Many of my clients complain that the knee extension machine is not comfortable. What are your thoughts? How would you effectively use this machine? What are your suggestions on quadriceps training?
As with all exercises (movements), you should always have a goal. If you were to state your goal is to isolate the knee extensors (quads), then the knee extension machine fits the goal. However, like many, this machine is considered a non-functional means of load application. The strength gained on this fixed plane apparatus is not useful unless a conscious effort is made to apply the strength through patterns of movement. Research has shown that unidirectional strength training (seated leg extension) of the agonist (quadriceps) can reduce co-contraction of the antagonist (hamstrings). This could be considered a serious situation, as it may compromise joint stability and predispose some population groups to an increased risk of injury. Unidirectional strength training is not advisable for people who require the control of joint stabilization through co-contraction. We are not saying this machine is bad! However, like all exercises, the selection should fit your objective!
For example, let's consider that your client’s goal is maximum muscle hypertrophy of the knee extensors. The knee extension machine can be a useful tool. Performed correctly, you can isolate knee extension, thus employ a stimuli to the quadriceps. The key component is in understanding the body, not the machine! In other words, do not conform to the machine - the machine should conform to you! Over the years, I have witnessed many participants sit in the leg extension machine without any attempt to make adjustments for their anatomy. Quite often, a person will sit in an externally rotated position at the hip, causing the knee, which is a functional hinge joint, to experience disproportionate loads. This improper alignment is analogous to hanging on a door as it swings.
To perform this isolated exercise as safe as possible, I have provided a knee extension machine guideline along with an alternative way to perform knee extension using a whole body approach. I hope this expands your thought process when considering exercises for your clients as well as yourself.
Knee Extension Machine Guidelines
- The axis of each knee must be aligned with the fixed axis of the machine.
- The knee caps should point straight up so they appear centered.
- The foot position is not an indicator of knee alignment
- The entire leg should be held firmly against the seat to prevent the butt from raising when initially lifting the load.
- It also prevents a "seesaw" action from being employed to lift more weight.
Performing a standing leg extension emphasizes the quadriceps while strengthening the stabilizers (the little muscles that keep the big muscles moving smoothly and efficiently). Improving the strength of the standing leg will help to preserve the hip, knee and ankles. Other benefits include:
- Improved coordination of legs, trunk and upper body
- Full body workout = greater caloric expenditure
- Multiple training angles
- Improved leg stamina
- Postural challenge
When performing the Standing Cable Knee Extension, follow these guidelines:
- Stand "tall" with working leg attached to an ankle cable strap.
- If support is available in front of you, use your hands to balance; otherwise balance free form.
- Draw your belly button in toward your spine.
- Straighten the cable-attached leg forward.
- Maintaining control, return to the start position and repeat movement.