[Effects of intrinsic foot muscle training in patients with ankle instability: a narrative review]

Ankle sprains are among the most common injuries in sports and can result in chronic ankle instability. In therapy and prevention, a sensorimotor training approach on the structures surrounding the ankle joint has proven to be effective. There is evidence that training the intrinsic foot muscles can also improve balance, for example.

The aim of this narrative review is to present evidence regarding intrinsic foot muscles training in patients with ankle instability.

In January 2022, a systematic literature search was conducted in the databases PubMed, Cochrane Library, EBSCOhost, PEDro, SPONET and BISp-Surf and was complemented by a freehand search. We searched for meta-analyses, systematic reviews and intervention studies that examined the effects of a form of intrinsic foot muscle training on patients with ankle instability. The qualitative evaluation of the literature and evidence was based on the risk-of-bias tool (RoB tool) of the Cochrane Handbook and the GRADE system.

Five randomised controlled trials involving 150 participants were included. Four trials used the Short-Foot Exercise (SFE), one trial used the Towel-Curl Exercise (TCE) and a toe-training program. The results of three studies showed a significant positive effect (p<0,05) on self-reported instability. Significant positive effects (p<0.05) on balance were shown for the SFE and the toe-training program, although the inclusion of the SFE in a training program did not result in any benefits. One study found significant positive effects (p<0.05) of the SFE on somatosensory function. All three forms of training led to significant (p<0.05) improvements in functional aspects.

The results of this narrative review show positive effects of training the intrinsic foot muscles in patients with ankle instability on self-reported instability, balance, somatosensory function and on functional aspects. SFE and toe training seem to be effective forms of training and could be a useful addition to conventional therapy. However, the quality of evidence is too low and further research is needed to make a clear recommendation.