Context: Ankle dorsiflexion range of motion (DF ROM) has been associated with a number of kinematic and kinetic variables associated with landing performance that increase injury risk. However, whether exercise-induced fatigue exacerbates compensatory strategies has not yet been established. Objectives: (1) Explore differences in landing performance between individuals with restricted and normal ankle DF ROM and (2) identify the effect of fatigue on compensations in landing strategies for individuals with restricted and normal ankle DF ROM. Design: Cross-sectional. Setting: University research laboratory. Patients or Other Participants: Twelve recreational athletes with restricted ankle DF ROM (restricted group) and 12 recreational athletes with normal ankle DF ROM (normal group). Main Outcome Measure(s): The participants performed 5 bilateral drop-landings, before and following a fatiguing protocol. Normalized peak vertical ground reaction force, time to peak vertical ground reaction force, and loading rate were calculated, alongside sagittal plane initial contact angles, peak angles, and joint displacement for the ankle, knee, and hip. Frontal plane projection angles were also calculated. Results: At the baseline, the restricted group landed with significantly less knee flexion (P = .005, effect size [ES] = 1.27) at initial contact and reduced peak ankle dorsiflexion (P < .001, ES = 1.67), knee flexion (P < .001, ES = 2.18), and hip-flexion (P = .033, ES = 0.93) angles. Sagittal plane joint displacement was also significantly less for the restricted group for the ankle (P < .001, ES = 1.78), knee (P < .001, ES = 1.78), and hip (P = .028, ES = 0.96) joints. Conclusions: These findings suggest that individuals with restricted ankle DF ROM should adopt different landing strategies than those with normal ankle DF ROM. This is exacerbated when fatigued, although the functional consequences of fatigue on landing mechanics in individuals with ankle DF ROM restriction are unclear.
Louis Howe, Jamie S. North, Mark Waldron, and Theodoros M. Bampouras
Bruno Luiz Souza Bedo, Guilherme Manna Cesar, Renato Moraes, Fábio Pamplona Mariano, Luiz Henrique Palucci Vieira, Vitor Luiz Andrade, and Paulo Roberto Pereira Santiago
Noncontact anterior cruciate ligament ruptures generally occur during unanticipated sidestep cutting maneuvers when athletes have their visual attention focused on the opponent. The authors investigated the influence of uncertainty related to the side to perform the sidestep cutting maneuver on knee kinematics of female handball athletes. A total of 31 female handball athletes performed the sidestep cutting maneuver during anticipated and uncertain conditions. During the uncertain condition, visual cues indicated the direction of the reactive sidestep cutting maneuver. Between-condition differences were compared using the Student t test for paired samples calculated with statistical parametric mapping. Lower knee flexion angle was detected during the uncertain condition compared with the anticipated condition for the nondominant limb (0%–8% of the sidestep cycle). Knee abduction was larger during the uncertain condition for both the dominant (15%–41% of the sidestep cycle) and nondominant (0%–18% of the sidestep cycle) limbs compared with the anticipated condition. The nondominant leg showed higher knee abduction (36%–68% of the sidestep cycle) during the uncertain condition compared with the anticipated condition. The athletes’ approach velocity was slower during the uncertain condition. The uncertain condition impacted knee kinematics and potentially positioned the joint at greater risk of injury by decreasing the flexion angle in the nondominant leg and increasing the joint valgus bilaterally.
Karin Weman Josefsson
Sweden has adopted a somewhat different approach to handle the corona pandemic, which has been widely debated both on national and international levels. The Swedish model involves more individual responsibility and reliance on voluntary civic liability than law enforcement, while common measures in other countries are based on more controlling strategies, such as restrictive lockdowns, quarantines, closed borders, and mandatory behavior constraints. This commentary aims to give a brief overview of the foundations of the Swedish model as well as a discussion on how and why it has been adopted in the Swedish society based on Swedish legislations, culture, and traditions. Finally, perspectives on how the Swedish model could be connected to the tenets of self-determination theory will be discussed.
