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Retraction. Pharmacokinetic Profile of Caffeine and Its Two Main Metabolites in Dried Blood Spots After Five Different Oral Caffeine Administration Forms—A Randomized Crossover Study

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Automated Classification of Manual Exploratory Behaviors Using Sensorized Objects and Machine Learning: A Preliminary Proof-of-Concept Study

Priya Patel, Harsh Pandya, Rajiv Ranganathan, and Mei-Hua Lee

Manual exploratory behaviors during object interaction that form the basis of tool use behavior, are mostly qualitatively characterized in terms of their frequency and duration of occurrence. To fully understand their functional and clinical significance, quantitative movement characterization is needed alongside their qualitative analysis. However, there are two challenges in quantifying them—(a) reliably classifying the type of movement and (b) performing this classification on a time series automatically. Here, we propose a machine learning-based classification method to address these challenges. We measured three common exploratory behaviors (object rotation, fingering, and throwing) in college-aged adults using “sensorized objects” that had wireless Inertial Measurement Units embedded in them. We then calculated several statistical features based on linear acceleration and angular velocity data to train machine learning classifiers to identify these behaviors. All classifiers identified the behaviors with a substantially higher accuracy (average accuracy = 84.95 ± 4.16%) than chance level (33.33%). Of all models tested, Support Vector Machine Quadratic, Support Vector Machine Medium Gaussian, and Narrow Neural Network were the best models in classifying the three behaviors (average accuracy = 89.34 ± 0.12%). This classification method shows potential for automating movement characterization of exploratory behaviors, thereby may aid early assessment of neurodevelopmental disorders.

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Chronic Adaptions in Quadriceps Fascicle Mechanics Are Related to Altered Knee Biomechanics After Anterior Cruciate Ligament Reconstruction

McKenzie S. White, Lucia M. Mancini, Luke Stoneback, Riann M. Palmieri-Smith, and Lindsey K. Lepley

Following anterior cruciate ligament reconstruction (ACLR), patients exhibit abnormal walking mechanics and quadriceps dysfunction. Quadriceps dysfunction has been largely attributed to muscle atrophy and weakness. While important, these factors do not capture intrinsic properties of muscle that govern its ability to generate force and withstand load. While fascicle abnormalities after ACLR have been documented in early stages of recovery (<12 mo), long-term effects of ACLR on fascicle mechanics remain unexplored. We evaluated quadriceps fascicle mechanics during walking 3 years post-ACLR and examined the relationship with knee mechanics. Participants included 24 individuals with ACLR and 24 Controls. Linear mixed models compared the ACLR, Contralateral, and Controls limbs for (1) quadriceps strength, (2) fascicle architecture and mechanics, and (3) knee mechanics. No difference in strength or overall fascicle length excursions was found between limbs. The ACLR limb exhibited longer fascicles at heel strike and peak knee extension moment (P < .001–.004), and smaller fascicle angles at heel strike, peak knee extension moment, and overall suppressed fascicle angle excursions (P < .001–.049) relative to the Contralateral and/or Control limb. This indicates an abnormality in fascicle architecture and mechanics following ACLR and suggests abnormalities in contractile function that cannot be explained by muscle weakness and may contribute to long-term gait irregularities.

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Measurement Position Influences Sex Comparisons of Distal Femoral Cartilage Thickness With Ultrasound Imaging

Harry S. Battersby, Ryan J. Evans, Iwi J. Eghobamien, and Derek N. Pamukoff

The purpose was to examine (1) the effect of measurement position and sex on femoral cartilage outcomes, and (2) the association between gait biomechanics and cartilage outcomes. Fifty individuals participated (25 males and 25 females; age = 20.62 [1.80] y). Ultrasound measured femoral cartilage thickness and echo-intensity at 90°, 115°, and 140° of knee flexion. Gait outcomes included the external knee adduction and knee flexion moments. Cartilage outcomes were compared using 2 (sex) × 3 (position) repeated-measures analysis of variance. Gait and cartilage associations were assessed using stepwise regression. Medial cartilage was thicker when measured at 90° compared with 115° (P = .02) and 140° (P < .01), and 115° compared with 140°, (P < .01) in males but not in females. Cartilage was thicker at 90° compared with 140° across both sexes within all regions (P < .01). Males had thicker cartilage than females in all positions (P < .01). Echo-intensity was lower at 90° than 115° (P < .01) and 140° (P = .01) in the central and lower at 90° than at 115° (P < .01) and 140° (P = .03) in lateral regions. No association was found between gait and cartilage outcomes. Ultrasound imaging position effects cartilage features more in males compared with females. Imaging position and sex influence cartilage outcomes and should be considered in study designs and clinical evaluation.

