Sample entropy (SampEn) is a widely used measure for estimating the regularity of center-of-pressure (COP) trajectories, with high COP regularity (low SampEn) commonly interpreted as ineffective postural control. The current study aimed to investigate one possible source of COP regularity—agonist–antagonist coactivation—resulting in joint stiffness or action stability. A cross-correlation analysis was conducted to determine the similarity (coactivation) level of 5 pairs of lower limb agonist–antagonist electromyographic signals. SampEn was applied to anteroposterior (ap) and mediolateral (ml) COP displacements. Electromyographic and COP signals were simultaneously derived from 25 active young adults (25.6 ± 4.0 years) during unipedal balancing on stable and multiaxial-unstable surfaces. Then, the correlation between individual agonist–antagonist cross-correlation coefficients and SampEn-COP was explored. The results show that only the tibialis anterior–peroneus longus (TA–PL) coactivations are negatively correlated with SampEn-COPap/ml (P ≤ .030) in both surface conditions, with greater TA–PL coactivation appearing with lower SampEn-COPap/ml. In addition, sex effects as one factor that might influence postural control were also tested. Women exhibited greater TA–PL coactivation (P = .017) and lower SampEn-COPap (P = .005) than men. Together, TA–PL coactivation could be one possible origin of COP regularity, but its effects might be detrimental to unipedal postural control, especially for women.
Browse
A Potential Mechanism Involved in the Regularity of Center-of-Pressure Displacements During Achieving Unipedal Equilibrium on Stable and Unstable Surfaces
Arunee Promsri
Effects of Changing Hip Position on Scapular Kinematics
Sarah E. Schlittler, David N. Suprak, Lorrie R. Brilla, and Jun G. San Juan
The effects of hip position and posture on scapular kinematics have yet to be explored. The purpose of this study was to measure differences in scapular kinematics with changing hip position. Scapular kinematics were measured during scapular plane humeral elevation. Twenty-four subjects were required to elevate the dominant arm up to 120° in the following randomized conditions: standing, seated, seated ipsilateral hip flexion, and seated contralateral hip flexion. Two-way analyses of variance were used to evaluate effects of shoulder elevation and hip position on scapular upward rotation, posterior tilt (PT), and external rotation. For external rotation, there was no significant interaction (P = .714) and no main effect of elevation (P = .618) or condition (P = .390). For PT, there was no significant interaction (P = .693) but significant main effects of elevation (P < .001) and condition (P < .001), with the greatest PT in standing. For upward rotation, there was no significant interaction (P = .698), a significant main effect of elevation (P < .001), and no significant effect of condition (P = .726). The effect on PT may not be clinically significant. These results may serve as a baseline measurement of healthy scapular kinematics across hip positions.
Normative Extensor Hallucis Brevis Muscle Activity During Locomotion Following the Development of a Novel Ultrasound-Guided Fine-Wire Electromyography Protocol
Kelly A. Robb, Keara Sutherland, and Stephen D. Perry
Fine-wire electromyography (EMG) is a traditional laboratory technique to estimate muscle activity of the small foot muscles, however, recordings have not been reported from extensor hallucis brevis (EHB). As an extensor of the great toe, EHB is an important muscle when studying physiological changes associated with foot pathologies such as hallux valgus. The purpose of this study was to develop an ultrasound-guided fine-wire EMG protocol to record EHB muscle activity and report normative EMG profiles of healthy young adults during locomotion. Sixteen asymptomatic young adults completed 20 walking trials at a self-selected velocity. Ensemble averages were calculated from the time normalized linear envelopes and represented from 0% to 100% of the single stance phase of gait. EHB muscle bursts were observed between 0% and 20% of the stance phase of gait in all participants. A second burst of EMG was observed between 80% and 100% of stance in 50% of the participants. This study introduces a novel ultrasound-guided EMG protocol and normative data from EHB recordings suggest a synergistic role to anterior compartment musculature at contact. These results provide preliminary insights into understanding the functional role of EHB and may help elucidate the biomechanical factors exacerbating the progression of hallux pathologies.
