Diet, Exercise and Bone Health

As a fitness pro, you can’t fix the genetic and environmental contributors to bone loss, but you can encourage physical activity and proper nutrition, both of which improve bone health. More than 70% of Americans don’t get the recommended amount of physical activity (Laskowski 2012), and 50% are considered deficient in vitamin D (Karaguzel & Holick 2010). One systematic review rated calcium, vitamin D, dairy and physical activity/exercise as the most important modifiable lifestyle factors that can influence the development of peak bone mass (NOF 2016).

Physical Activity

According to the Surgeon General, physical activity “is one of the most important controllable lifestyle changes to help prevent (or reduce the risk of) a number of chronic diseases” (OSG 2004), and although it is a leading health indicator, more than 80% of adults do not meet the guidelines for both aerobic and muscle-strengthening activities (ODPHP 2018).

McMillan et al. (2017) state that physical inactivity, or sedentary behavior, has been described as “the major public health problem of our time.” Physical activity is known to influence both bone and muscle metabolism; therefore, inactivity—or a decline in activity—can affect bone through those two pathways (Tagliaferri et al. 2015). Osteogenesis occurs in response to mechanical loading. Inactivity, with its lack of loading, prevents bones from receiving the signal to adapt, which causes bone loss. It’s a basic use-it-or-lose-it scenario.

While all exercises affect muscle and bone, recent research indicates that some activities help bones more than others. In program development, it is important to consider that the skeletal sites closest to the engaged muscle will have the biggest BMD increases (McMillan et al. 2017). For example, in sprinters and shot putters, BMD is highest in the legs and dominant arm, respectively. This is helpful to know when working with clients who have compromised BMD in certain sites.

Muscles are the key factor in exerting mechanical force on the skeleton, so increasing muscle strength is important—especially in the bones most likely to fracture (hips, wrists, vertebrae, etc.). See the article “Exercises for Clients with Osteoporosis” for bone-building exercises.

Nutrition

Proper diet pulls double duty: developing skeletal strength and maintaining bone’s role as a mineral storehouse. Minerals such as calcium and phosphorus, which the body must have in order to perform every day, are stored in bone. If the body can’t get these minerals from our diet, it takes them from our bones, reducing bone mass and strength (OSG 2004).

After age 30, calcium deficiencies can lead to a gradual bone loss as high as 0.5% per year (Karaguzel & Holick 2010). Calcium is a crucial part of young people’s diets, as half of the calcium in the adult skeleton is deposited during the ages of 13–17 (Karaguzel & Holick 2010).

Consuming calcium on its own, however, is not enough. Proper absorption of calcium depends on sufficient vitamin D intake, and some research has even suggested that calcium supplements without vitamin D supplementation may increase the risk of myocardial infarction (Rizzoli 2014). Interestingly, this increased risk is not evident when calcium is consumed from food, which is the intake method that is most highly recommended. Calcium can be obtained from a variety of food sources and, even for people with dietary restrictions such as dairy intolerance, there are many food sources available.

Dairy products, however, are the most efficient way to get enough calcium. One study evaluated the importance of dairy in calcium delivery and found that although calcium supplements can influence bone remodeling, dairy products have an additional benefit for bone growth. Dairy products provide more calcium, protein, magnesium, potassium, zinc and phosphorus per calorie than any other food (Rizzoli 2014). It would take 48 servings of whole grains or 24 servings of green vegetables to provide as much calcium as there is in a 200-millileter (6.76-ounce) glass of milk.

You may also have seen milk advertised as the perfect postworkout drink. Research into the effectiveness of fat-free milk versus an isoenergetic carbohydrate drink after resistance training found that milk promoted fat loss, lean-mass gains and BMD (Rizzoli 2014). Because calcium and vitamin D go hand in hand, many milks and yogurts are now fortified with vitamin D. Note that exposure to sunlight is still the most effective way to get enough vitamin D (Karaguzel & Holick 2010).

Although vitamin D is the main factor in calcium absorption, research suggests that absorption increases with higher dietary protein consumption in postmenopausal women (Tagliaferri et al. 2015) and that higher protein intake correlates to a lower rate of age-related bone loss (IOF 2017).

Note: Be aware of your scope of practice. You can inform clients about nutrition, but you cannot prescribe specific nutrients. Always refer your clients to their physician. In fact, suggesting they talk to their physician about bone health could be a motivating factor. Studies show that patients who are aware of their BMD numbers and fracture risk are more likely to adjust their calcium intake (Rizzoli 2014).

To read more about the workings of the skeleton and the risks of bone loss, please see “Bone Health: A Primer” in the online IDEA Library or in the June 2018 print issue of IDEA Fitness Journal. If you cannot access the full article and would like to, please contact the IDEA Inspired Service Team at (800) 999-4332, ext. 7.