This study evaluated the performance of 6 commercially available hard hat designs—differentiated by shell design, number of suspension points, and suspension tightening system—in regard to their ability to attenuate accelerations during vertical impacts to the head. Tests were conducted with impactor materials of steel, wood, and lead shot (resembling commonly seen materials in a construction site), weighing 1.8 and 3.6 kg and dropped from 1.83 m onto a Hybrid III head/neck assembly. All hard hats appreciably reduced head acceleration to the unprotected condition. However, neither the addition of extra suspension points nor variations in suspension tightening mechanism appreciably influenced performance. Therefore, these results indicate that additional features available in current hard hat designs do not improve protective capacity as related to head acceleration metrics.
Arthur Alves Dos Santos, James Sorce, Alexandra Schonning, and Grant Bevill
Naser Nawayseh and Saleh AlBaiti
In recent years, whole-body vibration (WBV) training has received an increasing interest in the sports and medical fields. However, there has been inconsistency among several studies regarding the effect of WBV training on the human body, which is partly due to the lack of the existence of guidelines for using WBV training machines. To understand the effect of WBV training on the human body and build the needed regulations, it is essential first to understand the biodynamic responses to vibration which represent how vibration is transmitted to and through the human body. The purpose of this study is to systematically review previous studies that measured biodynamic responses when using WBV training machines to highlight inconsistencies in their results and provide possible reasons for them. An extensive literature search was performed on the SCOPUS database to obtain relevant studies. One hundred and fifty-six potentially relevant studies were obtained but after further screening, 23 papers from 2007 to 2020 met inclusion criteria and were included in the study. The papers were analysed with respect to acceleration, transmissibility, interface force, and apparent mass during different vibration settings, body posture, age, and sex. Results and conflicts among studies were highlighted and possible explanations for the inconsistency were provided.
Xiu Hu, Shaojun Lyu, Min Mao, Jianwei Zhang, Wei Sun, Cui Zhang, and Qipeng Song
The team developed the newly compiled eight methods and five steps of Tai Chi (EMFSTC), which includes introductory routines to Tai Chi characterized by simple structures. This study examined the effectiveness of EMFSTC practice on balance control. A total of 31 participants were randomly assigned to EMFSTC (n = 15, age = 66.4 ± 1.7 years, received 16-week EMFSTC practice) or control (n = 16, age = 66.7 ± 1.8 years, received no practice) groups. Significant group by training interactions were observed. After EMFSTC practice, balance control improved, as indicated by decreased root mean square and mean velocity of center of pressure, proprioception threshold during knee extension, and plantar tactile sensitivity threshold at the arch. EMFSCT can be an effective rehabilitation modality to improve balance control among older adults.
Valters Abolins and Mark L. Latash
We present a review on the phenomenon of unintentional finger action seen when other fingers of the hand act intentionally. This phenomenon (enslaving) has been viewed as a consequence of both peripheral (e.g., connective tissue links and multifinger muscles) and neural (e.g., projections of corticospinal pathways) factors. Recent studies have shown relatively large and fast drifts in enslaving toward higher magnitudes, which are not perceived by subjects. These and other results emphasize the defining role of neural factors in enslaving. We analyze enslaving within the framework of the theory of motor control with spatial referent coordinates. This analysis suggests that unintentional finger force changes result from drifts of referent coordinates, possibly reflecting the spread of cortical excitation.
Konstantin Beinert, Katharina Deutsch, Sebastian Löscher, and Martin Diers
Patients with neck pain demonstrate a variety of sensorimotor impairments, such as decreased cervical joint position sense (CJPS) acuity, which might also be associated with an impaired internal body representation. The present study evaluated the effect of real-time visual feedback of the individual’s own neck on CJPS compared to observing a book. Twenty-three patients with neck pain participated in the experiment and received the interventions in randomized order on separate days in a within-subject pretest–posttest design. Before and immediately after each intervention, CJPS was measured by a therapist blinded to the intervention. The results demonstrate a significantly different development of CJPS (p = .04), with increased CJPS acuity after observing one’s own neck and decreased acuity after observing a book. Real-time visual feedback of the neck improved CJPS acuity in patients with neck pain without active movements of the neck, indicating the importance of central nervous system processing for CJPS acuity.
