Modulating Pendular Mechanics to Explore Whole-Body Energy Minimization During Walking

Abstract

Introduction: During level walking, humans adopt gait patterns that minimize the net energy cost of walking (NC_w). Metabolic energy is required by muscles to generate force and perform total positive mechanical work (W_tot). A component of W_tot is the external mechanical work (W_ext), which represents the work performed to lift and accelerate the body’s center of mass (CoM). The pendular exchange of potential and kinetic energy (R_step) during the walk reduces W_ext, thereby minimizing NC_w (Peyré-Tartaruga et al., 2021). Altered R_step has been associated with a higher NC_w in older and obese adults (Fernández Menéndez et al., 2020; Malatesta et al., 2003). Older adults exhibit lower R_step (Nùñez-Lisboa & Dewolf, 2025), whereas adults with obesity display higher R_step and lower W_ext (Fernández Menéndez et al., 2020), suggesting an adaptive mechanism that mitigates the increase in NC_w in this population (Fernández Menéndez et al., 2020). Therefore, this study aimed to examine the effects of modulating the pendular mechanism via a real-time visual biofeedback on the energetics and mechanics of walking in healthy individuals.

Method: 15 healthy adults (7 men and 8 women; height: 1.73±0.10 meters; body mass: 70.9±13.1 kg; age: 26.2±4.3 yr) walked 5 min at 4 km/h on an instrumented treadmill (Gaitway-3D, ®Arsalis, Belgium) in 3 different experimental conditions: 1) normal walking to assess the preferred R_step values (0%) and at 2) -10% and 3) +10% of preferred R_step values using a real-time visual biofeedback during the 5 min to obtain these targeted values. Gas exchanges were collected to assess the NC_w (J·kg^-1·m^-1). The ground reaction forces were measured to generate real-time visual biofeedback during -10% and +10% R_step trials and to assess walking mechanics (W_ext and R_step) during 30 seconds of each walking trial (Fernández Menéndez et al., 2020). Locomotor efficiency was calculated as W_ext divided by the NC_w (Griffin et al., 2003).

Result: NC_w increased significantly at +10% (p=0.010) and -10% (p<0.001) R_step conditions compared with the preferred value (0%). W_ext significantly increased at -10% than at 0% (p=0.006) and +10% (p<.001) R_step conditions, whereas it did not significantly differ between 0% and +10% R_step conditions (p=0.518). Locomotor efficiency significantly decreased at +10% R_step (9.2±2.7%) compared with 0% R_step conditions (12.2±2.0%; p=0.011) but did not significantly differ between 0% and -10% R_step conditions (11.5±4.2%, p=1.000).

Discussion: NC_w was minimized at the preferred R_step value and increased significantly at -10% and +10% R_step conditions. This confirms that the preferred pattern is the most economical, even when R_step is increased. At -10% R_step condition, the current increase in NC_w and W_ext suggests that targeting R_step through real-time visual biofeedback may have rehabilitative potential for increasing R_step and thereby reducing W_ext and NC_w in populations with naturally lower R_step during walking, such as older adults (Nùñez-Lisboa & Dewolf, 2025).

Conclusion: These results confirm that whole-body energy minimization is a central determinant of human gait behavior. Future longitudinal studies are required to determine the long-term effectiveness of real-time visual biofeedback interventions aimed at enhancing pendular transduction and reducing NC_w in older adults.