The primary purpose of this study was to examine lateral deviations in center of pressure as a result of an extreme-duration load carriage task, with particular focus on heel contact. A total of 20 (n = 17 males and n = 3 females) soldiers from a special operation forces unit (body mass 80.72 [21.49] kg, stature 178.25 [8.75] cm, age 26  y) underwent gait plantar pressure assessment and vertical jump testing before and after a 43-km load carriage event (duration 817.02 [32.66] min) carrying a total external load of 29.80 (1.05) kg. Vertical jump height decreased by 18.62% (16.85%) from 0.30 (0.08) to 0.24 (0.07) m, P < .001. Loading peak and midstance force minimum were significantly increased after load carriage (2.59 [0.51] vs 2.81 [0.61] body weight, P = .035, Glass delta = 0.44 and 1.28 [0.40] vs 1.46 [0.41] body weight, P = .015, Glass delta = 0.45, respectively) and increases in lateral center of pressure displacement were observed as a result of the load carriage task 14.64 (3.62) to 16.97 (3.94) mm, P < .029. In conclusion, load carriage instigated a decrease in neuromuscular function alongside increases in ground reaction forces associated with injury risk and center of pressure changes associated with ankle sprain risk. Practitioners should consider that possible reductions in ankle stability remain once load carriage has been completed, suggesting soldiers are still at increased risk of injury even once the load has been removed.
James Scales, Jamie M. O’Driscoll, Damian Coleman, Dimitrios Giannoglou, Ioannis Gkougkoulis, Ilias Ntontis, Chrisoula Zisopoulou and Mathew Brown
Walaa M. Elsais, Stephen J. Preece, Richard K. Jones and Lee Herrington
The superficial hip adductor muscles are situated in close proximity to each other. Therefore, relative movement between the overlying skin and the muscle belly could lead to a shift in the position of surface electromyography (EMG) electrodes and contamination of EMG signals with activity from neighboring muscles. The aim of this study was to explore whether hip movements or isometric contraction could lead to relative movement between the overlying skin and 3 adductor muscles: adductor magnus, adductor longus, and adductor gracilis. The authors also sought to investigate isometric torque–EMG relationships for the 3 adductor muscles. Ultrasound measurement showed that EMG electrodes maintained a position which was at least 5 mm within the muscle boundary across a range of hip flexion–extension angles and across different contraction levels. The authors also observed a linear relationship between torque and EMG amplitude. This is the first study to use ultrasound to track the relative motion between skin and muscle and provides new insight into electrode positioning. The findings provide confidence that ultrasound-based positioning of EMG electrodes can be used to derive meaningful information on output from the adductor muscles and constitute a step toward recognized guidelines for surface EMG measurement of the adductors.
Margaret A. Finley, Elizabeth Euiler, Shivayogi V. Hiremath and Joseph Sarver
Humeral elevation is a critical motion for individuals who use a manual wheelchair given that, in a typical day, wheelchair users reach overhead 5 times more often than able-bodied controls. Kinematic analyses in individuals with chronic spinal cord injury (SCI) have focused on weight-bearing tasks rather than overhead reaching. This technical report presents shoulder movement coordination during overhead reaching in individuals with newly acquired SCI. Eight volunteers with acute SCI and 8 matched, uninjured controls participated. Three-dimensional kinematics were collected during seated, humeral elevation. Scapular and thoracic rotations during humeral elevation were averaged across repetitions. The linear relationship of scapular upward rotation to humeral elevation provided movement coordination analysis. Maximal elevation was reduced in SCI with increased thoracic kyphosis. Medium to large effect sizes were found at each elevation angle, with reduced scapular external rotation, posterior tilt, and increased thoracic kyphosis for those with SCI. The linear relationship occurred later and within a significantly (P = .02) smaller range of humeral elevation in SCI. Altered movement coordination, including a diminished linear association of scapular upward rotation and humeral elevation (scapulohumeral rhythm), is found with reduced maximal elevation and increased thoracic kyphosis during overhead reaching tasks in those with acute SCI.
