Below is an interview on bone mineral density and content how it affects female swimmers and whats needed to help your body. Here is the latest article by; Dr. Phil Stanforth “Bone Mineral Content and Density Among Female NCAA Division I Athletes Across the Competitive Season and Over a Multi-Year Time Frame” and latest studies here.
1. What is the difference between bone mineral density and bone mineral content?
Bone mineral density is the actual density of the bone, whereas bone mineral content is the total amount of bone mineral content. Two individuals may have the same bone density but one of them may have more bone.
2. What are the main contributors for bone mineral density?
Age—BMD increases the most just before and during puberty. All the factors below probably affect the BMD changes during this time and throughout the lifespan.
Sex—men tend to have higher BMD than women.
Nutrition particularly calcium
Stress on the bone—impact/novel physical activities and strength activities.
3. How does a competitive sports season influence BMD and BMC?
A couple of studies with gymnasts showed it increased during the season and then decreased in the off-season. We didn’t see any effect of the season in our study. We speculate that the difference is that our athletes are training year round, so “off-season” isn’t off as far as conditioning is concerned. It is also possible that gymnastics are different and we didn’t study them.
4. How big of a problem are the non-weight bearing effects of swimming on BMD and BMC in the short-term (1 – 5 years)?
Studies show that swimmers have lower BMD/BMC than athletes in impact sports. We showed this in our study, but we also showed that female collegiate swimmers had BMD values that were similar to age matched control i.e. other college aged students. The difference in BMD between female swimmers and athletes in impact sports is seen as early as the ages of 7-9 where female gymnasts had higher BMD than female swimmers and the age of 13 when females in impact sports had higher BMD than female swimmers. It’s possible that collegiate swimmers don’t do as much high impact activity around the age of puberty and that is why there BMD is lower.
In our study, we actually saw a small increase in BMD for swimmers during their college years. This change was comparable to that seen in the other sports. We speculate that it was due to their weight training program, but our study wasn’t designed to examine this. It’s important to point out BMD increases with weight training may be more general in nature, but not specific to the areas that are most vulnerable—the hip and lumbar spine. It also appears that one needs to do pretty heavy lifting to see a difference.
5. How big of a problem is this over a lifespan?
Our swimmers had BMD values similar to the normal population. One would speculate that the issues for female swimmers would be similar to that of the typical female. In general bone density is maintained and then begins to decline in the mid-40’s/early 50’s. Eating properly, doing impact activities, and weight lifting can help maintain the BMD.
6. What should swim coaches, from age-group to college coaches, keep in mind regarding BMD and BMC?
Make sure that the athletes eat well and get in the appropriate amount of calcium. I think they should do some land power activities like box jumping on a regular basis. This may help increase/maintain hip BMD. And do pretty intense weight training for the big muscle groups.