In 2011 over 1.7 million people were hospitalized because of a fragility fracture, and direct costs associated with osteoporosis treatment exceeded 70 billion dollars in the United States. Failure to reach and maintain optimal peak bone mass during adulthood is a critical factor in determining fragility fracture risk later in life. Physical activity is a widely accessible, low cost, and highly modifiable contributor to bone health. Exercise is especially effective during adolescence, a time period when nearly 50% of peak adult bone mass is gained. Here, we review the evidence linking exercise and physical activity to bone health in women. Bone structure and quality will be discussed, especially in the context of clinical diagnosis of osteoporosis. We review the mechanisms governing bone metabolism in the context of physical activity and exercise. Questions such as, when during life is exercise most effective, and what specific types of exercises improve bone health, are addressed. Finally, we discuss some emerging areas of research on this topic, and summarize areas of need and opportunity.

The potential of task-specific training as a fall-prevention intervention was studied. The primary purpose of the study was to determine the extent to which a task-specific training protocol decreased the number of falls by middle-age and older women after a laboratory-induced trip. Secondary purposes were to explore the ability of trunk kinematics during the initial recovery step and the length of the initial recovery step to correctly classify the trip outcome and to quantify the extent to which the training protocol affected these variables. Healthy community-dwelling women (n = 52) were assigned to either a training group or a control group that received no training. Training group women participated in an individually tailored, task-specific training protocol during which forward-directed stepping responses were necessary to avoid a fall after treadmill-delivered postural disturbances. Following the protocol, the ability to avoid a fall after a laboratory-induced trip was assessed. The primary outcome variable was the success (recover) or failure (fall) of the posttrip stepping response. Compared with the control group, there were fewer falls by the trained women after the laboratory-induced trip (P < 0.001; odds ratio = 0.13). Using logistic regression, falls and recoveries after the trip were sensitively classified by trunk flexion angle at the completion of the initial recovery step and the length of the initial recovery step (sensitivity = 0.67, specificity = 0.98), the former of which improved as a result of the task-specific training protocol. The task-specific training protocol significantly reduced the number of falls after a laboratory-induced trip. Prospective study is required to determine whether this task-specific training reduces falls in the community and, consequently, may complement currently used exercise-based fall prevention intervention methods.

Trip-specific perturbation training reduces trip-related falls after laboratory-induced trips and, prospectively, in the community. Based on an emerging body of evidence, we hypothesize that using task-specific perturbation training as a stand-alone approach or in conjunction with conventional exercise-based approaches will improve the effectiveness of fall prevention interventions significantly.

Background The variability of step time and step width is associated with falls by older adults. Further, step time is significantly influenced when performing attention demanding tasks while walking. Without exception, step time variability has been reported to increase in normal and pathologically aging older adults. Because of the role of step width in managing frontal plane dynamic stability, documenting the influence of attention-demanding tasks on step width variability may provide insight to events that can disturb dynamic stability during locomotion and increase fall risk. Preliminary evidence suggests performance of an attention demanding task significantly decreases step width variability of young adults walking on a treadmill. The purpose of the present study was to confirm or refute this finding by characterizing the extent and direction of the effects of a widely used attention demanding task (Stroop test) on the step width variability of young adults walking on a motorized treadmill. Methods Fifteen healthy young adults walked on a motorized treadmill at a self-selected velocity for 10 minutes under two conditions; without performing an attention demanding task and while performing the Stroop test. Step width of continuous and consecutive steps during the collection was derived from the data recorded using a motion capture system. Step width variability was computed as the standard deviation of all recorded steps. Results Step width decreased four percent during performance of the Stroop test but the effect was not significant (p = 0.10). In contrast, the 16 percent decrease in step width variability during the Stroop test condition was significant (p = 0.029). Conclusion The results support those of our previous work in which a different attention demanding task also decreased step width variability of young subjects while walking on a treadmill. The decreased step width variability observed while performing an attention demanding task during treadmill walking may reflect a voluntary gait adaptation toward a more conservative gait pattern emphasizing frontal plane control of the trunk. Extension of the experimental paradigm to older adults and mechanistic approaches to link step width variability to dynamic stability, and falls, in a cause-effect manner are necessary.