Preferential Quadriceps Activation in Female Athletes with Incremental Increases in Landing Intensity

The purpose of this study was to identify alterations in preparatory muscle activation patterns across different drop heights in female athletes. Sixteen female high school volleyball players performed the drop vertical jump from three different drop heights. Surface electromyography of the quadriceps and hamstrings were collected during the movement trials. As the drop height increased, muscle activation of the quadriceps during preparatory phase also increased (p \u3c .05). However, the hamstrings activation showed no similar increases relative to drop height. Female athletes appear to preferentially rely on increased quadriceps activation, without an increase in hamstrings activation, with increased plyometric intensity. The resultant decreased activation ratio of the hamstrings relative to quadriceps before landing may represent altered dynamic knee stability and may contribute to the increased risk of ACL injury in female athletes

A Systematic Review of Sensorimotor Function during Adolescence: A Developmental Stage of Increased Motor Awkwardness?

Background Although adolescent motor awkwardness and increased injury susceptibility have often been speculated and researched, studies regarding adolescent regressions in motor control have yielded inconsistent conclusions. Thus, the relationship between adolescent maturation and injury risk remains unclear. The purpose of this study was to systematically review the literature relative to two questions: (1) Which sensorimotor mechanisms are not fully mature by the time children reach adolescence? and (2) Is adolescence a period when children exhibit delays or regressions in sensorimotor mechanisms

Longitudinal Sex Differences During Landing in Knee Abduction in Young Athletes

Purpose— The objective of this study was to determine if biomechanical and neuromuscular risk factors related to abnormal movement patterns increased in females, but not males, during the adolescent growth spurt. Methods— 315 subjects participated in two testing sessions approximately one year apart. Male and female subjects were classified based on their maturation status as pubertal or post-pubertal.Three trials of a drop vertical jump (DVJ) were collected. Maximum knee abduction angle and external moments were calculated during the DVJ deceleration phase using a 3D motion analysis system. Changes in knee abduction from the first to second year were compared among four subject groups (female pubertal, female post-pubertal, male pubertal and male post-pubertal). Results— There were no sex differences in peak knee abduction angle or moment during DVJ between pubertal males and females (p\u3e0.05). However, pubertal females increased peak abduction angle from the first to second year (pp=0.90) in the matched developmental stages. Following puberty, the peak abduction angle and moment were greater in females relative to males (angle: female -9.3±5.7°, male -3.6±4.6°, pp=0.017). Conclusion— This study identified, through longitudinal analyses, that knee abduction angle was significantly increased in pubertal females during rapid adolescent growth, while males showed no similar change. In addition, knee abduction motion and moments were significantly greater for subsequent year in young female athletes, following rapid adolescent growth, compared to males

Longitudinal Sex Differences During Landing in Knee Abduction in Young Athletes

Purpose— The objective of this study was to determine if biomechanical and neuromuscular risk factors related to abnormal movement patterns increased in females, but not males, during the adolescent growth spurt. Methods— 315 subjects participated in two testing sessions approximately one year apart. Male and female subjects were classified based on their maturation status as pubertal or post-pubertal.Three trials of a drop vertical jump (DVJ) were collected. Maximum knee abduction angle and external moments were calculated during the DVJ deceleration phase using a 3D motion analysis system. Changes in knee abduction from the first to second year were compared among four subject groups (female pubertal, female post-pubertal, male pubertal and male post-pubertal). Results— There were no sex differences in peak knee abduction angle or moment during DVJ between pubertal males and females (p\u3e0.05). However, pubertal females increased peak abduction angle from the first to second year (pp=0.90) in the matched developmental stages. Following puberty, the peak abduction angle and moment were greater in females relative to males (angle: female -9.3±5.7°, male -3.6±4.6°, pp=0.017). Conclusion— This study identified, through longitudinal analyses, that knee abduction angle was significantly increased in pubertal females during rapid adolescent growth, while males showed no similar change. In addition, knee abduction motion and moments were significantly greater for subsequent year in young female athletes, following rapid adolescent growth, compared to males

Longitudinal Documentation of Serum Cartilage Oligomeric Matrix Protein and Patient-Reported Outcomes in Collegiate Soccer Athletes over the Course of an Athletic Season

