Background: Race walking has grown in popularity in recent years and is rapidly becoming the favored pastime of recreational athletes. This trend possibly results from the belief that
race walking is a sport that provides valuable health and fitness benefits and has low risk of injury. However, researchers consider race walking as a sport event with a high risk of injury.
A 67 kg individual walking 50 km must absorb 2016 tons on each foot. Thus, race walkers are prone to overuse injuries, such as blisters, metatarsalgia, stress fractures, and knee pains, in their lower
extremities. During race walking, walkers have to recurrently undergo plantar compressive loading for 1 h to 4 h, when the musculoskeletal system is overloaded, overuse injuries may occur. In this
study, arch-supported functional insoles (International Biomechanics Limited, Hong Kong) were used to reduce plantar pressure loading during race walking .
Methods: Participants: A total of 20 male race walkers aged 21.19 ± 3.66 years were recruited from the provincial race walking team of Shandong, China. Testing Protocol: Each
participant did race walking (1) with functional insole (functional insoles placed in both shoes), and (2) with normal insole. Data Collection: Plantar pressure insoles (Rs-scan International, Olen,
Belgium) were used to collect plantar pressure data. Data Reduction: Eight anatomical sub-regions were identified as the medial heels, lateral heels, medial arch, lateral arch, MPJs 1 to 5 and the
hallux. Data Analysis: Two-way ANOVA with mixed design was used to compare plantar pressure among ten different parts of the foot and between two conditions.
Results: With normal insoles, the highest pressure was found on the MPJs and heels. The functional insoles reduced the pressures in these areas and increased the pressure of medial
arch. With functional insoles, the peak pressures significantly decreased in Hallux, MPJ1-4, Medial and lateral heel compared with those with normal insoles, but increased in Medial arch, and did not
change in MPJ5. Functional insoles similarly affected the impulse. With functional insoles, the impulses significantly decreased in Hallux, MPJ1-4, lateral arch, Medial and lateral heel compared with
those with normal insoles, but increased in Medial arch, and did not change in MPJ5. Meanwhile, the first peak of GRF decreased but the second peak remained unchanged.
Conclusion: During race walking, the peak pressure and impulse in the MPJs and heels were reduced by arch-supported functional insoles. As such, functional insoles can prevent
overuse injuries by offloading the peak pressures and impulse in the MPJs heads and heels and reduce the risk of overuse injuries in these parts. The reduction in the first GRF peak also suggests that
the insoles absorb the vertical shock during the strike phase of the heels and thus prevent the potential injury risks in the foot and leg.