Kinematic Sequence Differences Between Trained Baseball Players and Untrained Adolescent Individuals
Corey Wukelic, Sean Machak, Michael Gromeier, and Sarah P Shultz
An overhead throwing motion is a common gross motor skill often taught in early childhood to improve physical activity participation. Yet, research investigating motor efficiency in overhead throws often focuses on improving performance in trained individuals. This project compares kinematic sequencing between trained and untrained youth. After a brief warm-up, untrained high school students (N = 9) and trained high school and college students (N = 10) threw a weighted tennis ball for accuracy (N = 10 throws). Upper extremity angular velocities were collected using 3-dimensional inertial sensor motion capture. Kinematic sequencing of joints and segments (pelvis, trunk, shoulder, elbow, and wrist) was assessed using Kruskal–Wallis test; Friedman and Wilcoxon tests identified group differences between sequences. Seven independent kinematic sequences were identified (N = 2 unique trained; N = 3 unique untrained; N = 2 shared). The rankings for the trained group maintained a mostly consistent pattern with only elbow and wrist joints producing similar rankings. The untrained group lacked that consistency with similar rankings of elbow versus wrist and shoulder versus elbow. Trained individuals threw with a more efficient proximal-to-distal sequencing pattern than the untrained participants, specifically at the trunk and shoulder. Continuous training of gross motor skills beyond initial skill development is necessary to maintain motor proficiency.
Assessing the Use of Recommended Practices in Adapted Physical Activity/Education Experiential-Learning Programs
Layne Case, Joonkoo Yun, Megan MacDonald, Bridget E. Hatfield, and Samuel W. Logan
This study investigated the use of recommended practices in university-based experiential learning associated with adapted physical activity and education (APA/E) undergraduate courses. Participants (N = 165) were instructors of APA/E courses with an experiential-learning component and/or professionals involved in APA/E experiential-learning programs at their university. Participants completed an online questionnaire designed to describe program characteristics and evaluate the use of two sets of practices, including those recommended for involving students and people with disabilities. Findings highlight low proportions of the use of practices recommended for people with disabilities and indicate that significantly more practices recommended for students were implemented (Z = −10.45, p < .001). Findings from this study have several implications for evaluation and intervention in APA/E experiential learning, such as including the disability community in planning and designing programming to benefit both students and people with disabilities. Instructors should aim to increase their implementation of practices recommended for involving people with disabilities.
Can We Talk? Exploring the Effects of Mental Health Stigma, Support, and Openness on National Collegiate Athletic Association Student-Athlete Mental Health
Braden J. Brown, Ty B. Aller, Logan K. Lyons, Autumn Jenson, Audrey C. Juhasz, Jakob F. Jensen, and Jennifer L. Hodgson
National Collegiate Athletic Association (NCAA) student athletes may have more stigmatic views toward mental health (MH) and be less open to talking about or seeking support for MH struggles than their peers. This may contribute to and/or exacerbate existing MH challenges. This cross-sectional study explored the impact of MH stigma, support, and openness on student athletes’ levels of depression, anxiety, and stress among 478 NCAA student athletes representing 20 different sports from 56 universities. Results indicated that male, Black, Indigenous, People of Color (BIPOC), and Division I athletes reported higher levels of MH stigma. Compared with their White peers, BIPOC athletes exhibited less openness to talk about MH challenges. Division I and BIPOC athletes felt less supported to seek help for MH concerns. Structural equation modeling showed that MH stigma was positively associated with depression, anxiety, and stress, whereas MH openness was negatively associated with depression, anxiety, and stress. Research/practical implications, limitations, and future research and athletic department programming needs are discussed.
Psychological Profile of Hungarian International-Level Distance Runners
Bence Kelemen, Renátó Tóth, Ottó Benczenleitner, and László Tóth
The aim of the present study was to investigate the psychological profile of the 2023 Hungarian National Distance Running Team in terms of personality traits, motivational styles, and competitive anxiety and to explore specific psychosocial factors that characterize the athletes’ mental preparation. The 16 international-level competitors were assessed using validated questionnaires in Hungarian (Big Five Inventory, the revised Sport Motivation Scale, and Competitive State Anxiety Inventory-2), and university students competing at professional and semiprofessional levels served as the control group. Results indicated that elite distance runners were primarily intrinsically motivated. Their psychological profile appeared similar to profiles found among athletes in the control group. Significant differences were found in traits, such as openness, conscientiousness, and motivation. Neuroticism was positively associated with athletes’ cognitive and somatic anxiety, with self-confidence providing a protective role. Working with a sports psychologist appeared to have no significant measurable effect on athletes precompetition anxiety. Specific personality traits and motivational structures are essential for elite sporting performance. Further research is needed to better understand and determine the specific components of mental preparation.