Strength training has been growing in popularity over the last few decades and a good thing too. The benefits of strength training are numerous (1-11):
Increased Strength (duh).
Increased Speed, Power and Sporting Performance.
Decreased risk of injury.
Increased muscle mass.
Increased mobility and functionality.
Improved bone health.
Improved cognitive function and health.
Increased Cardiovascular health.
Even suggestions of decreased risk from Cancer.
To name a few...
Whilst it does finally feel that we are getting past the days of only associating strength training with pumped up bodybuilders, we do feel there is still a split of those who do strength training and those who don’t.
Those who do, love it and can’t get enough of it. While those who don’t now have different misconceptions and a world of social media to contend with when trying to figure out if it is for them or not.
This article aims to give an easy to understand low down on what strength is, what is useful, where to start and how to train safely.
So where else to start than.... what is strength?
Strength is the product of muscular action initiated and orchestrated by electrical processes in the nervous system of our bodies. Classically strength can be defined as the ability of a given muscle or group of muscles to generate force under specific conditions (11).
To expand and continue the orchestral theme; strength, and indeed all human movement, can be viewed in two parts.
The Conductor - our Brain and Central Nervous System(CNS) and the Band - the Muscles.
For simplicity's sake lets start with the band, or the muscles of the human body. The more muscle you have, the more potential you have to produce force. That goes without saying and makes common sense, although potential is the key word here.
Until relatively recently coaches and scientists believed that strength gains were predominantly from an increase in muscle mass, however recent research has shown this to be inaccurate.
To explain why we need to delve a little deeper into muscle physiology (Fig 1).A typical skeletal muscle is made up of thousands of ‘muscle fibres’. For example, the bicep brachii alone has been estimated to contain approximately 250000 muscle fibres (8).
These muscle fibres are controlled by nerve receptors called motor neurones. Each neurone controls a different number of muscle fibres from a few fibres per neurone to thousands of fibres at a time. It has been suggested there are in the region of half a million neurones in the human body (10) controlling millions and millions of fibres. The collective name for a neurone and all the fibres it controls is a motor unit.
Returning to the orchestral metaphor, imagine having to conduct a multi-million piece orchestra split down into half a million sections (strings, woodwind, brass etc). It would take some serious skill and a lot of practice! This is a relevant analogy to human movement and producing force.
The role of the Conductor, aka our brain and the neurological components of the muscles (the neuromuscular system) is the misunderstood or unknown (by many) aspect of strength and strength training.
All human movement is initiated from the brain and controlled by messages sent from the brain via the central nervous system.
Referring back to the muscle structure, our brain sends signals to the muscles needed to produce force, control acceleration and deceleration of limbs, and maintain balance. It also has to tell the muscles how many muscle fibres need to fire, how quickly and for how long force needs to be maintained.
Our ability to orchestrate these messages to multiple muscles and hundreds of thousands of muscle fibres, combined with the ability of those muscles to carry out the neural instructions, is what leads to our levels of strength and is a huge part of how we can improve it through strength training.
Moving from orchestral analogies to cars!
Imagine our bodies as cars. Most of us have huge potential horsepower, plenty of cylinders/muscle mass and potential to produce force. However we do not have the ability to access all of the cylinders at the same time, or synchronise these cylinders to work together effectively. Yes we could try to build more muscle but then what is the point if we can’t even use 100% of what we have?
Also of importance is our chassis (skeletal system, connective tissues; tendons and ligaments). Which needs to be robust enough to handle our potential power output.
Table 1.2 (4) shows the various different factors that can improve with strength training, muscle size (hypertrophy) is only one part of the puzzle.
Lets break this table down…
Firstly 1RM stands for the weight (or resistance) which an individual can lift for only one repetition, and is obviously is a measure of maximum strength. Therefore the higher the percentage the higher the force output, effort or weight lifted.
