Kristina S. Beekhuizen

Massed Practice versus Massed Practice with Stimulation: Effects on Upper Extremity Function and Cortical Plasticity in Individuals with Incomplete Cervical Spinal Cord Injury

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.

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.

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.

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.

Immediate effects of a thoracic spine thrust manipulation on the autonomic nervous system: a randomized clinical trial

Abstract Thoracic spine manipulation has been shown to be effective for the management of neck pain. The purpose of this study was to investigate the immediate effect of a T3–T4 spinal thrust manipulation on autonomic nervous system activity in subjects with chronic cervical pain. An additional aim was to determine if the manipulation resulted in an immediate pain relief in patients with chronic neck pain when compared to a placebo intervention. One hundred subjects with chronic neck pain were randomly assigned to receive either a thoracic thrust manipulation or a placebo intervention. The Friedmans test was used to evaluate the change in pupil diameter within both groups. The Wilcoxen signed-ranks test was used to explore pupil changes over time and to make paired comparisons of the pupil change between the groups. The Mann–Whitney U test was used to compare the change in pain perception for the chronic cervical pain group subjects receiving either the thrust manipulation or the placebo intervention. The results demonstrated that manipulation did not result in a change in sympathetic activity. Additionally, there was no significant difference in the subjects pain perception (P=0.961) when comparing the effects of the thrust manipulation to the placebo intervention within this group of subjects with chronic neck pain. The clinical impression of this study is that manipulation of the thoracic spine may not be effective in immediately reducing pain in patients with chronic neck pain.

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.

Implications for Physical Activity in the Population With Low Back Pain

Low back pain is considered the most prevalent pain complaint affecting the general population, with a reported lifetime prevalence of up to 75%. It is a recognized societal problem from both a disablement and economic perspective, with costs exceeding that of coronary artery disease, respiratory infections, and diabetes. The traditional concept of low back pain having a favorable natural history paints an overly optimistic prognosis when considering recent epidemiological data. From a prognostic perspective, more than three quarters of individuals will have a recurrence of their symptoms within a year from the initial onset, and up to 40% report a permanent reduction in activity participation. Fear of movement and avoidance of physical activity participation have been associated with a less than desirable prognosis, often times leading to chronicity. Although numerous interventions with often contradictory findings have been described for the population with low back pain, a consensus of research has implicated the resumption and pursuit of appropriate physical activity as an efficacious intervention. This article reviews the current evidence pertaining to physical activity participation in the population with low back pain and provides recommendations for identifying individuals who may be at risk for chronicity resulting from fear and avoidance of activity.

The Empty Can Exercise: Considerations for Strengthening the Supraspinatus

TRAINING PROGRAMS OFTEN INCLUDE PREVENTIVE EXERCISES DESIGNED TO STRENGTHEN THE ROTATOR CUFF MUSCULATURE. THE “EMPTY CAN” IS ONE OF THE MORE COMMON ROTATOR CUFF EXERCISES ADVOCATED TO STRENGTHEN THE SUPRASPINATUS MUSCLE. IMPLICATIONS SPECIFIC TO THE EMPTY CAN EXERCISE ARE DISCUSSED IN THIS COLUMN.