Kellie C. Huxel Bliven
Kellie Huxel Bliven and Karrie L. Hamstra-Wright
Karrie L. Hamstra-Wright and Kellie Huxel Bliven
The gluteus medius (GM) is thought to play an important role in stabilizing the pelvis and controlling femoral adduction and internal rotation during functional activity. GM weakness, resulting in decreased stabilization and control, has been suggested to be related to lower extremity dysfunction and injury. Many clinicians focus on strengthening the GM to improve lower extremity kinematics for the prevention and rehabilitation of injury. An indirect way to measure GM strength is through electromyography. It is generally assumed that exercises producing higher levels of activation will result in greater strengthening effects.3 Understanding what exercises result in the greatest level of GM activation will assist clinicians in their injury prevention and rehabilitation efforts.
Focused Clinical Question:
In a healthy adult population, what lower extremity exercises produce the greatest mean GM activation, expressed as a percentage of maximum voluntary isometric contraction?
Jessica R. Fairbairn and Kellie C. Huxel Bliven
Clinical Scenario: Until recently, injury epidemiology data on elite Paralympic athletes were limited. Current data suggest high rates of shoulder injury in wheelchair athletes. Differences in shoulder injury rates between sports have not been reported in this population. Clinical Question: Is the incidence of shoulder injury in elite wheelchair athletes different between sports? Summary of Key Findings: Shoulder injury rates are high in elite wheelchair athletes, particularly in sports such as field events and fencing that require a stable base (eg, trunk, core control) from which to perform. Wheelchair racing requires repetitive motions that contribute to shoulder injuries, but rates are lower than field sports and fencing. Wheelchair curling and sledge hockey have low shoulder injury risk. Clinical Bottom Line: Shoulder injury rates vary based on sport in elite wheelchair athletes. In addition to incorporating shoulder complex specific rehabilitation for overuse shoulder injuries, clinicians should focus on core and trunk stabilization in elite wheelchair athletes competing in sports, such as field events and fencing. Strength of Recommendation: Grade C evidence exists that reports shoulder injury rates among elite wheelchair athletes differ based on sport participation.
Kellie C. Huxel Bliven and Kelsey J. Picha
Kellie C. Huxel Bliven
Barton E. Anderson and Kellie C. Huxel Bliven
Research has shown a link between poor core stability and chronic, nonspecific low back pain, with data to suggest that alterations in core muscle activation patterns, breathing patterns, lung function, and diaphragm mechanics may occur. Traditional treatment approaches for chronic, nonspecific low back pain focus on exercise and manual therapy interventions, however it is not clear whether breathing exercises are effective in treating back pain.
Focused Clinical Question:
In adults with chronic, nonspecific low back pain, are breathing exercises effective in reducing pain, improving respiratory function, and/or health related quality of life?
Summary of Key Findings:
Following a literature search, 3 studies were identified for inclusion in the review. All reviewed studies were critically appraised at level 2 evidence and reported improvements in either low back pain or quality of life following breathing program intervention.
Clinical Bottom Line:
Exercise programs were shown to be effective in improving lung function, reducing back pain, and improving quality of life. Breathing program frequencies ranged from daily to 2–3 times per week, with durations ranging from 4 to 8 weeks. Based on these results, athletic trainers and physical therapists caring for patients with chronic, nonspecific low back pain should consider the inclusion of breathing exercises for the treatment of back pain when such treatments align with the clinician’s own judgment and clinical expertise and the patient’s preferences and values.
Strength of Recommendation:
Grade B evidence exists to support the use of breathing exercises in the treatment of chronic, nonspecific low back pain.
Kathleen A. Swanik, Kellie Huxel Bliven and Charles Buz Swanik
There are contradictory data on optimal muscle-activation strategies for restoring shoulder stability. Further investigation of neuromuscular-control strategies for glenohumeral-joint stability will guide clinicians in decisions regarding appropriate rehabilitation exercises.
To determine whether subscapularis, infraspinatus, and teres minor (anteroposterior force couple) muscle activation differ between 4 shoulder exercises and describe coactivation ratios and individual muscle-recruitment characteristics of rotator-cuff muscles throughout each shoulder exercise.
healthy, physically active men, age 20.55 ± 2.0 y.
