For Hamstrings & Quads
To save time, and since many gyms place their front and rear leg machines close together, try this superset. After at least a 10-minute warm-up on the stationary or recumbent bike or light weight warm-ups, begin with a set of heavy leg extensions for 8 reps.
Immediately upon completing the eighth rep, go right to the lying leg curl machine and do 15 reps. Once you’ve done the 15th leg curl rep, go right back to leg extension and lower the weight by 20% and do 12 reps. After the 12th rep, jump back on the leg curl machine, and increase the weight by 20% and do 12 reps.
After the 12th leg curl rep, immediately jump right back on the leg extension machine, decrease the weight by another 20% and do 20 reps. After the 20th leg extension rep, jump back on the leg curl machine, increase the weight by 20% and do 6-8 reps. Quickly get off the machine after your last rep and just stand in one place without moving for 20-30 seconds. THEN, take a step forward. What a pump.