It has been reported that gastrocnemius tightness and posterior talar glide are crucial factors influencing ankle dorsiflexion. However, the relationship of ankle dorsiflexion and these factors is not identified in previous studies. The purpose of this study was to identify the relationship of ankle dorsiflexion passive range of motion and gastrocnemius tightness and posterior talar glide. Twenty-five male subjects participated in this study. Bilateral weight-bearing ankle dorsiflexion passive range of motion and amount posterior talar glide of participants were measured using an inclinometer. Change in myotendinous junction of medial gastrocnemius was measured using ultrasonography to identify gastrocnemius tightness. Pearson product moment correlations were performed to examine correlations between ankle dorsiflexion passive range of motion and gastrocnemius tightness and posterior talar glide. Present findings revealed significant correlation between ankle dorsiflexion passive range of motion and gastrocnemius tightness (p=0.017, r=0.336). Also, ankle dorsiflexion passive range of motion was correlated with posterior talar glide (p=0.001, r=0.470). The present findings provide experimental evidence for factors influencing weight-bearing ankle dorsiflexion.

The purpose of this study was to investigate the effects of squat exercises with an upper limb resistance movement on the vastus medialis oblique, vastus lateralis, and gluteus maximus. This study recruited 16 healthy men. All subjects performed squat exercises with and without upper Limb resistance movements by using elastic tubing band. Electromyography (EMG) activity of the vastus medialis oblique, vastus lateralis, and gluteus maximus was recorded using a surface EMG system during these isometric squat exercises in both experimental conditions. The different muscle activation of the vastus medialis oblique, vastus lateralis, and gluteus maximus between the squat exercises with and without the upper limb resistance movement was analyzed using a paired t-test or Wilcoxon signed rank test. Our findings showed that the vastus medialis oblique, vastus medialis oblique/vastus lateralis ratio and gluteus maximus muscle activity was significantly increased during the squat exercise with upper limb resistance movements, as compared to the squat exercise without this component (p < .05). Based on our findings, the additional upper limb resistance movement may be a useful strategy to facilitate the vastus medialis oblique and gluteus maximus muscle activation during a squat exercise.

The purpose of this study was to examine the effects of abdominal hollowing with ultrasound biofeedback on multifidus and transversus abdominis/internal oblique muscle activities during lifting tasks. This study recruited 12 healthy men. All subjects received training on expiration without and with abdominal hollowing with ultrasound biofeedback. After receiving training for each condition, the thickness of transversus abdominis was measured using ultrasound, and then, electromyography activities of transversus abdominis/internal oblique and multifidus during lifting tasks were measured using a surface electromyography system. The differences in thickness of transversus abdominis and electromyography activities of transversus abdominis/ internal oblique and multifidus between the two conditions were analyzed using paired t-test. Thickness of transversus abdominis and transversus abdominis/internal oblique and multifidus activities were significantly increased during expiration with abdominal hollowing with ultrasound biofeedback compared to during expiration without abdominal hollowing (p < 0.05). These findings suggest that abdominal hollowing with ultrasound biofeedback is effective in increasing trunk stabilizer muscle activities during both static and dynamic tasks such as lifting.