Contexts: Directing an individual’s attention to the effect of the movements (external focus) has been shown to improve performance than directing attention to body movements (internal focus). However, the effect of attentional focus instructions specific to movement quality has not been investigated thoroughly. Objective: To compare the effects of internal and external focus instructions specific to body movements. Design: Mixed design, 2 (sex) × 2 (instructions). Settings: Laboratory setting. Participants: A total of 40 participants (males, n = 20; mean [SD]; age = 22.0 [2.19] y; height = 179.33 [5.90] cm; mass = 77.7 [13.04] kg; females, n = 20; age = 22.0 [3.87] y; height = 164.84 [5.80] cm; mass = 71.48 [20.66] kg) were recruited. Intervention: Participants completed 2 consecutive jumps (ie, a forward jump from a height and then a maximal vertical jump) with internal focus and external focus instructions. External focus was elicited by placing pieces of tape on the participants’ legs. Main Outcome measures: Landing quality was measured by the Landing Error Scoring System to assess movement quality, and the vertical jump height was measured by Vertec. Results: The performance results showed that the external focus condition resulted in superior vertical jump height compared with the internal focus condition (P < .05). Although landing quality did not show significant differences between 2 conditions, the effect size (η 2 = .09) indicated that landing quality was better when participants adopted an external, rather than an internal focus of attention (P = .07). Conclusions: The body-oriented instructions can be provided externally by adding artificial external cues and directing attention to them. Importantly, the findings were evident in a qualitative assessment that can be adopted by practitioners. The results suggest that practitioners should adopt an external focus cue for performance and also consider using an external focus for movement quality.
Masahiro Yamada and Louisa D. Raisbeck
Michael Dressing, Jillian Wise, Jennifer Katzenstein and P. Patrick Mularoni
Does academic-related anxiety contribute to an adolescent’s recovery process and return to activity after experiencing a concussion? The authors created a novel measure of academic-related anxiety (Mularoni Measure of Academic Anxiety following Concussion [MMAAC]) and administered it to adolescents following concussion in outpatient pediatric sports medicine clinics. Two previously validated measures of anxiety were also administered, and results were compared with the MMAAC scores as well as the lengths of time for return to school and sports. Results show that higher MMAAC scores positively correlate with the length of time an adolescent needs to return to school. Study results indicate that the MMAAC reliably measures academic-related anxiety in adolescents suffering from concussions and can be helpful in predicting a basic timetable for return to school. The authors believe that this brief survey can be used by physicians in clinic to evaluate anxiety and assist with return to school expectations to provide comprehensive recovery support.
Marzie Balali, Shahab Parvinpour and Mohsen Shafizadeh
The ability to coordinate different body parts under different constraints that are imposed by organism, environment, and tasks during motor development might be different in children. The aim of this study was to examine whether children with different motor development levels are different with regard to multijoint coordination during two-hand catching. Eighty-four children (age: 6.05 ±0.67 years) who were assessed on object control skills were recruited voluntarily. The biomechanical model was defined from 20 movements of seven segments (shoulders, elbows, wrists, and torso), and the principal component analysis was used to quantify the multijoint coordination and kinematic synergies during catching. The results showed that the redundancy of joints in two-hand catching is controlled by three kinematic synergies that defined the majority of the variance. The participants who were grouped based on their development levels did not show differences in the number and strength of synergies; however, they were different in the utilization of the kinematic synergies for successful catching. In conclusion, the number and the strength of the kinematic synergies during two-hand catching are not affected by the developmental levels and are related to the nature of the task.
Desiree Camara Miraldo, Renato Naville Watanabe and Marcos Duarte
This study describes an open data set of inertial, magnetic, foot–ground contact, and electromyographic signals from wearable sensors during walking at different speeds. These data were acquired from 22 healthy adults using wearable sensors and walking at self-selected comfortable, fast and slow speeds, and standing still. All data are publicly available in the Internet (https://doi.org/10.6084/m9.figshare.7778255). In total, there are data of 9,661 gait strides. This data set also contains files with the instants of the gait events identified using the foot–ground contact sensors and notebooks exemplifying how to access and visualize the data. This data set gives the opportunity to all interested researchers to work with such data, for example, making tests of algorithms for gait event estimation against a common reference, possible.
James Scales, Jamie M. O’Driscoll, Damian Coleman, Dimitrios Giannoglou, Ioannis Gkougkoulis, Ilias Ntontis, Chrisoula Zisopoulou and Mathew Brown
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.
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.