Low bone-mineral density (BMD) is associated with menstrual dysfunction and negative energy balance in the female athlete triad. This study determines BMD in elite female endurance runners and the associations between BMD, menstrual status, disordered eating, and training volume. Forty-four elite endurance runners participated in the cross-sectional study, and 7 provided longitudinal data. Low BMD was noted in 34.2% of the athletes at the lumbar spine, and osteoporosis in 33% at the radius. In cross-sectional analysis, there were no significant relationships between BMD and the possible associations. Menstrual dysfunction, disordered eating, and low BMD were coexistent in 15.9% of athletes. Longitudinal analysis identified a positive association between the BMD reduction at the lumbar spine and training volume (p = .026). This study confirms the presence of aspects of the female athlete triad in elite female endurance athletes and notes a substantial prevalence of low BMD and osteoporosis. Normal menstrual status was not significantly associated with normal BMD, and it is the authors’ practice that all elite female endurance athletes undergo dual-X-ray absorptiometry screening. The association between increased training volume, trend for menstrual dysfunction, and increased loss of lumbar BMD may support the concept that negative energy balance contributes to bone loss in athletes.
Noel Pollock, Claire Grogan, Mark Perry, Charles Pedlar, Karl Cooke, Dylan Morrissey and Lygeri Dimitriou
Saira Chaudhry, Dylan Morrissey, Roger C. Woledge, Dan L. Bader and Hazel R.C. Screen
Triceps surae eccentric exercise is more effective than concentric exercise for treating Achilles tendinopathy, however the mechanisms underpinning these effects are unclear. This study compared the biomechanical characteristics of eccentric and concentric exercises to identify differences in the tendon load response. Eleven healthy volunteers performed eccentric and concentric exercises on a force plate, with ultrasonography, motion tracking, and EMG applied to measure Achilles tendon force, lower limb movement, and leg muscle activation. Tendon length was ultrasonographically tracked and quantified using a novel algorithm. The Fourier transform of the ground reaction force was also calculated to investigate for tremor, or perturbations. Tendon stiffness and extension did not vary between exercise types (P = .43). However, tendon perturbations were significantly higher during eccentric than concentric exercises (25%–40% higher, P = .02). Furthermore, perturbations during eccentric exercises were found to be negatively correlated with the tendon stiffness (R 2 = .59). The particular efficacy of eccentric exercise does not appear to result from variation in tendon stiffness or extension within a given session. However, varied perturbation magnitude may have a role in mediating the observed clinical effects. This property is subject-specific, with the source and clinical timecourse of such perturbations requiring further research.