Numerous efforts have been made to test the OPTIMAL theory of motor learning in healthy children and adult populations. However, only a small number of studies have tested this theory in children ...with cognitive-motor disorders, such as developmental coordination disorder (DCD). The present study aims to examine the individual and additive effects of a visual illusion and self-controlled practice on a golf putting task in children at risk for DCD based on the OPTIMAL theory. Forty children at risk for DCD (mean age = 8.57 ± 1.05 years) were randomly assigned to four experimental groups (1-small visual illusion + self-controlled practice; 2-big visual illusion + self-controlled practice; 3-small visual illusion + yoked; 4-big visual illusion + yoked). Following 12 pretest trials of a golf putting task, the participants completed 5 blocks of 12 trials of practice on the first day. A retention test (12 trials) and a transfer dual-task test (12 trials) were conducted on the second day. The results indicated that in retention test the big visual illusion + self-controlled practice group was significantly better than the small visual illusion + yoked group (p = 0.01), while there was not any other significant difference between groups at retention test as well as between all groups at practice phase and transfer test (p > 0.05 for all comparisons). In other words, an additive effect has been observed just in the retention test but not the practice phase as well as transfer test. In general, the results of this study support the OPTIMAL theory of motor learning in children at risk for DCD and suggests to all educators who work with these children to use the combination of the visual illusion with self-controlled practice to improve the motor learning of children at risk for DCD.
OBJECTIVETo assess the role of sexual orientation and gender identity in the relationship between physical activity (PA), stress and resilience. PARTICIPANTSA nationally-representative sample of ...students (n = 91,718) from United States postsecondary institutions. METHODSStudents reported aerobic and strength training (ST) behaviors, stress, resilience, gender identity and sexual orientation. Moderated regressions examined the influence of gender identity and sexual orientation on the relationship between PA and stress or resilience. RESULTSMen and heterosexual students reported higher PA and resilience and lower stress than did women, gender minorities, and sexual minorities. Significant moderation was found for women, queer students, bisexual students, trans women and lesbians in the various models. CONCLUSIONSGender minority and sexual minority students display poorer levels of PA and mental health than cisgender and heterosexual counterparts, but this relationship varies by identity group.
Temporal prediction of the lower extremity (LE) injury risk will benefit clinicians by allowing them to better leverage limited resources and target those athletes most at risk.
To characterize the ...instantaneous risk of LE injury by demographic factors of sex, sport, body mass index (BMI), and injury history.
Descriptive epidemiologic study.
National Collegiate Athletic Association Division I athletic program.
A total of 278 National Collegiate Athletic Association Division I varsity student-athletes (119 males, 159 females; age = 19.07 ± 1.21 years, height = 175.48 ± 11.06 cm, mass = 72.24 ± 12.87 kg).
Injuries to the LE were tracked for 237 ± 235 consecutive days. Sex-stratified univariate Cox regression models were used to investigate the association between time to first LE injury and sport, BMI, and LE injury history. The instantaneous LE injury risk was defined as the injury risk at any given point in time after the baseline measurement. Relative risk ratios and Kaplan-Meier curves were generated. Variables identified in the univariate analysis were included in a multivariate Cox regression model.
Female athletes displayed similar instantaneous LE injury risk to male athletes (hazard ratio HR = 1.29; 95% CI= 0.91, 1.83; P = .16). Overweight athletes (BMI >25 kg/m2) had similar instantaneous LE injury risk compared with athletes with a BMI of <25 kg/m2 (HR = 1.23; 95% CI = 0.84, 1.82; P = .29). Athletes with previous LE injuries were not more likely to sustain subsequent LE injury than athletes with no previous injury (HR = 1.09; 95% CI = 0.76, 1.54; P = .64). Basketball (HR = 3.12; 95% CI = 1.51, 6.44; P = .002) and soccer (HR = 2.78; 95% CI = 1.46, 5.31; P = .002) athletes had a higher risk of LE injury than cross-country athletes. In the multivariate model, instantaneous LE injury risk was greater in female than in male athletes (HR = 1.55; 95% CI = 1.00, 2.39; P = .05), and it was greater in male athletes with a BMI of >25 kg/m2 than that in all other athletes (HR = 0.44; 95% CI = 0.19, 1.00; P = .05), but these findings were not significantly different.
In a collegiate athlete population, previous LE injury was not a contributor to the risk of future LE injury, whereas being female or being male with a BMI of >25 kg/m2 resulted in an increased risk of LE injury. Clinicians can use these data to extrapolate the LE injury risk occurrence to specific populations.
Greater passive hip range of motion (ROM) has been associated with greater dynamic knee valgus and thus the potential for increased risk of anterior cruciate ligament injuries. Normative data for ...passive hip ROM by sex are lacking.
To establish and compare passive hip ROM values by sex and sport and to quantify side-to-side differences in internal-rotation ROM (ROM
), external-rotation ROM (ROM
), and total ROM (ROM
).
Cross-sectional study.
