Morey J. Kolber

The reliability of hand-held dynamometry in measuring isometric strength of the shoulder internal and external rotator musculature using a stabilization device.

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 (ICCs) 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.

STRENGTH TESTING USING HAND-HELD DYNAMOMETRY

Abstract The reliability of strength measurements obtained during clinical examination has been the subject of many investigations. The need for an accurate, quantitative method to determine strength in multiple settings and environments is important for both examination and treatment. The purpose of this paper is to provide a review of the existing literature investigating the reliability and concurrent validity of hand-held dynamometry. A thorough review of the literature revealed that held dynamometry is a suitable alternative to traditional manual muscle testing as it exhibits good-to-excellent reliability, provides objective ratio data, and has the portability to be used in multiple environments. Hand-held dynamometry is a reliable method to determine the strength status and change status provided testing protocols are consistent.

The reliability and minimal detectable change of shoulder mobility measurements using a digital inclinometer

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.

Shoulder joint and muscle characteristics in the recreational weight training population.

Kolber, MJ, Beekhuizen, KS, Cheng, MS, and Hellman, MA. Shoulder joint and muscle characteristics in the recreational weight training population. J Strength Cond Res 23(1): 148-157, 2009-Shoulder disorders attributed to weight training are well documented in the literature; however, a paucity of 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.

Shoulder injuries attributed to resistance training: a brief review.

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.

The reliability and concurrent validity of scapular plane shoulder elevation measurements using a digital inclinometer and goniometer

This study investigated the reliability and concurrent validity of active shoulder elevation in the scapular plane (scaption) using a digital inclinometer and goniometer. Two investigators used a goniometer and digital inclinometer to measure scaption on 30 asymptomatic participants in a blinded repeated measures design. Good reliability was present with intraclass correlation coefficients (ICCs) for intrarater reliability of goniometry = 0.87, intrarater digital inclinometry = 0.88, interrater goniometry = 0.92, and interrater digital inclinometry = 0.89. The minimal detectable change (MDC95) for the interrater analysis indicated that a change equal to or greater than 8 degrees for goniometry and 9 degrees for inclinometry is required to be 95% certain that the change is not due to intertrial variability or measurement error. The concurrent validity between goniometry and digital inclinometry was excellent with an ICC value of 0.94 for both raters. The 95% limits of agreement suggest that the difference between these two measurement instruments can be expected to vary by up to ±11 degrees. The results support the interchangeable use of goniometry and digital inclinometer for measuring scaption. Clinicians and researchers should consider the MDC values presented when interpreting change during subsequent measurement sessions.

Reliability, Minimal Detectable Change, and Normative Values for Tests of Upper Extremity Function and Power

Negrete, RJ, Hanney, WJ, Kolber, MJ, Davies, GJ, Ansley, MK, McBride, AB, and Overstreet, AL. Reliability, minimal detectable change, and normative values for tests of upper extremity function and power. J Strength Cond Res 24(12): 3318-3325, 2010-The purpose of this study was to examine the test-retest reliability, minimal detectable change (MDC), and determine normative values of 3 upper extremity (UE) tests of function and power. One hundred eighty participants, men (n = 69) and women (n = 111), were tested on 3 UE strength and power maneuvers in a multicenter study to determine baseline normative values. Forty-six subjects returned for a second day of testing within 5 days of the initial assessment for the reliability component of the investigation. Explosive power was assessed via a seated shot-put test for the dominant and nondominant arms. Relationships between the dominant and nondominant arms were also analyzed. A push-up and modified pull-up were performed to measure the amount of work performed in short (15-second) bursts of activity. The relationship between the push-up and modified pull-up was also determined. Analysis showed test-retest reliability for the modified pull-up, timed push-up, dominant single-arm seated shot-put tests, and nondominant single-arm seated shot-put tests to be intraclass correlation coefficient(3,1) 0.958, 0.989, 0.988, and 0.971, respectively. The MDC for both the push-up and modified pull-up was 2 repetitions. The MDCs for the shot put with the dominant arm and the nondominant arm were 17 and 18 in., respectively. The result of this study indicates that these field tests possess excellent reliability. Normative values have been identified, which require further validation. These tests demonstrate a practical and effective method to measure upper extremity functional power.

