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It is now estimated that the prevalence of oral contraceptive use in athletic women matches that of women in the general population. The oral contraceptive pill (OCP) reduces cycle-length variability and provides a consistent 28-day cycle by controlling concentrations of endogenous sex hormones. The OCP is administered in three different forms that differ widely in chemical constitution and concomitant effects on the human body. As fluctuation in sex steroids are believed to be a possible causal factor in performance and exercise capacity, it is imperative to understand the effect of administering the various types of OCP on women. However, the research into oral contraceptives and exercise performance is not consistent. The type of OCP administered (monophasic, biphasic or triphasic), as well as the type and dose of estrogen and progestogen within, will have varying effects on exercise. To date, research in the area of oral contraceptives and exercise capacity is sparse and much has been plagued by poor research design, methodology and small sample size. It is clear from the research to date that more randomised clinical trials are urgently required to assess the array of OCP formulations currently available to women and their concomitant effect on health and exercise capacity. Therefore, the purpose of this article is to critically appraise the literature to date and to provide a current review of the physiological scientific knowledge base in relation to the OCP and exercise performance. In addition, methodological control, design and conduct will be considered with future areas of research highlighted.

HR-pQCT safely assessed important elements of bone microstructure in adolescents. Given the important contribution of bone geometry and structure to bone strength, it is essential to better understand the development and adaptation of these parameters in cortical and trabecular bone compartments.

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Objective: To explore potential factors that could be associated with low bone mineral density (BMD) in female endurance runners. Methods: Fifty two female endurance runners (1500 m to marathon), aged 18-44 years, took part. Body fat percentage, lumbar spine BMD, and femoral neck BMD were measured using the Hologic QDR 4500w bone densitometer. Data on training, menstrual cycle status, osteoporosis, and health related factors were obtained by questionnaire. Dietary variables were assessed from a prospective seven day dietary record of macronutrients and micronutrients. Results: The mean (SD) lumbar spine and femoral neck BMD were 1.11 (0.11) and 0.89 (0.12) g/cm 2 respectively. A backward elimination regression analysis showed that age, body mass, body fat, distance run, magnesium, and zinc intake were the variables significantly associated with BMD. Lumbar spine BMD (g/cm 2 ) = −1.90 + (0.0486 × age (years)) + (0.342 × log mass (kg)) − (0.000861 × age 2 (years)) − (0.00128 × distance (km/week)), with an R 2 = 30.1% (SEE = 0.089 (95% confidence interval (CI) 0.05 to 0.23); p<0.001). Femoral neck BMD (g/cm 2 ) = −2.51 − (0.00989 × age (years)) + (0.720 × log mass (kg)) + (0.000951 × magnesium (mg/day)) −(0.0289 × zinc (mg/day)) − (0.00821 × body fat (%)) − (0.00226 × distance (km/week)), with an R 2 = 50.2% (SEE = 0.100 (95% CI 0.06 to 0.22); p<0.001). The negative association between skeletal BMD and distance run suggested that participants who ran longer distances had a lower BMD of the lumbar spine and femoral neck. Further, the results indicated a positive association between body mass and BMD, and a negative association between body fat and BMD. Conclusions: The results suggest a negative association between endurance running distance and lumbar spine and femoral neck BMD, with a positive association between body mass and femoral neck and lumbar spine BMD. However, longitudinal studies are required to assess directly the effect of endurance running and body mass on BMD, and to see if the addition of alternative exercise that would increase lean body mass would have a positive effect on BMD and therefore help to prevent osteoporosis.

Bone is a complex structure with many levels of organization. Advanced imaging tools such as high-resolution (HR) peripheral quantitative computed tomography (pQCT) provide the opportunity to investigate how components of bone microstructure differ between the sexes and across developmental periods. The aim of this study was to quantify the age-and sex-related differences in bone microstructure and bone strength in adolescent males and females. We used HR-pQCT (XtremeCT, Scanco Medical, Geneva, Switzerland) to assess total bone area (ToA), total bone density (ToD), trabecular bone density (TrD), cortical bone density (CoD), cortical thickness (Cort.Th), trabecular bone volume (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular spacing standard deviation (Tb.Sp SD), and bone strength index (BSI, mg 2 /mm 4 ) at the distal tibia in 133 females and 146 males (15 to 20 years of age). We used a general linear model to determine differences by age-and sex-group and age  sex interactions ( p < 0.05). Across age categories, ToD, CoD, Cort.Th, and BSI were significantly lower at 15 and 16 years compared with 17 to 18 and 19 to 20 years in males and females. There were no differences in ToA, TrD, and BV/TV across age for either sex. Between sexes, males had significantly greater ToA, TrD, Cort.Th, BV/TV, Tb.N, and BSI compared with females; CoD and Tb.Sp SD were significantly greater for females in every age category. Males' larger and denser bones confer a bone-strength advantage from a young age compared with females. These structural differences could represent bones that are less able to withstand loads in compression in females. ß

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Our findings suggest that ImpactPA is significantly associated with bone architecture and bone strength in adolescent males and females.