Friday, June 29, 2012

Run For Your Life, But Not Too Far

Once again, we have a story of "the dose makes the poison." In the fitness world many believe that if running 5 miles is good for you, running 10 might double the benefit. Apparently not.

A recent study presented at the American College of Sports Medicine's annual meeting suggests that shorter distances (less than 20 miles per week) provide a greater mortality benefit. (1) While this is an unexpected finding, the more shocking news is that with increasing distance the reduction in mortality doesn't just level off but actually but reverses.

Dr. Duck-chul Lee led the research, a part of the Aerobics Center Longitudinal Study (ACLS) which includes 52,000 men and women in a retrospective analysis. Subjects entered the study free of cardiovascular disease, EKG abnormalities, diabetes and cancer. They were followed for 15 years.
Running was associated with a 19% lower risk of all-cause mortality compared with individuals who did not run.

Interestingly, how fast you run is important too. Subjects who ran 6 and 7 miles per hour had a significant (21% and 27%) lower risk of all-cause mortality. Those running faster (8 or more miles per hour) had a nonsignificant decrease in risk of all-cause mortality.

The most robust decrease in risk of death was seen in subjects who ran between 10 and 15 miles per week.

How often you run also makes a difference. The benefits of running were lost in those running more than 5 days per week.

While it is possible that some unmeasured variables might have contributed to these findings, the investigators corrected for other known factors such as age, gender, smoking status, blood pressure, and cholesterol levels.

The ACLS study coincides with the publication of a review paper in the Mayo Clinic Proceedings on the possible causes of heart damage seen in participants of long-distance endurance events (marathons, Ironman, long-distance cycling).(2) The review suggests that such activities may cause fibrosis of the heart muscle that can lead to arrhythmias and coronary artery calcification and hardening.

The bottom line is less is more. This data should not be a reason not to run. A regimen of up to 20 miles a week in 2 to 5 sessions at a pace below 8 miles per hour looks best.

So, run for your life, not too far, too fast, too often.  


1. Lee DC, Pate RR, Lavie CJ, et al. Running and all-cause mortality risk--is more better? American College of Sports Medicine 2012 Annual Meeting; June 2, 2012; San Francisco, CA. Presentation 3471.
2. O'Keefe JH, Patil HR, Lavie CJ, et al. Potential adverse cardiovascular effects from excessive endurance exercise. Mayo Clin Proc 2012; 87:587-595.

Men, Aging and Bone Loss

Osteoporosis, a weakening of bone that increases the risk for fracture, is usually thought of as a postmenopausal woman's problem. However, about 20% of the 44 million Americans who have osteoporosis or low bone mineral density are men.(1) And men fare less well with this potentially painful and debilitating condition.

30% - 40% of osteoporosis related fractures occur in men.(2) In those cases involving hip fracture, men have a mortality rate two to three times greater than women.(3,4,5) Because this represents a significant public health issue the Endocrine Society recently released a review of the topic with updated practice guidelines.

All adult men should have osteoporosis on their radar as one of the chronic conditions to monitor and take steps to prevent. Here is a brief overview of this condition and summary of the Endocrine Society's recommendations.

The increased risk of fracture due to osteoporosis occurs approximately 10 years later in men than women. Race, ethnicity, location and lifestyle all contribute to one's risk. North American and Northern European men have the highest rates of fracture due to osteoporosis, while Blacks and Asians have the lowest. (6)  Interestingly, the female to male ratio among Caucasians is about 3-4:1 whereas it is around 1:1 in Asians.(7) Smoking, sedentary lifestyle, and excessive alcohol consumption significantly increase risk.

Hormone levels play an important role. There is no question that the anabolic effects of testosterone are beneficial. But relatively recent investigation has demonstrated that estrogen is at least as important in men for healthy bone maintenance.(8)


Who is at risk and should be evaluated?
All men over 70 years of age and 50-69 year olds with a history of delayed puberty, hypogonadism, hyperparathyroidism, hyperthyroidism, chronic obstructive pulmonary disease, glucocorticoid or GnRH agonists, alcohol abuse or smoking.

Lifestyle recommendations include reduced alcohol intake for those men who consume three or more units of alcohol per day. Smoking cessation should also be a priority. They suggest weight-bearing activities for 30-40 minutes per session, three to four times per week. If vitamin D levels prove to be low (<30ng/ml) supplementation is encouraged targeting a blood 25(OH)D level of at least 30ng/ml. Men at risk for osteoporosis should consume 1000-1200 mg of calcium daily. Ideally this should come from dietary sources rather than supplements. A recent study suggests that calcium supplements may increase the risk for heart attack in women. This association has not been observed in men.

These interventions, in conjunction with a variety of medications when necessary, can prevent the progression of osteoporosis, a condition which need not compromise the quality of life.

(1) Burge R et al. 2007 Incidence and economic burden of osteoporosis-related fractures in the United States. J Bone Miner Res 22:465-475
(2) Bliue D et al. 2009 Mortality risk associated with low-trauma osteoporotic fracture and subsequent fracture in men and women. JAMA 301:513-521
(3) Frosen L et al. 1999 Survival after hip fracture: short- and long-term excess mortality according to age and gender. Osteoporos Int 10:73-78
(4) Haentjens P et al. 2010 Meta-analysis: excess mortality after hip fracture among older women and men. Ann Int Med 152:380-390
(5) Holt G et al. 2008 Gender differences in epidemiology and outcome after hip fracture: evidence from the Scottish Hip Fracture Audit. J Bone Joint Surg 90B:480-483
(6) Maggi S et al. 1991 Incidence of hip fractures in the elderly: a cross-national analysis. Osteoporos Int 1:232-241
(7) Kanis JA et al. 2002 International variations in hip fracture probabilities: implications for risk assessment. J Bone Miner Res 17:1237-1244
(8) Gennari L et al. 2008 Estrogen land fracture risk in men. J Bone Miner Res 23:1548-1551
(9) Watts NB et al. June 2012 Osteoporosis in Men: An Endocrine Society Clinical Practice Guideline. J Clin Endo Metab: 97(6):1802-1822