Strength

Relationship between Range of Motion, Strength, Upper Quarter Y-balance Test and a history of Shoulder Injury among NCAA Division I Overhead Athletes

Background: Several risk factors have been identified as contributors to the development of shoulder injuries, including glenohumeral internal rotation deficit, rotator cuff weakness, and shoulder instability. However, lasting deficits of the physical characteristics among overhead athletes with a history of a shoulder injury are unknown. Objective: To compare shoulder range of motion (ROM), strength, and upper-quarter dynamic balance between collegiate overhead athletes with and without a history of a shoulder injury. Methods: 58 overhead athletes were distributed into a shoulder injury history group (n=25) and healthy group (n=33). All participants were fully participating in NCAA Division I baseball, softball, volleyball, or tennis and free of any symptoms of shoulder injuries. An investigator measured active ROM for dominant shoulder internal rotation (IR), external rotation (ER), and horizontal adduction (HAD) using a digital inclinometer. Isometric strength for dominant shoulder IR and ER at 90° of abduction was measured using a hand-held dynamometer. The upper quarter dynamic balance was assessed via the Upper Quarter Y-Balance Test (UQYBT). Results: The injury group demonstrated a lower UQYBT mean score in the superolateral direction. However, there were no statistically significant intergroup differences in shoulder ROM, strength, ER/IR strength ratio, and UQYBT in the medial direction and inferolateral direction. Conclusions: Overhead athletes with a previous history of shoulder injury had poorer UQYBT in the superolateral direction despite a lack of ongoing symptoms or deficits in function. Well-planed dynamic balance training and related strengthening exercises may be warranted for overhead athletes to improve their upper quarter functions.
Listed In: Physical Therapy, Sports Science, Other


A preliminary study on quality of knee strength measurements by means of Hand Held Dynamometer and Optoelectronic System

Strength measurements are popular in the clinical practice to evaluate the health status of patients and quantify the outcome of training programs. Currently a common method to measure strength is based on Hand Held Dynamometers (HHD) which is operator-dependent. Some studies were conducted on repeatability of strength measurements but they were limited to the statistical analysis of repeated measurements of force. In this work, the authors developed a methodology to study the quality of knee flexion/extension strength measurements by measuring the effective HHD position and orientation with respect to the patient. HHD positioning attitude was measured by means of an Optoelectronic System for which a marker protocol was defined ad-hoc. The approach allowed to assess quality of measurements and operator’s ability by means of quantitative indices. The protocol permitted the evaluation of: angles of HHD application, angular range of motion of the knee and range of motion of the HHD. RMSE parameters allowed to quantify the inaccuracy associated to the selected indices. Results showed that the operator was not able to keep the subject’s limb completely still. The force exerted by the subject was higher in knee extension and the knee range of motion was higher than expected, however the operator had more difficulties in holding the HHD in knee flexion trials. This work showed that HHD positioning should be as accurate as possible, as it plays an important role for the strength evaluation. Moreover, the operator should be properly trained and should be strong enough to counteract the force of the subject.
Listed In: Biomechanical Engineering, Biomechanics, Physical Therapy, Sports Science