Your Threshold to Resistance-How to Determine if an Exercise is Safe
Is this exercise good for me?
Exercises in fitness industry are often identified as “safe” or “unsafe”. In reality, the same exercise can be safe for one and unsafe for another. It’s the readiness of ones body that determines whether one should perform a given exercise. The body has a threshold to resistance, and once crossed, injuries may ensue. To prevent these injuries, a personal trainer should plan a strategic progression of exercises that will eventually raise the threshold to resistance.
Personal trainers often condemned a number of exercises as “bad” for you. These exercises are considered to put too much stress on a targeted joint(s) or muscle groups. For example, many personal fitness trainers and some physical therapy practitioners would claim that the knee extension exercise can be dangerous because it may place great amount of shear force on the knee. It is often suggest that a healthy alternative exercise to knee extension is a squat, because the forces are more efficiently distributed through the body.
Identifying an exercise as dangerous greatly oversimplifies the issues. The reality is that there are no “bad” or “good” exercises, but rather the safety of an exercise depends on the readiness of a joint being loaded. This is why one client may feel pain in the knee when performing knee extension while another client may feel the same pain while performing squats. The client performing knee extension may have weak quadricep muscles, and therefore performing knee extension with a heavy weight may be dangerous to him/her. On the other hand, the other client may have unstable foot and ankle but strong quadricep muscle. Such client would benefit more from knee extension exercise, while squats may be dangerous to him/her. Both of these client may be experiencing the same symptom, however, they qualitively differ in their capacity to withstand physical load.
All joints, and the muscles that stabilize them, have set threshold to a mechanical load they can withstand. A heavy load or exorbitant frequency can exceeded the threshold of a muscle group. Let’s take running for example. The mechanics of running should not be stressful. However, the cumulative effect of that load can inflict injury. So this takes us to the original question; is running a safe exercise? Many researchers recently have been suggesting that running may not be safe. Many runners have problems with over pronating at their feet. It is important to remember that the foot must pronate every time it lands on the ground in order to absorb the shock. However, if this is repeated at a frequency that the body cannot handle, than it is likely that the pronating system will collapse. In other words, if the foot can pronate properly throughout the entire run, than running is a safe exercise. On the other hand, I keep hearing how sand volleyball is a good sport for the knees because a.) of a softer absorption due to the sand b.) the feet are not restricted by shoes so the mechanics of the feet are properly expressed. Nevertheless, plenty people that play beach volleyball suffer from issues such as back pain, knee, and feet pain. Once again, it is erroneous to say that a particular sport is “good” for your knees or your back. A volleyball player whose muscles of the feet are not stable is likely to suffer knee and back pain because the demand placed on the feet in the sand are too great. Feet in the sand have to work harder as compared to playing on hard court while wearing shoes. As the feet are overstressed, the forces from the ground are poorly translated to the rest of the body, causing the knees and the back to suffer. So the bottom line is, running, sand volleyball, or any other sport/exercise can be safe and beneficial but only if the body is ready for such stress
How to increase threshold to stress
Strategically progressed exercise program in my opinion is the most effective method to raising ones threshold to physical stress. For example, a personal training client has a shoulder pain when performing a military press. It is important to identify a motion that is the weakest (or most limited in range of motion). Let’s say that this personal training client has hard time raising his/her arm to the side past a 110º angle. If necessary, I would use muscle activation technique to stabilize the joint. I would then design very light exercise that would train that movement only up to 90º angle. Isometrics (for definition on isometrics refer to my web site under resources/Jan 09 news letter) are also very effective. A client would basically LIGHTLY push his/her arm against a stable object in the direction of the affected range of motion. With time, the range of motion should improve, however the threshold for physical stress may still be low. An exercise like shoulder press with dumbbells may be advised (using light weights). When the motion is stable under light weight through the entire range of motion, a heavier weight is advised to increase the strength and therefore the threshold to physical stress. After this point the client may return to military press.
The following are some key points about strategic exercises:
- find the most weak/limited component of movement
- regress intensity of exercises when movement is unstable and progress only once you gain stability through such movement
- Never train through (joint) pain!!
- Allow enough rest in between workouts
- alter exercise modalities (heavy lifting vs. light, circuit training vs. cross training) and body parts.
Published : February, 2009