Nathan Morelli, Nicholas R. Heebner, Courtney J. DeFeo, and Matthew C. Hoch
Objective: To determine the influence of a cognitive dual task on postural sway and balance errors during the Concussion Balance Test (COBALT). Methods: Twenty healthy adults (12 females, eight males; aged 21.95 ± 3.77 years; height = 169.95 ± 9.95 cm; weight = 69.58 ± 15.03 kg) partook in this study and completed single- and dual-task versions of a reduced COBALT. Results: Sway velocity decreased during dual-task head rotations on foam condition (p = .021, ES = −0.57). A greater number of movement errors occurred during dual-task head rotations on firm surface (p = .005, ES = 0.71), visual field flow on firm surface (p = .008, ES = 0.68), and head rotations on foam surface (p < .001, ES = 1.61) compared with single-task conditions. Cognitive performance was preserved throughout different sensory conditions of the COBALT (p = .985). Discussion: Cognitive dual tasks influenced postural control and destabilized movements during conditions requiring advanced sensory integration and reweighting demands. Dual-task versions of the COBALT should be explored as a clinical tool to identify residual deficits past the acute stages of concussion recovery.
Michael Burkhardt, Erin Burkholder, and John Goetschius
Context: Dynamic balance exercises are commonly utilized during ankle sprain and chronic ankle instability (CAI) rehabilitation. Blood flow restriction (BFR) has been used to enhance muscle activity during exercise and improve outcomes of traditional rehabilitation exercises in clinical populations. Objective: Examine the effects of BFR on lower-extremity muscle activation during dynamic balance exercises in individuals with CAI. Design: Crossover study design. Setting: Laboratory. Patients or Other Participants: Twenty-five (N = 25) young adults with a history of CAI. Interventions: Participants performed dynamic balance reaching exercises during 2 randomized order conditions, BFR, and control. For each condition, participants performed 2 trials of balance exercises. Each trial included 4 sets (30 × 15 × 15 × 15) of reaches in anterior, posteromedial, and posterolateral directions. For the BFR condition, the authors placed a cuff around the proximal thigh at 80% of arterial occlusion pressure. For the control condition, no cuff was worn. Main Outcome Measure(s): The authors recorded normalized electromyography muscle activation of the vastus lateralis, soleus, tibialis anterior, and fibularis longus during balance exercise trials and recorded participants’ ratings of perceived postural instability and exertion after each trial of balance exercises. Results: The authors observed greater vastus lateralis (P < .001, d = 0.86 [0.28 to 1.44]) and soleus (P = .03, d = 0.32 [−0.24 to 0.87]) muscle activation during balance exercises with BFR than control. The authors observed no differences in tibialis anterior (P = .33, d = 0.09 [−0.46 to 0.65]) or fibularis longus (P = .13, d = 0.06 [−0.50 to 0.61]) muscle activation between the conditions. The authors observed greater ratings of perceived postural instability (P = .004) and exertion (P < .001) during balance exercises with BFR than control. Conclusions: Individuals with CAI demonstrated large increases in vastus lateralis and small increases in soleus muscle activation during dynamic balance exercises with BFR. The BFR had no effect on fibularis longus and tibialis anterior muscle activation. Individuals with CAI perceived greater postural instability and exertion during dynamic balance exercises with BFR.
