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Michelle A. Sandrey

Clinical Question: Is there sufficient evidence to determine which low back instability tests should be incorporated into a stabilization classification exam for athletes? Clinical Bottom Line: There is moderate level 2 evidence to include, but not to use in isolation, the prone instability test along with other instability tests in a stabilization classification exam.

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Kimberly Somers, Dustin Aune, Anthony Horten, James Kim and Julia Rogers

Context: Limited ankle dorsiflexion (DF) range of motion has been correlated with decreased flexibility of the gastrocnemius/soleus complex. Decreased ankle DF range of motion can lead to an increase in lower-extremity injuries, for example, acute ankle sprains, Achilles tendinopathy. Objective: The purpose of this study was to determine whether a single application of the intervention to the gastrocnemius/soleus complex via multidirectional self-myofascial release using a foam roller, multiplanar dynamic stretch performed in downward dog, or a combination of both techniques acutely improved ankle DF. Design: Subjects were assigned to groups via random card selection. Investigators provided verbal cues as needed to yield correct performance of interventions. Both interventions were performed twice for 1 minute using a dynamic walking rest of 30.48 m at a self-selected pace between interventions. Statistical analyses were completed using a 1-way analysis of variance, at α level ≤ .05. Setting: A convenience sample study. Participants: A total of 42 asymptomatic physical therapy students (18 females and 24 males) with mean age of 26.12 (4.03) years volunteered to participate. Interventions: Multidirectional self-myofascial release using a foam roller, multiplanar dynamic stretch performed in downward dog, or a combination of both techniques. Main Outcome Measures: Weight-bearing right ankle DF measurements were recorded in centimeters using a forward lunge technique (intraclass correlation coefficient = .98, .97, and .96). Results: Data analysis revealed no significant difference between the 3 groups in all pre–post measurements (P = .82). Mean (SD) measurements from pretest to posttest for myofascial release, dynamic stretching, and combination interventions were 0.479 (0.7) cm, 0.700 (0.7) cm, and 0.907 (1.4) cm, respectively. Conclusion: Until further studies are conducted, the selection of technique to increase ankle DF range of motion should be based on each individual patient’s ability, preference, and response to treatment.

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Pedro L. Valenzuela, Javier S. Morales, Adrián Castillo-García and Alejandro Lucia

Purpose: To determine the acute effects of ketone supplementation on exercise performance (primary outcome) and physiological and perceptual responses to exercise (secondary outcomes). Methods: A systematic search was conducted in PubMed, Web of Science, and SPORTDiscus (since inception to July 21, 2019) to find randomized controlled trials assessing the effects of acute ketone supplementation compared with a drink containing no ketones (ie, control intervention). The standardized mean difference (Hedges g) between interventions and 95% confidence interval (CI) were computed using a random-effects model. Results: Thirteen studies met all inclusion criteria. No significant differences were observed between interventions for overall exercise performance (Hedges g = −0.05; 95% CI, −0.30 to 0.20; P = .68). Subanalyses revealed no differences between interventions when analyzing endurance time-trial performance (g = −0.04; 95% CI, −0.35 to 0.28; P = .82) or when assessing the separate effects of supplements containing ketone esters (g = −0.07; 95% CI, −0.38 to 0.24; P = .66) or salts (g = −0.02; 95% CI, −0.45 to 0.41; P = .93). All studies reported increases in plasma ketone concentration after acute ketone supplementation, but no consistent effects were reported on the metabolic (plasma lactate and glucose levels), respiratory (respiratory exchange ratio, oxygen uptake, and ventilatory rate), cardiovascular (heart rate), or perceptual responses to exercise (rating of perceived exertion). Conclusions: The present findings suggest that ketone supplementation exerts no clear influence on exercise performance (from sprints to events lasting up to ∼50 min) or metabolic, respiratory, cardiovascular, or perceptual responses to exercise. More research is needed to elucidate if this strategy could provide ergogenic effects on other exercise types (eg, ultraendurance exercise).

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Brian Tyo, Rebecca Spataro-Kearns and David R. Bassett Jr.

