 31% higher (average across speeds) in OLD ( P < 0.05). The integrity of the passive pendulum like interchange of mechanical energies of the centre of mass (COM B ), an energy‐saving mechanism, was maintained in OLD. Furthermore, total mechanical work, determined from fluctuations in mechanical energy of COM B and of body segments relative to COM B , was not significantly elevated in OLD. This resulted in a lower efficiency in OLD (−17%, P < 0.05). Co‐activation, temporally quantified from electromyography recordings, was 31% higher in OLD for antagonist muscles of the thigh ( P < 0.05). Thigh co‐activation was moderately correlated with C W at three speeds ( r = 0.38–0.52, P < 0.05). Conclusion: Healthy septuagenarians with no gait impairment have an elevated C W which is not explained by an elevation in whole body mechanical work. Increased antagonist muscle co‐activation (possibly an adaptation to ensure adequate joint stability) may offer partial explanation of the elevated C W .