Send letter to journal:
Re: Pseudo science

Dear Editor

Does BJSM even use its review process? Being a runner and running trainer and scientist, I am embarrased about this article.[1] The news *running is unhealthy* quickly went the round. Here in Germany it already was in TV text, in several online newspapers (with headlines like 'Run into Osteoporosis'), and has reached internet discussion boards. It will supposedly appear in printed matter starting tomorrow.

The authors measured bone mineral density in female endurance runners. What, if there was no correlation between running and bone mineral density? No paper! There was no non-running group for comparison. What, if there was no correlation between running distance and bone mineral density? No paper!

Fortunately, there was a correlation.

The results of the regression analyses suggest that the bone mineral density of the lumbar spine and femoral neck are controlled by different parameters. They also suggest that aging alone increases the bone mineral density in the lumbar spine at ages from 18 to 28, whereas it decreases in the femoral neck from age 18. Does anybody believe this?

The suggested effects of running on bone mineral density are in the range of the standard deviations of the measurements. If they even existed, they would be overprinted by the much stronger effects of other parameters (according to the regression equations), i.e. age.

The regression equation regarding the bone mineral density of the femoral neck leads to manifold surprising results. For example, that the entire suggested effect of running would be compensated by a half Mg fizzy tablet per day.

This paper is a perfect example of pseudo-science. The Press turns its 'suggestions' into 'truths'. Thousands of female runners are made feeling insecure. It's embarrassing.

Reference

(1) M Burrows, A M Nevill, S Bird, and D Simpson. Physiological factors associated with low bone mineral density in female endurance runners. Br J Sports Med 2003;37:67-71.

Send letter to journal:
Re: Is athlete bone loss due to excess hormone 1,25-D?

Dear Editor

We cannot help but note the correlation between the results of this study of female athletes, and the study conducted on male long distance runners in Denmark [1]. We propose that sunshine might be the common factor driving the observed bone loss in these two, apparently disparate, sets of athletes.

The secosteroid hormone 1,25-dihydroxyvitamin-D (1,25-D) is a potent stimulator of osteoclast activity [2], and excessive levels of 1,25-D have a direct effect on BMD [3].

1,25-D is manufactured by skin keratinocytes upon exposure to sunlight [4]. Sunscreens have no measurable effect on the amount of 1,25-D produced by solar exposure [5].

Endurance runners are clearly exposed to unusual amounts of direct sunlight during both practice and competition, and we believe that excessive concentrations of 1,25-D could well have been an unconfounded variable in this study.

We would urge measurement of the level of this hormone during any future study of BMD in outdoor athletes.

References

(1) Hetland ML, Haarbo J, Christiansen C. Low bone mass and high bone turnover in male long distance runners. J Clin Endocrinol Metab 1993 Sep;77(3):770-5.
Pubmed Abstract

(2) Manolagas SC. Birth and Death of Bone Cells. Basic Regulatory Mechanisms and Implications for the Pathogenesis and Treatment of Osteoporosis. Endocr Rev 2000 Apr 01;21(2): 115-137.
 Publisher Full Text.

(3) Adams JS, Lee G. Gains in Bone Mineral Density with Resolution of Vitamin D Intoxication. Ann Intern Med 1997 Aug 1;127(3):203-6.
Publisher Full Text

(4) Marshall TG, Marshall FE. New Treatments Emerge as Sarcoidosis Yields Up its Secrets.Clinmed 2003 Jan 27;2003010001 Full Text