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Context: Early physical activity (PA) after concussion may promote symptom resolution. Prior studies have investigated exercise frequency/duration, yet precise PA intensity or volume required for optimal recovery requires further investigation. moderate to vigorous physical activity (MVPA) is beneficial for physical health. We investigated whether sedentary time, light activity time, MVPA time, or activity frequency in the weeks following concussion are associated with time to symptom resolution among adolescents. Design: Prospective cohort study. Methods: Adolescents 10–18 years of age were tested ≤14 days of concussion and followed until symptom resolution. At the initial visit, participants rated symptom severity and were provided wrist-worn activity trackers to monitor PA for the following week. PA behavior was categorized each day based on heart rate: sedentary (resting), light PA (50%–69% age-predicted max heart rate), and MVPA (70%–100% age-predicted max heart rate). Symptom resolution was defined as the date when participants reported cessation of concussion-like symptoms. Patients were not given specific PA instructions, though some may have received instructions from their physician. Results: Fifty-four participants were included in the study (54% female; mean age = 15.0 [1.8] y; initially assessed 7.5 [3.2] d after concussion). Female athletes recorded more sedentary time (900 [46] vs 738 [185] min/d; P = .01; Cohen d = 0.72), and less time in light PA (194.7 [64.5] vs 224 [55] min/d; P = .08; Cohen d = 0.48) and MVPA (23 [17] vs 38 [31] min/d; P = .04; Cohen d = 0.58) than male athletes. After adjusting for sedentary time, hours per day with >250 steps, sex, and initial symptom severity, more MVPA time was associated with faster symptom resolution time (hazard ratio = 1.016; 95% confidence interval, 1.001–1.032; P = .04). Conclusion: Our findings offer preliminary insight into how varying PA intensities affect concussion recovery, as MVPA may be a higher intensity than what is typically prescribed in concussion care.

Background: This study adds to the current literature by using a novel device-based method to explore where preschool children are physically active outside of home and childcare settings. This study combined accelerometry with geospatial data to explore the influence of the environment on preschool children’s physical activity by objectively identifying the locations where preschool children engage in moderate to vigorous physical activity (MVPA) within and outside of their neighborhood. Methods: Accelerometry, Global Positioning System, and Geographic Information Systems data from 168 preschool children aged 2–5 years were processed in ArcGIS Pro to identify locations (per 25 × 25-m fishnet cell) with high MVPA counts. Locations with high MVPA counts were defined as those with the top 20% of MVPA counts per fishnet cell. The land use for high MVPA count location was determined for 3 domains: <500 m from home, 500 to 1600 m from home, and >1600 m from home. Results: Locations with high MVPA counts <500 m from home were playgrounds (66.6%), schools (16.7%), and parks (16.7%). Locations with high MVPA counts 500 to 1600 m from home included playgrounds (33.3%), nonhome residential (29.6%), childcare centers (11.1%), and parks (3.7%). Locations with high MVPA counts >1600 m from home included nonhome residential (54.7%), sports and recreation centers (11.1%), playgrounds (6.8%), and parks (5.3%). Conclusions: Our findings highlight that local parks and playgrounds provide physical activity opportunities for preschool children, yet beyond the local neighborhood, the homes of others are important locations for preschool children to accumulate MVPA. These findings can be used to inform the design of current and future neighborhood places to better accommodate preschool children’s MVPA.

Purpose: This study examined the underlying mechanisms of postactivation potentiation and the time course of muscular- and neural-related variables. Methods: Fourteen trained males executed 4 sets of six 6-second maximum isometric conditioning plantar flexions, with 15 seconds and 2 minutes of interval between the contractions and sets, respectively. Peak twitch torque (TT), rate of torque development, time to peak torque, half relaxation time, and the neural-related variables of H-reflex and electromyogram, normalized to the maximum M-wave (H/M and RMS/M, respectively), were evaluated, as well as the level of the voluntary activation, assessed by the twitch interpolation technique. All neural-related variables were analyzed for the trial within each set when TT was maximal and for the trial within each set when the neural-related variable itself was maximal. Results: Compared with the baseline measures, TT and rate of torque development significantly increased in all sets (P < .001), whereas time to peak torque and half relaxation time significantly decreased in sets 1 to 4 and 2 to 4, respectively (P < .001). However, H/M and the RMS/M did not change for the repetition of each set for which the TT was maximal (P > .05). Interestingly, the within-set maximum H/M ratio of the lateral gastrocnemius muscle revealed a significant increase in all sets (P < .05), compared with the baseline measures. Conclusion: One set of 4 contractions with 6-second duration is sufficient to cause postactivation potentiation for most participants, whereas peak TT augmentation does not coincide with changes in the examined neural-related variables. Further experiments should consider the time lag on their maximal values and their inherent between-participants variability.

