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.

Results

• 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.

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.

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.

Mens-fitness-and-health.com 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.

Active vs. Passive Recovery Between Exercise Bouts

Active recovery between bouts of exercise involves the performance of low-level exercise rather than rest, while passive recovery involves rest only. Opinions vary as to whether active or passive recovery produces better performance on subsequent exercise bouts. Two articles in the January 2011 issue of the Journal of Strength and Conditioning Research ( vol. 25, no. 1) address this issue.

The first article, by Toubekis et al. (pp. 109-116), examined the effects of passive and active rest on repeated swim sprint speed:

Experimental Procedure
10 male competitive swimmers averaging 18 years of age performed eight 25-meter swim sprints separated by 2 minute recovery periods. After the last 25-m sprint, a 6 minute recovery period was provided before a single 50-meter sprint. On different occasions each subject’s recovery periods were as follows:

• A - passive rest
• B - swimming continuously at 40% of the maximum velocity they could sustain for 100-m.
• C - swimming continuously at 60% of the maximum velocity they could sustain for 100-m.

The 25-m sprints took in the range of 11.5-13.0 seconds to complete.

Results:

• Statistically, the passive recovery and 40% of max speed recovery produced significantly faster 25-m times than did the 60% of max speed recovery.
• The average 25-m time with the passive recovery was faster than the time with the 40%-max recovery. However, the difference did not reach statistical significance.
• There was no statistically significant difference between recovery methods for the 50-m sprint.

The second article, by Miladi et al. (pp. 205-210) examined the effects of recovery by passive rest, active rest, and dynamic stretching on 4-minute work bouts and subsequent stationary bicycling time to exhaustion.

Experimental Procedure:
10 soccer athletes averaging 26 years of age exercised on a stationary bicycle at high intensity (20% higher than the power output they exhibited at their maximal rate of oxygen uptake) 4 times for 30 seconds, with 30 seconds of passive rest in between for a total of 3.5 minutes. They then had a 4 minute recovery period before doing another 3.5-minute exercise bout of the same kind. Following another 4-minute recovery period, they then cycled as long as they could at the same high intensity used in the exercise bouts. On three different occasions the 4-minute recovery periods consisted of:

• passive recovery: no exercise
• active recovery: they kept cycling, but at low intensity (30% of the power output at their maximal rate of oxygen uptake)
• dynamic stretching using 4 different lower body stretches, each done for 30 seconds. Between the stretches, "dynamic awakening" muscular exercises were done.

Results

• Dynamic stretching and active recovery both resulted in significantly longer time until exhaustion (~20%) than passive recovery.
• Dynamic stretching resulted in about 8% longer time until exhaustion than active recovery, but the difference didn't reach statistical significance.

Bottom Line
The first study indicates that passive recovery or low-intensity active recovery were most effective for 2-minute recovery periods separating 11.5-13.0 second bouts of swim sprinting. However, the second study found that stretching or active recovery was more effective than passive recovery following 3.5 minute work bouts separated by 4-minute recovery periods. The main difference between the studies lies in the duration of the work bouts and rest periods. The activities also differed - swimming and cycling.

Looking at the results of these two studies and the results of similar studies, it appears that for short sprints (under 20 seconds) and short rest periods (under 3 minutes) passive recovery is most effective, allowing short-term energy stores in the muscles to replenish. However, for longer sprints and longer recovery periods, active recovery or dynamic stretching may be more effective.

Since the effectiveness of a recovery method depends on sprint duration, recovery interval, and type of activity, it seems best for coaches to try the different recovery methods to see which one is most effective for their specific sport program.

13 Iowa Football Players with Rhabdomyolysis: A Case of Coaching Incompetence

Thirteen University of Iowa football players were recently hospitalized for rhabdomyolysis caused by extreme physical exertion. Symptoms of the ailment include dark-colored urine, fatigue, muscle weakness, and muscle tenderness. Although the athletes have since been released from the hospital, information has not been released as to whether any permanent injury has resulted.

Rhabdomyolysis is a serious medical problem. It occurs when myoglobin leaks out of muscle cells due alcoholism, crush injuries, heatstroke, extreme physical exertion and other causes. Just as hemoglobin in red blood cells carries oxygen to the muscles and other body tissue to provide energy through oxidation of carbohydrates and fats, myoglobin carries oxygen within the muscle cells to the mitochondria, which are the oxidative energy-production units within the cells. Myoglobin is a large molecule and, when it leaks into the blood stream, it travels to the kidneys for removal. However, the myoglobin molecules are too large for the kidneys to readily clear, and can easily block the kidney’s filtration system. In addition, myoglobin breaks down into potentially harmful compounds. Permanent kidney damage or even kidney failure may result, which may require lifelong dialysis or a kidney transplant. See the National Institutes of Health for further information on rhabdomyolysis.

Extreme muscle soreness brings with it with a significant risk for rhabdomyolysis. Virtually all muscle soreness is attributable to the eccentric phase of exercise, which occurs when the muscle is lengthened while resisting. This occurs in the lowering phase of every weightlifting or calisthenic repetition, and also in the initial ground-contact phase of running, particularly downhill running. It also occurs during the deceleration phase of sports activities, as in braking for directional change and bringing a moving limb to a halt.

