Muscle Failure – What is it and why it is important?
To properly train using High Intensity Training methods you need to understand what momentary muscle failure is and why it is important. In simple terms it means you perform as many repetitions as you can. But there is a bit more you should understand to obtain full benefit from your exercises.
Muscle Failure Basics
Muscles fibers actually work in just two ways. They contract or shorten and also they can lengthen back to an extended of stretched position. The shortening form of contraction is termed concentric contraction. When the muscle are lengthening the term is eccentric contraction. The terms positive and negative contraction are often used to describe there two types of exercise movements. It should be noted that you are stronger with eccentric contractions than you are with concentric contraction. If you think about it, your body naturally HAS to work this way. You can lift something heavy and you will always have the strength to lower it back down. If it were the other way around, you would be able to lift something heavy but than you would always drop it immediately. Nature knew how to design logical muscle function!
As you go thru a normal strength training exercise you will be contracting the muscle thru the full range of motion for that particular movement. As you continue to perform the repetitions you become more and more fatigued obviously. You want to fully stress and fatigue the muscle in a safe and proper fashion. It is this form of stress that will eventually provide your fitness benefits. 
There are various types of muscle fibers within the major muscle groups. Each has it’s own function and ability. The most efficient training exercise is one that will use all the available muscles fibers. This is accomplished by exercising the muscle to the point of momentary muscle failure. This is the point at which you can no longer complete another repetition in good form. You want to push yourself to the point when you fail in you attempt to complete the movement. Usually this point of failure will occur at about the mid range of the movement.
Let’s use push-ups as an example. You do several push-ups in good form. It gets harder as you go along. You are getting very fatigued. You complete a repetition that is very hard to do. But then you try to do another one and about have way up your pushing muscles are so tired you have to cannot complete the push-up you are attempting. You are pushing up as hard as you can but there is zero movement upward. You are going no further. This is the point of concentric momentary muscle failure. Now you lower your self slowly back down and you have successfully reached failure!
Intensity is Hard to Perform
Training to failure is certainly difficult. It requires disciple and the proper attitude. It is my belief that understanding the significant benefit you obtain by working to muscle failure will help you train in this high intensity fashion. Many people are following programs that are simply based on doing a certain number of reps per exercise. The problem with that is it almost guarantees that you will NOT work to muscle failure and you will NOT get full benefit form the exercise. If you say to yourself “I will try to do 10 reps” you will probably do your 10 reps and stop, ending your exorcise short of muscle failure. A much better approach is to have the attitude that “I will do as many reps as I can possibly do in good form”. With that type of thinking you are much more likely to work harder and get more benefit from your fitness training.
Another part of the exercise attitude has to do with your perception of the “training to failure” process. You will certainly feel you muscles working hard and the harder your work the more you feel them. It is common for a person to think of this feeling as “pain”. If you perform a set of leg extensions to failure you may find it rather painful. Your attitude of this feeling of muscle pain can be altered. You may benefit if you think of it not as pain but something else, perhaps as “muscle fatigue sensation” or as the “muscle fiber recruitment process”. Pain is generally considered as a very negative word so labeling it as something else will hopefully make the process and the feeling far more tolerable. It really is a matter of your attitude!
Is Training to Muscle Failure Safe?
The simple answer is YES, Training to muscle failure is safe if done correctly. As with any form of exercise you should consult with you medical profession if you have any physical concerns prior to undertaking any exercise routine. From a mechanical standpoint the structural forces should not create a potential of injury. In general muscle and tendon injuries such as strains and pulls occur when a sudden force is applied to them. The muscle structure is damaged because of the excessive forces applied. When you are doing resistance training is good form, meaning using slow and controlled movement, the amount of force will be approximately the same as the amount of weight being moved.
For example if you are lifting 50 pounds the amount of force required to move the weight will be approximately 50 pounds. But if the movement used is faster the acceleration increases the force placed on the muscles and connective tissue. This is determined by the Law of Movement equation that states Force equals Mass times Acceleration. This is why proper form is vital to decreasing the risk of injury. This also shows why activities that use fast explosive movement such as Powerlifting and Cross Fit training place additional and potentially injurious force on the muscles, tendons and joints.
As a person fatigues while training toward failure the ability of the muscle to exert excessive forces is greatly decreased. In the case of an exercise using a 50 pound weight, at the point of failure the muscle is fatigued to the point that it can only create 50 pounds or less of force. You are so fatigued that you cannot exert enough tension to create potentially harmful forces. That is why the weight can no longer be lifted. At that point there is very little risk of a force related injury.
You can easily perform this educational demonstration with a simple experiment you can do at home. Stand on a bathroom scale holding a dumbbell. Let’s say your bodyweight is 150 pounds and you stand still on the scale with a 10 pound dumbbell. The scale with read at 160 pounds obviously. Then quickly jerk the weight up by doing something like a fast curling motion or a fast overhead press motion. Watch the scale closely. When the dumbbell is moved quickly the reading on the scale will jump up fast and may go up as high as 170 or 175 pounds, actually reading more that than your combined bodyweight and dumbbell weight. That is because of the additional force created by the upward movement. Then just as suddenly the scale’s reading will drop down below 160. That occurs because your acceleration created momentum which carries the weigh up for a large portion of the range of motion.
There is initially a high spike in force followed by by a momentum phase where decreased muscle tension if used. So if the scale reads 152 pounds that means that 80 percent of the 10 pound dumbbell weight is not being lifted by muscle tensing throughout a significant portion of the range of motion. If you do the same thing but move in a slow manner the scale’s reading will be about 160 throughout showing that you need to exert about 10 pounds of force to move the 10 pounds and that there’s is no period of excessively high downward forces. This is because you have eliminated the use of momentum to help carry the weight. The obvious conclusion is that using proper slow form keeps the correct tension thru the range of motion and avoids excessive forces.
With a good understanding of training to muscle failure and how to do so in proper form you are well on your way to conducting highly effective workouts. The benefits you can obtain from a High Intensity Training routine will include –
- Muscle Strengthening and Hypertrophy
- Improved Metabolism and Faster Rate of Burning Calories
- Reduction in Bodyfat
- Decreased Risk of Injury
- Improved Heart and Cardiorespiratory Health
- Helps Manage Blood Sugar Levels and Reduces Risk of Diabetes
- Promotes Greater Mobility and Flexibility
- Boosts your Self-Esteem
- Improves Brain Health and Cognitive Function
- Improves Bone Health Reducing Risk of Osteoporosis and Bone Injuries
- Promotes a Better Quality of Life
- Assists in Maintaining Mental Health
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