What is Short Arc Quads?
Short arc quads is a famous exercise that helps increase the strength of the muscles around the knee joint. You may have heard physical therapists mentioning about or providing this famous exercise as part of a session or home exercise program.
What muscles are involved in Short Arc Quads?
As the name suggests this exercise works on quadriceps muscles. Quadriceps is a group of four muscles. Short arc quads particularly work on vastus medialis muscle. This particular muscle is found to be active during terminal stage of knee extension (knee straightening that is).
The terminal stage of knee extension is a last 15 to 20 degrees of knee straightening from full knee flexion. Terminal knee extension is important in many functional activities like standing, walking, going up and down the steps etc. In addition, terminal knee extension determines the overall strength of the knee joint. It also is associated positively to reduce fall risk in the elderly person.
How to perform Short Arc Quads?
Short arc quads is nothing but performing last 15 to 20 degrees of knee extension. It is usually performed in a long sitting position. One can also perform the same exercise in supine (lying on back) position. Depending on the strength of the muscle, a physical therapist may perform this exercise in a prone position to use gravity in favor rather than against. When appropriate one should perform this exercise with external weight to increase the strength of the muscle.
So in a long sitting position, place a rolled towel or a bolster (roller) under your knee. Gently, raise your heels so that your knee comes to full extension (straight) position. Hold this position for 3 to 5 seconds in a pain-free range.
Since this exercise only works to strengthen the particular muscle, it is advisable to transfer to functional activities when you have good muscle strength. Examples of some functional activities are performing sit to stand, squatting, walking, running etc that can work on the whole body including quadriceps. Also, the majority of these exercises include different contractions of the same muscles. So it challenges the muscle more than just plane strengthening exercise.
When to perform Short Arc Quads?
There are many indications to perform this exercise. Below are the major symptoms that a person should perform short arc quads.
- Osteoarthritis of knees and hips
- Knee pain
- DJD of Knee
- Prior or after the knee replacement surgery
- Knee ligaments surgery
- Knee meniscus injury or surgery
- After hip surgery
How to progress Short Arc Quads?
As I mentioned earlier, one can start short arc quads in long sitting or supine position. The next step to progress is to add some weight gradually to the exercise. The good rule of thumb is to start with 2 lb weight and ask a person to perform 10 repetitions pain-free.
If a person is unable to perform this then you want to reduce the weight or reduce the number of repetitions. You can increase the weight gradually, or increase the frequency of the exercise. The other idea is to increase the hold at the full extension – like 3 to 5 seconds of hold at each extension. You can work your way up to 10 seconds of a hold.
The difference in increasing the repetitions versus increasing the hold is the type of muscle fibers being targeted on. The previous one targets fast twitch muscle fibers while later targets on slow twitch muscle fibers. Concentration on different fibers helps you to perform different types of activities. In usual cases, it does not matter a lot and just concentrating on both will be a good idea. Contradictory, if a person is training for specific sports than working on specific muscle fibers will make difference. For example, fast twitch muscle fibers more concentrate on force generation, speed of the movement, while slow twitch muscle fibers work on endurance, agility etc.
As I mentioned earlier, one can perform functional activities concentrating on the whole body when they are ready.