John J. McMahon, Jason P. Lake, Nicholas J. Ripley and Paul Comfort
The purpose of this study was to determine the usefulness of calculating jump take-off momentum in rugby league (RL) by exploring its relationship with sprint momentum, due to the latter being an important attribute of this sport. Twenty-five male RL players performed 3 maximal-effort countermovement jumps on a force platform and 3 maximal effort 20-m sprints (with split times recorded). Jump take-off momentum and sprint momentum (between 0 and 5, 5 and 10, and 10 and 20 m) were calculated (mass multiplied by velocity) and their relationship determined. There was a very large positive relationship between both jump take-off and 0- to 5-m sprint momentum (r = .781, P < .001) and jump take-off and 5- to 10-m sprint momentum (r = .878, P < .001). There was a nearly perfect positive relationship between jump take-off and 10- to 20-m sprint momentum (r = .920, P < .001). Jump take-off and sprint momentum demonstrated good–excellent reliability and very large–nearly perfect associations (61%–85% common variance) in an RL cohort, enabling prediction equations to be created. Thus, it may be practically useful to calculate jump take-off momentum as part of routine countermovement jump testing of RL players and other collision-sport athletes to enable the indirect monitoring of sprint momentum.
Bethany L. Anderson, Rod A. Harter and James L. Farnsworth II
Clinical Scenario: Dynamic stretching and foam rolling are commonly used by athletes to reduce injury and enhance recovery, thereby improving athletic performance. In contrast to dynamic stretching, little research has been conducted on the acute effects of foam rolling as part of the preexercise warm-up routine. Previously, when researchers implemented foam rolling with static stretching as a warm-up, some found that foam rolling slightly improved flexibility and performance outcomes. More recent research has shown that dynamic stretching is favorable to static stretching when used as a warm-up strategy. Therefore, adding foam rolling to dynamic stretching is hypothesized to create more significant improvements in flexibility and performance compared with adding foam rolling to static stretching. Focused Clinical Question: In active individuals, does foam rolling in addition to dynamic stretching lead to enhanced performance compared with dynamic stretching alone? Summary of Key Findings: Four randomized controlled trials were included. Two studies concluded that the addition of foam rolling to dynamic stretching increased vertical jump height more than dynamic stretching alone, while 2 studies found no difference between these treatment groups. Two studies concluded that the addition of foam rolling increased agility performance compared with dynamic stretching alone, while one study found no difference between treatment groups and one study did not measure agility. All 4 studies reviewed concluded that foam rolling did not improve flexibility more than dynamic stretching alone. Clinical Bottom Line: Foam rolling in conjunction with dynamic stretching may further improve an athlete’s agility and power output; however, little improvement has been observed with foam rolling in regard to athlete flexibility when compared with completing dynamic stretching programs alone. Strength of Recommendation: Inconsistent findings from 4 randomized controlled trials suggest there is Grade C evidence to support the inclusion of foam rolling in a dynamic warm-up.
Paige Guild, Monica R. Lininger and Meghan Warren
Clinical Scenario: Female college student-athletes (SA) often experience time loss from musculoskeletal injuries to the lower extremities. This can lead to lengthy rehabilitation, expensive medical bills, and declines in health-related quality of life. Identifying at-risk athletes prior to the start of an athletic season may allow coaches or athletic trainers to prescribe an injury prevention program. Clinical Question: In female college SA, are preseason single leg hop (SLH) scores associated with identifying those at risk for lower-extremity musculoskeletal injuries? Summary of Key Findings: Five prospective cohort studies in female SA scored athletes on the SLH prior to the start of the athletic sport season. One of 5 studies found an association of SLH with injury risk. An additional 2 studies found that the SLH as part of a battery of functional performance tests was associated with injury risk in some anatomic locations (eg, thigh/knee), but not overall injury risk. Clinical Bottom Line: Methodological limitations of the reviewed studies limits a final conclusion, and there is insufficient evidence to determine if the SLH should be used as a sole functional performance test to identify at-risk female SA; it may be useful as part of a battery of functional performance tests for female college SA. Strength of Recommendation: All studies were prospective cohort studies (level 3).
