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Tal Krasovsky, Rawda Madi, Eyal Fruchter, Elias Jahjah, and Roee Holtzer

Texting while walking is an increasingly common, potentially dangerous task but its functional brain correlates have yet to be reported. Therefore, we evaluated prefrontal cortex (PFC) activation patterns during single- and dual-task texting and walking in healthy adults. Thirteen participants (29–49 years) walked under single- and dual-task conditions involving mobile phone texting or a serial-7s subtraction task, while measuring PFC activation (functional near-infrared spectroscopy) and behavioral task performance (inertial sensors, mobile application). Head lowering during texting increased PFC activation. Texting further increased PFC activation, and decreased gait performance similarly to serial-7 subtraction. Our results support the key role of executive control in texting while walking.

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Fatemeh Zahed and Max Berniker

Reaches in experimental settings are commonly found to be straight. This straightness is robust to physical, but not visual, perturbations. Here, we question whether typical visual feedback contributes to this finding by implicitly promoting straight movements. To do so, we replaced the conventional feedback depicting the hand’s location with feedback depicting the limb’s orientation. Reaching movements with three different visual feedback conditions were examined. In the final condition, the subject’s arm was depicted as two rotating links, and targets were depicted as two links indicating a desired arm posture. We found that by replacing standard cursor feedback, reaches became curved and arched to the target. Our findings further demonstrate that depicted feedback influences movements, and feedback depicting the limb, in particular, may elicit curved reaches.

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Shuaijie Wang, Yi-Chung (Clive) Pai, and Tanvi Bhatt

Older adults could experience split falls or feet-forward falls following an unexpected slip in gait due to different neuromuscular vulnerabilities, and different intervention strategies would be required for each type of faller. Thus, this study aimed to investigate the key factors affecting the fall types based on regular gait pattern. A total of 105 healthy older adults who experienced a laboratory-induced slip and fall were included. Their natural walking trial immediately prior to the novel slip trial was analyzed. To identify the factors related to fall type, gait characteristics and demographic factors were determined using univariate logistic regression, and then stepwise logistic regression was conducted to assess the slip-induced fall type based on these factors. The best fall-type prediction model involves gait speed and recovery foot angular velocity, which could predict 70.5% of feet-forward falls and 86.9% of split falls. Body mass index was also a crucial fall-type prediction with an overall prediction accuracy of 70.5%. Along with gait parameters, 84.1% of feet-forward falls and 78.7% of split falls could be predicted. The findings in this study revealed the determinators related to fall types, which enhances our knowledge of the mechanism associated to slip-induced fall and would be helpful for the development of tailored interventions for slip-induced fall prevention.

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Gabriella M. Milef, Logan E. Miller, Daniella M. DiGuglielmo, Tanner D. Payne, Tanner M. Filben, Jillian E. Urban, and Joel D. Stitzel

Head impact exposure is often quantified using peak resultant kinematics. While kinematics describes the inertial response of the brain to impact, they do not fully capture the dynamic brain response. Strain, a measure of the tissue-level response of the brain, may be a better predictor of injury. In this study, kinematic and strain metrics were compared to contact characteristics in youth football. Players on 2 opposing teams were instrumented with head impact sensors to record impact kinematics. Video was collected to identify contact scenarios involving opposing instrumented players (ie, paired contact scenarios) and code contact characteristics (eg, player role, impact location). A previously validated, high-resolution brain finite element model, the atlas-based brain model, was used to simulate head impacts and calculate strain metrics. Fifty-two paired contact scenarios (n = 105 impacts) were evaluated. Lighter players tended to have greater biomechanical metrics compared to heavier players. Impacts to the top of the helmet were associated with lower strain metrics. Overall, strain was better correlated with rotational kinematics, suggesting these metrics may be better predictors of the tissue-level brain response than linear kinematics. Understanding the effect of contact characteristics on brain strain will inform future efforts to improve sport safety.

