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Thursday, March 31, 2011

Is Cycling Actually Detrimental to Bone Health?

An article by Nichols and Rauh in the Journal of Strength and Conditioning Research (vol. 25, no. 3, March, pp. 727-734, 2011) showed that hours of weekly bicycling exercise, in the absence of weight-resisted or impact exercise may actually be worse for bone density than no exercise at all. While such exercise seems fine for keeping the heart, lungs, and circulatory system healthy, and bodyweight under control, the evidence shows that it is a poor exercise for bone health.

Experimental Procedure
The study tracked, over a 7-year period, bone density in the lumbar spine, total hip, and femoral neck (segment of the thigh bone adjacent to the pelvis) as well as body fat and lean tissue measurements of 19 Master’s competitive cyclists and 18 non-athletes, who averaged 51 years of age at the start of the study.

  • At both the initial and final testing, the cyclists had consistently lower bone mineral density at all sites measured than the non-athletes.
  • After statistical adjustment for changes in body mass index, lean mass, calcium intake and exercise habits, the cyclists lost more bone mineral density over the 7 years than the non-athletes.
  • The subjects who reported doing weight-bearing or impact exercise lost significantly less bone density in the spine and femoral neck than those who did not do such exercise.
  • At initial testing, 84% of the cyclists and 50% of the non-athletes met the criterion for osteopenia (subnormal bone density).
  • At the final testing, 90% of the cyclists and 61% of the non-athletes met the criterion for osteopenia.
  • Six of the cyclists but only one of the non-athletes had full-blown osteoporosis (critically low bone-density) by the end of the study.
  • Even when they were made aware of bone-density problems, very few of the subjects changed their diets to include more calcium.
Bottom Line
The evidence provides a strong indication that cycling is not beneficial to bone health. If done in the absence of weight-resisted exercise (e.g. squat, deadlift) or impact exercise (e.g. running, gymnastics, dance) bone loss is likely to result. One hypothesis is that the lack of impact or weight on the bone fails to stimulate mineralization, while calcium-containing sweat is lost during heavy cycling exercise. Another possibility is that endurance exercise tends to suppress testosterone, which helps maintain bone mass. Older competitive cyclists are at great risk for bone fracture because of their low bone density and high risk of bicycle crashes. Weight-resisted or impact exercise should be started when people are young because that is when bone is most readily mineralized.

Tuesday, March 29, 2011

Maintaining Strength and Muscle Mass As We Age

An article entitled, “Staying Strong: How exercise and diet can help preserve your muscles” appeared in the April 2011 issue of the Nutrition Action Health Letter, a publication of the Center for Science in the Public Interest. The article stated some interesting facts, including:
  • Starting in their late 30s and early 40s, most people lose a quarter pound of muscle per year.
  • Several studies have shown that resistance exercise can restore and preserve strength and power, even at an advanced age.
  • Resistance exercise also helps prevent loss in bone density and may even reverse age-related loss.
  • People with Type II diabetes can lower their blood sugar by doing resistance exercise.
  • After a large protein feeding (~ 30 grams, the quantity in 4 ounces of cooked meat) both younger and older people show equivalent protein synthesis (muscle-building) responses.
  • After a small protein feeding (~ 14 grams, the quantity in an egg plus a glass of  milk) younger people synthesize about half the protein they synthesized in the large feeding BUT PEOPLE OVER 60 SHOW ALMOST NO PROTEIN SYSTHESIS. In other words, the larger protein portions are necessary for the older people to synthesize any protein at all. However, anything above 30 grams of protein in a meal is either burned off as energy or stored as fat. So extremely large protein meals do not aid in muscle-building.
  • Of the 9 essential amino acids that our bodies can’t manufacture and must ingest, leucine is by far the most important for muscle development, especially for older individuals. Researchers recommend a minimum of 3 grams of leucine per meal, in addition to other amino acids. Animal products generally have relatively high percentages of leucine. Protein from whey (a byproduct of cheese-making) is relatively high in leucine and makes a good protein supplement.
  • Plant protein contains a smaller percentage of leucine, but soy is the best of the common plant proteins in regard to leucine content.
  • According to researchers, ingesting protein shortly after exercise provides the greatest boost for muscle building. Two hours is the longest one should wait before ingesting protein after resistance exercise.
  • While the U.S. Institute of Medicine set a Recommended Daily Allowance (RDA) of 0.36 grams of protein per pound bodyweight per day, researchers feel that about 0.50 grams of protein per pound bodyweight per day can best promote muscle building and minimize muscle loss as we age.
Bottom Line
Regular resistance exercise and adequate protein intake are essential for increasing and maintaining strength and muscle mass, especially as we age. A daily protein intake of half a gram per pound bodyweight is recommended (e.g. a 200 lb person should take in 100 grams of protein daily). The protein should not be concentrated in one meal but should be distributed over the day in meals containing about 30 grams of protein.

Thursday, March 3, 2011

New Army Physical Fitness Test to Simulate Battlefield Activities

On February 28, 2011 the Official U.S. Army website reported that, after 30 years of using the same physical fitness test, the Army is developing a new physical fitness test battery to better simulate battlefield activities. The previous test was comprised of the following 3 tests done with a short rest in between:
  • As many pushups as possible in 2 minutes
  • As many situps as possible in 2 minutes
  • Running 2 miles a quickly as possible
Scoring was based on age and gender. See our web site for testing details and scoring charts.
The revised test has not been finalized, but trials are being held this month on 7 Army bases and at the U.S. Military Academy at West Point. A review and approval process will take place before full implementation. The article states that there will be a general physical readiness test for all soldiers and a physical readiness test for those going into combat:

Army Physical Readiness Test
  • 60-yard shuttle run
  • one-minute rower (see diagram)
  • standing long-jump
  • one-minute push-up
  • 1.5 mile run
Army Physical Readiness Test
The examinee will be timed while performing the following obstacle-course sequence while wearing a combat uniform and helmet and carrying a rifle:
  • 400-meter run
  • Low hurdles
  • high crawl
  • Over and under
  • casualty drag
  • Balance beam while holding ammo cans
  • Point and move
  • 100 yard shuttle sprint while holding ammo cans
  • Agility sprint around cones
See the Army article for a diagram of the course. As with the current Army Physical Fitness Test, scoring charts will be developed that take age and gender into consideration.

The change in the fitness tests appears to be a good one because the new test more closely simulates battlefield physical demands. It might even be better if the Physical Readiness Test were performed while the examinees carried a combat load similar to those normally worn by soldiers. is very supportive of functional training that seeks to improve performance in sports, combat, or daily living. Function-based training programs emphasize improved physical performance rather than appearance. Workouts designed to “get big” generally train isolated muscle groups and do not prepare the body for strenuous whole-body physical demands.