Physical Activity and Bone Health

SUMMARY Weight-bearing physical activity has beneficial effects on bone health across the age spectrum. Physical activities that generate relatively high-intensity loading forces, such as plyometrics, gymnastics, and high-intensity resistance training, augment bone mineral accrual in children and adolescents. Further, there is some evidence that exercise-induced gains in bone mass in children are maintained into adulthood, suggesting that physical activity habits during childhood may have long-lasting benefits on bone health. It is not yet possible to describe in detail an exercise program for children and adolescents that will optimize peak bone mass, because quantitative dose-response studies are lacking. However, evidence from multiple small randomized, controlled trials suggests that the following exercise prescription will augment bone mineral accrual in children and adolescents: Mode: impact activities, such as gymnastics, plyometrics, and jumping, and moderate intensity resistance training; participation in sports that involve running and jumping (soccer, basketball) is likely to be of benefit, but scientific evidence is lacking Intensity: high, in terms of bone-loading forces; for safety reasons, resistance training should be <60% of 1-repetition maximum (1RM) Frequency: at least 3 d·wk−1 Duration: 10–20 min (2 times per day or more may be more effective) During adulthood, the primary goal of physical activity should be to maintain bone mass. Whether adults can increase bone mineral density (BMD) through exercise training remains equivocal. When increases have been reported, it has been in response to relatively high intensity weight-bearing endurance or resistance exercise; gains in BMD do not appear to be preserved when the exercise is discontinued. Observational studies suggest that the age-related decline in BMD is attenuated, and the relative risk for fracture is reduced, in people who are physically active, even when the activity is not particularly vigorous. However, there have been no large randomized, controlled trials to confirm these observations, nor have there been adequate dose-response studies to determine the volume of physical activity required for such benefits. It is important to note that, although physical activity may counteract to some extent the aging-related decline in bone mass, there is currently no strong evidence that even vigorous physical activity attenuates the menopause-related loss of bone mineral in women. Thus, pharmacologic therapy for the prevention of osteoporosis may be indicated even for those postmenopausal women who are habitually physically active. Given the current state of knowledge from multiple small randomized, controlled trials and large observational studies, the following exercise prescription is recommended to help preserve bone health during adulthood: Mode: weight-bearing endurance activities (tennis; stair climbing; jogging, at least intermittently during walking), activities that involve jumping (volleyball, basketball), and resistance exercise (weight lifting) Intensity: moderate to high, in terms of bone-loading forces Frequency: weight-bearing endurance activities 3–5 times per week; resistance exercise 2–3 times per week Duration: 30–60 min·d−1 of a combination of weight-bearing endurance activities, activities that involve jumping, and resistance exercise that targets all major muscle groups It is not currently possible to easily quantify exercise intensity in terms of bone-loading forces, particularly for weight-bearing endurance activities. However, in general, the magnitude of bone-loading forces increases in parallel with increasing exercise intensity quantified by conventional methods (e.g., percent of maximal heart rate or percent of 1RM). The general recommendation that adults maintain a relatively high level of weight-bearing physical activity for bone health does not have an upper age limit, but as age increases so, too, does the need for ensuring that physical activities can be performed safely. In light of the rapid and profound effects of immobilization and bed rest on bone loss, and the poor prognosis for recovery of mineral after remobilization, even the frailest elderly should remain as physically active as their health permits to preserve skeletal integrity. Exercise programs for elderly women and men should include not only weight-bearing endurance and resistance activities aimed at preserving bone mass, but also activities designed to improve balance and prevent falls. Maintaining a vigorous level of physical activity across the lifespan should be viewed as an essential component of the prescription for achieving and maintaining good bone health. INTRODUCTION In Caucasian, postmenopausal women, osteoporosis is defined as a bone mineral density (BMD) value more than 2.5 standard deviations below the young value with or Whether the should to women, women of or men remains to be In the and the of osteoporosis is increasing at than be by the increase in the of in have a on and of The rate for elderly in the following fracture is as high as with no in current it has been that the of will to by the with a increase in men than in women BMD the risk of with as with a to the that bone mass the risk of have the of and from bone mass can be through pharmacologic physical activity is the only that can increase bone mass and and the risk of in bone health with the risk of with training and the bone loss with However, the of will be on the of physical activity to risk for to or of exercise training to the effects of physical activity on forces be to bone to an and a increasing It is important to that the to bone is physical of bone than the or with exercise (e.g., Physical can be by on the bone but is more by such as