Page 136 - Athletic Health Handbook
P. 136
elect to consume unusual diets that adverse consequences, because of the exercise and/or leanness might impair
may lead to low intake of calcium, corresponding reduced calcium avail- bone mass accrual. Furthermore,
vitamin D, and other nutrients ability. Similarly, the high-protein excessive leanness and/or exercise
important to bone. diets selected by some athletes might may adversely impact the skeleton by
impair bone accrual as doubling causing hypogonadism. This factor is
Given the social, physiologic, and of protein intake increases urinary of particular importance in women
psychological complexities of adoles- calcium loss by 50 percent. However, as a recognized element in the female
cence, there is no simple solution to it is probable that this loss easily can athlete triad of anorexia, amenorrhea,
this calcium insufficiency epidemic. be compensated for by increased and low bone mass.10
However, dairy product consumption calcium intake. As such, athletes
remains an excellent option. In addi- ingesting high-protein diets should It is apparent from the above that
tion, a growing number of calcium- be advised to include 1,200–1,500 young athletes, particularly females
fortified foods and improved calcium mg of calcium daily in their diet. who are excessively lean (but probably
supplements exist and should also males) will not attain their
be recommended. Role of Exercise in Bone Mass potential peak bone mass because of
a combination of sex steroid insuffi-
Furthermore, calcium insufficiency It is well known that the skeleton ciency, low body weight, and inade-
is often worsened by impaired absorp- responds to the load applied to it. quate nutrient intake. Ultimately,
tion caused by vitamin D insuffi- For example, individuals who are this will translate into increased
ciency. Hypovitaminosis D (not true excessively lean throughout childhood osteoporotic fracture risk in later life.
rickets or osteomalacia) is extremely and adolescence may have more
common8 because of low exposure difficulty reaching peak bone mass Conclusion
to sunlight coupled with difficulty than their heavier counterparts,
in attaining adequate dietary intake. because of the reduced weight borne In summary, the primary prevention
Simple daily multivitamin use should by their skeleton. of osteoporosis must begin in child-
correct this situation. hood. Concrete suggestions in this
Therefore, childhood and adoles- regard have been published7 and
Given the above assumptions, it is cence may be a singular opportunity include stressing the importance of
appropriate that bone health measures to attain long-term skeletal benefit nutrition and exercise for bone health.
often focus on calcium and vitamin through exercise. In fact, weight-bear- This clarifies misconceptions that
D. However, it is important to ing activity may have a greater impact dairy products are somehow “bad,”
recognize that a multitude of other on peak bone mass than dietary encourages prevention of vitamin D
nutritional factors influence skeletal calcium intake.9 Specifically, whereas insufficiency by recommending daily
development, including protein, exercise increases bone mass in adults, multivitamin use, restriction of
phosphorus, magnesium, manganese, it appears that bone geometry can be carbonated beverages in schools at
and zinc, among others. Clearly, favorably altered by exercise only in meal times, and intensification of
simple calcium supplementation does young individuals. This permanent efforts to reduce alcohol and tobacco
not correct these multiple nutrient change in bone shape likely confers use. Because of their access and rapport
deficiencies, which emphasizes the life-long benefit from greater bone with athletes, sports medicine physi-
need for a well-balanced diet. In this strength and fracture resistance. cians are uniquely positioned to
regard, it is evident that adolescents implement such recommendations.
with eating disorders or who other- Finally, whereas most bone mass
wise voluntarily restrict their diet has been acquired by age 20, the
(e.g., wrestlers) may negatively additional consolidation that occurs
impact bone accrual. over the subsequent ~10 years may
be influenced favorably by exercise.
In addition to dietary insufficien- Thus, exercise in general is “good”
cies, nutritional excesses may impede and a sedentary lifestyle “bad” for
bone mass attainment. Specifically, attaining an individual’s genetically
excess phosphate and caffeine inges- determined peak bone mass. However,
tion from soft drinks increases urinary it should be mentioned that abrupt
calcium excretion. Although the role onset of frequent intense exercise
of these nutrients on peak bone mass may lead to stress fractures. Athletes
attainment has not been defined should also be aware that excessive
clearly, it is reasonable to expect

THE ROLE OF BONE MASS IN OSTEOPOROSIS 136
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