Bikes and Bones
Inspired by the AmGen Tour of California, coming through Santa Cruz, I am thinking about the bone density of the world’s top cyclists. In the past 5 years, much has changed in the way we think about exercise and bone density. We used to think that weight-bearing or weight training exercise was the best for building bone. So, just what exercise is best for building bone? And, what can avid cyclists do to preserve their bones?
We understand that bones need unique forces to stimulate osteoblasts to make new bone. Exercises that involve repetitive activity, such as swimming, paddling, running, and cycling, work well at first, but their effects are diminished over time and eventually can lead to bone loss. Swimming actually decreases bone density and a study of water polo players showed that over the season, the players lost bone density in their legs and gained bone density in their arms! (Kavouras, 2006) Swimming simulates a low gravity environment like being in space. Astronauts lose bone density at an alarming rate while in space. Many drugs were originally developed for astronauts to prevent bone loss. Obviously, the space program has a lot of money to devote to this type of research. Cycling is a close second to swimming in the bone density race. It is only a little better than swimming and much worse than running in building bone. (Rector, 2008) Cycling is non-impact and repetitive and the more cycling the less responsive the bone. Competitive cyclists generally don’t do any weight training to be as light as possible. Cyclists stay in rounded spinal positions for long periods of time which can be detrimental for putting the spinal vertebrae at risk for fractures in those with low bone density. Ever seen the cyclist’s humpback?
Another aspect to consider with repetitive high-intensity exercise is the fact that muscles need calcium for contractions and when the calcium stores run out in the bloodstream, where do the muscles get their calcium? From the bones! Bones are the storehouse for the body’s minerals: calcium, magnesium, boron, manganese, zinc, potassium, copper, etc. Vitamin D is also very important for absorption of calcium. For some mysterious reason, studies have shown that worldwide, people are low in vitamin D levels. If you cycle many miles per week, replace your calcium with at least 1500 mg per day and take 1000 IU’s of Vitamin D (this RDA recommendation has increased from 400 IU’s).
Let’s put the best exercises for building bone in order: gymnastics, volleyball, soccer, high-impact aerobics, tennis, strength training, running, cycling and swimming….you get the idea.
If you are an avid cyclist and care about preserving your bones, it is a good idea to include strength or jumping training for the hips. (squats, lunges, vertical jumps off an 8” step) Add some back extension exercises for strengthening the bones of the spine. You might question, “back extension exercises”? Sinaki, a scientist from the Mayo Clinic has been doing research for about 25 years on exercise and bone, and has found that spinal extension exercises performed in the prone position to strengthen the back muscles are the best for building bone in the spine. (Sinaki, 2007) Think of the Roman Chair in the gym…
If you are going to start strength training….How many repetitions? How much resistance? How often?
Repetitions: A set of 10 repetitions should be very difficult to complete if you are training at the right weight and training for strength. If you can complete 20 repetitions, the weight is too light and won’t build strength or stimulate bone.
Resistance: For lunges, squats and back extensions use the heaviest weight that you can lift 8-10 times.
Frequency: Anywhere from 1-3 times per week sessions of weight training or high impact exercise has been shown to stimulate bone.
Dynamic High Impact Exercise: Adding some weight-bearing dynamic high impact activities would be a good idea for cyclists to incorporate in their training programs. Since cycling does not include impact, I think that this type of exercise is imperative for the devoted cyclist in preservation of bone density. FYI: Walking does NOT build bone!
Whatever you do, don’t quit cycling, especially if it makes your heart sing! One study showed that the bone density of exercisers as compared to non-exercisers can be exactly the same, but the quality of the non-exercisers bone is different. The bones of exercisers are stronger and less prone to fracture! (Tolomio, 2008) Bone quality is very difficult to measure, is very expensive to measure and puts one in the vicinity of high doses of radiation.
So keep cycling, add a little impact exercise, take extra calcium and Vitamin D and enjoy life!
If you have any questions about this article or about bone health, feel free to write or call 831-476-3100.
REFERENCES:
1) Barry DW, Kohrt WM. BMD decreases over the course of a year in competitive male cyclists. J Bone Miner Res. 2008 Apr;23(4):484-91.
This study showed that from pre-season to post-season, cyclists showed a progressive loss of bone density in all areas of the femur (hip/thigh bone)
2) Campion F, Nevill AM, Karlsson MK, Lounana J, Shabani M, Fardellone P, Medelli J. Bone Status in Professional Cyclists. Int J Sports Med. 2010 Apr 29.
BMD was measured in 30 professional road cyclists mean age: 29, height, weight, fat mass, VO(2) max as compared 30 young healthy males used as reference with similar characteristics as well as calcium intake. Bone density of the skull was similar but in arms, legs, spine, pelvis, and femoral neck the cyclists were significantly lower. The femoral neck was 18% lower in the cyclists.
3) Kavouras SA, Magkos F, Yannakoulia M, Perraki M, Karipidou M, Sidossis LS.
Water polo is associated with an apparent redistribution of bone mass and density from the lower to the upper limbs. Eur J Appl Physiol. 2006 Jun;97(3):316-21.
4) Rector RS, Rogers R, Ruebel M, Widzer MO, Hinton PS. Lean body mass and weight-bearing activity in the prediction of bone mineral density in physically active men. J Strength Cond Res. 2009 Mar;23(2):427-35.
This study showed that long-term running and resistance training increase bone density while cycling does not.
5) Rector RS, Rogers R, Ruebel M, Hinton PS. Participation in road cycling vs running is associated with lower bone mineral density in men. Metabolism. 2008 Feb;57(2):226-32.
Cyclists had significantly lower BMD of the whole body and spine than the runners, despite having similar age, weight, body mass index, body composition, hormonal status, current activity level, and nutrient intakes. 63% percent of the cyclists had osteopenia of the spine or hip, compared with 19% of runners. The cyclists were 7 times more likely to have osteopenia of the spine than runners, controlling for age, body weight, and bone-loading history.
6) Sinaki M. The role of physical activity in bone health: a new hypothesis to reduce risk of vertebral fracture. Phys Med Rehabil Clin N Am. 2007 Aug;18(3):593-608.
Sinaki discusses her research in spinal extension exercise and increased bone density of the spinal vertebrae.
7) Smathers AM, Bemben MG, Bemben DA. Bone density comparisons in male competitive road cyclists and untrained controls. Med Sci Sports Exerc. 2009 Feb;41(2):290-6.
Cyclists had lower bone density than age and body-mass matched controls even with higher calcium intake.
8) Tolomio S, Ermolao A, Travain G, Zaccaria M. Short-term adapted physical activity program improves bone quality in osteopenic/osteoporotic postmenopausal women. J Phys Act Health. 2008 Nov;5(6):844-53.
by Sherri R. Betz, PT, GCS, CEEAA, PMA®-CPT
TheraPilates® Physical Therapy Clinic, Santa Cruz, CA
Chair of the Bone Health Special Interest Group American Physical Therapy Association
Board Member American Bone Health
Polestar Pilates Educator
PMA® Certified Pilates Teacher
www.therapilates.com