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Ivonne H.F. Duiser, Annick Ledebt, John van der Kamp, and Geert J.P. Savelsbergh

We examined the effects of number of and separation between support lines on handwriting characteristics of primary school students with satisfactory and unsatisfactory handwriting. Students (mean age 7.9 years) copied a text on paper with a baseline and with two or four support lines with a separation of 3 or 4 mm between the central lines. Handwriting size, velocity, and smoothness were determined for the four conditions relative to baseline. Children with unsatisfactory handwriting wrote larger and had more lifts during baseline condition. Writing between support lines, especially with small separation, immediately reduced the size of handwriting, but also adversely affected velocity and smoothness. Future research is needed to assess long-term effects.

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Shinji Yamaguchi, Yujiro Kawata, Yuka Murofushi, Nobuto Shibata, and Tsuneyoshi Ota

This study examined the stress coping strategies of athletes with high psychological vulnerability. The participants were 487 university athletes (mean age = 19.8 years, SD = 0.88, 153 women). Data were collected using the Vulnerability Scale for University Athletes and General Coping Questionnaire and analyzed by conducting a multivariate analysis of variance. The results showed significant relationships between vulnerability and coping strategies (r = .11−.39). Vulnerability was most strongly related to the emotional support seeking aspect of emotion-oriented coping (r = .39). There was no significant difference in cognitive reinterpretation (r = .07). Vulnerability had a stronger relationship with emotion-oriented than problem-oriented coping, and high (vs. low) vulnerability athletes had significantly higher emotion-oriented-coping scores. These results suggest that vulnerable athletes need to be provided with appropriate emotional support to cope with stressful situations, as they rely heavily on a stress management strategy focusing on emotion regulation.

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Tatiana Tapajcikova, Dávid Líška, Ladislav Batalik, Clea P. Tucker, and Alena Kobesova

High-quality sensory perception and body scheme (somatognosis) are important aspects for sport performance. This study compares stereognosis, body scheme, and kinesthesia in a group of 36 competitive karate athletes against a control group of 32 general population participants. The stereognosis Petrie test, two body scheme tests, and three kinesthesia tests served as outcome measurement tools. No significant difference was found in the stereognosis Petrie test, for the dominant (p = .389) or the nondominant (p = .791) hand, nor in the kinesthesia test (dominant, p = .661 and nondominant, p = .051). Karate athletes performed significantly better in the body scheme tests, that is, fist width estimation (p = .024) and shoulder width estimation (p = .019), as well as in karate-specific kinesthesia tests, that is, single punch (p = .010) and triple punch (p = .001). This study confirms competitive karate athletes have significantly better somatognosis, and better accuracy when performing quick dynamic movements compared with the general population.

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Megan J. Schroeder, Samuel A. Acuña, Chandramouli Krishnan, and Yasin Y. Dhaher

Changes in knee mechanics following anterior cruciate ligament (ACL) reconstruction are known to be magnified during more difficult locomotor tasks, such as when descending stairs. However, it is unclear if increased task difficulty could distinguish differences in forces generated by the muscles surrounding the knee. This study examined how knee muscle forces differ between individuals with ACL reconstruction with different graft types (hamstring tendon and patellar tendon autograft) and “healthy” controls when performing tasks with increasing difficulty. Dynamic simulations were used to identify knee muscle forces in 15 participants when walking overground and descending stairs. The analysis was restricted to the stance phase (foot contact through toe-off), yielding 162 separate simulations of locomotion in increasing difficulty: overground walking, step-to-floor stair descent, and step-to-step stair descent. Results indicated that knee muscle forces were significantly reduced after ACL reconstruction, and stair descent tasks better discriminated changes in the quadriceps and gastrocnemii muscle forces in the reconstructed knees. Changes in quadriceps forces after a patellar tendon graft and changes in gastrocnemii forces after a hamstring tendon graft were only revealed during stair descent. These results emphasize the importance of incorporating sufficiently difficult tasks to detect residual deficits in muscle forces after ACL reconstruction.