The present study investigated the intrarater reliability, interrater reliability and minimal detectable change at the 90% confidence interval (MDC₉₀) of active shoulder range of motion measurements using digital inclinometry. Two investigators each measured two repetitions of active flexion, abduction, external rotation (ER), and internal rotation (IR) on the nondominant shoulder of 30 asymptomatic participants in a blinded repeated measures design. Results indicated good intrarater reliability with Intraclass Correlation Coefficients (ICCs) (3, k) of Flexion=0.83, Abduction=0.91, ER=0.94 and IR=0.87. Interrater ICC values (2, k) were moderate to good with Flexion=0.58, Abduction=0.95, ER=0.88 and IR=0.93. The MDC₉₀ for the interrater analysis indicated that a change of equal to or greater than 8° (Flexion), 4° (Abduction), 8° (IR), and 9° (ER) would be required to be 90% certain that the change is not due to intertrial variability or measurement error. Digital inclinometry appears to be a reliable instrument for quantifying normal shoulder mobility when strict measurement protocols are adhered to. Clinicians and researchers should consider the MDC values presented when interpreting change values during subsequent measurement sessions.

Although hand-held dynamometry is considered an objective method of measuring strength, the reliability of the procedure can be compromised by inadequate tester strength and insufficient stabilization of the dynamometer and subject. The purpose of this study was to investigate the test-retest reliability of a hand-held dynamometer with the use of a portable stabilization device while testing the shoulder internal and external rotator musculature. The isometric strength of the shoulder rotator musculature was tested twice in 30 asymptomatic adult volunteers (15 male and 15 female) between 18 and 63 years of age by using an intrasession design. Consistency of the testing protocol was maintained through the use of an arm stabilization apparatus, which fixed the arm in 30° of the scapular plane and a portable dynamometer stabilization device. Intraclass correlation coefficients (ICC's) were high, ranging from ICC (3,1) = 0.971–0.972 for the test-retest trials of internal and external rotation. There was no significant difference between sessions one and two for maximum internal rotation (p = 0.431) and maximum external rotation strength (p = 0.780). The results indicate that the testing protocol with stabilization device is a reliable method for measuring strength of the internal and external rotator shoulder musculature.

The popularity of resistance training (RT) is evident by the more than 45 million Americans who engage in strength training regularly. Although the health and fitness benefits ascribed to RT are generally agreed upon, participation is not without risk. Acute and chronic injuries attributed to RT have been cited in the epidemiological literature among both competitive and recreational participants. The shoulder complex in particular has been alluded to as one of the most prevalent regions of injury. The purpose of this manuscript is to present an overview of documented shoulder injuries among the RT population and where possible discern mechanisms of injury and risk factors. A literature search was conducted in the PUBMED, CINAHL, SPORTDiscus, and OVID databases to identify relevant articles for inclusion using combinations of key words: resistance training, shoulder, bodybuilding, weightlifting, shoulder injury, and shoulder disorder. The results of the review indicated that up to 36% of documented RT-related injuries and disorders occur at the shoulder complex. Trends that increased the likelihood of injury were identified and inclusive of intrinsic risk factors such as joint and muscle imbalances and extrinsic risk factors, namely, that of improper attention to exercise technique. A majority of the available research was retrospective in nature, consisting of surveys and descriptive epidemiological reports. A paucity of research was available to identify predictive variables leading to injury, suggesting the need for future prospective-based investigations.

Evidence-based research exists to describe risk factors inherent to participation. Shoulder joint and muscle characteristics in the recreational weight training (RWT) population were investigated to determine specific risk-related adaptations that may occur from participation. Ninety participants, men between the ages of 19 and 47 (mean age 28.9), including 60 individuals who participated in upper-extremity RWT and 30 controls with no record of RWT participation, were recruited. Active range of motion (AROM), posterior shoulder tightness (PST), body weight-adjusted strength values, and agonist/antagonist strength ratios were compared between the RWT participants and the control group. Statistical analysis identified significant differences (p < 0.001) between the groups when analyzing shoulder mobility. The RWT participants had decreased mobility when compared with the control group for all AROM measurements except external rotation, which was greater. Strength ratios were significantly greater in the RWT group when compared with the control group (p ≤ 0.001), implying agonist/antagonist muscle imbalances. The findings of this investigation suggest that RWT participants are predisposed to strength and mobility imbalances as a result of training. The imbalances identified have been associated with shoulder disorders in the general and athletic population; thus, these imbalances may place RWT participants at risk for injury. Common training patterns are biased toward large muscle groups such as the pectorals and deltoids but neglect muscles responsible for stabilization such as the external rotators and lower trapezius. Exercise selection that mitigates strength and mobility imbalances may serve to prevent injury in this population. Clinicians and strength and conditioning professionals should consider the biomechanical stresses and adaptations associated with RWT when prescribing upper-extremity exercises....