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.

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 (MDC(90)) 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 MDC(90) indicates that a change of greater than or equal to 4 degrees (IR), 5 degrees (ER), and 8 degrees (PST) would be required to be 90% certain that the change is not due to intertrial variability or measurement error.

Test-retest reliability and minimal detectable change of the hexagon agility test.

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.

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

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

Sensory stimulation augments the effects of massed practice training in persons with tetraplegia.

OBJECTIVE: To compare functional changes and cortical neuroplasticity associated with hand and upper extremity use after massed (repetitive task-oriented practice) training, somatosensory stimulation, massed practice training combined with somatosensory stimulation, or no intervention, in persons with chronic incomplete tetraplegia. DESIGN: Participants were randomly assigned to 1 of 4 groups: massed practice training combined with somatosensory peripheral nerve stimulation (MP+SS), somatosensory peripheral nerve stimulation only (SS), massed practice training only (MP), and no intervention (control). SETTING: University medical school setting. PARTICIPANTS: Twenty-four subjects with chronic incomplete tetraplegia. INTERVENTIONS: Intervention sessions were 2 hours per session, 5 days a week for 3 weeks. Massed practice training consisted of repetitive practice of functional tasks requiring skilled hand and upper-extremity use. Somatosensory stimulation consisted of median nerve stimulation with intensity set below motor threshold. MAIN OUTCOME MEASURES: Pre- and post-testing assessed changes in functional hand use (Jebsen-Taylor Hand Function Test), functional upper-extremity use (Wolf Motor Function Test), pinch grip strength (key pinch force), sensory function (monofilament testing), and changes in cortical excitation (motor evoked potential threshold). RESULTS: The 3 groups showed significant improvements in hand function after training. The MP+SS and SS groups had significant improvements in upper-extremity function and pinch strength compared with the control group, but only the MP+SS group had a significant change in sensory scores compared with the control group. The MP+SS and MP groups had greater change in threshold measures of cortical excitability. CONCLUSIONS: People with chronic incomplete tetraplegia obtain functional benefits from massed practice of task-oriented skills. Somatosensory stimulation appears to be a valuable adjunct to training programs designed to improve hand and upper-extremity function in these subjects.

Massed practice versus massed practice with stimulation: effects on upper extremity function and cortical plasticity in individuals with incomplete cervical spinal cord injury.

OBJECTIVE: To determine the effect of massed practice (MP) versus massed practice combined with somatosensory stimulation (MP+SS) on cortical plasticity and function in persons with incomplete tetraplegia. METHODS: Ten subjects were assigned to either MP or MP+SS. Median nerve stimulation (500 ms train, 10 Hz, 1 ms pulse duration) was delivered at the intensity eliciting a motor threshold response. Training sessions were 5 d/week for 3 weeks at 2 h/session. Outcome measures included 1) motor-evoked potentials (MEPs) elicited via transcranial magnetic stimulation (TMS), motor threshold (MT) and MEP amplitude at 1.2 MT; 2) maximal pinch grip force; 3) Wolf Motor Function Test (WMFT) and Jebsen Hand Function Test. RESULTS: The MP+SS group demonstrated significant improvements (P < 0.05) in pinch grip strength (190%), WMFT scores (52%), and Jebsen test scores (33%), whereas the MP group demonstrated significant improvement (P < 0.05) only in Jebsen test scores (11%). No significant changes were detected in cortical excitability in the MP+SS or MP group. CONCLUSIONS: The findings of this preliminary study suggest that MP+SS results in greater increases in pinch strength and timed functional test scores than MP. Optimal stimulation paradigms and training methods are needed to further test this strategy.

New perspectives on improving upper extremity function after spinal cord injury.

Injury to the cervical spinal cord adversely affects arm and hand function to varying degrees depending on the level and severity of injury. These impairments typically result in reduced independence in the performance of activities of daily living and limit participation in recreational activities. There is evidence to suggest individuals with incomplete spinal cord injury may benefit from intensive rehabilitation interventions aimed at improving hand and arm function. Massed practice (repetitive activity-based training) and somatosensory stimulation (prolonged peripheral nerve electrical stimulation at submotor threshold intensity) are 2 interventions that have been shown to improve strength and function in individuals with stroke, presumably by changing cortical excitability. These techniques, however, had not previously been investigated in individuals with spinal cord injury (SCI). In this article the stroke and SCI literature supporting the use of massed practice and somatosensory stimulation as a potential rehabilitative tool to promote recovery of function in individuals with incomplete cervical spinal cord injury (SCI) is reviewed. Recently published research using these novel techniques in which a combination of massed practice and somatosensory stimulation resulted in increased pinch grip strength and upper extremity function in individuals with incomplete cervical SCI when compared to subjects participating in massed practice alone is presented.