Purpose: The purpose of this study was twofold: (1) to determine if the Digi-Walker SW-200 (SW-200), New Lifestyles NL-2000 (NL-2000), and Omron HJ-303 (HJ-303) yield similar daily step counts compared to the StepWatch-3; and (2) to determine if pedometer error is influenced by adiposity and/or stepping rate in African American women. Methods: 60 participants (28.0 ± 9.8 y) wore the devices for three weekdays. ANOVAs were performed to determine if body mass index (BMI) and device were related to steps per day, and to determine if BMI and device were related to error. Stepwise linear regressions were performed to determine which variables contributed to pedometer error. Results: StepWatch-3 counted significantly more steps than all other devices within each BMI category (p < .01). The NL-2000 had significantly less error in the normal (−13.4%) and overweight (−14.9%) groups compared to the SW-200 (−26.2% and −33.3%) and HJ-303 (−32.5% ad −31.5%) (p < .05). The SW-200 had significantly more error in the obese group (−50.7%) compared to the NL-2000 (−17.1%) and HJ-303 (−26.0%) (p < .05). NL-2000 error was not related to any variables while the SW-200 error was related to waist circumference (WC) and the HJ-303 error was related to percentage of slow steps. Conclusion: In African American women adiposity is more strongly related to more pedometer error in a device using a spring-levered mechanism (SW-200). Accumulating steps at a slow rate is related to more pedometer error when using a device with a step filter (HJ-303).

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Anantha Narayanan, Farzanah Desai, Tom Stewart, Scott Duncan and Lisa Mackay

Background: Application of machine learning for classifying human behavior is increasingly common as access to raw accelerometer data improves. The aims of this scoping review are (1) to examine if machine-learning techniques can accurately identify human activity behaviors from raw accelerometer data and (2) to summarize the practical implications of these machine-learning techniques for future work. Methods: Keyword searches were performed in Scopus, Web of Science, and EBSCO databases in 2018. Studies that applied supervised machine-learning techniques to raw accelerometer data and estimated components of physical activity were included. Information on study characteristics, machine-learning techniques, and key study findings were extracted from included studies. Results: Of the 53 studies included in the review, 75% were published in the last 5 years. Most studies predicted postures and activity type, rather than intensity, and were conducted in controlled environments using 1 or 2 devices. The most common models were support vector machine, random forest, and artificial neural network. Overall, classification accuracy ranged from 62% to 99.8%, although nearly 80% of studies achieved an overall accuracy above 85%. Conclusions: Machine-learning algorithms demonstrate good accuracy when predicting physical activity components; however, their application to free-living settings is currently uncertain.

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Rodrigo Rodrigues Gomes Costa, Rodrigo Luiz Carregaro and Frederico Ribeiro Neto

Context: There seems to be no consensus on which aspects better distinguish the different levels of spinal cord injury regarding body composition, strength, and functional independence. Objective: The study aimed to determine which variables better differentiate tetraplegia (TP) from paraplegia and high paraplegia (HP) from low paraplegia (LP). Design: Cross-sectional study. Setting: Rehabilitation hospital network. Patients: Forty-five men with spinal cord injury, n = 15 for each level (TP, HP, and LP) causing complete motor impairment (American Spinal Injury Association Impairment Scale: A or B) were enrolled in the study. Main Outcome Measures: The 1-maximum repetition test, functional independence measure, spinal cord independence measure, and body composition (skinfold sum, body fat percentage, and body mass index) were assessed. Discriminant analysis was carried out using the Wilks lambda method to identify which strength and functional variables can significantly discriminate subjects for injury classification (TP, HP, and LP). Results: The discriminant variable for TP versus HP was body mass index and for TP versus LP was 1-maximum repetition (P ≤ .05). There were no variables that discriminated HP versus LP. Conclusions: The discriminant variables for TP versus HP and TP versus LP were body mass index and 1-maximum repetition, respectively. The results showed that HP and LP are similar for strength and functional variables.