forces during weight-bearing activities. forces in the of forces (e.g., may also bone but is more to that is to skeletal to training is the of bone it for to the of bone and a of is required to a bone mass that is The to the effects of physical activity on bone mass in is the of mineral per or volume of bone is the standard of BMD in and The and are the of by because are to methods of risk for osteoporosis include of and of the an of bone is to and does not involve to but should be only as a BMD is the of bone in and BMD has been to for or more of the in bone However, studies of suggest that in BMD in response to the effects on bone increases in BMD with increases in bone of The of bone has a to bone because the resistance of bone to or loading is to bone may to increase during bone is an important of of the effects of on bone should not only in bone mass, but in and and when possible The to the more to fracture are to the in BMD in the of and the decline in BMD after the age of to a decline in physical and bone and resistance to fracture not only on the of bone by but also bone methods are that the of with or with quantitative or The of or bone the of bone or of is important to the of the and However, of bone can be at in only by bone or the not yet can be from of bone from and from to training and from and from in that the response to loading in have not yet been in but are to in The of is to for the of physical activities that are likely to bone health. The current physical activity as it to increasing peak bone mass, age-related bone loss, and and will be have been to loading of the but will on the the physical activities that are likely to of the and of the bone-loading of controlled of these to determine their relative to the response bone of loading forces have effects only the to bone is and in loading of bone does not the response that with loading of have the to of not exercise running and jumping, and resistance have been that can or bone mass, In general, running and of moderate intensity have been to have effects on bone mass and in the and of the and in and However, in bone mass, and have been in response to exercise that is particularly in that resistance training in jumping to a and have been to have effects on and bone of the and that has been to the effects of in is controlled in of the and of the has an physical activity in that it and of the loading of loading of bone to the in to that the response to loading is when a of loading are into multiple by rest It has not yet been such are to of loading The primary with intensity include magnitude and is a of the of bone that from an and is as a of the of to the It has been that magnitude is to the but evidence suggests that rate is also an important loading and peak magnitude to be a of in bone mass also bone rate in an in the need for studies of the effects of that generate high magnitude and such as jumping activities. and of loading The of and loading that only a loading (e.g., per of relatively high magnitude to optimize the bone increasing the of loading by no in a more of loading in from a of as as per day bone mass and of the increasing the of per day not It should be that, in these studies, the of likely those during physical activities. 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However, to a of evidence to these will not be of physical activity in bone mass in children and adolescents primary with risk for osteoporosis is the peak bone mass during childhood and the suggest that bone loss as as the bone increases or remains the that and bone mass to increase in young women into the It has been that bone mass is in children who are physically active than in those who are active and in children who in activities that generate high impact forces (e.g., and than in those who in activities that impact forces (e.g., or are not (e.g., studies have on jumping and activities on the that high-intensity forces, gains in bone mass than to forces forces during jumping can times and some generate forces that are times in forces during or running are times of the studies of children as of programs and and studies that children who in the jumping and programs bone mass to a extent than children who in activities. that to loading increases in bone mass of the and on it is recommended that physical activity for children should include activities that generate relatively high forces, such as jumping, and running bone mineral accrual rate has been to at with of bone mineral a of Thus, the may a relatively of in to peak bone mass. studies that and have BMD when with adolescents The is in who in sports that generate high-intensity or forces (e.g., gymnastics, lifting) and in who in sports that generate loading have been exercise studies of all with in BMD in response to of resistance training of resistance training and with or of and In increases in BMD in response to 3 of or of resistance training The the studies that an of exercise and those that to do the of the However, these studies a small of and be have been no studies that the effects of exercise training on the bone of in exercise volume or studies have to determine at in the the is to the benefits of physical activity or exercise the of of and on bone mineral in and on in response to exercise in only the of of on and BMD in and and bone gains in the but not the when with BMD of the and of with for of in BMD in and at but in at and with a at on these observations, bone to be to during through to the that has been for peak bone mineral accrual the of remains a need for to the and of exercise to augment bone accrual and the during the when loading is The evidence to the prescription for children relatively high impact and activities, such as plyometrics, gymnastics, and resistance activities appear to be in