Up until now, few athletes have had much concern about the health of their bones. They figure, and rightly so, that if they eat plenty of high quality food and get lots of exercise - two requirements of good bone health - that they will be fine. Generally, this is true for people who exercise moderately, but recent evidence has suggested that athletes who perform heavy exhaustive exercise in a non weight bearing manner may be at greater risk of bone abnormalities.
An interesting study reported in Sports Medicine Digest looked at high-performance athletes and bone status. The study was originally designed to look at the bone density of weight lifters and used four Tour de France cyclists as a control group. The researchers were examining how weight bearing exercise may promote increased bone density and needed athletes (cyclists) who performed exercise in a non weight bearing manner as a control to compare the difference.
Using dual photon absorptiometry technology, the researchers found a mean increase in bone density of 18% in the lumbar spine (lower back) and 32% in the femoral neck (upper thigh) in the 21 high-performance weight lifters studied. These findings were encouraging, but not surprising. However, in the control group of cyclists, the scientists were shocked to find that over the three week period of racing in the Tour de France, the athletes experienced a mean loss of about 25% of their spinal bone mass. The investigators believe that these values are indicative of whole body bone mass, which means that extremely heavy exercise over a three week period may cause the body to lose as much as 25% of its total bone mass!
"We do not know the cause of the bone loss," say Niethard and Gussbacher, the two principal researchers in the study. "Normally you would not lose this much bone if you lay in bed for a month. The bone loss is greater than you would expect in any severe wasting disease."
As stated, the researchers are not sure why the cyclists are losing so much bone mass, but speculate that it may have something to do with the non weight bearing nature of cycling and the extended period of high intensity, high volume stress of the Tour. Niethard points out that the athletes in the Tour de France are rarely spending any time standing. They are either riding or lying down recovering.
Although it is unlikely that you or I would extend ourselves as much as a professional cyclist in the Tour de France, it is still unsettling to know that heavy endurance exercise may have some negative effects on the health status of our bones. The question now is whether there is anything we can do about it?
As far as I know, there has been no research investigating prophylactic measures in the prevention of athletic bone loss during high intensity/volume training as found by the researchers. This, however, does not mean there is nothing you can do about it. I suggest consuming plenty of foods rich in protein, calcium, magnesium, phosphorus, and vitamin D, especially during times of high volume/intensity training. This may be very important for female athletes, especially senior female athletes, because they make less bone than do men, lose it faster, and live longer. Replacing estrogen at menopause may be very important and a doctor should be consulted regarding this situation. Also, avoiding excessive amounts of alcohol, caffeine, dietary fibre, and over supplementation of magnesium and phosphorus may be important for optimal bone health.
As I just noted, taking too much of one nutrient will interfere with the absorption and use of other important bone nutrients. However, this may be remedied by taking a multi nutrient bone supplement found at most good health food stores. Consuming these nutrients with dairy products may also improve the bioavailability. There is some evidence that lactose (milk sugar) can improve the absorption of calcium.
Another option for endurance athletes who wish to offset the possible bone loss that may accompany heavy endurance training and racing is to perform resistance training. As noted by the researchers Niethard and Gussbacher, weight training increases the bone density of weight lifting athletes. It may be beneficial for endurance athletes to perform strength training exercises during the off season, and if possible, year round. Exercises like squatting, seated leg extensions, hamstring curls, good mornings, lunges, lower back hyperextensions and calf raises are all possible choices for building bone mass in the lower body and back.
Cyclists often experience lower back pain with heavy training and long hours on the road. It may be possible that bone loss in the lower spine, due to heavy exercise, may be the cause of this pain. Proper nutrition and strength training could minimize this suffering.
Finally, this suspected rapid bone loss during heavy exercise may be why some athletes are more prone to stress fractures and other skeletal injuries. If you are one of those athletes predisposed to this, you may want to try boosting your nutrition with bone nutrients, build bone mass with resistance exercise during the off season, and structure your training in a well design progressive build-up that will allow the body to adapt to the stresses of exercise.
The above cited researchers have stumbled across a finding that may prove to be very important in the management of athletic health. This research, however, is very preliminary and much more work is needed before any conclusions can be made. At this point, do not be afraid to train and race heavily as long as you consume a mixed diet. If you are still a little anxious about this potential problem, a good nutrient supplement for bones may be useful and can be found at most health food stores.
1. Rapid Bone Loss in High-Performance Male Athletes. Sports Medicine Digest, 18:20, 1996.
2. Wardlaw, Vitamins. In: Contemporary Nutrition, St. Louis: Mosby, 1994, pp. 221.
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