Lower-body workouts, including leg extensions, are a necessary but often neglected aspect of weight training. Working out the legs is crucial to achieving overall fitness. A number of compound exercises will engage the muscles that comprise the lower body, but these routines engage most of your leg muscles all at the same time. To target specific muscles, use isolation exercises. For the legs, effective weight-training exercises require the use of a machine.
Effective leg extensions primarily target the quadriceps, but also incorporate both sections of the trapezius and the levator scapulae for stabilization. As an isolation exercise, the leg extension will engage the quadriceps through two phases: the lift phase and the control phase. During the lift phase, the quads contract as you bend at the knee. During the control phase, you slowly lower the resistance against gravity, stressing the quads as they extend.
For leg extensions that successfully isolate the quadriceps muscles, you have three types of available equipment: the seated lever machine, the lying lever machine and the standing cable-pulley machine. Both styles are simple to use and provide an effective exercise, but each only engages the primary target of the quads. The standing cable-pulley machine brings in a broader network of muscles to stabilize you as you stand, but it requires you to attach an ankle strap to your leg, maintain perfect posture as you bend at the knee, and permits you to work out only one leg at a time. With the lever extension machine, you can engage both legs simultaneously.
Sets and Reps
You can use a number of set/rep systems for your leg extensions, but determining the most effective depends on your goals. If you’re seeking to improve the muscular endurance of your quads for certain types of athletic performance, go with light weight through 15 to 20 repetitions. If you want to develop mass and power in the quads, cap the number of reps at between eight and 10, and go heavier on the weight. Remember, leg extensions are an isolation exercise, so don’t overstress your quads by trying to lift too much weight.
Rest and Recovery
To be ultimately effective, follow up your leg extensions with enough rest time to recover and let your quad muscles regenerate. It helps to organize your workouts so that all of your lower-body exercises are performed in the same session. Wait at least one full day before working out the quads again, but two full days is better. The only way your leg extensions will be effective is if you can improve your performance during the exercise through multiple sessions. Overtraining will diminish your performance and increase your risk of muscle strain and injury.
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