Test-Retest Reliability and Minimal Detectable Change of the Hexagon Agility Test

Beekhuizen, KS, Davis, MD, Kolber, MJ, and Cheng, MSS. Test-retest reliability and minimal detectable change of the hexagon agility test. J Strength Cond Res. 23(7):2167-2171, 2009-The purpose of this study was to examine the test-retest reliability and minimal detectable change (MDC95) of the hexagon test. The hexagon test is a routinely used measure of agility in the sports and rehabilitation professions, yet its reliability has not been investigated in prior research. A total of 26 college-aged men (n = 17) and women (n = 9) of various activity levels were recruited to participate in 3 testing sessions: baseline, 1 hour after baseline, and 48 hours after baseline. The results of this study indicated excellent test-retest reliability for both same-day intraclass correlation coefficient (ICC) model 3,1 = 0.938 and between-day ICC (3,1) = 0.924 analyses. The MDC95 for the hexagon test was 1.015 seconds. A significant difference in the mean times was identified during the same-day test-retest sessions (p < 0.001) but not the between-day test-retest sessions (p = 0.18). The significant differences identified between the baseline and the same-day retest session suggests a learning effect. The hexagon test shows excellent reliability for measuring agility, which supports its use as a tool to assess athletic performance and lower-extremity agility. Evidence of reliability, in addition to its ease of administration, makes the hexagon test a practical and effective method to measure agility. When using this test as a measure of agility, a change of greater than 1.015 seconds is necessary to be 95% certain that the change in time reflects improvement and exceeds measurement error. A practice trial is recommended prior to recording scores to attenuate the possibility of a learning effect.

Reliability and minimal detectable change of inclinometric shoulder mobility measurements

The shoulder complex is one of the most commonly affected regions for which individuals present to physical therapy. Numerous shoulder disorders result in altered mobility with posterior shoulder tightness (PST), impaired internal rotation (IR), and either decreased or increased external rotation (ER) often reported in research investigations. The accurate assessment of shoulder mobility is an integral component of both the physical therapy examination and intervention. Therefore, the reliability and sensitivity to change of instruments used to measure mobility must be established. The purpose of this study was to investigate the intrarater reliability and minimal detectable change (MDC90) of inclinometric measurements designed to quantify shoulder mobility. Active shoulder IR, ER, and passive PST were measured on the nondominant side of 30 asymptomatic volunteers in an intersession design. Intraclass correlation coefficients (ICCs) using model 3, k were excellent using the protocols described in this investigation with IR = 0.987, ER = 0.970, and PST = 0.964. The MDC90 indicates that a change of greater than or equal to 4° (IR), 5° (ER), and 8° (PST) would be required to be 90% certain that the change is not due to intertrial variability or measurement error.

Shoulder joint and muscle characteristics among healthy female recreational weight training participants.

Kolber, MJ and Corrao, M. Shoulder joint and muscle characteristics among healthy female recreational weight training participants. J Strength Cond Res 25(X): 000-000, 2010-Shoulder disorders attributed to weight training are well documented in the literature, with prevalence rates exceeding that of the general population. Although researchers have identified both intrinsic and extrinsic risk factors among men who participate in weight training, a paucity of evidence-based research exists to describe risk factors inherent to participation among women. The purpose of this study was to investigate shoulder joint and muscle characteristics among healthy female recreational weight training (RWT) participants to determine specific risk-related adaptations that may occur from training. Eighty-eight women aged 18-55 (mean 26.8), including 57 who participated in upper extremity RWT and 31 controls with no record of RWT participation were recruited. Active range of motion (AROM), posterior shoulder tightness (PST), glenohumeral (GH) joint laxity, body weight-adjusted strength and strength ratios of force couples were compared between the RWT and control groups. Statistical analysis identified significant differences (p ≤ 0.004) between groups when analyzing shoulder internal rotation AROM, PST, and joint laxity. The RWT participants had decreased internal rotation AROM, greater PST, and anterior GH joint hyperlaxity when compared to the control group. No differences in strength ratios between groups were identified (p ≥ 0.109) implying the absence of weight training-induced muscle imbalances. The findings of this investigation suggest that female RWT participants are predisposed to mobility imbalances as a result of training. The imbalances identified in this investigation have been associated with shoulder disorders in both the general and athletic population thus may place weight training participants at risk for injury. Clinicians and strength and conditioning professionals should consider the biomechanical stresses and adaptations associated with RWT when prescribing exercises. Exercise prescription that mitigates mobility imbalances may serve to prevent injury in this population.