Sports Medicine

Maturation Phase and Sex Shape Injury Risk in Junior Tennis

In 100 academy junior tennis players followed across 15 seasons, injury incidence and burden varied by biological maturity phase and sex. Boys had their highest injury incidence and days lost during the six months around peak height velocity compared with early pre-PHV. Girls instead showed peak incidence and burden more than 18 months after PHV, again higher than in early pre-PHV. A 4.5-year range in age at PHV underscores the need for individualized, maturation- and sex-specific screening and load management. 1

Nordic Hamstring Training Lengthens Fascicles Without Overstraining Sarcomeres

Nine weeks of supervised Nordic hamstring training in recreationally active adults increased peak knee flexor torque by about 40%. After training, participants tolerated 37% greater knee extension and 4% longer muscle–tendon length at peak torque during the exercise. Biceps femoris long-head fascicles reached 25% longer lengths at peak torque, yet estimated active sarcomere length remained unchanged. These adaptations are consistent with adding sarcomeres in series, offering a plausible mechanism for the Nordic exercise’s hamstring injury–protective effects. After three weeks of detraining, torque and fascicle length declined, while muscle–tendon and sarcomere lengths at peak torque remained similar to post-training. 2

Navicular Stress Fractures: Growing Support for Early ORIF in High-Level Athletes

Navicular stress fractures are uncommon but high-risk injuries in jumping and running athletes due to limited vascularity and a central watershed zone. Conservative management has traditionally involved six weeks of nonweightbearing, with concern for delayed union and slower return to sport. Recent retrospective literature summarized here suggests ORIF for type 2–3 lesions yields quicker return to activity and fewer complications in high-level athletes. The authors advocate a low threshold for operative fixation in young, high-performance patients, particularly when intrinsic risk factors are present. 3

Hip Abductor Strength Alone Shows Limited Influence on Running Mechanics

This scoping review identified 19 studies on hip abductor strength and running biomechanics in healthy runners. Most work was cross-sectional, with only two small, methodologically limited intervention trials. Across studies, associations between hip abductor or external rotator strength and kinematic or kinetic variables were inconsistent. There was no convincing evidence that strengthening these muscles alone produced systematic or predictable changes in running gait. These findings suggest clinicians should not expect isolated hip strengthening to reliably normalize running biomechanics in otherwise healthy runners. 4