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Matthieu Dagenais, Nancy M. Salbach, Dina Brooks and Kelly K. O’Brien

Purpose: To assess the criterion and construct validity of the Fitbit Zip® to measure physical activity among adults living with HIV. Methods: Participants were video recorded completing 2 walk tests while wearing the Fitbit Zip® and completed 3 self-reported physical activity questionnaires 1 week later. The authors calculated intraclass correlation coefficients (ICCs) to determine agreement between the number of steps taken and distance walked (Fitbit Zip®) with the visual count of number of steps taken and actual distance walked (walk tests). The authors tested 15 a priori hypotheses about predicted associations between questionnaire scores and physical activity measured by the Fitbit Zip®. Results: Among the 34 participants, there was “excellent” agreement between the number of steps taken measured by the Fitbit Zip® and visually counted number of steps taken (ICC = .99) and number of steps taken at slow (ICC = .75), moderate (ICC = .85), and fast (ICC = .78) walking speeds. There was “poor” agreement between the Fitbit Zip® recorded distance and actual determined distance walked (ICC = .20). Three (20%) construct validity hypotheses were confirmed. Conclusions: The Fitbit Zip® demonstrated criterion validity for its ability to measure number of steps taken but not distance walked, and did not demonstrate construct validity for measuring physical activity among adults with HIV.

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James J. Annesi

Background: Physical activity (PA)–related mood improvement is important because it positively affects predictors of weight-management behaviors. Methods: Decline in PA, mood, and exercise self-efficacy after an initial 6 months of gains were assessed in 93 women in a behavioral obesity treatment. Results: Reduction in change in PA during months 6 to 24, but not actual PA, significantly predicted increased negative mood. For participants whose negative mood increased, their 7 days per week PA regimens were reduced by ∼2.5 days per week versus ∼1 day per week without an increase. Exercise self-efficacy significantly mediated the PA–mood change relationship. Conclusions: Mood-related benefits of sustaining PA beyond initial treatment months were clarified.

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Carl Foster, Jos J. de Koning, Christian Thiel, Bram Versteeg, Daniel A. Boullosa, Daniel Bok and John P. Porcari

Background: Pacing studies suggest the distribution of effort for optimizing performance. Cross-sectional studies of 1-mile world records (WRs) suggest that WR progression includes a smaller coefficient of variation of velocity. Purpose: This study evaluates whether intraindividual pacing used by elite runners to break their own WR (1 mile, 5 km, and 10 km) is related to the evolution of pacing strategy. We provide supportive data from analysis in subelite runners. Methods: Men’s WR performances (with 400-m or 1-km splits) in 1 mile, 5 km, and 10 km were retrieved from the IAAF database (from 1924 to present). Data were analyzed relative to pacing pattern when a runner improved their own WR. Similar analyses are presented for 10-km performance in subelite runners before and after intensified training. Results: WR performance was improved in 1 mile (mean [SD]: 3:59.4 [11.2] to 3:57.2 [8.6]), 5 km (13:27 [0:33] to 13:21 [0:33]), and 10 km (28:35 [1:27] to 28:21 [1:21]). The average coefficient of variation did not change in the 1 mile (3.4% [1.8%] to 3.6% [1.6%]), 5 km (2.4% [0.9%] to 2.2% [0.8%]), or 10 km (1.4% [0.1%] to 1.5% [0.6%]) with improved WR. When velocity was normalized to the percentage mean velocity for each race, the pacing pattern was almost identical. Very similar patterns were observed in subelite runners in the 10 km. When time improved from 49:20 (5:30) to 45:56 (4:58), normalized velocity was similar, terminal RPE increased (8.4 [1.6] to 9.1 [0.8]), coefficient of variation was unchanged (4.4% [1.1%] to 4.8% [2.1%]), and VO2max increased (49.8 [7.4] to 55.3 [8.8] mL·min−1·kg−1). Conclusion: The results suggest that when runners break their own best performances, they employ the same pacing pattern, which is different from when WRs are improved in cross-sectional data.

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Steven Salaga, Scott Tainsky and Michael Mondello

The authors demonstrate that betting market outcomes are a statistically significant and economically relevant driver of local market television viewership in the National Basketball Association. Ratings are higher when the local market team covers the point spread and when point spread outcome uncertainty is increased. They further illustrate that point spread market outcomes have a larger relative impact on viewership in less-popular games and when the local market team is expected to perform poorly. This suggests wagering market access serves as insurance to the league and its franchises against reduced viewership in games that are less appealing to consumers. The results assess the degree to which wagering interest has driven past revenues as well as how the legalization of sports wagering may influence future revenues.