Barefoot running typically produces a shift in foot strike and stride mechanics that alters how forces travel through the lower limb. Research led by Daniel E. Lieberman Harvard University showed that many runners who remove shoes naturally adopt a forefoot or midfoot strike, which often reduces the early vertical impact peak and loading rate measured at initial contact. That change tends to lower abrupt knee loading but increases demand on ankle and foot structures.
Kinematics and loading changes
Experimental work by Marco Squadrone and Carlo Gallozzi University of Turin compared barefoot and shod conditions and found consistent changes in stride: shorter stride length, higher cadence, less knee extension at contact, and greater ankle plantarflexion moments. These adaptations increase activation in the calf muscles and the Achilles tendon, raising repetitive tensile loading on the posterior chain while concentrating pressure under the forefoot and metatarsal heads. Surface stiffness and running speed modulate these effects; softer or uneven ground blunts some impact differences seen on hard laboratory floors.
Injury risk, relevance, and adaptation
Evidence about overall injury risk remains mixed. The reduction in knee joint impact may lower risk for some problems such as patellofemoral pain, but the increased stresses on the foot and Achilles are associated with a higher risk of plantar metatarsal stress injuries and Achilles tendinopathy in runners who transition too quickly. Habitually barefoot populations studied by Lieberman Harvard University and others show different foot morphology and gait patterns developed over childhood, suggesting that lifetime adaptation matters; sudden transition in adult runners transfers loads to tissues that may be unprepared to tolerate them. Cultural practices, typical surfaces, and footwear history therefore shape both immediate biomechanics and long-term injury patterns.
Clinical and practical implications emphasize gradual exposure, strength training for intrinsic foot and calf muscles, and attention to surface and mileage progression. For research and policy, high-quality longitudinal studies are needed to determine whether biomechanical benefits translate into fewer overall injuries for diverse runner groups. In the meantime, individual factors such as previous injury history, training environment, and running goals should guide whether and how someone experiments with barefoot or minimalist running.