Problem statement: The proprioception information is a prerequisite for balance, body's navigation system and the movement coordinator. The aim of this study was to investigate the effects of fatigue and chronic ankle instability on dynamic postural control. Approach: Thirty physical education students (14 males, 16 females) in two groups (15 healthy age = 21.78±0.79 years, height = 168.3±5.6 cm and weight = 63.6±2.6 kg, 15 with chronic ankle instability age = 21.43±0.83 years, height = 168.4±5.5 cm and weight = 63.3±3.2 kg) participated in this study voluntary. Star Excursion Balance Test was used for evaluation of dynamic postural control. Subjects performed a functional fatigued protocol that lasted 15 min. Using the Borg scale, also measured rating of perceived exertion before, middle and after the fatigue protocol. Results: The findings indicated that dynamic postural control decreased after fatigue in two groups (p<0.05). In contrast, there was only significance different between two groups after fatigue in lateral and antrolateral directions of Star Excursion Balance Test (p<0.05). Conclusion: Fatigue and chronic ankle instability can effect on dynamic postural control also, combination fatigue and chronic ankle instability can increase this effect. High incidence of ankle sprains especially in lateral and antrolateral directions which lead to reducing of balance can be practical guideline for training programs and management of fatigue in athletes. This finding also helps to sport physiotherapists to more emphasis on ankle sprain in rehabilitations on lateral and antrolateral directions.

Background: Lateral ankle sprain is one of the most common injuries among athletes, which can cause chronic ankle instability (CAI) in most athletes. Objectives: This study compared the core muscle endurance ratio and static and dynamic postural control in female athletes with and without CAI. Methods: Sixty female athletes (30 with CAI, 30 without CAI) participated in this study voluntarily. McGill's test measured the endurance of the trunk extensors, flexors, and lateral flexors muscles. The stork test was used to measure static postural control and the Y balance test was used to measure dynamic postural control. Independent sample t-test was used to compare different parameters between the two groups. Results: The findings showed there was a significant difference between the two groups in flexor/ extensor endurance ratio and the endurance ratio of the dominant lateral flexors/non-dominant side. In static postural control, there was a significant difference between the two groups. In dynamic postural control, there was no significant difference between the groups in the anterior direction and the posteromedial direction, but there was a significant difference in the posterolateral direction. Conclusions: According to findings, female athletes with CAI have a lower endurance ratio in the core stability muscles and weaker postural control compared to healthy athletes. It is suggested to pay more attention to these factors in female athletes with CAI and design special exercises to prevent re-injury.

Asymmetric musculoskeletal adaptations, resulting from the type of sports, may lead to shoulder injuries due to altered shoulder mechanics and increased pressure on tissues. This study compared the scapulohumeral rhythm (SHR) ratio, flexibility, posterior capsule stiffness (PCS), and shoulder muscle strength between volleyball players as unilateral overhead athletes and swimmers as bilateral overhead athletes. Fifty-seven young overhead athletes, 30 volleyball players, and 27 swimmers participated in this study voluntarily. The SHR, PCS, and shoulder internal and external rotation ranges of motion (ROM) and strength in dominant and non-dominant limbs were measured using an inclinometer. Nicholas’s hand dynamometer was also used to evaluate the strength of internal and external shoulder rotators. Findings indicated sport type had a significant effect on SHR ratio from 0˚ to 45˚ (p = 0.002), and from 0˚ to 135˚ (p = 0.002), external rotation (ER) ROM (p = 0.004), PCS (p = 0.002), internal (p = 0.004), and external (p = 0.002) rotator strength. Furthermore, the main effects of the dominance or non-dominance limb were significant for the scapular upward rotation (SUR) at 0˚ humeral elevation (p = 0.03) and external rotator strength (p = 0.01). On the other hand, the SHR ratio from 0˚ to 45˚ (p = 0.01) and from 0˚ to 90˚ (p = 0.01) was significantly less for the dominant limb than the non-dominant limb in volleyball players. Also, the pectoralis minor length was significantly shorter in the dominant limb compared to the non-dominant limb in volleyball players (p = 0.01). Furthermore, the dominant limb exhibited greater ER.ROM (p = 0.01) and external rotator strength (p = 0.02) compared to the non-dominant limb in volleyball players. Finally, swimmers had a significant difference in internal (p = 0.01) and external rotator strength (p = 0.01) between the dominant and non-dominant limbs. The effect of type sport on SUR at 0˚ and 135˚ humeral elevation, SHR from 0˚ to 45˚ and 135˚ hemeral elevation, internal rotators strength, PCS, and ER.ROM also the effect of dominance or non-dominance limb on SUR at 0˚ humeral elevation and external rotators strength can help physiotherapists and sports trainers to design prevention of injuries strategies in young overhead athletes.