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Can We Just Play? Internal Validity of Assessing Physiological State With a Semistandardized Kicking Drill in Professional Australian Football

Adriano Arguedas-Soley, Tzlil Shushan, Andrew Murphy, Nicholas Poulos, Ric Lovell, and Dean Norris

Purpose: To examine associations between exercise heart rate (HRex) during a continuous-fixed submaximal fitness test (CF-SMFT) and an intermittent-variable protocol (semistandardized kicking drill [SSD]) in Australian Football athletes, controlling for external intensities, within-session scheduling, and environmental conditions. Methods: Forty-four professional male Australian Football athletes (22.8 [8.0] y) were monitored over 10 sessions involving a 3-minute CF-SMFT (12 km·h−1) as the first activity and a SSD administered 35.7 (8.0) minutes after the CF-SMFT. Initial heart rate and HRex were collected, with external intensities measured as average velocity (in meters per minute) and average acceleration–deceleration (in meters per second squared). Environmental conditions were sampled. A penalized hierarchical linear mixed model was tuned for a Bayesian information criterion minima using a 10-fold cross-validation, with out-of-sample prediction accuracy assessed via root-mean-squared error. Results: SSD average acceleration–deceleration, initial heart rate, temperature, and ground hardness were significant moderators in the tuned model. When model covariates were held constant, a 1%-point change in SSD HRex associated with a 0.4%-point change in CF-SMFT HRex (95% CI, 0.3–0.5). The tuned model predicted CF-SMFT HRex with an average root-mean-squared error of 2.64 (0.57) over the 10-fold cross-validation, with 74% and 86% of out-of-sample predictions falling within 2.7%-points and 3.7%-points, respectively, from observed values, representing the lower and upper limits for detecting meaningful changes in HRex according to the documented typical error. Conclusions: Our findings support the use of an SSD to monitor physiological state in Australian Football athletes, despite varied scheduling within session. Model predictions of CF-SMFT HRex from SSD HRex closely aligned with observed values, considering measurement imprecision.

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Changes in Hip Isometric Strength of Female College Soccer Players After High-Workload Training Session

Maxine Furtado Mesa, Jeffrey R. Stout, L. Colby Mangum, Kyle S. Beyer, Michael J. Redd, and David H. Fukuda

Context: The hip adductor and abductor muscles play vital roles as stabilizers in the lower-extremity. Their activation during soccer-specific actions is essential, but local muscular fatigue can hinder athletic performance and increase the risk of injury. Design: This study aimed to observe the variations in frontal plane hip strength in female college soccer players before and after a high-workload soccer-specific training session. Furthermore, the study sought to compare the relative changes in hip strength with the internal and external load measures obtained during that session. Methods: Twenty female college soccer players participated in a retrospective observational study. Isometric hip adductor and abductor strength were measured before and after a training session in the college spring season. Measurements were taken with a handheld dynamometer (MicroFET 2) while the players were supine. Global positioning system sensors (Catapult Vector S7), commonly worn by players during training sessions and competitive matches, were used to measure external and internal loads. Statistical analyses were performed using paired samples t test to assess hip adductor and abductor strength changes before and after the training session. Spearman rank was used to identify correlation coefficients between global positioning system data and isometric hip strength. Results: The findings revealed significant decreases in the strength of the right hip adduction (P = .012, −7% relative change), right abduction (P = .009, −7.6% relative change), and left abduction (P = .016, −4.9% relative change) after the training session. Furthermore, relative decreases in hip isometric adduction and abduction strength are related to the distance covered at high speeds. Conclusion: The results of this study highlight that hip isometric adduction and abduction strength tend to decrease after exposure to high workloads during soccer-specific training.

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Does a Hip Muscle Activation Home Exercise Program Change Movement Patterns on the Forward Step-Down Test?

