Muscle Activation Blog –Series
Timo Haikarainen
Muscle activation blog –series 1/4
Muscle activation ability – put thought and effort into this, if you feel like improving!
This blog text is about the development of some very critical factors in strength training. Some of the things will be quite, let’s say, ‘professional or hi-tech’ while others are rather ‘normal and common sense’. It is important to keep in mind that 95% of essential factors related to strength development are just simple and common sense. In this text I will cover a theme, which in the talks is termed often as a “feel”, “innervation” or something along those lines. So what I will go through is the activation ability of the muscle. The subject is very wide and involves very large amount of sub-factors. But we need to start from somewhere so let’s start with activation capacity of the muscles.
Muscle activation capacity – crucial factor for strength development
The muscles are activated via the central nervous system. In simple terms, an idea to execute movement arises in the motor cortex of the brain. From there neural impulses travel downwards along spinal cord and then along motor nerves all the way to the muscles responsible to execute the movement. In the muscle neural impulses, after several chemical reactions, causes contraction of the muscle.
Muscles must therefore be able to activate effectively, in order to produce power efficiently. We should be able to command muscle tissue (we happen to have) to do what we want, as efficiently as possible. It has been argued whether humans can activate their muscles completely. According to several investigations complete activation is not possible and activation deficit tends to increase, for example with aging and after (bed-rest-like) inactivity. Activity deficit phenomena can be studied with the method called superimposed twitch. In this method, motor nerve is stimulated electrically during maximal voluntary contraction. If stimulation causes a peak in the strength production, there is an activation deficit in the muscle. Method is applicable to laboratory conditions and of course, as any method, it has it shortcomings (Shield et al. 2004). From my experience using the method in the research setting, I can tell the method is not the most enjoyable, although it doesn’t rank in the top in the most annoying methods either.
Next blog in will answer the question, whether average person training in the gym has activation deficit or not?
Figure 1: Superimposed twitch method can be used to assess the ability to activate muscles. Individual is doing maximal contraction and if the electrical stimulation results in an increase in force, there is an activation deficit. Activation percentage can be assessed by comparing the force of the twitch during maximal contraction to one given to relaxed muscle.
