New Stimulus & ROM
Question: I am an avid biker, so I use my legs quite intensely. Nearly daily, in fact. A week ago I squatted; I was incredibly sore, for nearly the entire week. What's the deal?! I use my legs ALL the time!
*Followup questions: Do you squat often? If so, did you perform an unusual amount of volume? More than you're accustomed to?
*Followup answer: This was my first time squatting in nearly a month.
Answer: Any new stimulus placed upon the body will usually result in some type of soreness. Since you hadn't squatted in a month, the novel movement shocked your system. More importantly, though, although you use your legs "intensely" on a regular basis, you're not taking them through a full range of motion -- the range of motion a squat would take your lower extremity through. When you bike, your knee and hip joints remain in a somewhat flexed position. Because of this angle, your muscles aren't activated while stretched; you're used to hours of concentric contraction. (Check out the Concentric-Eccentric video from a few days ago.) When you squat, you've performing a contraction that is not normal to you. Because you're not used to the stretched state while under load, you experienced trauma to your muscle fibers. This could have happened with something as simple as 2 sets of 5-8 reps. Someone who only executes the leg extension then performs a squat for the first time in a month would experience the same result, FYI. In the future, I would incorporate more squatting, and other compound movements into your routine. The increased strength you gain will give you just a little more force on each revolution as you pedal. And you won't be as sore if you get into a more regular lifting routine.