Background The role of lower extremity (LE) muscle strength for predicting traumatic knee injury in youth athletes is largely unknown. Aims The aim was to investigate the influence of LE muscle strength on traumatic knee injury in youth female and male athletes. Methods 225 athletes (40% females) from sport senior high schools in Sweden were included in this case-control study. The athletes recorded any traumatic knee injury that had occurred during their high-school period in a web-based injury form. A one repetition maximum (1RM) barbell squat test was used to measure LE muscle strength. The 1RM was dichotomised to analyse 'weak' versus 'strong' athletes according to the median (weak median vs strong median). Results 63 traumatic knee injuries, including 18 ACL injuries, were registered. The majority of injured female athletes were in the weak group compared with the strong group (p=0.0001). The odds of sustaining a traumatic knee injury and an ACL injury was 9.5 times higher and 7 times higher, respectively, in the weak median group compared with the strong median group in females (p 0.011). A relative 1RM squat 1.05 kg (105% of bodyweight) was established as the best cutoff value to distinguish high versus low risk of injury in female athletes. No strength-injury relationships were observed for the male athletes (p !0.348). Conclusions Weaker LE muscle strength predicted traumatic knee injury in youth female athletes, but not in males. This suggests that LE muscle strength should be included in injury screening in youth female athletes.

Proteins are held together in the native state by hydrophobic interactions, hydrogen bonds and interactions with the surrounding water, whose strength as well as spatial and temporal distribution affects protein flexibility and hence function. We study these effects using 10 ns molecular dynamics simulations of pure water and of two proteins, the glutamate receptor ligand binding domain and barnase. We find that most of the noncovalent interactions flicker on and off over typically nanoseconds, and so we can obtain good statistics from the molecular dynamics simulations. Based on this information, a topological network of rigid bonds corresponding to a protein structure with covalent and noncovalent bonds is constructed, with account being taken of the influence of the flickering hydrogen bonds. We define the duty cycle for the noncovalent interactions as the percentage of time a given interaction is present, which we use as an input to investigate flexibility/rigidity patterns, in the algorithm FIRST which constructs and analyses topological networks.

Reduced isometric hip-abductor strength predisposed competitive male soccer players to noncontact lateral ankle sprains.

Background: Although the restoration of quadriceps strength symmetry is a primary rehabilitation goal after anterior cruciate ligament reconstruction (ACLR), little is known about the potential relationship between quadriceps strength symmetry and psychological readiness to return to play (RTP). Hypothesis: Quadriceps strength symmetry will be associated with psychological readiness to RTP after ACLR. Secondarily, injury mechanism will influence the association between quadriceps strength and psychological readiness to RTP. Study Design: Retrospective cohort. Level of Evidence: Level 3 (cohort study). Methods: A total of 78 female patients completed strength testing and the Injury–Psychological Readiness to Return to Sport (I-PRRS) scale at an outpatient clinical facility as part of return to sport testing after ACLR. Linear regression analysis was used to assess the relationship between the I-PRRS and the independent variables of interest (quadriceps strength symmetry and injury mechanism). Results: For all patients combined, a significant symmetry × mechanism interaction was found. When split by injury mechanism, a significant linear relationship was found between quadriceps strength symmetry and the I-PRRS score in patients who experienced a noncontact injury (n = 55; P = 0.01; R2 = 0.24). No such relationship was found for those who experienced a contact injury (n = 23; P = 0.97; R2 = 0.01). Conclusion: Greater quadriceps strength symmetry was associated with greater psychological readiness to RTP in female athletes after ACLR. This relationship, however, was present only in those who experienced a noncontact injury. Clinical Relevance: Clinicians should consider both the physical and the psychological factors in assessing a patient’s readiness to RTP. This may be particularly important for those who have experienced an ACL tear through a noncontact mechanism.

Using a Bodyblade during shoulder exercises results in greater shoulder- and back-muscle recruitment than dumbbells. The Bodyblade Pro can activate multiple muscles in a single exercise and thereby minimize the need for multiple dumbbell exercises. The Bodyblade Pro is an effective device for shoulder- and back-muscle activation that warrants further use by clinicians interested in its use for rehabilitation.