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Alternative Models for Pelvic Marker Occlusion in Cycling

Alberto Galindo-Martínez, Juan Miguel Vallés-González, Alejandro López-Valenciano, and Jose L.L. Elvira

Bike fitting aims to optimize riders’ positions to improve their performance and reduce the risk of injury. To calculate joint angles, the location of the joint centers of the lower limbs needs to be identified. However, one of the greatest difficulties is the location of the hip joint center due to the frequent occlusion of the anterior superior iliac spine markers. Therefore, the objective of this study was to validate a biomechanical model adapted to cycling (modified pelvic model, MPM), based on the traditional pelvic model (TPM) with an additional lateral technical marker placed on the iliac crests. MPM was also compared with a widely used model in cycling, trochanter model (TM). Thirty-one recreational cyclists pedaled on a roller bike while the movement was captured with a 7-camera VICON system. The position of the hip joint center and knee angle were calculated and compared with the TPM continuously (along 10 pedaling cycles) and discreetly at 90° and 180° crank positions. No significant differences were found in the position of the hip joint center or in the knee flexion/extension angle between the TPM and the MPM. However, there are differences between TPM and TM (variations between 4.1° and 6.9° in favor of the TM at 90° and 180°; P < .001). Bland–Altman graphs comparing the models show an average difference or bias close to 0° (limits of agreement [0.2 to −8.5]) between TPM and MPM in both lower limbs and a mean difference of between −4° and −7° (limits of agreement [−0.6 to −13.2]) when comparing TPM and TM. Given the results, the new cycling pelvic model has proven to be valid compared with the TPM when performing bike fitting studies, with the advantage that the occluded markers are avoided. Despite its simplicity, the TM presents measurement errors that may be relevant when making diagnoses, which makes its usefulness questionable.

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Dose–Response Effect of an Inertia Flywheel Postactivation Performance Enhancement Protocol on Countermovement Jump Performance

Keegan B. Hall, Maarten A. Immink, David T. Martin, Hunter Bennett, and Robert G. Crowther

The purpose of this study was to investigate the dose–response effect of a high-load, 6-repetition, maximum effort inertial flywheel (IFw) squat postactivation performance enhancement (PAPE) protocol on countermovement jump (CMJ) performance metrics. Thirteen subjects completed 5 squat testing sessions: 1 session to determine back-squat 6-repetition maximum, 1 session to determine 6-repetition maximum IFw load, and 3 sessions to investigate the dose–response effect of an IFw PAPE protocol set at the load determined in the second session. In the IFw PAPE sessions, subjects completed either 1, 2, or 3 sets of IFw squats, then performed 5 CMJs over 12 minutes (1, 3, 6, 9, and 12 min post-IFw). All CMJ tests were conducted on a force platform where CMJ performance outcomes and impulse variables were calculated. There was no main time or volume effect for jump height, contact time, reactive strength index, peak force, or any of the impulse variables. A main time effect was identified for flight time (P = .006, effect size = 0.24) and peak power (P = .001, effect size = 0.28). The lack of change in jump height may indicate that too much fatigue was generated following this near-maximal IFw squat protocol, thereby reducing the PAPE effect.

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Lower-Extremity Energetic Distribution During Rate-Controlled Ballet Jumps (Sautés) in Healthy Dancers

Amanda C. Yamaguchi, Lindsey H. Trejo, Hai-Jung Steffi Shih, David Ortiz-Weissberg, and Kornelia Kulig

Dancers frequently perform jumps in the context of a prolonged, continuous dance piece. The purpose of this study is to explore the lower-extremity energetics in healthy dancers performing repetitive dance jumps (sautés) before and after typical dance-specific choreography. Lower-extremity kinetic data were collected from 14 healthy female dancers during a series of sautés performed before and after 3 minutes of dance. Percent contributions of the lower-extremity joints to the whole-limb mechanical energy expenditure during ground contact were calculated. The jumps performed at the beginning were compared with the jumps at the end of the dance choreography. Dancers maintained the jump rate and consistent whole-limb mechanical energy expenditure between the jump series. As expected, for both jump series, the sautés had greater relative energetic contribution from the ankle and knee as compared with lesser contribution from the hip and toe. However, we observed lesser contribution from the knee and greater contribution from the hip after a 3-minute dance. After performing typical dance choreography, the dancers demonstrated a distal to proximal redistribution of individual joints’ contribution to whole-limb mechanical energy expenditure.

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National Collegiate Athletic Association Coaches’ Beliefs Toward Seeking Mental Health Services for Themselves: Instrument Validation and Exploratory Investigation

Kim Tolentino and Johannes Raabe

While the environment in which National Collegiate Athletic Association coaches operate makes them susceptible to mental health issues, many do not seek professional help. The Reasoned Action Approach posits that attitudes, perceived behavioral control, and perceived norms shape intentions for help-seeking behaviors. This study was designed to: (a) validate two commonly utilized instruments measuring psychological help-seeking beliefs for use with National Collegiate Athletic Association coaches; (b) assess coaches’ attitudes, perceived behavioral control, and perceived norms toward seeking mental health services for themselves; and (c) examine differences in beliefs based on gender, race, coaching role, age, and coaching experience. N = 1,424 National Collegiate Athletic Association Division I, II, and III coaches participated. Confirmatory factor analyses indicated the Inventory of Attitudes Toward Seeking Mental Health Services provides valid and reliable measurements for participants’ beliefs toward seeking services for themselves. Participants reported moderately positive attitudes, perceived behavioral control, and perceived norms. Male coaches indicated significantly lower positive beliefs than female coaches.