Hananeh Younesian, Thomas Legrand, Ludovic Miramand, Sarah Beausoleil, and Katia Turcot
Inertial measurement units and normative values enable clinicians to quantify clinical walking tests and set rehabilitation goals. Objectives of this study were (1) to compare time- and distance-based walking tests in individuals with lower limb amputation (iLLA) and normative values following rehabilitation discharge (T1) and 6 weeks after discharge (T2) and (2) to investigate spatiotemporal and foot kinematic parameters over a 6-minute walk test using inertial measurement units. Twelve iLLA participated in this study. Distance, cadence, stance ratio, loading rate ratio, push-up ratio, path length, and minimum toe clearance were analyzed during 6-minute walk test. Nonparametric repeated-measures analysis of variance tests, Bonferroni corrections, were performed. Time of distance-based walking tests diminished at T2 (P < .02). Compared with normative values, walking performance in iLLA was reduced. Cadence at T2 increased significantly (P = .026). Stance ratio increased in both legs at T2 (P < .05). Push-up ratio tended to decrease at T2 in the amputated leg (P = .0003). Variability of path length and minimum toe clearance at T2 were less than at T1 in the nonamputated leg (P < .05). Spatiotemporal improvement at T2 could be due to prosthesis adaptation in iLLA. The lower performance of the functional walk test compared with normative values could be due to amputation and pain-related fatigue.
Sara Oliveira, Marina Cunha, António Rosado, and Cláudia Ferreira
This study aimed to test a model that hypothesized that the compassionate coach, as perceived by the athletes, has an impact on athlete-related social safeness and psychological health, through shame and self-criticism. The sample comprised 270 Portuguese adult athletes, who practiced different competitive sports. The path analysis results confirmed the adequacy of the proposed model, which explained 45% of the psychological health’s variance. Results demonstrated that athletes who perceive their coaches as more compassionate tend to present higher levels of social safeness (feelings of belonging to the team) and of psychological health, through lower levels of shame and self-criticism. These novel findings suggest the importance of the adoption of supportive, warm, safe, and compassionate attitudes from coaches in athletes’ mental health. This study also offers important insights by suggesting that feelings of acceptance and connectedness in team relationships may be at the root of athletes’ emotional processes and well-being.
Eric J. Shumski, Tricia M. Kasamatsu, Kathleen S. Wilson, and Derek N. Pamukoff
Research has identified an increased risk of lower extremity injury postconcussion, which may be due to aberrant biomechanics during dynamic tasks. The purpose of this study was to compare the drop landing biomechanics between individuals with and without a concussion history. Twenty-five individuals with and 25 without a concussion history were matched on age (±3 y), sex, and body mass index (±1 kg/m2). Three-dimensional landing biomechanics were recorded to obtain dependent variables (peak vertical ground reaction force, loading rate, knee flexion angle and external moment, knee abduction angle and external moment, and knee flexion and abduction angle at ground contact). A 1-way multivariate analysis of variance compared outcomes between groups. There was no difference in drop landing biomechanics between individuals with and without a concussion history (F 10,39 = 0.460, P = .877, Wilk Λ= .918). There was an effect of time since concussion on knee flexion characteristics. Time since most recent concussion explained a significant amount of variation in both peak (ΔR 2 = .177, β = −0.305, ΔP = .046) and initial ground contact (ΔR 2 = .292, β = −0.204, ΔP = .008) knee flexion angle after covarying for sex and body mass index. Therefore, time since concussion should be considered when evaluating biomechanical patterns.
Jill L. McNitt-Gray
Susumu Iwasaki, Mary D. Fry, and Candace M. Hogue
The purpose of this study was to examine the mediating role of mindful engagement in the relationship between male high school athletes’ motivational climate perceptions on their teams (i.e., caring, task-, and ego-involving climate) to athlete coachability. Athletes (N = 164, M age = 15.58 years) from multiple sports completed measures assessing mindful engagement in sport (Cognitive and Affective Mindfulness Scale—Revised), Caring Climate Scale, task- and ego-involving climate perceptions (Perceived Motivational Climate in Sport Questionnaire), and coachability (Athletic Coping Skills Inventory). Initial bivariate correlations linked mindful engagement and coachability positively with perceptions of a caring and task-involving climate and negatively with ego-involving climate perceptions. Structural equation modeling analyses then revealed mindful engagement mediated the relationship between climate and coachability. Encouraging coaches and players to foster a caring/task-involving climate might assist in enhancing athletes’ mindful engagement in sport, which may positively influence the degree to which they are coachable.