While moving, I lifted and carried multiple containers of text-books with no problems. While hiking the South Sister, I carried a back-pack with extra clothing and extra water for sharing and/or safety with no problems at all. During the summer, I completed two triathlons with no trouble at all. I then stopped swimming and started lifting weights and strained my back in one week's time.
The strain is on the right side and seems to be a deep pain. I think I know when it occurred, and it's a good example of improperly using equipment. I sat down on a "multi" machine and prepared to use the "lat-pull down" part of the machine. I didn't notice the position of the dual back-support/chest support relative to the pull-down bar, and quickly reached up to grasp the bar. During this process, my body naturally adjusted to an abnormal position. I also remember I slight rotation, which was probably due to an unbalanced vector multiple reaction of the chest support. Initially, I felt a strain and was happy I didn't hurt my back. After-all, I began lifting because I wasn't to meet women. Statistically, I have a greater chance of "talking" to a woman in our community exercise facility than I do while swimming, mountain biking, or running. Anyhow, I have experienced some pretty serious pain in the last few days, and I have had some difficulty putting on my socks, or bending over in general. That should attract women!
What did I strain? A mutifidus? I hope so because that is a cool name for a muscle. What about the Illiocostalis lumborum? Maybe the rotators or semispinalis was strained. I am getting older; I'm a 39 year old divorced male, so it may be a muscle's aponeueoses since collagen is a major component. As one gets older, we lose some of the visco-elastic behavior of certain fibers. Silly-puddy is a good example of a visco-elastic material, and the Deborah number is a measure of a viscous or elastic response. I am an older male who doesn't drink enough water but exercises regularly; since the human body is pretty efficient, my body probably conserves water by "directing" it to more important organs. Although the back muscles are important, stability isn't difficult to achieve while swimming or running. On the other hand, I did bike and that requires a little more action. Still, not the immediate reaction caused by the inappropriate use of equipment designed for stressing back muscles is a different region of the body. In addition to conservation of water, the concentration of water in connective tissue usually drops as one ages. In turn, the fibers become less elastic. As such, tears and bulges can occur in muscle. Now, back to the Deborah number which is a fitting name considering my real reason for lifting! It is a measure of the time scale of deformation and relates to a "solid" as behaving as an "elastic solid" or a "viscous liquid". If a muscle's connective tissue has lost water, the collagen fibers don't "slide" so easily. As such, an instantaneous force could cause the connective tissue to "tear". Back to Silly Puddy.: Grab it with two hands and slowly pull it apart. The middle section will flow from the force of gravity. On a molecular level, the molecules are "sliding" over each other like a "fluid" or viscous material. Now, make a ball out of the silly puddy and throw against the wall or floor. It behaves like an elastic solid and bounces. If you form the ball into a "cylinder", grab it on each end and pull it apart quickly, it will shear like a metal. Is this what happened to me? Although some connective tissue exhibts visco-elastic properties, the tear would probably look more like a "fraying" rope.