مجله بیومکانیک ورزشی
سال پنجم شماره 3 (پاییز 1398)

Performing repetitive overhead movements puts stress on the shoulder joint, leading to uneven shoulders and pain in the shoulder joint. The purpose of this study was to evaluate and compare the strength and Range of Motion (ROM) of internal and external rotator muscles in volleyball players with and without uneven shoulders.

This is a descriptive and causal-comparative study conducted on 30 volleyball players randomly assigned into two groups of patients with uneven shoulders and healthy peers. A dynamometer (Manual muscle testing) was used to measure the strength of the rotator muscles at zero degrees,  a goniometer to measure the ROM of muscles, and a scoliometer device to measure the symmetry of shoulders.

There was a significant difference in the strength of internal (P=0.03) and external (P=0.02) rotator muscles between groups with and without uneven shoulders. The ROM of internal (P=0.02) and external (P=0.03) rotator muscles were also significantly different between the two groups.

 High muscle strength in volleyball players with uneven shoulders is a risk factor. Limitations in the ROM of rotator muscles in the shoulder joint of these athletes showed the need for more attention to preventive approaches by creating corrective strategies.

 This study aimed to examine the effect of fatigue on postural balance of young women using Electromyography (EMG) of lower extremity muscles and measuring the foot plantar Center of Pressure (COP) displacement.

Participants were 10 young women (mean age, 26.4±3.01 years; mean weight, 65.5±5.75 kg; mean height, 165±2.61; BMI, 24.08±2.08 kg/m2) with no history of lower limb injury or balance problems. To evaluate their static balance, the stork test was used and the foot plantar COP was measured by force plates. To measure fatigue, three parameters of muscle power (P), median frequency of muscle (F) and Root Mean Square (RMS) of raw EMG signals were calculated. Data were analyze din SPSS V. 16 and MATLAB software using Mann-Whitney U test.

fatigue had a significant effect on P and RMS parameters (P<0.05), but did not significantly affect the F. It increased P and decreased RMS. The highest change in the P parameter was seen in biceps femoris muscle; the highest change in the F parameter was related to semitendinosus muscle; and the highest change in the RMS parameter was related to gastrocnemius lateralis and gastrocnemius medialis muscles.

 There is a negative relationship between fatigue of the lower extremity muscles and balance impairment; by increasing the level of fatigue in the muscles, balance is more impaired.

Upper Crossed Syndrome (UCS) is a disorder caused by muscle imbalance of the upper quadrant of the body. Using National Academy of Sports Medicine (NASM) protocol for corrective exercises is one of the new approaches to restore muscle balance, and prevent/correct postural abnormalities. The purpose of the present study is to evaluate the effect of an 8-week NASM corrective exercise program on UCS.

Participants were 30 female students with forward head > 46 degrees, forward shoulder > 52 degree and thoracic kyphosis > 42 degrees, who were selected using a purposive sampling method and then randomly divided into control and intervention groups. The intervention group received corrective exercise program for eight weeks, three sessions per week. Forward head and shoulder angles were measured using side photography, and thoracic kyphosis angle was measured using a flexible ruler (r=0.093) before and after intervention. Paired t-test and analysis of covariance were used for data analysis at the significance level of P≤0.05.

 The mean angles of forward head, forward shoulder and thoracic kyphosis decreased significantly after 8 weeks of NASM corrective exercise in the intervention group compared to the control group.

 Corrective trainers and therapists are advised to regularly use the NASM corrective exercise program proposed in this study for UCS patients.

 The purpose of the present study was to compare the effects of functional and non-functional fatigue protocols on the dynamic balance of amateur basketball players.

 Ten amateur basketball players (mean age= 21.4±1.5 years, mean height= 177.5±7.1 cm, and mean weight= 67.4±8.5 kg) volunteered to participate in this study. Stair climbing and specific basketball movement circuit training were used to induce the non-functional and functional fatigues, respectively. Dynamic balance was measured by the postural stability test (level 2) using the Biodex balance system. Paired T-test and independent T-test were used for data analysis at a significance level of P<0.05.

 Dynamic balance of subjects was decreased after inducing both fatigue protocols, where the non-functional fatigue protocol reduced the overall balance by 21.39%, and the functional protocol reduced it by 10.49%. There was a significant difference between the pre-test and post-test scores of overall balance and the balance in the anterior-posterior direction following the non-functional fatigue protocol (P=0.03).

 Non-functional fatigue protocol affects the dynamic balance of basketball players more than the functional protocol. Therefore, using different types of specialized exercises to experience the period of fatigue may be effective in improving the balance of basketball players.

 Anterior cruciate ligament injury is often non-traumatic and occurs in landing and cutting following an incorrect knee joint alignment. The present study aimed to compare the knee joint kinematic parameters of adolescent female athletes during sidestep cutting maneuver before and after fatigue in predictable and unpredictable settings.

 This is a quasi-experimental study conducted in the summer 2019. The study population consists of all adolescent female athletes in Kerman, Iran. Of these, 49 athletes were selected using purposive and convenience sampling methods. Each subject first ran a distance (10 m) and then made a vertical jump towards the ball at the specified location. Afterwards, she ran to the cutting location (a 3-m distance) and performed sidestep cutting at the specified angle, predictably or unpredictably, before and after fatigue. Kinematic data were recorded at a sampling rate of 200 HZ, and then analyzed in MATLAB and SPSS software using mixed repeated measures ANOVA at the significant level of P<0.05.

 Statistical analysis results showed that sidestep cutting maneuver after fatigue, despite a significant decrease in knee flexion (P=0.001), significantly increased the knee valgus (P=0.001) and tibia rotation (P=0.001) angles.

 There is an increased risk of injury due to changes in kinematic parameters caused by fatigue and unpredictable cutting maneuvers.

 Quadriceps weakness is common after Anterior Cruciate Ligament (ACL) injury and subsequent surgery. Preoperative defects affect postoperative outcomes. The purpose of this review study was to investigate whether preoperative exercises can affect the postoperative outcomes after ACL reconstruction.

 The searching for papers was conducted in the PubMed database among the studies from 1990 to 2019 using following keywords: ACL preoperative exercise, prehabilitation ACL, and preoperative protocol. The initial search yielded 442 papers. Then, based on the inclusion and exclusion criteria, 10 papers were selected for the final review. Methodological quality of the studies was assessed by using the Physiotherapy Evidence Database (PEDro) scale and the Critical Appraisal Skills Program (CASP).

 Some preoperative exercises (traditional, strength, and neuromuscular) can significantly increase the knee extensor strength and knee function in men and women after surgery in the short and long periods. The mean PEDro score for 8 randomized controlled trials was 6, indicating their moderate methodological quality. Moreover, the CASP score for 2 cohort studies was 10 and 11 out of 12.

 Preoperative rehabilitation consisting of neuromuscular and strength exercises followed by a criterion-based postoperative rehabilitation program cause greater functional outcomes and faster recovery of the knee extensor strength after ACL reconstruction. Preoperative rehabilitation should be considered as a standard treatment to maximize functional outcomes after ACL reconstruction.