Higher anterior knee laxity influences the landing biomechanics displayed by pubescent girls

Despite an increase in anterior knee laxity (AKL) during the adolescent growth spurt in girls, it is unknown whether landing biomechanics are affected by this change. This study investigated whether pubescent girls with higher AKL displayed differences in their lower limb strength or landing biomechanics when performing a horizontal leap movement compared to girls with lower AKL. Forty-six pubescent girls (10–13 years) were tested at the time of their peak height velocity (PHV). Passive AKL was quantified and used to classify participants into higher (HAKL; peak displacement > 4 mm) and lower (LAKL; peak displacement < 3 mm) AKL groups (n = 15/group). Three-dimensional kinematics, ground reaction forces (GRF) and muscle activation patterns were assessed during a horizontal leap landing. HAKL participants displayed significantly (P < 0.05) reduced hip abduction, increased hip abduction moments, as well as earlier hamstring muscle and later tibialis anterior activation compared to LAKL participants. Girls with HAKL displayed compensatory landing biomechanics, which are suggested to assist the functional stability of their knees during this dynamic task. Further research is warranted, however, to confirm or refute this notion.     

Effects of obesity on breast size,thoracic spine structure and function,upper torso musculoskeletal pain and physical activity in women

Purpose:This study investigated the effects of obesity on breast size,thoracic spine structure and function,upper torso musculoskeletal pain and physical activity participation in women living independently in the community.Methods:A total of 378 women were divided into 3 groups(Not Overweight:body mass index(BMI)=22.5±0.2 kg/m^2(mean±SE);Overweight:BMI=27.4±0.3 kg/m^2;Obese:BMI=35.4±0.3 kg/m^2).Outcome variables of breast volume(mL),thoracic flexion torque(N·m),thoracic kyphosis(degrees),upper torso musculoskeletal pain(score) and time spent in physical activity(min) were calculated and compared among the 3 groups,adjusting for between-group differences in age.Results:There was a significant main effect of BMI on all outcome variables.Participants classified as Obese displayed significantly larger breasts,had greater thoracic flexion torques and reported less time participating in physical activity relative to the participants who were classified as Not Overweight and Overweight.Participants in the Obese group also displayed significantly more thoracic kyphosis and reported significantly more upper torso musculoskeletal pain compared to their counterparts who were classified as Not Overweight.Conclusion:This study is the first to demonstrate that increased obesity levels were associated with compromised kyphosis and loading of the thoracic spine,as well as increased symptoms of upper torso musculoskeletal pain and reduced time spent in physical activity in women living in the community.We recommend further research to determine whether evidence-based interventions designed to reduce the flexion torque generated on the thoracic spine can improve these symptoms of upper torso musculoskeletal pain and the ability of women with obesity to participate in physical activity.