Tiffany Toong, Katherine E. Wilson, Anne W. Hunt, Shannon Scratch, Carol DeMatteo, and Nick Reed
Context: Current international consensus endorses a multimodal approach to concussion assessment. However, the psychometric evaluation of clinical measures used to identify postconcussion performance deficits once an athlete is asymptomatic remains limited, particularly in the pediatric population. Objective: To describe and compare the sensitivity and specificity of a multimodal assessment battery (balance, cognition, and upper and lower body strength) versus individual clinical measures at discriminating between concussed youth athletes and noninjured controls when asymptomatic. Design: Prospective cohort study. Setting: Hospital laboratory setting. Participants: A total of 32 youth athletes with a concussion and 32 matched (age and sex) noninjured control participants aged 10–18 years. Intervention(s): Participants were administered preinjury (baseline) assessments of cognition (Immediate Post-Concussion Assessment and Cognitive Testing [ImPACT]), balance (BioSway), and upper and lower body strength (grip strength and standing long jump). Assessments were readministered when concussed participants reported symptom resolution (asymptomatic time point). Noninjured control participants were reassessed using the same time interval as their concussion matched pair. Sensitivity and specificity were calculated using standardized regression-based methods and receiver operating characteristic curves. Main Outcome Measures: Outcome measures included baseline and postinjury ImPACT, BioSway, grip strength, and standing long jump scores. Results: When asymptomatic, declines in performance on each individual clinical measure were seen in 3% to 22% of the concussion group (sensitivity = 3%–22%) compared with 3% to 13% of the noninjured control group (specificity = 87%–97%) (90% confidence interval). The multimodal battery of all combined clinical measures yielded a sensitivity of 41% and a specificity of 77% (90% confidence interval). Based on discriminative analyses, the multimodal approach was statistically superior compared with an individual measures approach for balance and upper and lower body strength, but not for cognition. Conclusions: Results provide a foundation for understanding which domains of assessment (cognition, balance, and strength) may be sensitive and specific to deficits once symptoms resolve in youth athletes. More work is needed prior to clinical implementation of a preinjury (baseline) to postinjury multimodal approach to assessment following concussion in youth athletes.
Leanne K. Elliott, Jonathan A. Weiss, and Meghann Lloyd
Early motor skill interventions have been shown to improve the motor skill proficiency of children with autism spectrum disorder; however, little is known about the secondary effects associated with these types of interventions (e.g., influence on behavior, social skills, family dynamics). The purpose of this qualitative study was to (a) investigate parents’ perceptions of the child-level benefits associated with a fundamental motor skill intervention for their 4-year-olds with autism spectrum disorder and (b) explore how child-level benefits influenced the family unit. Eight parents (N = 8) were interviewed (semistructured) about their experiences with the intervention for their child(ren); the study was grounded in phenomenology. Five main child-level benefits emerged, including improvements with (a) motor skills, (b) social skills, (c) listening skills, (d) turn-taking skills, and (e) transition skills. The child-level benefits then extended to family members in a number of ways (e.g., more positive sibling interactions). These findings highlight several important secondary effects that should be investigated in future research.
Valerie A. Troutman and Michele J. Grimm
An Interactive Digital Experience as an Alternative Laboratory (IDEAL) was developed and implemented in a flipped biomechanics classroom. The IDEAL challenge problem was created to more closely simulate a real-world scenario than typical homework or challenge problems. It added a more involved story, specific characters, simple interaction, and student-led inquiry into a challenge problem. Students analyzed musculoskeletal biomechanics data to conduct a forensic biomechanics investigation of an individual who suffered a fracture. Students ultimately approached the IDEAL problem with a greater appreciation and enjoyment than previous open-ended challenge problems—those that were assigned in a traditional problem-statement manner—throughout the semester. Students who were more fully engaged in the IDEAL challenge problem, as evidenced by the fact that they requested all of the evidence on their own, also performed better on the final report grade. This signals improved learning with respect to biomechanical analysis when the students were creatively participating in the storyline surrounding the forensic investigation.
Silvia G.R. Neri, Juscelia Cristina Pereira, Ana Cristina de David, and Ricardo M. Lima
The aim of this study was to investigate the influence of body fat distribution on postural balance and lower-limb muscle quality in women aged 60 years and over. Two hundred and twenty-two volunteers took part in this cross-sectional analysis. Participants underwent body fat distribution assessment using dual-energy x-ray absorptiometry and were classified as nonobese, gynoid obese, or android obese. Postural balance was assessed during quiet standing, with and without vision restriction, using a force platform. Specific torque was defined as the ratio of knee extensors peak torque (evaluated by an isokinetic dynamometer) to the lean mass of the same limb (evaluated by dual-energy x-ray absorptiometry). Compared with nonobese participants, both obese groups exhibited higher range of postural sway along the anteroposterior and mediolateral axes (P < .05). However, there were no differences between participants with gynoid and android obesity. The android obese group exhibited greater speed of postural sway in the condition without vision restriction than both nonobese (P = .040) and gynoid obese (P = .004) groups. Regarding muscle quality, only participants with gynoid obesity (P = .004) presented lower specific torque than their nonobese peers. These results may be clinically useful when designing falls prevention exercises targeting the obese population.