Background Previous studies reported that one-leg squat has various advantages in functional activities, no study has studied the effect of muscle activity on ankle stability. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons. org/licenses/by-nc/4.0) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Purpose The purpose of this study was to investigate the differential effects of squat type on the activity of the tibialis anterior, peroneus longus and tibialis posterior muscle for ankle stability.Study design Cross-sectional study. MethodsThe participants were 30 healthy adults. During each squat execution, tibialis anterior, peroneus longus and tibialis posterior muscle activities were assessed using surface electromyography under control of each squat posture. ResultsThe muscle activity of the tibialis anterior and peroneus longus applying Bulgarian split squat was significantly higher than lunge squat. However, the activity of the tibialis posterior showed no significance between squat conditions. Conclusions This study demonstrated that Bulgarian squat was more effective at eliciting ankle dorsiflexor and evertor that are known as important role for ankle stability.Key words Ankle stability; Bulgarian squat; Electromyography; Peroneus longus; Tibialis anterior. Research ReportComparison of Activities of Leg Muscles according to Lunge Squats and Bulgarian Split Squats Journal of KEMA of CAI.11 Previous studies have shown that one leg squat requires more neuromuscular activity due to reduced mediolateral base of support compared to two leg squats. 11-13Increased neuromuscular activity has also been reported to have a positive effect on proprioception and strength in functional activities. [11][12][13] Although many studies have reported that one-leg squat has various advantages in functional activities, no study has studied the effect of muscle activity on ankle stability. Therefore, the objective of this study was to investigate the effect of two types of single-leg squat exercise commonly used in clinical practice for strengthening and rehabilitation of lower limbs on muscles activity of the tibialis anterior (TA), peroneus longus (PL), and tibialis posterior (TP). The hypothesis of this study was that muscle activities of TA, PL, and TP muscles at Bulgarian split squat could be higher than those at lunge squat. METHODSThis study recruited 30 healthy volunteers (15 males, 15 females) who met the selection criteria. Participants were given a detailed explanation of the study procedure. Written informed consent was obtained from each participant. This study was conducted in accordance with principles of the Declaration of Helsinki.Volunteers who were able to maintain single-leg squat posture for longer than 10 s to check shank muscles activity were recruited for this study. Volunteers who had any neurological, musculoskeletal, or cardi...