BACKGROUND: Serum cartilage oligomeric matrix protein (sCOMP) is a biomarker for cartilage degradation. Patient-reported outcomes (PRO) are used to document postinjury recovery and may be used to prospectively identify changes in the course of a season. It is unknown what effect intense, continuous physical activity has on sCOMP levels and PRO values in athletes over the duration of a soccer season. HYPOTHESIS/PURPOSE: The purpose of this study was to longitudinally document sCOMP levels and to determine whether changes in PROs occur in collegiate soccer athletes during a season. The hypotheses tested were that sCOMP levels and PRO scores would remain stable over the duration of the spring soccer season. STUDY DESIGN: Case series; level of evidence, 4. METHODS: Twenty-nine National Collegiate Athletic Association Division-I soccer athletes (18 men, 11 women; age, 19.6 ± 1.2 years; height, 177.8 ± 7.4 cm; mass, 73.8 ± 10.2 kg) participated in 3 (pre-[T(1)], mid-[T(2)], and postseason [T(3)]) data collection sessions. Subjects were included if they were participants in the spring soccer season and were free of severe knee injury at the time of data collection. At each session, subjects completed PROs (Lysholm, International Knee Documentation Committee scores) before serum collection. RESULTS: For sCOMP (ng/mL), there was a significant effect for time, with significant increases at T2 (1723.5 ± 257.9, P \u3c .001) and T3 (1624.7 ± 231.6, P = .002) when compared with T1(1482.9 ± 217.9). For each of the PROs, there was a significant effect for time from T1-T3, and at T2-T3 for the IKDC. CONCLUSION: These data indicate sCOMP levels increased as athletes reported an increased level of function over time. However, the differences in sCOMP levels did not reach the calculated minimal detectable change (MDC) value and the differences in PRO scores did not reach previously calculated MDC values. It is unclear whether these increases in sCOMP levels were caused by an increase in cartilage matrix breakdown or turnover. Even though these elevations may not be clinically meaningful, this biomarker may have the potential to be used for future research studies investigating the effects of exercise on overall joint health in longitudinal studies. In addition, these results indicate fluctuations in sCOMP occur during a competitive season and must be taken into consideration for future biomarker studies

Periodization in Anterior Cruciate Ligament Rehabilitation: New Framework Versus Old Model? A Clinical Commentary

The physiological and psychological changes after anterior cruciate ligament reconstruction (ACLR) do not always allow a return to sport in the best condition and at the same level as before. Moreover, the number of significant re-injuries, especially in young athletes should be considered and physical therapists must develop rehabilitation strategies and increasingly specific and ecological test batteries to optimize safe return to play. The return to sport and return to play of athletes after ACLR must progress through the recovery of strength, neuromotor control, and include cardiovascular training while considering different psychological aspects. Because motor control seems to be the key to a safe return to sport, it should be associated with the progressive development of strength, and cognitive abilities should also be considered throughout rehabilitation. Periodization, the planned manipulation of training variables (load, sets, and repetitions) to maximize training adaptations while minimizing fatigue and injury, is relevant to the optimization of muscle strengthening, athletic qualities, and neurocognitive qualities of athletes during rehabilitation after ACLR. Periodized programming utilizes the principle of overload, whereby the neuromuscular system is required to adapt to unaccustomed loads. While progressive loading is a well-established and widely used concept for strengthening, the variance of volume and intensity makes periodization effective for improving athletic skills and attributes, such as muscular strength, endurance, and power, when compared with non-periodized training. The purpose of this clinical commentary is to broadly apply concepts of periodization to rehabilitation after ACLR

Central exclusive production of longlived gluinos at the LHC

We examine the possibility of producing gluino pairs at the LHC via the exclusive reaction pp -> p+gluino+gluino+p in the case where the gluinos are long lived. Such long lived gluinos are possible if the scalar super-partners have large enough masses. We show that it may be possible to observe the gluinos via their conversion to R-hadron jets and measure their mass to better than 1% accuracy for masses below 350 GeV with 300/fb of data.Comment: 13 pages, 9 figures. Minor corrections to version