Michele Forgiarini Saccol

Functional torque ratios and torque curve analysis of shoulder rotations in overhead athletes with and without impingement symptoms

Abstract In this study, we evaluated the peak torque, functional torque ratios, and torque curve profile of the shoulder rotators in overhead athletes with impingement symptoms so as to examine possible alterations in response to sports training and shoulder pain. Twenty-one overhead athletes with impingement symptoms were compared with 25 overhead athletes and 21 non-athletes, none of whom were symptomatic for impingement. The participants performed five maximal isokinetic concentric and eccentric contractions of medial and lateral shoulder rotations at 1.57 rad · s−1 and 3.14 rad · s−1. Isokinetic peak torque was used to calculate the eccentric lateral rotation-to-concentric medial rotation and the eccentric medial rotation-to-concentric lateral rotation ratios. An analysis of the torque curve profiles was also carried out. The eccentric lateral rotation-to-concentric medial rotation torque ratio of asymptomatic athletes was lower than that of non-athletes at both test velocities. The concentric medial rotation isokinetic peak torque of the asymptomatic athletes, at 3.14 rad · s−1, was greater than that of the non-athletes, and the peak appeared to occur earlier in the movement for athletes than non-athletes. These findings suggest that there may be adaptations to shoulder function in response to throwing practice. The eccentric medial rotation-to-concentric lateral rotation torque ratio was altered neither by the practice of university-level overhead sports nor impingement symptoms.

Shoulder rotator strength and torque steadiness in athletes with anterior shoulder instability or SLAP lesion.

OBJECTIVES To investigate shoulder rotator strength and steadiness in athletes with anterior instability and superior labrum anterior posterior (SLAP) lesion. DESIGN Cross-sectional laboratory study. METHODS Athletes with anterior shoulder instability (instability group, n=10) and a SLAP lesion (SLAP group, n=10) were compared with healthy athletes matched by age, anthropometrics and sport (control group for shoulder instability, n=10 and control group for SLAP, n=10). Torque steadiness was evaluated with three 10s submaximal isometric contractions (35% of peak torque) with the arm at 90° of shoulder abduction and 90° of external rotation. The mean isometric torque, standard deviation and coefficient of variation were measured from the steadiness trials. To evaluate shoulder rotator strength, concentric isokinetic tests (90°/s, 180°/s) were performed at the 90-90° position and peak torque to body mass and shoulder external to internal rotation ratio variables were analyzed. The variables were tested with the instability and control groups with respect to shoulder instability and between the SLAP and control groups for SLAP lesion using the Mann-Whitney test. RESULTS The SLAP group presented a higher coefficient of variation than the SLAP control group (p=0.003). Regarding shoulder strength, the internal and external shoulder rotators were weaker in the instability group than in the instability control group (p<0.05). CONCLUSIONS Athletes with anterior shoulder instability presented shoulder rotation weakness, while athletes with a SLAP lesion showed higher torque fluctuation during internal rotation. These results indicate that there are different alterations to strength and sensory motor control in each condition.

Shoulder internal and external rotations torque steadiness in overhead athletes with and without impingement symptoms

OBJECTIVES This study aimed to investigate torque steadiness of shoulder internal and external rotations in regularly training overhead athletes with and without impingement symptoms. DESIGN Cross-sectional laboratory study. METHODS Three groups were evaluated: athletes with impingement symptoms (n=21), asymptomatic athletes (n=25) and non-athletes (n=21). To assess torque steadiness, the participants performed 3 submaximal contractions (35% of peak torque) for 10s each, with the arm at 90° of shoulder abduction and 90° of external rotation. The standard deviation, coefficient of variation, mean exerted torque and time to stability were measured from the steadiness trials. RESULTS The standard deviation of internal rotation was higher in asymptomatic athletes than in non-athletes (p<0.01); however, there was no difference between the athletes with impingement symptoms and the other groups. The other variables presented no differences among the groups. CONCLUSIONS Higher torque fluctuation of shoulder internal rotation in asymptomatic athletes may point to neuromuscular adaptations related to throwing training. However, the steadiness patterns of athletes with impingement symptoms did not differ from those of asymptomatic athletes or non-athletes.

Isokinetic dynamometry applied to shoulder rotators - velocity limitations in eccentric evaluations.

The objectives of this study were to evaluate if collegiate overhead athletes, with and without shoulder pain, and non-athletes could reach a preset velocity in internal and external shoulder rotation isokinetic evaluations; and to evaluate the correlation between torque and velocity. Controlled laboratory study, cross-sectional. Evaluations were performed using the isokinetic dynamometer Biodex System 3. Participants were assessed seated, with the arm at 90° of shoulder abduction and 90° of elbow flexion, from neutral rotation to 90° of external rotation. Five maximal contractions of isokinetic concentric and reactive eccentric internal and external rotation were performed at the velocities 90°/s, 180°/s and 240°/s. Data were processed with using MatLab. Most participants did not reach the isokinetic phase during eccentric tests at 180°/s and 240°/s, particularly in the external rotators evaluation. High correlations between torque and velocity of eccentric tests were found. The groups presented no differences in maximal velocity attained in trials which preset velocity was not reached. These results call into question the use of reactive eccentric tests at velocities higher than 180°/s for the isokinetic evaluation of shoulder external rotators in collegiate overhead athletes and non-athletes in this specific position. In such cases, careful evaluation of the velocity is recommended to determine if the isokinetic phase was reached.