We investigated the association between the cross-sectional area (CSA) of the gluteus medius muscle (GMM) and activities of daily living in patients with hip fractures. This retrospective cohort study comprised 111 patients aged ≥65 years who underwent hip fracture rehabilitation. The CSA of the GMM was measured using computed tomography scans in the early stages of hospitalization. The group with decreased CSA of the GMM had a median GMI ≤17 cm²/m² for male patients and ≤16 cm²/m² for female patients. Patients in the group with decreased CSA of the GMM had lower functional independence measure gains than those in the control group. After adjusting for confounders, we found that decreased CSA of the GMM was significantly associated with lower functional independence measure gains (β: −0.432, p < .001). In patients with hip fractures, decreased CSA of the GMM was associated with decreased activities of daily living.

Most people with intellectual disabilities have comorbid health conditions, which will impact optimization of sporting performance. Classification is used in Paralympic events to ensure that those with similar levels of functional ability compete fairly against each other. An evidence-based approach needs to be developed for athletes with intellectual disabilities to be classified in relation to their overall functional capacity into competition groups of similar ability. This research builds on previous work using the taxonomy of The International Classification of Functioning, Disability and Health (ICF) to group athletes with intellectual disabilities into comparable competition groups as an approach to Paralympic classification. Three groups of athletes—Virtus, Special Olympics, and Down syndrome—are compared using the ICF questionnaire indicating functional health status in relation to sporting performance. The questionnaire was found to discriminate between athletes with Down syndrome and other athletes, and an approach to using a cutoff score to develop competition classes is explored.

Purpose: To investigate the indirect measurement of 1-repetition-maximum (1RM) free-weight half-squat in high-level sprinters using the load–velocity relationship. Methods: Half-squat load and velocity data from 11 elite sprinters were collected in 2 separate testing sessions. Approximately 24 hours prior to the first testing session, sprinters completed a fatiguing high-intensity training session consisting of running intervals, staircase exercises, and body-weight exercises. Prior to the second testing session, sprinters had rested at least 48 hours. Two different prediction models (multiple-point method, 2-point method) were used to estimate 1RM based on the load and either mean or peak concentric velocity data of submaximal lifts (40%–90% 1RM). The criterion validity of all methods was examined through intraclass correlation coefficients, coefficient of variation (CV%), Bland–Altman plots, and the SEM. Results: None of the estimations were significantly different from the actual 1RM. The multiple-point method showed higher intraclass correlation coefficients (.91 to .97), with CVs from 3.6% to 11.7% and SEMs from 5.4% to 10.6%. The 2-point method showed slightly lower intraclass correlation coefficients (.76 to .95), with CVs 1.4% to 17.5% and SEMs from 9.8% to 26.1%. Bland–Altman plots revealed a mean random bias in estimation of 1RM for both methods (mean and peak velocity) ranging from 1.06 to 13.79 kg. Conclusion: Velocity-based methods can be used to roughly estimate 1RM in elite sprinters in the rested and fatigued conditions. However, all methods showed variations that limit their applicability for accurate load prescription for individual athletes.

Deficits in movement patterns during cutting while running might place soccer players at risk of injury. The objective was to compare joint angles and intersegment coordination between sexes and ages during an unanticipated side-step cutting task in soccer players. This cross-sectional study recruited 11 male (four adolescents and seven adults) and 10 female (six adolescents and four adults) soccer players. Three-dimensional motion capture was used to measure lower-extremity joint and segment angles as participants performed an unanticipated cutting task. Hierarchical linear models examined relationships between joint angle characteristics with age and sex. Continuous relative phase was used to quantify intersegment coordination amplitude and variability. These values were compared between age and sex groups using analysis of covariance. Adult males had greater hip flexion angle excursions than adolescent males, while adult females had smaller excursions than adolescent females (p = .011). Females had smaller changes in hip flexion angles (p = .045), greater hip adduction angles (p = .043), and greater ankle eversion angles (p = .009) than males. Adolescents had greater hip internal rotation (p = .044) and knee flexion (p = .033) angles than adults, but smaller changes in knee flexion angles at precontact compared with stance/foot off (p < .001). For intersegment coordination, females were more out-of-phase than males in the foot/shank segment in the sagittal plane. There were no differences in intersegment coordination variability between groups. Differences in joint motion during an unanticipated cutting task were present between age groups and sexes. Injury prevention programs or training programs may be able target specific deficits to lower injury risk and improve performance.