Injury to the quadriceps muscle group is a common injury in sports, and MMA is no different. Currently, there are at least two MMA athletes rehabbing from tears to the quadriceps muscles- Alistair Overeem and Ryan Jimmo. Jimmo is set to return to the Octagon June 15 at UFC 161 after injuring his quad in February. Overeem injured his quad in early March, and is now rehabbed to the point where he is engaging in three hour training sessions, as he recently noted on Twitter. Experience tells me that there are probably many quad injuries in MMA that are never reported as injuries, since they are not severe enough to limit the athlete's training.
The quadriceps muscle group is composed of four muscles on the front of the thigh. One of these muscles, the rectus femoris, is particularly vulnerable to injury because it crosses the hip joint and the knee joint and is subject to forces and stress generated by both joints.
The quadriceps are primarily active in kicking, jumping, running- basically, everything that you do on your feet. For the MMA athlete, quad muscle injuries can occur in a few different ways. One of the more interesting injuries involves a sudden, forceful eccentric contraction of the quads. An eccentric contraction, sometimes called the "braking" contraction, is one in which the muscle is contracting and maintaining tension while it is lengthening. (For example, the quads are maintaining eccentric contraction when you descend stairs.) This type of injury could occur when a fighter plants his foot in a bent-knee position to execute a quick direction change. In this instance, the quads will have a sudden eccentric load across the muscles.
Another mechanism of quad injury that could occur in the cage is through forceful extension (or straightening) of the knee. The quads generate power to extend the knee when finishing off a kick. When the lower leg meets a resistance (ie, the opponent's head/body/leg) and comes to a sudden stop, one of the quadriceps muscles can be strained. Regardless of the method of injury, muscle fatigue has been shown to play a role in acute muscle injury, meaning that a fatigued quad muscle could be more prone to a strain (or tear).
Recovery from a quadriceps tear can take up to 12 weeks, depending on the severity of the injury. There are no real consensus criteria for safe return to sport activity following muscle strain injuries. Therefore, the experience and MMA-specific knowledge of the fighter's rehab team is very important. Ultimately, the fighter needs to perform well on functional tests that simulate actual combat (grappling, striking, jumping, cutting, etc.), without an increase in pain or swelling at the injured area of the quadriceps.
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