The energetics and mechanics of walking were investigated at different speeds, both at the freely chosen stride frequency (FCSF) and at imposed ones (up to +/- 40% of FCSF). Metabolic energy expenditure was minimized at FCSF for each speed. Motion analysis allowed to calculate: the mechanical internal work rate (Wim), needed to move the segments with respect to the body center of mass (bcm); the external work rate (Wext), necessary to move bcm in the environment; and the total work rate (Wtot), equal to Wint + Wext. Wtot, explains the metabolic optimization only at high speeds, while Wexp differently from previously reported, displays minima which better predict FCSF at all speeds (exception made for 1.39 m.s-1). This is probably caused by an overestimation of Wint due to a more ballistic movement of the limbs at low speeds (and low frequencies). The tendency of Wext to increase at high frequencies is due to a persistent minimal vertical excursion of bcm (about 0.02 m, the "locomotory dead space''). While the match between mechanics and energetics (at FCSF and imposed frequencies) occurs to a certain extent, it could be improved by removing the methodological assumptions about the energy transfer between segments and by the possibility to account for the coactivation of antagonist muscles.
|Titolo:||Effects of stride frequency on mechanical power and energy expenditure of walking|
MINETTI, ALBERTO ENRICO (Primo)
|Settore Scientifico Disciplinare:||Settore BIO/09 - Fisiologia|
|Data di pubblicazione:||ago-1995|
|Appare nelle tipologie:||01 - Articolo su periodico|