Changes in fatigue, multiplanar knee laxity, and landing biomechanics during intermittent exercise.

Context: Knee laxity increases during exercise. However, no one, to our knowledge, has examined whether these increases contribute to higher-risk landing biomechanics during prolonged, fatiguing exercise.

Objectives: To examine associations between changes in fatigue (measured as sprint time [SPTIME]), multiplanar knee laxity (anterior-posterior [APLAX], varus-valgus [VVLAX] knee laxity, and internal-external rotation [IERLAX]) knee laxity and landing biomechanics during prolonged, intermittent exercise.

Changes in drop-jump landing biomechanics during prolonged intermittent exercise.

Background: As injury rates rise in the later stages of sporting activities, a better understanding of lower extremity biomechanics in the later phases of gamelike situations may improve training and injury prevention programs.

Hypothesis: Lower extremity biomechanics of a drop-jump task (extracted from a principal components analysis) would reveal factors associated with risk of anterior cruciate ligament injury during a 90-minute individualized intermittent exercise protocol (IEP) and for 1 hour following the IEP.

Study Design: Controlled laboratory study.

Multiplanar knee laxity increases during a 90-min intermittent exercise protocol.

Purpose: This study aimed to examine changes in sagittal (AP LAX), frontal (VV LAX), and transverse (IER LAX) plane knee laxity in men and women during an intermittent exercise protocol (IEP) simulating the intensity and duration of a soccer match.

Methods: Intercollegiate/club athletes (29 females and 30 males) were measured on AP LAX (-90 to 130 N) before and after warm-up and every 15 min during and for 1 h after the IEP. VV LAX (± 10 N · m) and IER LAX (± 5 N · m) were measured before and after warm-up, at the end of each 45-min half, and at 30 min after exercise.

Associations between lower extremity muscle mass and multiplanar knee laxity and stiffness: a potential explanation for sex differences in frontal and transverse plane knee laxity.

Background: Compared with men, women have disproportionally greater frontal (varus-valgus) and transverse (internal-external) plane laxity and lower stiffness, despite having similar sagittal (anterior-posterior) plane laxity and stiffness. While the underlying cause is unclear, the amount of lower extremity lean mass (LELM) may be a contributing factor.

Hypothesis: Lower extremity lean mass would be a stronger predictor of frontal and transverse plane laxity and incremental stiffness than the sagittal plane.