But before you believe it, bear in mind that the 'athletes' in this study were actually adult sheep, not humans at all (Radin, EL, et al, 'Effect of Prolonged Walking on Concrete on the Knees of Sheep,' Journal of Biomechanics, Vol. 15(7), pp. 487-492, 1982). The study's authors provided no clues as to whether the sheep had engaged in strength training prior to their 2.5 years of death-marching, and a sceptic could reasonably argue that loading forces - and the musculoskeletal responses to those loading forces - might be somewhat different in human knees, compared with what happens in sheep. Although we haven't fallen prey to the popular idea that sports shoes are 'medicine' against injury, we should at least also point out that the sheep in the study were not clad in expensive clodhoppers, but preferred to clatter about on unshod hooves.
However, we've saved the juiciest bit for last. Although the hard-walked sheep had shoddier cartilage, their knee-joint bones had remodelled themselves and were unusually strong! In addition, there was no real evidence that osteoarthritis was present, so the sheep had adapted pretty well to their marathon-a-day schedules.
Similarly, research with rabbits has also failed to link running with the progression of knee osteoarthritis (Videman, T, 'The Effect of Running on the Osteoarthritic Joint: An Experimental Matched Pair Study with Rabbits,' Rheumatol Rehabil, Vol. 21(1), p. 1, 1982).
'The runners did not have a higher incidence of severe knee and hip pain than the swimmers, nor did the runners undergo surgical procedures more often'
Better still, a follow-up study carried out with humans also failed to link locomotory movements on terra firma with long-term leg damage. Former college athletes from seven major US colleges were interviewed by questionnaire; 504 had been cross-country runners, and 287 were swimmers. The follow-up periods ranged from two to 55 years, with a mean of 25 years; the oldest subject was 77 and the youngest 23, with a mean of 57. As it turned out, the runners did not have a higher incidence of severe knee and hip pain, or even moderate discomfort, comp-ared to the swimmers, nor did the runners undergo surgical procedures for the relief of pain more often. In other words, there was no evidence at all to support the idea that running sports 'broke down the knees'.
The researchers also failed to link either running mileage or the number of years spent running with the development of osteoarthritis (Sohn, Roger S and Micheli, Lyle J, 'The Effect of Running on the Pathogenesis of Osteoarthritis of the Hips and Knees,' Clinical Orthopaedics and Related Research, Vol. 198, pp. 106-109, September 1985).
Briefly, an even better study carried out at Stanford University determined that disabling problems in the legs were five times as likely to occur in sedentary individuals, compared to athletes who engaged in running. Shockingly, the Stanford researchers' data ran against the idea that more running meant more injury, finding that running 15 miles per week cut muscular and skeletal problems by 60%, compared with running five miles per week or less (Anderson, O, 'What's the Truth about Running and Bad Knees?' Running Research News, Vol. 11(8), pp. 10-12, October 1995).
The lesson? If you want your legs to fall apart, your best strategy is to do nothing. If you become sedentary, your leg muscles and bones will decline in function at a rather brisk and predictable rate. Despite what you may hear from the chattering classes, banging your bones and joints around a bit ends up protecting them, instead of wearing them down.