bone mineral accrual when or in the Further, because of bone may as important of bone that are of BMD and because it that be particularly to during of it will be important to determine the of exercise on bone in children and adolescents. of physical activity in young adults peak bone mass is to be by the of the the may be the for studies of and a of sports suggest that have BMD when with BMD to be in who in sports that involve high-intensity loading forces, such as gymnastics, and and in who in sports such as of studies include such as and of controlled studies of have in bone mass through of training or in of level than in and after of of and in from to all increases in or BMD of skeletal by the of exercise performed during of training In for BMD during the and during the of studies in from to have the effects of that generate relatively high forces (e.g., resistance training, on bone mass of women. The of these studies increases in BMD In of studies of resistance training that to a on exercise intensity only to moderate or of 1-repetition Exercise intensity high in the but only the exercise performed and exercise may have for of the and because it performed in a studies an in BMD in response to relatively In there no in BMD but a in BMD after of resistance training; exercise intensity moderate 1RM). 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The rate of loss by skeletal and is likely by such as and physical it to determine the extent to the decline in bone mass is an of the In women, at the in rapid bone loss that is from the age-related bone of and postmenopausal suggest that even vigorous of physical activity do not prevent the loss of bone mineral have been no studies of women to determine exercise can the loss of bone during the However, the the of therapy and physical activity with to relative risk for fracture risk by in women on of physical activity when with women not on women not on those in the of physical activity also a in fracture suggesting that a high level of physical activity may prevent even it does not bone mass remains a of bone mass with than mass or mass, although mass may also be an Thus, physical activities that help preserve muscle mass (e.g., resistance may also be in preserving bone mass. 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on to that of the and postmenopausal women not on It should be that the exercise in the than as be In a of a small of postmenopausal women, who during jumping activity preserved BMD to a extent than is evidence that exercise with therapy may be in that the response of bone to have the that a of as a of postmenopausal the of bone to loading there is evidence that that generate high-intensity loading forces are more in increasing BMD in postmenopausal women on than in women not on although is not a It is also not the effects of and are or the response of bone to The of osteoporosis prevention has on women because the of does not increase in men the or on the of physical activity to preserve bone health of men is but is important to the of elderly strong BMD and in who or more times per BMD than men who In a of and the rate of bone loss in with the in BMD in men who their running The general from a of exercise studies that exercise can improve or maintain BMD in men studies have the effects of resistance training on bone mass in men The of exercise from 3 to and exercise intensity moderate to but of the studies beneficial effects of resistance training on at the the that not a a moderate exercise In general, the in BMD in response to exercise of the relative magnitude as has been in women, although increases in heart who performed of resistance exercise training Thus, the of exercise programs that help to preserve bone mass in women also appear to be in Physical activity and fracture risk with in because of BMD or (e.g., or of the of the The of are the and the and of the have been no randomized, controlled trials of the of exercise to and such a be to in because of the large and of that be is evidence from a on a small of postmenopausal women that a of the of the However, evidence from trials that physical activity the of or is evidence from studies that physical is a risk for The of fracture has been to be in who physically active than in those who women and men who stair or weight-bearing more than as likely to a fracture as those who physically active, even after for in mass and in activities of more than men and women that the of fracture in active people who as high as in those who physically active In the men who participation in vigorous physical activity a relative risk of fracture than men who indicated not in vigorous physical activity The of more than postmenopausal women that the relative risk of fracture by for 3 of physical is to of per week women who at least a risk of fracture with who than suggests that even weight-bearing such as may be beneficial in fracture even in BMD be physical activity may help to prevent by preserving bone mass by the of falls. to poor muscle of and as as such as and Exercise will be in only are to in the of that are to with exercise (e.g., poor muscle or of and of trials suggest that exercise trials that endurance training risk of in It be that some studies have or no of exercise on the of that exercise does not risk in elderly women and men for the of a that studies who likely multiple risk for that not be to be by exercise (e.g., poor Further, the exercise intensity is in studies of the only gains in muscle that help risk are it be that the for increases as people more physically active, particularly in elderly The of exercise likely to remains because studies with and a in the of activity to or of and of training It that balance training is a component of these programs and should be in exercise for at risk