[Purpose] Functional instability leads to a delay in the muscle reaction time and weakness of the peroneal muscles. The present study examined the effects of transcutaneous electrical nerve stimulation during balance exercise on patients with functional instability of the ankles, including the ability to land after jumping at the center of foot pressure. [Subjects] The subjects were seven males with a history of ankle sprain. All had a sprained ankle score of ≤80 points on Karlson’s functional instability test. [Methods] They were asked to jump over a 20-cm-high platform sideways for 10 consecutive seconds on a force plate with one leg. The length of the center of pressure was measured for comparison of balance exercise and balance exercise with simultaneous transcutaneous electrical nerve stimulation. [Results] The length of the center of foot pressure on the sprain side was significantly greater than on the non-sprain side under both conditions. Under the balance exercise with simultaneous transcutaneous electrical nerve stimulation therapy condition, the length of the center of foot pressure on the sprain side was significantly reduced, with the values being 627.0 ± 235.4 and 551.8 ± 171.1 mm before and after the challenge, respectively. [Conclusion] Ankle instability on the sprain side was significantly reduced under the balance exercise with simultaneous transcutaneous electrical nerve stimulation therapy condition before and after the challenge. Peroneal muscles showed increased activity caused by common peroneal innervation.

This paper is one of the serial study on underwater walking in flood disaster evacuation.

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This study aimed to examine the relationship between chronic ankle sprain instability and ultrasonography of the peroneus muscles during a single-leg standing task. [Participants and Methods] We examined nine college-aged students with a history of lateral ankle joint sprain with chronic ankle sprain instability scores less than 24. Participants underwent ultrasonographic measurement of the pennation angle and muscle thickness of the peroneal and gastrocnemius muscle groups of both legs. In addition, participants were evaluated for fluctuation by the root mean square calculated from accelerations in the anteroposterior, lateral-horizontal, and vertical directions during the single-leg standing position by affixing the accelerometer to their waist. Measurement results were compared between sprain and non-sprain sides. [Results] Ultrasonography revealed a significant reduction in the feathered pennation angle of the long peroneal muscle on the side of the sprain, but no other significant differences. Also, significant extension was observed on the side of the sprain in the anteroposterior and vertical directions during single-leg standing; however, no significant differences were found in the lateral-horizontal direction. [Conclusion] Participants with chronic ankle sprain instability exhibited greater fluctuation in the anteroposterior and vertical directions. Such fluctuations are believed to be compensatory in nature because the feathered horn of the long peroneal muscle is decreased, and pronation of the forefoot is difficult during one-leg standing.

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