Ke’La Porter, Carolina Quintana and Matthew Hoch
Clinical Scenario: Neurocognitive performance may put individuals at a greater risk for lower-extremity musculoskeletal injuries. Research has observed the relationship between lower-extremity musculoskeletal injury and baseline neurocognitive performance; however, the understanding of this relationship is lacking. Exploring this relationship may give further insight into musculoskeletal injury and provide innovative directions for musculoskeletal injury prevention. Clinical Question: Is there a relationship between neurocognitive performance and lower-extremity biomechanics during a jumping or cutting task in healthy adult athletes? Summary of Key Findings: The literature was searched for articles that examined the relationship of a baseline neurocognitive test and a biomechanical analysis following a sports-related task. A total of 3 cross-sectional articles were included. All 3 studies concluded that poorer neurocognitive performance was associated with biomechanical faults that are linked to increased risk or rate of lower-extremity musculoskeletal injury. Clinical Bottom Line: Based on the evidence included, there is a moderate-level evidence to support the relationship between neurocognition and lower-extremity biomechanics in healthy adult athletes. Strength of Recommendation: In accordance with the van Tulder approach, there is a moderate level of evidence due to consistent findings from a combination of high- and limited-quality articles.
Luca Puce, Ilaria Pallecchi, Lucio Marinelli, Maria May, Laura Mori, Piero Ruggeri and Marco Bove
Context: Kinesio Taping (KT) produces several clinical effects, including pain relief, edema absorption, and improved muscle performance. When applied in the insertion to origin mode, it is claimed to inhibit excessive muscle contractions. Objective: Investigate whether KT applied in the insertion to origin mode could reduce the exaggerated reflex contraction of spastic muscles. Design: Randomized crossover trial, with a restricted block randomization. Setting: Clinical laboratory and swimming pool. Patients: Seven para-swimmers. Intervention: KT, applied in inhibitory mode, to investigate its effect on knee extensor spasticity. Main Outcome Measures: Primary outcome is stretch reflex, as compared with clinical assessment of spasticity by Modified Ashworth Scale and self-perceived spasticity by numeric rating scale. Secondary outcomes were Medical Research Council for strength of knee extensor muscles and chronometric swimming performance in 100-m freestyle. Results: KT significantly decreased the amplitude of stretch reflex (P < .001), whereas the placebo treatment produced no significant effects. Scores of Medical Research Council for strength and Modified Ashworth Scale did not change after KT, whereas numeric rating scale scores for spasticity significantly decreased (P = .001). The swimming performance was significantly improved after KT treatment as compared with baseline (P < .01). Conclusions: This exploratory study performed on para-athletes suggests that KT could reduce spasticity. This outcome has 3-fold implications for clinical, rehabilitation, and sport methods.
Kellie C. Huxel Bliven
Kathryn A. Coniglio and Edward A. Selby
Pathological exercise behavior is pervasive in eating disorder psychopathology, yet minimal treatment guidance exists for extinguishing it as little is known about how to differentiate pathological from healthy exercise. The purpose of this study was to characterize pathological exercise in terms of motivation to increase the specificity with which both pathological and healthy exercise is described and to inform treatment interventions. Latent profile analysis characterized homogenous groups based on exercise motivation in two samples: college women (n = 200) and women with eating psychopathology (n = 211). These profiles were compared on levels of eating and general psychopathology and emotion dysregulation. Three profiles emerged describing sedentary, pathological exercise, and athlete groups in the first sample, and five profiles describing neutral, sedentary, weight loss, athlete, and pathological exercise groups emerged in the second sample. Findings indicate that motivation style is salient in defining pathological exercise and may, therefore, be a clinically useful treatment target.