Effects of yoga intervention during pregnancy: a review for current status.

OBJECTIVES: The purpose of this article is to review all randomized control trials (RCTs) that have looked at the health effects of yoga on pregnancy, and to present their evidence on the specific ways in which pregnant women, and their infants can benefit from yoga intervention. The purpose is also to determine whether yoga intervention during pregnancy is more beneficial than other physical exercises. METHODS: Four databases were searched using the terms "yoga and (pregnancy or pregnant or prenatal or postnatal or postpartum)." Databases were searched from January 2004 to February 2014. RESULTS: Ten randomized controlled trials were evaluated. The findings consistently indicate that yoga intervention presented with lower incidences of prenatal disorders (p ≤ 0.05), and small gestational age (p < 0.05), lower levels of pain and stress (p < 0.05), and higher score of relationship (p < 0.05). In addition, yoga can be safely used for pregnant women who are depressed, at high-risk, or experience lumbopelvic pain. Moreover, yoga is a more effective exercise than walking or standard prenatal exercises. CONCLUSIONS: The findings suggest that yoga is a safe and more effective intervention during pregnancy. However, further RCTs are needed to provide firmer evidence regarding the utility and validity of yoga intervention.

Predicting the Risk of Injuries Through Assessments of Asymmetric Lower Limb Functional Performance: A Prospective Study of 415 Youth Taekwondo Athletes.

Background: The impact of interlimb asymmetries on sport injuries is unclear because of inconsistent findings, and there is a lack of research on youth athletes and the sport of taekwondo. Purpose: To examine the effects of functional interlimb asymmetries on noncontact lower limb injuries in youth athletes. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 415 taekwondo athletes (318 boys and 97 girls) aged 6 to 17 years underwent baseline testing to determine interlimb asymmetries through the single-leg countermovement jump (CMJ), hop, and triple hop tests as well as the Star Excursion Balance Test. The athletes were then evaluated for 12 months to observe the occurrence of noncontact lower limb injuries. Results: During the study, 98 athletes (70 boys and 28 girls) sustained at least 1 noncontact lower limb injury. Athletes with higher interlimb asymmetries in single-leg CMJ height showed a significantly increased risk of noncontact lower limb injuries (boys: odds ratio [OR], 1.053 [95% CI, 1.027-1.080], P < .001; girls: OR, 1.070 [95% CI, 1.016-1.128], P = .011). Asymmetry in single-leg CMJ height of ≥15.28% was found to be the cutoff point for predicting noncontact lower limb injuries in boys (OR, 4.652 [95% CI, 2.577-8.398]; P < .001). Conclusion: This study highlights the utility of interlimb asymmetries in unilateral jump performance as a tool for assessing the risk of noncontact lower limb injuries in youth taekwondo athletes of both sexes. A proper evaluation of interlimb asymmetries may improve prevention strategies for youth athletes.

Association between Inter-Limb Asymmetries in Lower-Limb Functional Performance and Sport Injury: A Systematic Review of Prospective Cohort Studies.

BACKGROUND: Inter-limb asymmetry in lower-limb functional performance has been associated with increased risk of sport injury; however, findings are not always consistent. PURPOSE: To conduct a systematic review on whether inter-limb asymmetry in lower-limb functional performance can predict sport injury. METHODS: Four electronic databases (MEDLINE, EMBASE, Web of Science, and SportDiscus) were systematically searched for prospective cohort studies reporting the association between inter-limb asymmetry in lower-limb functional performance and sport injury. RESULTS: A total of 28 prospective cohort studies were included in the analyses. Collectively, the findings were highly inconsistent, and a clear statement on the association between each asymmetry and sport injury was difficult. CONCLUSIONS: Highly inconsistent findings make it difficult to create clear recommendations on the relationship between the inter-limb asymmetry in lower-limb functional performance (power, muscle flexibility, and dynamic balance) and sport injury. The influence of potential factors (selection of tests/parameters, participant characteristics, definition of injury, and ways of calculating asymmetry) should be considered when using previous findings.

The effect of fatigue on asymmetry between lower limbs in functional performances in elite child taekwondo athletes.

BACKGROUND: Inter-limb asymmetry above a certain threshold in functional performance indicates increased injury risk in sports. Fatigue has been found to increase bilateral asymmetry in lower-limb jumping performance among high-school and adult athletes, whereas this impact has not been examined in child athletes. This study aimed to examine the effect of fatigue on inter-limb asymmetry in functional performances in elite Taekwondo athletes aged between 9 and 11 years. METHODS: Performance of single-leg jumps, Star Excursion Balance Test (SEBT), and muscle (hamstring and gastrocnemius) flexibility were measured for 13 elite male child Taekwondo athletes (aged 9.85 ± 0.80 years) at both the rested and fatigued states to examine the inter-limb asymmetry. A two-way repeated measures ANOVA was conducted to examine for difference and the interaction between limb (dominant, non-dominant leg) and state (rested, fatigued state) for each test. Paired t test or Wilcoxon signed-rank test was used to compare the asymmetry magnitude at the rested vs. fatigued state for each test, and the variation of performance post fatigue in the dominant vs. non-dominant leg when appropriate. RESULTS: The inter-limb asymmetry in triple-hop distance significantly (p = 0.046) increased with fatigue, whereas the asymmetry significantly (p = 0.004) decreased with fatigue in anterior (ANT) reach distance in SEBT. A significant (p = 0.027) limb by state interaction was shown for posterolateral (PL) reach distance in SEBT, wherein a significant (p = 0.005) bilateral difference was only shown at the rested state. The PL reach distance showed a significantly greater decrease (p = 0.028) post fatigue when using the dominant leg for support compared to using the non-dominant leg. CONCLUSIONS: Fatigue significantly impacts inter-limb asymmetry in jump performances and dynamic balance for child athletes, while the variation of inter-limb asymmetry post fatigue may be different across tests. For the purpose of injury prevention, practitioners should consider assessing the inter-limb asymmetry for children at both the rested and fatigued state and be mindful of the fatigue response of each leg in functional tests.