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Age-Related Constraints in the Visuomotor Plasticity of Postural Control as Revealed by a Whole-Body Mirror Learning Task

Iasonas Christodoulou, Vasileios Mylonas, Theodoros M. Kannas, Charalampos Sotirakis, Lida Mademli, Evangelia Kouidi, and Vassilia Hatzitaki

Whether visuomotor plasticity of postural control is a trainable feature in older age remains an open question despite the wealth of visually guided exercise games promising to improve balance skill. We asked how aging affects adaptation and learning of a visual feedback (VF) reversal during visually guided weight shifting and whether this skill is modulated by explicit knowledge. Twenty-four older (71.43 ± 2.54 years) and 24 young (24.04 ± 0.93 years) participants were exposed to a 180° VF reversal while tracking a horizontally moving target by voluntarily weight shifting between two force platforms. An explicit strategy was available to half of the participants with detailed instruction to counter the VF rotation. Individual error data were fitted to an exponential function to assess adaptation. Fewer older (12/24) than younger (21/24) participants adapted to the VF reversal, displaying error curves that fitted the exponential function. Older adults who adapted to the VF reversal (responders, n = 12) reached an asymptote in performance in the same weight shifting cycle and displayed a similar mean asymptotic error compared with young participants. Young but not older responders exhibited an aftereffect when the VF reversal was removed. Instruction did not influence spatial error modulations regardless of age. The large individual variations within the older adults’ group during early adaptation suggest age-specific limitations in using explicit cognitive strategies when older adults are exposed to an abrupt mirror feedback reversal that requires a change in weight shifting direction during whole-body postural tracking.

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Volume 41 (2024): Issue 1 (Jan 2024)

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Volume 28 (2024): Issue 1 (Jan 2024)

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Impaired Neuromotor Control During Gait in Concussed Adolescents—A Frequency Analysis

Divya Jain, Valentina Graci, Megan E. Beam, Christina L. Master, Laura A. Prosser, Catherine C. McDonald, and Kristy B. Arbogast

Disruptions in gait function are common after concussion in adolescents; however, the neuromotor control deficits driving these gait disruptions are not well known. Fifteen concussed (age mean [SD]): 17.4 [0.6], 13 females, days since injury: 26.3 [9.9]) and 17 uninjured (age: 18.0 [0.7], 10 females) adolescents completed 3 trials each of single-task gait and dual-task gait (DT). During DT, participants simultaneously walked while completing a serial subtraction task. Gait metrics and variability in instantaneous mean frequency in lower extremity muscles were captured by inertial sensors and surface electromyography, respectively. A 2-way analysis of covariance was used to compare gait metrics across groups and conditions. Functional principal components analysis was used to identify regions of variability in instantaneous mean frequency curves. Functional principal component scores were compared across groups using a Welch statistic. Both groups displayed worse performance on gait metrics during DT condition compared to single-task, with no differences between groups (P < .001). Concussed adolescents displayed significantly greater instantaneous mean frequency, indicated by functional principal component 1, in the tibialis anterior, biceps femoris, and semitendinosus (P < .05) during single-task and DT compared with uninjured adolescents. Our observations suggest that concussed adolescents display inefficient motor unit recruitment lasting longer than 2 weeks following injury, regardless of the addition of a secondary task.

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A Program and Session Evaluation of Student-Athletes’ Experiences Participating in a Mental Illness Destigmatization Intervention

Graig M. Chow, Nicole T. Gabana, Charles Cox, Brandon T. Cooper, and Matthew D. Bird

Evidence-based stigma reduction interventions for student-athletes exist, but researchers have focused on assessing their effectiveness with little attention paid to understanding how participants experience such programs. The current study aimed to qualitatively evaluate a mental illness destigmatization intervention delivered to 35 National Collegiate Athletic Association Division I student-athletes. The program consisted of four weekly 1 hr empirically based sessions. Program-level results showed that participants increased their understanding of student-athlete mental health and identified actionable ways to combat stigma. Session-level results revealed intervention components impacted knowledge and application consistent with their theoretical underpinnings (i.e., mental health literacy). Practical guidelines based on the findings suggest stigma reduction interventions aimed at student-athletes should provide information specific to the athletic context (i.e., common symptoms experienced by athletes), consider content that moves beyond mental health literacy (e.g., contact-based interventions), and present opportunities for participants to apply what they have learned (i.e., roll play displaying empathy).

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Psychology of Ultrarunning: Evaluating Validation, Social Identity, and Disharmony in the Long-Distance Experience

Thomas S. Mueller

This study (N = 394) investigated motivators and detractors in ultrarunners. Latent factors Validation, Social Identity, and Disharmony were identified. Network analysis supported Social Identity through the hub node “ultra tells a lot about me” associated with “glimpse of who I am” with “can tell a lot about the person.” The regression “upset if unable to participate,” F(5, 365) = 16.90, p < .001, R 2 = .019, view Cognitive Involvement (t = 4.54, p < .001), Disharmony (t = 2.96, p = .003), and Social Identity (t = 2.41, p = .016) as significant predictors. “Lone Wolf” isolationist runners were highly masculine and motivated by emotional involvement. Back and middle of the pack runners viewed Disharmony differently than front of the pack runners. Text analysis sentiment “Affect Friends and Family” supports the Disharmony factor. Event promoters and product marketers should acknowledge ultrarunning motivators and detractors, and promote wellness among competitors.