More recently, myofilament protein changes have been studied in humans in response to resistance training. Again, researchers are not completely clear about the molecular mechanisms of change, and an alteration of fiber-type composition in the myofilament may not be the answer many athletes have long assumed. This study looked at the muscle specific tension in the quadriceps femoris and vastus lateralis of forty-two young men. Researchers report a 17% increase in specific muscle tension after a period of resistance training, despite a decrease in the presence of MyHC, myosin heavy-chain. This study concludes that there is no clear relationship between fiber-type composition and in vivo muscle tension, nor was there evidence of myofilament packing in the trained muscles.