Grains of Salt
Everyone has pet peeves. One of mine involves the current relationship between the media and medicine.
It seems to me that the past few years have seen an exponential increase in media coverage of medical study “results.” Newspapers, magazines, and TV news programs report almost daily on the latest findings on this and that, that and this. And while I believe wholeheartedly in freedom-of-the-press, I also believe in the old maxim “a little knowledge can be a dangerous thing.” Too often, the information transmitted is incomplete, simplified, and frequently downright misleading to the general public.
Truth be told, the lay public is ill equipped to analyze and understand the complexities of scientific studies. Additionally, the pressures brought to bear on scholarly investigators these days is so intense that the design and methodology of studies is very often compromised. In fact, a former director of the Duke U. Center for Health Policy Research and Education recently asserted that only about 1% of articles in medical journals are scientifically sound!
A perfect example of this appeared today in Runner’s World Online (January 8, 2002), in an article discussing a study published in the International Journal of Sports Medicine (January 2002). Researchers from Great Britain examined the relationship between stretching and running economy. According to the article, the results of the study were the opposite of the “conventional wisdom” held by most running experts that holds that greater flexibility facilitates increased running economy (i.e., the efficient use of oxygen). In this study, runners with the worst flexibility – as measured by scores on a “sit and reach test” – had the highest running economy! The head researcher theorized (note the word) that “stiffer musculotendinous structures reduce the aerobic demand of submaximal running by facilitating a greater elastic energy return” during the running stride. In other words, tighter muscles act like springs of some sort. Now, that may sound like a plausible explanation, enough perhaps to allow some reluctant stretchers a convenient excuse to save themselves time every day. The problem is, there are some real problems with these findings due to what some might consider a narrow scope and even, perhaps, a faulty experimental design.
First of all, the number of runners studied (32) would probably be considered by most researchers to be a too-small sample size; the smaller the sample, the less reliable the results. Second, defining flexibility by the sit and reach test is questionable: the alleged “tightness” could have more to do with the spine than the hamstrings, so this test’s relationship to running economy is not really valid. Even if it did give an accurate representation of hamstring flexibility, this is only one muscle group. It does nothing to test the opposing muscles – the hip flexors – that could have as much impact on a runner’s performance.
More important, perhaps, is the fact that this study only looked at the correlational result between a flexibility test and a running economy test in a group of athletes. It did not consider the question of whether each individual’s oxygen usage changed after they followed a stretching program for some period of time. Such an investigation would more accurately assess the value of stretching in relation to the improvement of performance.
This is just one example of the dangers inherent in too readily accepting as gospel the summary findings of studies that are reported by the media. As Mark Twain once said, there are three types of lies: lies, damned lies, and statistics. All research should be reviewed with a healthy dose of skepticism by the lay public and with a fine toothed comb by the professional community, before any findings are applied. In other words, before you jump on any bandwagon that will change your approach to training, injuries, etc., take what you hear and read with a grain of salt.
But then again, studies do show that consumption of salt leads to high blood pressure, heart disease …