Adolescents running in conventional running shoes have lower vertical instantaneous loading rates but greater asymmetry than running barefoot or in partial-minimal shoes

Footwear may moderate the transiently heightened asymmetry in lower limb loading associated with peak growth in adolescence during running. This repeated-measures study compared the magnitude and symmetry of peak vertical ground reaction force and instantaneous loading rates (VILRs) in adolescents during barefoot and shod running. Ten adolescents (age, 10.6 & PLUSMN; 1.7 years) ran at self-selected speed (1.7 & PLUSMN; 0.3 m/s) on an instrumented treadmill under three counter-balanced conditions; barefoot and shod with partial-minimal and conventional running shoes. All participants were within one year of their estimated peak height velocity based on sex-specific regression equations. Foot-strike patterns, peak vertical ground reaction force and VILRs were recorded during 20 seconds of steady-state running. Symmetry of ground reaction forces was assessed using the symmetry index. Repeated-measures ANOVAs were used to compare conditions (& alpha;=.05). Adolescents used a rearfoot foot-strike pattern during barefoot and shod running. Use of conventional shoes resulted in a lower VILR (P < .05, d(z) = 0.9), but higher VILR asymmetry (P < .05) than running barefoot (d(z) = 1.5) or in partial-minimal shoes (d(z) = 1.6). Conventional running shoes result in a lower VILR than running unshod or in partial-minimal shoes but may have the unintended consequence of increasing VILR asymmetry. The findings may have implications for performance, musculoskeletal development and injury in adolescents.

Automated summary

Footwear may moderate the asymmetry in lower limb loading during peak growth in adolescence. This study compared the effects of barefoot and shod running on vertical ground reaction force and loading rates in adolescents. The use of conventional running shoes resulted in lower loading rates but higher asymmetry compared to running barefoot or wearing partial-minimal shoes. These findings have implications for performance, musculoskeletal development, and injury in adolescents.