Athletic training with minimal footwear strengthens toe flexor muscles

Abstract

During the propulsive phase of human locomotion, long and short toe flexor muscles (TFM) are exposed to mechanical stimuli caused by ground reaction forces. Further, flexible footwear seems to facilitate increased loading on foot structures. The purpose of the study was to evaluate the effects of high intensity athletic training with minimal footwear on TFM strength. Forty-seven female sport students participated and were randomly divided in three groups: the experimental group (EG; n = 18; 25 ± 5 yrs, 59 ± 6 kg) and the training control group (TG; n = 18; 23 ± 2 yrs, 64 ± 6 kg) performed high intensity athletic training (3 weeks, 5 times per week, 30 min per session) on the forefoot. The EG wore a minimal shoe, the TG performed the exercises with traditional training shoes. The basic control group (CG; n = 11; 27 ± 5 yrs, 63 ± 7 kg) participated in no training programme. To evaluate the training effects on TFM strength, maximum metatarsal phalangeal joint (MPJ) plantar flexion moments during maximal voluntary isometric contractions (MVIC) at 0° and 25° MPJ dorsal flexion were measured in a custom made dynamometer before and after the training intervention. The results showed that (1) in 0° MPJ dorsal flexion, MPJ moments were significantly increased in the EG (p < 0.01) and TG (p < 0.05) and differed significantly to the CG (p < 0.05); (2) in 25° MPJ dorsal flexion, TFM strength was significantly increased in the EG (p < 0.01), but not in the TG and CG (p > 0.05). In this joint angle position the EG significantly differed from the TG and CG (p < 0.05). The results of the study show that athletic exercises with minimal footwear strengthen TFM after three weeks intensive training.