Station-based, preparticipation screening.
A total of 339 National Collegiate Athletic Association Division I athletes, consisting of 168 women (age = 19.2 ± 1.2 years, height = 169.0 ± 7.2 cm, mass = 65.3 ± 10.2 kg) and 171 men (age = 19.4 ± 1.3 years, height = 200.0 ± 8.6 cm, mass = 78.4 ± 12.0 kg) in 6 sports screened over 3 years: soccer (58 women, 67 men), tennis (20 women, 22 men), basketball (28 women, 22 men), softball or baseball (38 women, 31 men), cross-country (18 women, 19 men), and golf (6 women, 10 men).
Passive hip ROM was measured with the athlete lying prone with the hip abducted to 20° to 30° and knee flexed to 90°. The leg was passively internally and externally rotated until the point of sacral movement. Three measures were averaged for each direction and leg and used for analysis. We compared ROM
, ROM
, ROM
(ROM
= ROM
+ ROM
), and relative ROM (ROM
= ROM
- ROM
) between sexes and among sports using separate 2 × 6 repeated-measures analyses of variance.
Women had greater ROM
(38.1° ± 8.2° versus 28.6° ± 8.4°; F
= 91.74, P < .001), ROM
(72.1° ± 10.6° versus 64.4° ± 10.1°; F
= 33.47, P < .001), and ROM
(1.5° ± 16.0° versus -7.6° ± 16.5°; F
= 37.05, P < .001) than men but similar ROM
(34.0° ± 12.2° versus 35.8° ± 11.5°; F
= 1.65, P = .20) to men. Cross-country athletes exhibited greater ROM
(37.0° ± 9.3° versus 30.9° ± 9.4° to 33.3° ± 9.5°; P = .001) and ROM
(5.9° ± 18.3° versus -9.6° ± 16.9° to -2.7° ± 17.3°; P = .001) and less ROM
(25.7° ± 7.5° versus 35.0° ± 13.0° to 40.2° ± 12.0°; P < .001) than basketball, soccer, softball or baseball, and tennis athletes. They also displayed less ROM
(62.7° ± 8.1° versus 70.0° ± 9.1° to 72.9° ± 11.9°; P < .001) than basketball, softball or baseball, and tennis athletes.
Women had greater ROM
than men, resulting in greater ROM
and ROM
. Researchers should examine the extent to which this greater bias toward ROM
may explain women's greater tendency for dynamic knee valgus. With the exception of cross-country, ROM values were similar across sports. The clinical implications of these aberrant cross-country values require further study.
A decrease in the mass and volume of Western Palmer Land has raised the prospect that ice speed has increased in this marine‐based sector of Antarctica. To assess this possibility, we measure ice ...velocity over 25 years using satellite imagery and an optimized modeling approach. More than 30 unnamed outlet glaciers drain the 800 km coastline of Western Palmer Land at speeds ranging from 0.5 to 2.5 m/d, interspersed with near‐stagnant ice. Between 1992 and 2015, most of the outlet glaciers sped up by 0.2 to 0.3 m/d, leading to a 13% increase in ice flow and a 15 km3/yr increase in ice discharge across the sector as a whole. Speedup is greatest where glaciers are grounded more than 300 m below sea level, consistent with a loss of buttressing caused by ice shelf thinning in a region of shoaling warm circumpolar water.
Key Points
We provide the first observation of changing ice flow in Western Palmer Land
Between 1992 and 2015, ice speed and discharge increased by 13% and 15 km3/yr, respectively
The most affected glaciers are deeply grounded and flow into a thinning ice shelf, in an ocean where circumpolar deep water is shoaling
Screening methods for anterior cruciate ligament (ACL) injuries often involve double-leg landings, though the majority of ACL injuries occur during single-leg landings. Differences in kinematic ...temporal characteristics between single-leg and double-leg landings are poorly understood. The purpose of this study was to examine discrete and temporal kinematics associated with functional valgus collapse during single-leg and double-leg landings (LANDSL and LANDDL). Three-dimensional kinematics were obtained during the landing phases of LANDSL and LANDDL in ninety participants (45 females: 20.1 ± 1.7 yr, 165.2 ± 7.6 cm, 68.6 ± 13.1 kg; 45 males: 20.7 ± 2.0 yr, 177.7 ± 8.5 cm, 82.8 ± 16.3 kg). Peak joint angles and time series curves for frontal and transverse plane hip and knee kinematics were analyzed with an RMANOVA (discrete variables) and Statistical Parametric Mapping (SPM) paired t-tests (time series). LANDSL elicited greater knee abduction than LANDDL from 0 to 35% (0–73 ms) but greater knee adduction from 54 to 100% (112–207 ms). Peak knee abduction was 2.0° greater during LANDDL than during LANDSL (p < .001). LANDSL elicited greater hip adduction than LANDDL from 2 to 33% (4–69 ms) and greater hip abduction from 49 to 100% (102–207 ms). Peak hip adduction was 4.6° greater during LANDSL than during LANDDL (p < .001). LANDSL elicited less knee internal rotation from 0 to 3% and greater hip internal rotation from 52 to 75% of the landing phase. Peak transverse plane joint angles did not differ between tasks. During the time frame in which ACL injuries are thought to occur, LANDSL elicited frontal plane knee and hip movement consistent with risky biomechanics. Researchers and clinicians should be cognizant of how a chosen screening task alters observed kinematic effects.