Risk Factors for Non-Contact Lower-Limb Injury: A Retrospective Survey in Pediatric-Age Athletes.

BACKGROUND: Risk factors for non-contact lower-limb injury in pediatric-age athletes and the effects of lateral dominance in sport (laterally vs. non-laterally dominant sports) on injury have not been investigated. PURPOSE: To identify risk factors for non-contact lower-limb injury in pediatric-age athletes. METHODS: Parents and/or legal guardians of 2269 athletes aged between 6-17 years were recruited. Each participant completed an online questionnaire that contained 10 questions about the athlete's training and non-contact lower-limb injury in the preceding 12 months. RESULTS: The multivariate logistic regression model determined that lateral dominance in sport (adjusted OR (laterally vs. non-laterally dominant sports), 1.38; 95% CI, 1.10-1.75; p = 0.006), leg preference (adjusted OR (right vs. left-leg preference), 0.71; 95% CI, 0.53-0.95; p = 0.023), increased age (adjusted OR, 1.21; 95% CI, 1.16-1.26; p = 0.000), training intensity (adjusted OR, 1.77; 95% CI, 1.43-2.19; p = 0.000), and training frequency (adjusted OR, 1.36; 95% CI, 1.25-1.48; p = 0.000) were significantly associated with non-contact lower-limb injury in pediatric-age athletes. Length of training (p = 0.396) and sex (p = 0.310) were not associated with a non-contact lower-limb injury. CONCLUSIONS: Specializing in laterally dominant sports, left-leg preference, increase in age, training intensity, and training frequency indicated an increased risk of non-contact lower-limb injury in pediatric-age athletes. Future research should take into account exposure time and previous injury.

Bilateral difference between lower limbs in children practicing laterally dominant vs. non-laterally dominant sports.

Bilateral asymmetry in lower-limb power and dynamic balance has been associated with increased risk of sport injury, whereas there is a lack of research examining this asymmetry for child athletes. Twenty-eight fencers (19 boys and 9 girls, aged 9.71 ± 1.08 years) and 28 Taekwondo athletes (19 boys and 9 girls, aged 9.71 ± 1.08 years) were examined on the single-leg jump and Star Excursion Balance Test (SEBT) performance. A mixed model design ANOVA (2 [Sex: Boys, Girls] × 2 [Sport group: Fencing, Taekwondo] × 2 [Limb: Dominant, Non-dominant Leg]) was conducted to examine for difference for each test. There was a significant main effect of limb on hop and triple hop distance (p < 0.05). A significant limb by sex interaction (p = 0.000) was shown for the single-leg countermovement jump (CMJ) performance, wherein a bilateral difference was only shown in boys. In SEBT, a main effect (p = 0.007) of limb was identified for posterolateral (PL) reach distance. A limb by sex interaction (p = 0.009) was also shown for posteromedial (PM) reach distance, wherein a bilateral difference was only shown in girls. These findings suggest that child athletes in both laterally dominant and non-laterally dominant sports showed inter-limb asymmetry of leg power and dynamic balance. Sex should be an important consideration when evaluating bilateral difference of leg power and dynamic balance for child athletes.

The Influence of X-Factor (Trunk Rotation) and Experience on the Quality of the Badminton Forehand Smash.

No existing studies of badminton technique have used full-body biomechanical modeling based on three-dimensional (3D) motion capture to quantify the kinematics of the sport. The purposes of the current study were to: 1) quantitatively describe kinematic characteristics of the forehand smash using a 15-segment, full-body biomechanical model, 2) examine and compare kinematic differences between novice and skilled players with a focus on trunk rotation (the X-factor), and 3) through this comparison, identify principal parameters that contributed to the quality of the skill. Together, these findings have the potential to assist coaches and players in the teaching and learning of the forehand smash. Twenty-four participants were divided into two groups (novice, n = 10 and skilled, n = 14). A 10-camera VICON MX40 motion capture system (200 frames/s) was used to quantify full-body kinematics, racket movement and the flight of the shuttlecock. Results confirmed that skilled players utilized more trunk rotation than novices. In two ways, trunk rotation (the X-factor) was shown to be vital for maximizing the release speed of the shuttlecock - an important measure of the quality of the forehand smash. First, more trunk rotation invoked greater lengthening in the pectoralis major (PM) during the preparation phase of the stroke which helped generate an explosive muscle contraction. Second, larger range of motion (ROM) induced by trunk rotation facilitated a whip-like (proximal to distal) control sequence among the body segments responsible for increasing racket speed. These results suggest that training intended to increase the efficacy of this skill needs to focus on how the X-factor is incorporated into the kinematic chain of the arm and the racket.