Surface Stiffness and Footwear Affect the Loading Stimulus for Lower Extremity Muscles When Running

Abstract

Surface stiffness and footwear affect the loading stimulus for lower extremity muscles when running. J Strength Cond Res 36(1): 82-89, 2022-Running in minimal footwear or barefoot can improve foot muscle strength. Muscles spanning the foot and ankle joints have the potential to improve performance and to reduce overuse injury risk. Surface stiffness or footwear use could modify the intensity of training stimuli acting on lower extremity joints during running. The purpose of this study was to systematically investigate external ankle, knee, and hip joint moments during shod and barefoot running while considering the stiffness of the running surface. Two footwear conditions (barefoot and neutral running shoe) and 4 surface conditions (Tartan, Tartan + Ethylene Vinyl Acetate [EVA] foam, Tartan + artificial turf, Tartan + EVA foam + artificial turf) were tested at 3.5 m•s 21 . Repeated measures analysis of variance revealed that barefoot running in general and running barefoot on harder surfaces increased and decreased ankle (between +5 and +26%) and knee (between 0 and 211%) joint moments, respectively. Averaged over all surfaces, running barefoot was characterized by a 6.8˚more plantarflexed foot strike pattern compared with running shod. Foot strike patterns were more plantarflexed on harder surfaces; the effects, however, were less than 3˚. Most surface effects were stronger in barefoot compared with shod running. Surface stiffness may be used to modulate the loading intensity of lower extremity muscles (in particular extrinsic and intrinsic foot muscles) during running. These results need to be considered when coaches advise barefoot running as a method to improve the strength of extrinsic and intrinsic foot muscles or when trying to reduce knee joint loading.

Mechanical Properties of Treadmill Surfaces Compared to Other Overground Sport Surfaces

“…Collectively, these findings suggest that researchers, clinicians and athletes using a lab-TR for specific purposes must carefully choose the model to be used, since this may affect the generalizability of clinical assessments or research performed on the treadmill, potentially leading to erroneous research findings [3,13,18,31,34]. For example, our findings imply that marked differences in mechanical properties between treadmill and overground surfaces could critically affect footwear studies using treadmills to assess the effects of running shoes on running economy and running biomechanics [35][36][37], since the optimal footwear on a treadmill may not necessarily be the optimal footwear on an overground surface. Therefore, researchers using treadmills to reproduce overground conditions in research or clinical settings should attempt to use a treadmill whose surface mimics as closely as possible the mechanical properties of the specific overground surface, since the comparability between both conditions will vary depending on the treadmill platform [18].…”

Plantar Loads of Habitual Forefoot Strikers during Running on Different Overground Surfaces

“…The overground surface is also an essential factor that has been studied in recent years [6,7]. Many investigators have identified the overground surface as an important variable that can affect load absorption mechanisms as revealed in the kinematics and kinetics of the lower limbs during running [7][8][9][10]. The accumulation of plantar loads could lead to chronic injuries when running for more than 64 km per week [2] and excessive plantar loads are considered to be a major cause of overuse running injuries [11,12].…”

Barefoot Running on Grass as a Potential Treatment for Plantar Fasciitis: A Prospective Case Series

“…Linked to this explanation is the runner’s acute exposure to a new foot-surface environment via the pliable (grass) surface used. Plantar pressure and external ankle joint moments are lower running on a pliable surface relative to firm surfaces [ 34 , 35 ]. This is coupled with the knowledge that runners, whether habitually shod or barefoot, use a more varied foot-strike pattern on soft surfaces [ 36 ].…”