Abstract
Dear Editor:
First, the title of this article is misleading. Thermography is incapable of “assessing the efficacy of a therapeutic exercise program” because a program's efficacy depends upon what the goal of the program may be. If therapeutic exercise (an all-inclusive term) is being used to improve strength, then its efficacy is assessed on the basis of strength gain. Similarly, if therapeutic exercise is given to improve endurance, or cardiovascular fitness, or whatever, its efficacy will be determined by those outcome measures. Thermography cannot fulfill that requirement. And indeed, the study described in this article had nothing to do with using thermography to “assess the efficacy of a therapeutic exercise program.” Instead, the exercises that were given were designed to produce muscle damage, as determined by the development of delayed (late)-onset muscle soreness (DOMS). DOMS is clearly not a goal of therapeutic exercise.
Second, the purpose for using thermography in this study was based on the supposition that “…individuals with diabetes may have altered feeling of DOMS or may not feel this type of muscle soreness due to their neuropathies.” This theme of diminished ability to perceive pain is repeated several times. For example, (1) in the Abstract we are told, “But because they [patients with diabetes] usually have neuropathies, they may not feel this soreness appropriately, leading to premature return to exercise and causing further damage.” (2) In the Introduction, we are told, “However, people who have diabetes often have neuropathies, and in this case they may not be able to feel the muscle pain as well as normal individuals, thereby giving false VAS [visual analog scale] readings.” And, (3) “The advantage of using thermal imaging is that, unlike subjective pain measurements, which can be altered by the individual's sensation of pain and the associated neuropathies from diabetes, thermal imaging would actually provide very useful information relative to the damage in the muscle.” In other words, the authors are driving home their point that thermography should be able to detect temperature increases due to the inflammatory response associated with DOMS, thus providing evidence of damage that these patients might not be able to sense.
However, the results of this study did not bear out this presumption of impaired pain sensation. To the contrary, subjects with diabetes actually reported more pain following the prescribed exercises than did the subjects who did not have diabetes. Therefore, this study did not support the speculative basis upon which it was conceived. Patients with diabetes were quite capable of knowing when the exercise damaged their muscles. They felt the pain. The logical conclusion then is that one does not need infrared thermography to know that exercising subjects with diabetes have damaged their muscles. They are quite capable of reporting they hurt. But, the authors blithely ignore this contradiction to their basic premise and conclude the Discussion with these two sentences: “Thermal imaging would then be a painless and noninvasive way of detecting DOMS in its early stages, which could minimize further injuries from over-exercising both in healthy individuals and in people who have diabetes. This could be more beneficial for the individuals with diabetes as they do not always realize that they are sore, because of the neuropathies and impairments they may have.” 1 Not according to this study.
Third, inspection of Table 1 shows that for both the abdominal and biceps muscle groups, the diabetes subjects were on average twice the age of their counterparts without diabetes. The authors apparently missed the importance of this glaring discrepancy between the groups as there is no further mention of it in the article. But using the data given in the Table, a t test for independent means showed that indeed the ages of the normal and diabetes subjects are significantly different (P<0.001) in both muscle groups. Therefore, for all we know, this study compared responses to a DOMS-inducing exercise not between subjects with and without diabetes, but between “young” and “elderly” subjects.