Got Vertical? How to Measure for Explosive Strength

What Is Explosive Strength?

Explosive strength is defined as the ability to cause or produce high forces at short range with little effort. This term refers to the ability of a muscle group to generate high amounts of force when subjected to a load applied over relatively small distance.

The definition of explosive strength was first proposed by John Bloch (1926) in his book “Strength” (Bloch, J., 1926). The concept of explosive strength is based on the fact that the human body is capable of generating high levels of force under certain conditions. These are not always ideal situations, but they do occur.

In order to understand why it occurs, one must consider that muscles have two main functions: contraction and relaxation. When contracting, muscles shorten their length and lengthen their diameter while maintaining a constant amount of tension. During relaxation, muscles relax and return to their original length and diameter.

When performing any type of exercise, the primary function of the muscle fibers is to contract. However, during these contracted states there are other functions occurring such as metabolic processes that require energy (glycogen), cellular repair processes (myofibrillar protein synthesis), etc. These activities may take place in the resting state or they may occur after contraction.

The last states of a muscle fiber that we will address is relaxation and the ability of a muscle to relax quickly. When a muscle contracts, it fatigues. Fatigue is the state where a muscle can no longer maintain adequate force to overcome the resistance applied to it. You can test this by extending your arm straight out from your side and raising it up until you can’t lift it any further.

This is the point of fatigue. When your arm has fatigued, you can’t bring it back down to your side.

If you hold the fatigued position for a short period of time, the muscle will relax and you can lower your arm. If you wait too long, the muscle will no longer be able to relax and you may need the help of another person to lower your arm. The ability to relax is also a function of the metabolic and energy processes that are occurring within your muscle fibers and blood vessels.

Arteries have a dual purpose in that they not only deliver blood to your muscles, but they also receive blood from your muscles. The contraction and relaxation of your muscles not only effect the delivery of blood, but also the amount of refilling of your arteries.

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If you contract your muscle fibers, the arteries are compressed decreasing the amount of blood they can hold. When you relax your muscle fibers, the arteries fill back up to maximum capacity. So, although your muscle fibers are able to relax and refilling can occur, they may not completely fill back up (depending on how long you held the contraction) and re-expand to their original diameter.

When a muscle fiber is fatigued it has also gone through a process known as molecular diffusion. This process is another one of those maintenance functions that transpire in your muscle fibers or any other living cell for that matter.

Molecular diffusion (or osmosis) is when a substance moves from an area of high concentration to an area of low concentration. When you contract a muscle fiber, the amount of potassium within that muscle fiber becomes greatly concentrated. It is important that the amount of potassium within the muscle fiber remain relatively constant.

For this reason, when the amount of potassium becomes excessively concentrated, it leaves the muscle fiber and enters the bloodstream. It then migrates into the area of your body that has the lowest amount of potassium (usually your blood plasma). In any case, if the muscle fiber doesn’t completely relax and refill with blood, the potassium will not be able to return to its original state. In other words, you will have less potassium within that muscle fiber which may lead to muscle cramps and/or fatigue.

One last process that occurs within your muscle fibers is autogenic inhibition. Autogenic means “self” and inhibition simply means to impede or restrict. So, autogenic inhibition is a process within the muscle fibers that restrains their ability to contract.

When a group of muscle fibers are repeatedly contracted and relaxed (like when you do repetitions at the gym) autogenic inhibition gradually sets in and therefore restricts the ability of those muscle fibers to contract. If autogenic inhibition worked instantly, you would not be able to do more than one repetition with any weight because your muscles would instantly fatigue. Fortunately, it takes a little time for the autogenic inhibition process to set in so you can do more than one repetition.

As you can see, the body is extremely complex. You have to control intricate muscular movements while maintaining metabolic and energy processes within your body. This is why even the most basic of our daily functions can be a challenge. In this respect the body can be seen as a finely tuned machine that requires maintenance and energy.

On this level, the body is a machine of flesh, bones, muscles, and organs.

If you think about it, your body is an extremely complex organism made up of many smaller and simpler organisms (cells). In order for your body to be able to produce the energy required to sustain itself and the energy required for movement, it requires fuel. This fuel comes in the form of bio-chemicals produced by plants through photosynthesis.

Sources & references used in this article:

Effects of plyometric training on the explosive strength of volleyball players by R Dhauta, S Bura – Indian Journal of Physical Education, Sports …, 2014 – indianjournals.com

The effect of plyometric training program on young volleyball players in their usual training period by K Vassil, B Bazanovk – Journal of Human Sport and Exercise, 2012 – redalyc.org

Impact of whole-body vibration training versus fitness training on muscle strength and muscle mass in older men: a 1-year randomized controlled trial by A Bogaerts, C Delecluse, AL Claessens… – The Journals of …, 2007 – academic.oup.com

The effects of eccentric contraction duration on muscle strength, power production, vertical jump, and soreness by JN Mike, N Cole, C Herrera… – Journal of Strength …, 2017 – ingentaconnect.com

The effect of exercises by using VertiMax device in the development of explosive strength and defensive blocking for handball players by HAA Al-Lami, YH Abbas, HAM Al-Raheem – 2020 – rua.ua.es

Measurement of Explosive Leg Strength in Relation To Different Axes by A Khatun – 2015 – kheljournal.com

Body composition, isometric hand grip and explosive strength leg–similarities and differences between novices and experts in an international competition of … by FJ Diaz-Lara1ABCDE, JMG García1ACDE… – researchgate.net

Comparative effect of two variations of circuit training on explosive strength, strength endurance and speed of movement of judokas by P Ahmed – 2018 – theyogicjournal.com