of muscle has been as of the of and fracture in the elderly because of beneficial effects on multiple risk for such as of and is evidence that the gains in after a of resistance training to an increase in physical activity in adults as as in the elderly in The of even elderly to exercise at relatively high may be habitually the of programs that the training that has been to increase muscle and improve is likely by the of such programs a Weight-bearing physical activity has beneficial effects on bone health across the age spectrum. is evidence that physical activities that generate relatively high-intensity loading forces, such as plyometrics, gymnastics, and high-intensity resistance training, augment bone mineral accrual in children and adolescents. is with the from studies of that the response to is by loading forces that a high magnitude and Further, there is some evidence that exercise-induced gains in bone mass in children are maintained into adulthood, suggesting that physical activity habits during childhood may have long-lasting benefits on bone health. It is not yet possible to describe in detail an exercise program for children and adolescents that will optimize peak bone mass, because quantitative dose-response studies are lacking. However, evidence from multiple small randomized, controlled trials suggests that the following exercise prescription will augment bone mineral accrual in children and adolescents: Mode: impact activities, such as gymnastics, plyometrics, and jumping, and moderate intensity resistance training; participation in sports that involve running and jumping (soccer, basketball) is likely to be of benefit, but scientific evidence is lacking Intensity: high, in terms of bone-loading forces; for safety reasons, resistance training should be of Frequency: at least 3 d·wk−1 Duration: 10–20 min (2 times per day or more may be more effective) During adulthood, the primary goal of physical activity should be to maintain bone mass. Whether adults can increase BMD through exercise training remains equivocal. When increases have been reported, it has been in response to relatively high intensity weight-bearing endurance or resistance exercise; gains in BMD do not appear to be preserved when the exercise is discontinued. Observational studies suggest that the age-related decline in BMD is attenuated, and the relative risk for fracture is reduced, in people who are physically active, even when the activity is not particularly vigorous. However, there have been no large randomized, controlled trials to confirm these observations, nor have there been adequate dose-response studies to determine the volume of physical activity required for such benefits. has that loading in bone resistance to that are than the increases in bone mass. the that physical activity can fracture risk even in the of in of in will large randomized, controlled trials of the effects of physical activity on fracture although in to the in of bone will from multiple small randomized, controlled trials of the of exercise to increase or maintain BMD suggests that the bone health of adults will be by the of a high level of physical as recommended by the the activity is weight-bearing in It is important to note that, although physical activity may counteract to some extent the aging-related decline in bone mass, there is currently no strong evidence that even vigorous physical activity attenuates the menopause-related loss of bone mineral in women. Thus, pharmacologic therapy for the prevention of osteoporosis may be indicated even for those postmenopausal women who are habitually physically active. Given the current state of knowledge from multiple small randomized, controlled trials and studies, the following exercise prescription is recommended to help preserve bone health during adulthood: Mode: weight-bearing endurance activities (tennis; stair climbing; jogging, at least intermittently during walking), activities that involve jumping (volleyball, basketball), and resistance exercise (weight lifting) Intensity: moderate to high, in terms of bone-loading forces Frequency: weight-bearing endurance activities 3–5 times per week; resistance exercise 2–3 times per week Duration: 30–60 min·d−1 of a combination of weight-bearing endurance activities, activities that involve jumping, and resistance exercise that targets all major muscle groups It is not currently possible to easily quantify exercise intensity in terms of bone-loading forces, particularly for weight-bearing endurance activities. However, in general, the magnitude of bone-loading forces increases in parallel with increasing exercise intensity quantified by conventional methods (e.g., percent of maximal heart rate or percent of 1RM). The general recommendation that adults maintain a relatively high level of weight-bearing physical activity for bone health does not have an upper age limit, but as age increases so, too, does the need for ensuring that physical activities can be performed safely. In light of the rapid and profound effects of immobilization and bed rest on bone loss, and the poor prognosis for recovery of mineral after remobilization, even the frailest elderly should remain as physically active as their health permits to preserve skeletal integrity. Exercise programs for elderly women and men should include not only weight-bearing endurance and resistance activities aimed at preserving bone mass, but also activities designed to improve balance and prevent falls. Maintaining a vigorous level of physical activity across the lifespan should be viewed as an essential component of the prescription for achieving and maintaining bone health. will be required to the and of physical activity that will be in and maintaining skeletal and fracture for the of by the and by and the and