Author(s): LUC, V., MEDOLAGO, A., FRANKL, F., ANTENUCCI, L., FINIEL, L., BORRANI, F., MALATESTA, D., Institution: UNIVERSITÉ DE LAUSANNE, Country: SWITZERLAND, Abstract-ID: 2110

INTRODUCTION:
During level walking, humans adopt gait patterns that minimize the net energy cost (NCw). Metabolic energy is required by muscles to generate force and perform total positive mechanical work (Wtot). The main component of Wtot is the external work (Wext), which is the work performed to lift and accelerate the body’s center of mass. The pendular exchange of potential and kinetic energy (Rstep) reduces Wext, thereby minimizing NCw (1). Altered Rstep has been associated with a higher NCw in older and obese adults compared with young and lean individuals (2,3). However, older adults logically exhibited lower Rstep (4), whereas adults with obesity showed higher NCw despite a greater Rstep (2), making the relationship between Rstep and NCw equivocal. This study thus aimed to examine the acute effects of modulating the pendular mechanism via visual biofeedback on the energetics and mechanics of walking in healthy individuals.
METHODS:
15 adults walked 5 min at 4 km/h on an instrumented treadmill in 3 different experimental conditions: 1) normal walking to assess the preferred Rstep values (0%), 2) at -10% and 3) +10% of preferred Rstep values using a real-time visual biofeedback (VB). Gas exchanges were collected to assess the NCw. The ground reaction forces were measured to generate real-time VB and to assess Wext and Rstep during the trials. Locomotor efficiency was calculated as Wext divided by the NCw.
RESULTS:
NCw increased significantly at +10% (p=0.01) and -10% (p<0.001) Rstep conditions compared with the preferred value (0%). Wext significantly increased at -10% than at 0% (p=0.01) and +10% (p<0.001) Rstep conditions, whereas it did not significantly differ between 0% and +10% (p=0.52) Rstep conditions. Locomotor efficiency significantly decreased at +10% Rstep (p=0.01) compared with 0% Rstep conditions but did not significantly differ between 0% and -10% Rstep conditions (p=1).
CONCLUSION:
These results confirm, at the individual level, that whole-body energy minimization is a key determinant of human gait behavior. The increased NCw in the +10% Rstep condition, despite a more effective pendular mechanism and Wext values similar to the preferred Rstep condition, indicates that walking optimization reflects a trade-off between pendulum-like energy savings and muscular efficiency.


References:
1. Peyré-Tartaruga, L. A., Dewolf, A. H., di Prampero, P. E., Fábrica, G., Malatesta, D., Minetti, A. E., Monte, A., Pavei, G., Silva-Pereyra, V., Willems, P. A., & Zamparo, P. (2021). Experimental Physiology, 106(9), 1897‑1908.
2. Fernández Menéndez, A., Uva, B., Favre, L., Hans, D., Borrani, F., & Malatesta, D. (2020). Journal of Applied Physiology (Bethesda, Md.: 1985), 129(1), 194‑203.
3. Malatesta, D., Simar, D., Dauvilliers, Y., Candau, R., Borrani, F., Prefaut, C., & Caillaud, C. (2003). Journal of Applied Physiology (Bethesda, Md.: 1985), 95(6), 2248‑2256.
4. Nùñez-Lisboa, M. N., & Dewolf, A. H. (2025). npj aging, 11(1).