Intramuscular coordination: refers to the ability of muscle fibres within the muscle to function as they should. Continuing a theme, do all the flutes do as they're told, are all the string section awake? The components of intramuscular coordination are as follows:
Synchronization - the capacity to contract motor units simultaneously or with a minimum lag (that is, with a delay less than five milliseconds)
Recruitment - the capacity to recruit motor units simultaneously
Rate coding - the capacity to increase firing rate of motor units in order to express more strength
Intermuscular coordination, on the other hand, is the capacity of the nervous system to coordinate the muscles required by the exercise/movement, with the aim of making the gesture more efficient. Can we get the strings and the brass working together? As the nervous system becomes familiar with the exercise/movement and we get more efficiant fewer motor units get activated by the same weight, which leaves more motor units available for activation by higher weights.
Disinhibition of inhibitory mechanisms. Referring back to the car analogy, these are the inbuilt mechanisms that prevent the chassis from being damaged. Our body has the same inbuilt mechanisms to protect us from getting injured. For example, to prevent you from lifting a weight that would cause you damage. We occasionally see cases where people disinhibit these mechanisms in fight or flight mode, lifting huge weights to save a loved one or themselves from danger. We can also disinhibit these mechanisms through strength training, in effect teaching the body that we are capable of producing these forces safely, while also eliciting adaptations within our “chassis” making it more robust.
Finally hypertrophy or muscle mass, if the body feels we need more muscle fibres to withstand a stress or a load it will build new muscle but only if supported through correct diet and under certain stimulus.
What is interesting from Table 1, is at which intensities certain adaptations occur. Pay attention to the relevent repetitions and have a think about what exercises would fit these repetition ranges for you?
<70% Resistance (A resistance at which you can perform only 10-12 repetitions in one go)
A resistance of up to 70% is optimal for developing intermuscular coordination. Learning which muscles to use and when. We will achieve strength gains from this level of training by learning to more efficiently complete an exercise or movement pattern.
At this resistance, muscle fiber recruitment is not high as it does not need to be, also this resistance is not heavy enough to inhibit protective mechanisms.
70-80% Resistance (A resistance at which you can perform only 8-10 repetitions in one go)
As we increase the resistance we hit more optimal conditions for hypertrophy, however there are other factors that will effect this. We also start to demand more of the muscles meaning muscle fiber recruitment increases as do the inhibitory effects.
>85% Resistance (A resistance at which you can perform only 1-5 repetitions in one go)
A high resistance of 85-100% of 1RM provides the best stimulus to improve intramuscular factors affecting strength as well as disinhibiting inhibitory mechanisms. Now we have enough resistance to need to fully recruit muscle fibres.
It is also worth noting that lifting heavier does not mean building more muscle.
Lets think outside the box...If we look at the repetition ranges related to each training resistance and now start to think not just about a weight on a bar, resistance can come from many different sources such as:
External resistance (dumbbells, kettlebells, med balls, barbells etc)
Bodyweight( TRX, yoga, calisthenics, pilates)
Many people may find they max out at 8-10 full press ups or less, and some pilates or yoga movements may replicate repetition ranges where you start to fatigue before 12 or 15 repetitions.
You may not have been throwing iron around, or may not want to but you still can and possible still have been strength training and not even know it!
A good training program will cover all of these resistances at some point! Initially building up a movement ability and efficiency, before increasing the resistance to develop a robustness to our muscles and bodies under load and in turn preparing our bodies to lift at near maximal intensities.
Many people try to skip phases and this is where people get injured, while those who are nervous about lifting "heavy" weights (for risk of getting bulky) ironically get stuck at a higher rep range (lower resistance) that more lends itself to muscle growth.
While we know the above information is quite "deep" hopefully it does give you a basic understanding and target to think about next time you are training in any form.
In part two we will discuss training for Strength vs training to build Muscle....so keep an eye out for more useful takeaways next month......
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2. Baechle, T., 2016. Essentials of strength training and conditioning. Champaign, IL: Human Kinetics.
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10. Moini, J. and Piran, P., 2020. Functional and clinical neuroanatomy.
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