Effects of footwear with different longitudinal bending stiffness on biomechanical characteristics and muscular mechanics of lower limbs in adolescent runners

Background: Running shoes with carbon plates have beenidentified to have positive effects on improving running performance from abiomechanical perspective. However, the specific difference between the effectsof carbon plates with different longitudinal bending stiffness (LBS)onbiomechanical characteristics and muscular mechanics of lower limbs inadolescent runners remains unclear. This study aimed to identify the differencein biomechanical characteristics and muscular mechanics in lower limbs during runningstance phases between wearing shoes with low longitudinal bending stiffness(Llbs) and high longitudinal bending stiffness (Hlbs) carbon plates inadolescent runners.

Methods: 10 male adolescent runners with a habit of dailyrunning exercise (age: 13.5 ± 0.6 years; height: 166.3 ± 1.9 cm; bodyweight:50.8 ± 3.1 kg; foot length: 25.4 ± 0.2 cm) were recruited and asked to conducttwo times of tests by wearing shoes with Llbs and Hlbs carbon plates in arandomized order. Paired t-test and statistical parametric mapping (SPM)analysis were used to identify the difference in biomechanical characteristicsand muscular mechanics in lower limbs during running stance phases.

Result: Under the condition of wearing shoes with Hlbs, thetime of foot contact significantly increased, whereas the range of motion (ROM)of hip and metatarsophalangeal (MTP) in the sagittal plane significantlyreduced as well as the peak moment of ankle joint in the sagittal plane. Theactivations of vastus medialis, vastus lateralis, flexor digitorum brevis (flexdig brevis), and flexor hallucis longus (flex hall long) significantlyincreased under the condition of wearing shoes with Hlbs. According to theresults of the SPM analysis, the joint angles (hip, ankle, and MTP), the netjoint moments (knee, ankle, and MTP), and the muscle forces (gluteus maximusand tibialis anterior) were significant difference during the running stancephase between conditions of wearing shoes with Hlbs and Llbs.

Conclusion: Running shoes with Llb carbon plates areappropriate for adolescent runners due to the advantages of biomechanicalcharacteristics and muscular mechanics.