There is no excuse for any strength and conditioning coach to induce rhabdomyolysis. The press has reported that the workouts of the Iowa football players were extremely severe and may have been used as a punishment. One athlete said, “I had to squat 240 pounds 100 times and it was timed. I can’t walk and I fell down the stairs.” Another one said, “Hands Down the hardest workout I’ve ever had in my life!”. In addition, the severe workout occurred just after the athletes returned from winter break, during which most of them had not engaged in heavy resistance exercise. That made them particularly vulnerable to extreme muscle soreness and rhabdomyolysis.

Such an approach is totally unnecessary. Firstly, exercise should never be used as a punishment. Secondly, any knowledgeable and competent coach has to be aware that any exercise regimen that induces extreme muscle soreness presents a significant risk for rhabdomyolysis. Muscle soreness is not a prerequisite for muscle strengthening! The most effective way to increase strength is to start with light resistance and gradually increase the weight lifted over a period of time as the muscles strengthen. High repetitions are totally unnecessary for strength and power athletes like football players. Muscle fatigue following a workout is expected and desirable within limits, but muscle soreness is unnecessary and can actually slow down progress in strength development.

An extensive article and interview of coaches, doctors, and a parent of one of the players is available on the Internet.

Fatty Liver Disease: Another Reason to Avoid Obesity

An article in the January 2011 issue of the Harvard Health Letter reveals that the epidemic of obesity has increased the occurrence of fatty liver disease. Previously, most cases of fatty liver disease were related to excess alcohol consumption, but now, many cases are related to excess body fat, which can lead to Type II diabetes. Fatty liver disease affects 70-90% of those who are obese and/or have diabetes.

Abdominal obesity can lead to metabolic syndrome (elevated blood pressure and levels of triglycerides and blood sugar, and low HDL (good cholesterol). Overfilled fat cells become resistant to insulin (which lowers blood sugar by storing it in the cells) resulting in excess fatty acids in the blood. Fat then accumulates in liver cells, which can lead to inflammation and liver tissue damage.  This can in turn bring about liver fibrosis (buildup of fibrous tissue) or cirrhosis (buildup of scar tissue). Cirrhosis increases the risk of liver cancer.

Fatty liver disease increases the risk of heart attack and stroke because a fatty liver produces inflammatory factors that can promote the deposition of plaque in the arteries, leading to arterial narrowing.

The only effective treatment for fatty liver disease is to lose weight.

Bottom Line
If you want to avoid or reverse fatty liver disease, avoid gaining unnecessary body fat or lose existing excess body fat through a program of good nutrition and exercise. Both caloric restriction and exercise are essential parts of any weight-loss program.

As We Age, Cholesterol Level Loses Its Value as a Risk Factor

Because both a high total cholesterol level and a high LDL-cholesterol level are risk factors for heart disease, statin drugs, which lower both levels, are widely prescribed. In the U.S., more prescriptions are written for Lipitor, the most popular statin, than for any other drug. Estimates for the number of people who take statins range between 11 million and 30 million. But should so many people be taking statins? A recent analysis, in which scientists reviewed 14 studies that included data from over 34,000 patients, showed little evidence that statins prevent heart trouble in patients with no history of cardiovascular disease. And because there is some evidence linking low cholesterol levels with increased risk of death from other causes, the study authors feel that doctors should be more cautious about prescribing statins.

An important factor to consider when deciding whether or not to prescribe statins is the patient’s age. A study by Kronmal et al., entitled, “Total Serum Cholesterol levels and mortality risk as a function of age” in the Archives of Internal Medicine (vol. 153, pp. 1065-1073, 1993) examined how age affected the ability of cholesterol level to predict the risk of dying, and it showed that the predictive value declined with age.
The most important consideration when judging mortality risk is the overall likelihood of dying from any cause. In that regard, at age 40, those people with higher total serum cholesterol levels had a significantly higher all-cause mortality risk. However, the relationship declined with age, and by age 60, the relationship between total cholesterol level and all-cause mortality had vanished. By age 80, the relationship actually reversed, so that those with higher cholesterol levels were at significantly lower risk of dying.

Looking specifically at the risk of death from coronary heart disease, the death risk at ages 40, 50, and 60 years was greater for those with higher cholesterol levels, although the effect got smaller with age. By age 70, the relationship was still positive but weak, but by age 80 the relationship reversed, and those with higher cholesterol levels actually had less chance of dying.

Looking at death due to causes other than heart disease, (e.g. cancer), from age 50 on, there was a lower risk of dying as cholesterol levels rose. This apparent protective effect of cholesterol against non-heart-disease death increased with age. Seventy-three percent of 80 year-old men with cholesterol levels above 240 survived for 5 years, while only 49% of those with levels below 240 did. The effect was in the same direction but weaker for women, with a 74% and 70% 5-year survival rates for women with cholesterol levels respectively above and below 240 mg/dl. In regard to cancer alone, higher cholesterol level was associated with lower death risk.

Bottom Line
The current practice of the medical establishment of prescribing statins to anyone with a total cholesterol level above 200 appears to be unjustified. For patients with elevated cholesterol levels and a history of heart disease, statins provide a proven reduction in risk. However, for patients with mildly elevated levels and no history or heart disease, the evidence in favor of prescribing statins is weak or nonexistent. And for men above age 70, even those with cholesterol levels above 240, statins could very well increase the risk of death.