Motor imagery (MI) has emerged as an individual factor that may modulate the effects of attentional focus on motor skill performance. In this study, we investigated whether global MI, as well as its ...components (i.e., kinesthetic MI, internal visual MI, and external visual MI) moderate the effect of attentional focus on performance in a group of ninety-two young adult novice air-pistol shooters (age: M = 21.87, SD = 2.54). After completing the movement imagery questionnaire-3 (MIQ-3), participants were asked to complete a pistol shooting experiment in three different attentional focus conditions: (1) No focus instruction condition (control condition with no verbal instruction) (2) an internal focus instruction condition, and (3) an external focus condition. Shot accuracy, performance time, and aiming trace speed (i.e., stability of hold or weapon stability) were measured as the performance variables. Results revealed that shot accuracy was significantly poorer during internal relative to control focus condition. In addition, performance time was significantly higher during external relative to both control and internal condition. However, neither global MI, nor its subscales, moderated the effects of attentional focus on performance. This study supports the importance of attentional focus for perceptual and motor performance, yet global MI and its modalities/perspectives did not moderate pistol shooting performance. This study suggests that perception and action are cognitively controlled by attentional mechanisms, but not motor imagery. Future research with complementary assessment modalities is warranted to extend the present findings.
Purpose
Greater femoral internal rotation (via anteversion or passive hip ROM) is associated with knee biomechanics thought to contribute to anterior cruciate ligament (ACL) injury, but it is unknown ...if femoral internal rotation contributes to actual ACL injury occurrence. The objective of this systematic review and meta-analysis was to quantify the extent to which femoral anteversion and hip range of motion (ROM) influence knee biomechanics consistent with ACL injury and actual ACL injury occurrence.
Methods
Using PRISMA guidelines, PubMed, CINAHL, SportDiscus, and Scopus databases were searched. Inclusion criteria were available passive hip ROM or femoral anteversion measure, ACL injury OR biomechanical analysis of functional task. Two reviewers independently reviewed titles, abstracts, and full texts when warranted. Included studies were submitted to Downs & Black Quality Assessment Tool. Meta-analyses were conducted for comparisons including at least two studies.
Results
Twenty-three studies were included (11 injury outcome, 12 biomechanical outcome). Decreased internal rotation ROM was significantly associated with history of ACL injury (MD -5.02°; 95% CI -8.77°—-1.27°;
p
= 0.01;
n
= 10). There was no significant effect between passive external rotation and ACL injury (MD -2.62°; 95% CI -5.66°—- 0.41°;
p
= 0.09;
n
= 9) Participants displaying greater frontal plane knee projection angle had greater passive external rotation (MD 4.77°; 95% CI 1.17° – 8.37°;
p
= 0.01;
n
= 3). There was no significant effect between femoral anteversion and ACL injury (MD -0.46°; 95% CI -2.23°—1.31°;
p
= 0.61;
n
= 2). No within-sex differences were observed between injured and uninjured males and females (
p
range = 0.09 – 0.63).
Conclusion
Though individuals with injured ACLs have statistically less passive internal and external rotation, the observed heterogeneity precludes generalizability. There is no evidence that femoral anteversion influences biomechanics or ACL injury. Well-designed studies using reliable methods are needed to investigate biomechanical patterns associated with more extreme ROM values within each sex, and their prospective associations with ACL injury.
Level of evidence:
IV.
Sexual self-efficacy (SSE), one's perceived control of or confidence in the ability to perform a given sexual outcome, predicts sexual behavior; however, important questions remain regarding whether ...gender modifies observed associations. In a comprehensive review of peer-reviewed HIV-prevention literature focusing on youth (ages 10 to 25) in sub-Saharan Africa, we measured and assessed the influence of SSE on condom use and sexual refusal, overall and by gender. Our results, after reviewing 63 publications, show that SSE is inconsistently measured. Most studies measured condom use self-efficacy (CUSE) (96.8%) and/or sexual refusal self-efficacy (SRSE) (63.5%). On average, young men had higher CUSE than young women, while young women had higher SRSE than young men. While cross-sectional studies reported an association between high SSE and sexual behaviors, this association was not observed in interventions, particularly among young women who face a disproportionate risk of HIV acquisition. In all, 25% of intervention studies demonstrated that fostering CUSE increased condom use among young men only, and one of two studies demonstrated that higher SRSE led to reduced frequency of sexual activity for both men and women. Future research and HIV-prevention interventions must be gender targeted, consider improving CUSE for young men, and move beyond limited individual-level sexual behavior change frameworks.
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