Erin McCallister, Caroline Hughs, Mia Smith, and Daniel W. Flowers

Context: Poor knee biomechanics contribute to knee joint injuries. Neuromuscular control over knee position is partially derived from the hip. It is unknown whether isolated activation training of the gluteal muscles improves lower-extremity frontal plane mechanics. This study examined if a home-based hip muscle activation program improves performance on the Forward Step-Down Test as well as increases surface electromyography (sEMG) activation of the gluteal muscles. Design: The study utilized a single-group repeated-measures design. Methods: Thirty-five participants (24 females, mean age = 23.17 [SD 1.36] years) completed an 8-week hip muscle activation program. The Forward Step-Down Test score and sEMG of gluteus maximus and medius were assessed preintervention and postintervention. Results: Forward Step-Down Test scores improved significantly from preintervention (Mdn = 3.5) to postintervention (Mdn = 3.0, T = 109, P = .010, r = .31.), but this result did not meet clinical significance. sEMG analysis revealed a significant increase in mean gluteus maximus activation (P = .028, d = 1.19). No significant dose–response relationship existed between compliance and the Forward Step-Down Test scores or sEMG results. Conclusions: A home-based hip activation program increases gluteus maximus activation without clinically significant changes in frontal plane movement quality. Future studies may find clinical relevance by adding motor learning to the activation training program to improve functional muscle use.

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Effectiveness of Platelet-Rich Plasma in Reducing Pain and Increasing Function After Acute Lateral Ankle Sprain: A Critically Appraised Topic

Erin Frey, Christopher D. Brown, and Brady Tripp

Clinical Scenario: Ankle sprains are one of the most common injuries in athletics, and many lead to recurrent sprains, chronic ankle instability, and persistent symptoms. Treatment improvements are needed. Platelet-rich plasma (PRP) involves formulating autologous plasma with higher platelet concentration to be injected in the desired tissue. There is currently high-quality evidence supporting the use of PRP with lateral epicondylitis and knee osteoarthritis to accelerate the healing process and decrease pain. Clinical Question: Does the injection of PRP relieve pain faster and improve function compared with no injection or placebo in patients with a lateral ankle sprain? Summary of Key Findings: A computerized search yielded 191 studies; of these, 3 studies fit the inclusion and exclusion criteria. PRP injection reduces pain and increases function after lateral ankle sprain 5 to 8 weeks after intervention. Clinical Bottom Line: The use of PRP after lateral ankle sprain to decrease pain and increase function is supported with moderate evidence. Strength of Recommendation: Based on the Strength of Recommendation Taxonomy, evidence from the included studies is considered as level B, reflecting limited quality patient-oriented evidence.

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The Effects of Augmenting Balance Training with Stroboscopic Goggles on Postural Control in Chronic Ankle Instability Patients: A Critically Appraised Topic

Joshua S. Mohess, Hyunwook Lee, Serkan Uzlaşir, and Erik A. Wikstrom

Clinical Scenario: Individuals with chronic ankle instability (CAI) typically complete balance training protocols to improve postural control and reduce recurrent injury risk. However, the presence of CAI persists after traditional balance training protocols suggesting that such programs may be missing elements that could be beneficial to patients. Visual occlusion modalities, such as stroboscopic goggles, may be able to augment balance training exercises to further enhance postural control gains in those with CAI. However, a cumulative review of the existing evidence has yet to be conducted. Focused Clinical Question: Does wearing stroboscopic goggles during balance training result in greater improvements to postural control than balance training alone in those with CAI? Summary of Key Findings: All 3 studies indicated that the stroboscopic goggles group had statistically significant improvements in either a measure of static or dynamic postural control relative to the standard balance training group. However, significant improvements were not consistent across all postural control outcomes assessed in the included studies. Clinical Bottom Line: Postural control may improve more in those with CAI when stroboscopic goggles were worn while completing balance training exercises relative to completing balance training exercises alone. Strength of Recommendation: Overall, consistent moderate- to high-quality evidence was present in the 3 studies, suggesting grade C evidence for the use of stroboscopic goggles during balance training in those with CAI.

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Erratum. Sport Psychology Practitioners’ Contributions to the Drafting Process of a Professional Esports Team: A Case Study

Case Studies in Sport and Exercise Psychology