Use variable resistance equipment to boost testosterone and get bigger.

HYPOTHESIS Variable resistance equipment — such as cam-based exercise machines, strength bands and chains — provides greater resistance throughout the range of motion. Free weights and standard machines — such as the leg press, Smith machine and cable station — do not provide variable resistance. Benefits of variable resistance include the recruitment of more muscle fibers during an exercise for greater strength and size gains, and higher levels of anabolic hormones, such as testosterone and growth hormone.

RESEARCH Researchers at the University of Jyväskylä (Finland) wanted to see if variable resistance machines boosted testosterone and GH more than standard machines. Male subjects performed five sets of 10 reps on a standard leg press or on a leg press that provided variable resistance by increasing resistance toward the top of the movement. The researchers measured the men’s testosterone and GH before and after workouts on the different machines.

FINDINGS As reported in Medicine and Science in Sports and Exercise, testosterone levels increased by almost twice as much on the variable resistance machines compared to the regular leg press.

CONCLUSION It appears that using variable resistance equipment can bump up testosterone levels more than invariable resistance equipment.

APPLICATION Many bodybuilders claim that free weights have far more benefits than weight machines. However, this study shows that using cam-based weight machines, which allow the resistance to increase during the range of motion at the point where muscles are strongest, can lead to higher levels of testosterone. Although this study did not use strength bands, it could be projected that since strength bands also provide variable resistance, they also have that effect. So consider adding machine exercises at least toward the end of workouts and using strength bands occasionally in your training.