Female athletes are at a 4- to 6-fold increased risk of anterior cruciate ligament (ACL) injury compared with male athletes. There are several medical, emotional and financial burdens associated with these injuries. Sex hormones may be involved in the ACL injury disparity, with potential associations reported between phases of the menstrual cycle and ACL injury rates. The reported relationships between ACL injury and menstrual status may be related to associated changes in ligament mechanical properties from cyclic fluctuations of female sex hormones. A PubMed electronic database literature search, including MEDLINE (1966-2005) and CINAHL (1982-2005), with the search terms 'menstrual cycle' and 'knee laxity' was used for this systematic review. Studies were included in this systematic review if they were prospective cohort studies and investigated the association between the menstrual cycle and anterior knee laxity in females. Nine prospective cohort studies, published as 11 articles, were included in the systematic review. Six of nine studies reported no significant effect of the menstrual cycle on anterior knee laxity in women. Three studies observed significant associations between the menstrual cycle and anterior knee laxity. These studies all reported the finding that laxity increased during the ovulatory or post-ovulatory phases of the cycle. A meta-analysis, which included data from all nine reviewed studies, corroborated this significant effect of cycle phase on knee laxity (F-value = 56.59, p = 0.0001). In the analyses, the knee laxity data measured at 10-14 days was >15-28 days which was >1-9 days. Future studies testing the relationship between the menstrual cycle and potentially associated parameters should consider the limitations outlined in this article and control for potential biases and confounders. Power analyses should be utilised. Subjects should be randomly entered into the studies at alternate points in the cycle, and standard and consistent data acquisition and reporting methods should be utilised. Future studies should clearly define what constitutes a 'normal' cycle and appropriate control subjects should be utilised. Furthermore, there is a need to define cycle phase (and timing within cycle phase) with actual hormone levels rather than a day of the cycle. Although hormone confirmations were provided in many of the studies that selected specific days to depict a particular cycle for all women, it is unknown from these data if they truly captured times of peak hormone values in all women. A combined systematic review and meta-analysis of the literature indicate that the menstrual cycle may have an effect on anterior-posterior laxity of the knee; however, further investigation is needed to confirm or reject this hypothesis.

Our results indicate that there is a significant correlation between estradiol, estriol, and progesterone and ACL stiffness suggesting that fluctuating levels of sex hormones may influence the stiffness of the ACL near ovulation. Future studies that examine the relationship between sex hormones and the physical properties of the ACL should be focused near the ovulation phase of the menstrual cycle.

Introduction Older adults with a high number of chronic conditions and who live in environments that do not promote physical activity have great difficulty initiating and adhering to exercise programs. Novel lifestyle activity interventions that can effectively increase physical activity may address disparities in health in these populations. This study evaluates the effects of the Baltimore Experience Corps program, a community-based volunteer program, on walking activity in older adults. Methods The Baltimore Experience Corps Trial is a sex-stratified RCT that recruited participants from 2006 to 2009. Older adult participants aged ≥60 years (n=123) were from a nested objective physical activity trial within the larger Baltimore Experience Corps Trial. Participants randomized to the intervention group were placed as volunteers within the Baltimore public school system for 2 years. The primary study outcome was objectively measured total amount of walking activity measured in steps/day. Differences between intervention and control groups were measured at 12 and 24 months using linear mixed effects models. Data were analyzed in 2014. Results At 24 months, women, but not men, in the intervention group showed an increased amount of walking activity, averaging 1,500.3 (95% CI=77.6, 2,922.9) greater steps/day compared with the control group. Women in the control group declined by 1,191.6 (95% CI= − 2243.7, −139.5) steps/day at 24 months compared to baseline. Conclusions A community-based volunteer intervention increased walking activity among older women, who were at elevated risk for both inactivity and adverse health outcomes.

Frequent physical activity in midlife may be associated with risk of greater severity and frequency of menopausal hot flashes.

Study Design: One-group discriminant analysis. Objective: To determine whether 1 MHz of continuous ultrasound can identify tibial stress fractures in subjects. Background: Stress fractures can lead to loss of function or to more serious nonunion fractures. Early diagnosis is important to reduce the risk of further injury and to assure a safe return to activity. Therapeutic ultrasound has been reported to be an accessible, less expensive alternative in diagnosing stress fractures compared with other diagnostic techniques. Methods and Measures: Twenty-six subjects (12 men, 20.33 2 1.37 years; 14 women, 20.78 2 3.8 years) with unilateral tibia pain for less than 2 weeks volunteered to participate in the study. Continuous, 1 MHz ultrasound was applied to the uninvolved and involved tibias at 7 increasing intensities for 30 seconds each. Subjects completed a visual analog scale after the application of each intensity to assess the pain response to ultrasound. Results from the visual analog scale were compared to magnetic resonance imaging (MRI) findings to determine if continuous ultrasound could predict whether subjects had a normal MRI, increased bone remodeling, or advanced bone remodeling consistent with a stress fracture. Results: Discriminant analysis on the visual analog scale correctly classified subjects into 1 of 3 clinical classification groups in 42.31 % of the cases. None of the subjects found to have a stress fracture by MRI were correctly identified by continuous ultrasound. This resulted in a predicted sensitivity of 0% and a predicted specificity of 100%. Conclusions: A protocol using visual analog scores after the application of 1 MHz continuous ultrasound is not sensitive for identifying subjects with tibial stress fractures. 1