Because runners do the same movement over and over again, too much of it without too introducing variations in distance or speed can be the cause of excessive friction between the cartilages surrounding the knee, resulting in an irritation of the soft issues within as well as the posterior surface of the knee cap. (fitnessandpower.com)
In all cases, the problem lay with contaminated nickel plating and debris found in the fuel pump, which causes excessive friction resulting in possible pump failure. (topspeed.com)
You get a temporary flat stomach that looks fantastic on the beach, but you also get a tucked pelvis, no butt muscles used when walking, no real core engagement, and excessive friction in the lumbar spine, hips and knees... and a hypertonic pelvic floor. (thebellemethod.com)