Osteopenia is a weakening or decalcification of bone, decreasing overall bone density below normal. Those who suffer from osteopenia are at greater risk for developing osteoporosis later in life. Exercise under normal conditions is a preventative measure against osteoporosis, but when coupled with low body weight, it may become a risk factor for it.
Osteopenia Development
There are two main types of cells in bone that regulate bone density: osteoblasts and osteoclasts. The osteoblasts are responsible for taking nutrients and creating new bone, whereas the osteoclasts break down old, brittle bone and the nutrients are reabsorbed into the bloodstream. In normal bone, this process is at an equilibrium, not breaking down any more bone than is being created, but osteopenia may develop when there is an imbalance. If the osteoclast activity outweighs the osteoblast activity, bone density will begin to decrease. Osteoclasts may be activated either by a decrease in blood calcium or vitamin D, as well as a lack of estrogen. Therefore, osteopenia in young women is usually caused by low calcium in the diet or a low body weight, decreasing estrogen release in the body. Older women tend to develop osteopenia post-menopause because of the overall decrease in estrogen. Osteopenia is defined as a bone density one standard deviation below the average 30-year-old white woman.
Benefits of Exercise
Bones function similarly to muscles in that if they are stressed, they will grow. The same way a person lifts weights to increase muscle size, adding load or weight to a bone will increase bone density. Weight bearing exercise such as jogging, team sports like basketball and walking increase the stress on bone, causing more bone mineral to be laid down. Additionally, the main concern of those with osteopenia is having a fall and breaking a bone. Exercise increases muscle strength and stability, preventing future falls.
Negative Effects of Exercise
While moderate exercise may help decrease the risk of developing osteoporosis or falls, extreme exercise may exacerbate the condition. First, large volumes of exercise over long periods of time put permanent stress on bone, not allowing for time to recover. This will inhibit the osteoblast (bone building) activity, and decrease bone density. Also, women who are very intense exercisers tend to have a low body fat percentage and overall low body weight. This condition is associated with low estrogen and poor dietary intake. Both the decreased estrogen and lack of calcium in the diet signal the osteoclasts to break down bone.
Risk Factors
You may be at risk for developing osteopenia if you have a low body weight, low body fat percentage, and either are sedentary or an extreme exerciser. If you have been diagnosed with low estrogen or have amenorrhea (lack of menstrual cycle) you are also at risk. Other risk factors include low blood vitamin D and frequent use of tobacco. Research has indicated that there is a genetic link for osteoporosis, meaning that it can be passed down from your parents or grandparents, so those with a history of the disease are more at risk. Women are more likely to develop osteoporosis than men, and the risk increases with age.
Diagnosis/Treatment
Because osteopenia has no symptoms, it is important to talk to your doctor if you are at risk. Your doctor will perform a bone scan using a DEXA (dual energy x ray) to determine your bone density as compared to the national average. Your will be given a T score, meaning how many standard deviations away from the average your bone density is. A T score of 1 (1 standard deviation) is the cut-off for osteopenia, and a T score of 2.5 or greater is the cut-off for osteoporosis. Your treatment will depend on the severity of diagnosis; mild osteopenia can be treated by either correcting problems with diet and exercise or in some cases prescribing estrogen. More severe cases of osteoporosis may need to be treated with prescription bisphosphanates, which inhibit osteoclast activity. While these drugs are still controversial, they have been shown to increase bone density.
Member Comments