4 rehabilitation exercises: pitchback, PNF D2 pattern with tubing, push-up plus, and slide board.
Main Outcomes Measures:
Mean coactivation level, coactivation-ratio patterns, and level (area) of muscle-activation patterns of the subscapularis, infraspinatus, and teres minor throughout each exercise.
Coactivation levels varied throughout each exercise. Subscapularis activity was consistently higher than that of the infraspinatus and teres minor combined at the start of each exercise and in end ranges of motion. Individual muscle-recruitment levels in the subscapularis were also different between exercises.
Results provide descriptive data for determining normative coactivation-ratio values for muscle recruitment for the functional exercises studied. Differences in subscapularis activation suggest a reliance to resist anteriorly directed forces.
Julie A. Siegmund, Kellie C. Huxel and C. Buz Swanik
Determining whether there are compensations in those with jumper’s knee (JK) might further our understanding of the condition.
Comparing lower extremity kinematics and jump performance of basketball athletes with JK with those of healthy controls (C).
Repeated-measures control-match design.
24 male basketball players (12 JK, 12 C) matched by height, weight, position, experience, and frequency of play.
Standing countermovement and running layup jumps.
Main Outcome Measures:
Maximum vertical-jump height, footfall landing, and lower extremity sagittal-plane kinematics.
There were no significant group differences (P > .05) in vertical-jump height (JK = 64.3 ± 8.6 cm, C = 63.0 ± 9.8 cm) or layup height (JK = 71.3 ± 11.6 cm, C = 73.3 ± 11.0 cm). JK subjects landed flat footed (50%) more than controls (8%). JK subjects showed significantly more hip flexion (JK = 105° ± 24.8°, C = 89.8° ± 14.1°; P = .039) with decreased hip acceleration during the countermovement (JK = −3039 ± 1392°/s2, C = −4229 ± 1765°/s2; P = .040). When landing from the countermovement jump, JK subjects had significantly less knee acceleration (JK = −4960 ± 1512°/s2, C = −6736 ± 2009°/s2; P = 023) and in the layup showed significantly less ankle dorsiflexion (JK = 106.5° ± 9.0°, C = 112.5° ± 7.7°; P = .048) and hip acceleration (JK = − 2841 ± 1094°/s2, C = −3912 ± 1575°/s2; P = .033).
Compensatory strategies observed in JK subjects might help maintain performance, because their jump height was similar to that of healthy controls.
Stephen J. Thomas, Kathleen A. Swanik, Charles “Buz” Swanik, Kellie C. Huxel and John D. Kelly IV
Pathologies such as anterior instability and impingement are common in baseball and have been linked to decreases in internal rotation (IR) and concurrent increases in external rotation (ER). In addition, alterations to scapular position have been identified in this population, but the chronology of these adaptations is uncertain.
To determine whether there is a change in range of motion and scapular position after a single baseball season.
19 high school baseball players (age 16.6 ± 0.8 y, mass 78.6 ± 12.0 kg, height 180.3 ± 6.2 cm).
Subjects were measured for all dependent variables at preseason and postseason.
Main Outcome Measures:
Participants were measured for glenohumeral (GH) IR and ER with the scapula stabilized. Total GH range of motion was calculated as the sum of IR and ER. Scapular upward rotation was measured at 0°, 60°, 90°, and 120° of GH abduction in the scapular plane, and scapular protraction, at 0°, hands on hips, and 90° of GH abduction.
Overall, the dominant arm had significantly less GH IR (11.4°, P = .005) and significantly more ER (4.7°, P = .001) than the nondominant arm. Total motion in the dominant arm was significantly less than in the nondominant arm (6.7°, P = .001). Scapular upward rotation in the dominant arm significantly increased at 0° (2.4°, P = .002) and significantly decreased at 90° (3.2°, P = .001) and 120° (3.2°, P < .001) of abduction from preseason to postseason. Scapular protraction in the nondominant arm significantly decreased at 45° (0.32 cm, P = .017) and 90° (0.33 cm, P = .006) from preseason to postseason.
These data suggest that scapular adaptations may be acquired over a relatively short period (12 wk) in a competitive baseball season. Competitive high school baseball players also presented with significant GH motion differences between their dominant and nondominant arms. Total motion was also significantly less in the dominant arm than in the nondominant arm.