Weighted Shoes in the Wild: Initial Insights into the Relationship Between the Effort of Walking and the Amount of Walking Performed

Abstract

PurposeWalking comprises a large portion of active energy expenditure in humans. Interventions that increase or decrease the energy expended on each step, such as ankle weights or energy-saving orthoses, may therefore strongly impact fitness. The overall effect of increasing or decreasing per-step energy use is unclear, however, because people may choose to walk less or more, respectively, in response. MethodsIn this study, healthy college students with normal body mass index wore weighted and unweighted shoes embedded with an inertial measurement unit for one week each. Community-based walking data were analyzed for number of steps, distance traveled and walking speed. Oxygen consumption using each set of shoes at a range of speeds were measured in a laboratory setting and used to estimate metabolic energy expended during community-based walking. A survey measured subjective response to each pair of shoes. ResultsThe weighted shoes increased per-step energy cost by about 26%. Subjects strongly disliked the weighted shoes (P = 0.001) and found them tiring (P = 0.003). Despite this dislike, subjects did not significantly reduce distance walked (P = 0.6), number of steps (P = 0.7), or average speed (P = 0.9) compared to normal shoes. This led to a small but not statistically significant increase in energy expended during walking over a five-day period (12.3 {+/-} 9.6% increase, P = 0.2). On the final collection day this trend appeared to reverse, with fewer steps taken and lower metabolic energy expended with the weighted shoes. Twenty-four subjects were recruited but only ten completed the protocol, with dislike of the weighted shoe condition being the primary reason for dropout. ConclusionsIncreasing the energy cost of each step led to greater energy expended through walking. However, there are indications that behavioral changes would be greater with a longer intervention or increased retention. For example, the large dropout rate suggests that some subjects avoided walking with the weighted shoes entirely, simply by leaving the study. Follow-on studies among patient groups may reveal a fitness benefit to either increasing or reducing the energy cost of walking.