When I mention to people that I do powerlifting, invariably I get the same reaction: a glance up and down my moderately trim 5’4’’ frame and a raise of the eyebrows as if to say ‘but….you’re not exactly big are you?’ I tend to laugh it off and simply say that you don’t have to be big to be strong. But that leaves things tantalisingly unexplained.
The perceived correlation between size and strength is very strong in the popular imagination, despite there being evidence around us that strength is not solely a consequence of size. I am willing to bet that most people can think of someone they know who is surprisingly strong despite not being big and beefy.
Often my interlocutor, especially if she is female, will go on to remark that she has “no strength” or very little strength – as if strength is something you are either born with or you’re not. But it actually has more to do with practise: if you lift heavy weights on a regular basis you will get stronger regardless of size.
Track and field athletes for example train with weights even though they don’t always want to get bigger or heavier. What they want is to increase their strength-to-bodyweight ratio and become more powerful. John Shepherd, in an article in Peak Performance, points out:
“The British triple jumper Jonathan Edwards regularly used high-weight, low-repetition weight workouts. The world record holder and Olympic champion was literally as light as a feather (he weighed in at his peak at 65kg), yet was incredibly powerful.”
But people still assume that if you lift weights you will necessarily get bigger, leading to those familiar misconceptions about strength training and getting bulky. So what is strength?
Definition of strength
A definition I like is: strength is the ability to exert force. Specifically it is muscles that are exerting force in order to contract. They may be contracting in order to pick up a pen or to pick up a heavy barbell. Clearly they will need to exert more force to pick up the barbell than to pick up the pen!
There are two key factors that determine how much force a muscle can exert: muscle size and neurological efficiency, or how well the nervous system can coordinate muscle contractions.
Everybody knows that muscle size is a factor in strength, but they don’t realise that the behaviour of the body’s central nervous system is just as important, if not more important, in how strong you are.
The central nervous system (CNS) coordinates muscle activity in the body. Each muscle has many neurons which are connected to the CNS and each neuron controls a group of muscle fibres. The neuron and its group of fibres is called a motor unit and there are many motor units in each muscle. When the muscle needs to contract, the CNS recruits however many motor units it thinks it needs in order to complete the task. So the role of the CNS in muscular activity is a crucial one – it is like a general controlling the troops.
Different muscles have different sized motor units depending on the job they need to do. A large muscle which is required to produce large amounts of force may have up to 1000 muscle fibres per motor unit, whereas a small muscle making fine movements, such as the muscles of the eye, may only have 10 fibres per motor unit.
Strength is a function of the number of motor units that the nervous system can recruit in order to lift a single weight. An untrained person may only be able to recruit a maximum of 70% of the available motor units in their muscles for one lift, whereas a trained and experienced lifter may be able to recruit 95% or above. The trained lifter is therefore more neurologically efficient than the untrained lifter. Most powerlifting and Olympic weightlifting training is designed to improve this neurological efficiency.
The more experienced the lifter and the better the CNS at recruiting motor units, the more the lifter will be affected by CNS fatigue. When a beginner is lifting close to their apparent maximum effort, the motor unit recruitment is still comparatively modest and the nervous system can recover quickly. In fact the beginner trainee is more likely to suffer from muscular fatigue due to the muscles not being adapted to training. However when an experienced lifter is training maximal or close to maximal weights, the motor unit recruitment is very high and it causes greater nervous system fatigue and comparatively little muscular fatigue. A maximal strength session for an experienced lifter is very tiring.
It is possible for people to get stronger – sometimes much stronger -simply by increasing the response of the nervous system to having to lift a weight. This explains why we hear about people demonstrating extraordinary strength in extreme life-or-death situations, such as a woman being able to lift a car off someone trapped beneath it.
According to Zatsiorsky and Kraemer, “when untrained subjects receive hypnotic suggestions of increased strength, they exhibit strength increases”, which seems to be due to the central nervous system (CNS) activating many more motor units than normal. Elite strength and power athletes train to be able to do this at will.
The amount of force a muscle can exert – how strong it is – is related to its cross-sectional area. Strength can be increased by increasing the size (or specifically the cross-sectional area) of the individual muscle fibres. This means that people with a large number of fibres have greater potential for strength than people with a small number of fibres – regardless of their bodyweight. Increasing the size of muscle fibres is achieved through a combination of training and nutrition.
This also means that any gains in muscle mass should result in increased strength, all other things being equal. So there is a relationship between bodyweight and strength but the biggest people are not necessarily the strongest in relation to their bodyweight.
Smaller people have shorter bones and therefore shorter muscles. This means that in two people with the same amount of muscle, the shorter-boned person will have muscles with a greater cross-sectional area. The shorter person therefore potentially has a better strength-to-bodyweight ratio.
However the person with longer bones has the potential to gain more muscle mass overall and therefore get stronger in the absolute sense.
Relative strength and absolute strength
This difference between relative strength and absolute strength is an important one, since many sports are judged on relative strength. Olympic weightlifting and powerlifting, together with boxing, wrestling and other martial arts are all categorised in weight classes, so you are competing with other people of around the same bodyweight. Gymnastics is also a sport where strength is relative to bodyweight. In sports where the weight is not relative to bodyweight – throwing events or American football, for example – then absolute strength is important.
Notice also that in those sports mentioned where relative strength is important, athletes are often quite short – gymnasts, powerlifters, martial artists – whereas in sports where absolute strength is important, athletes tend to be tall – American football, shot-put and so on.
In sports where relative strength is the key comparator, smaller people will tend to come out stronger because strength can’t increase at the same rate as size. In Olympic weightlifting, the world record clean and jerk in the Men’s 56kg category is 3 times body weight (Halil Mutlu, 168kg) whereas in the super-heavyweight category (>105kg) it is 1.68 times body weight (Hossein Rezazadeh, 263kg). The lightest lifter is almost twice as strong as the heaviest lifter, relative to bodyweight.
Slow twitch and fast twitch muscle fibres
Most people have heard that there are three types of muscle fibre: slow twitch and two types of fast twitch. Slow twitch fibres have a slower firing rate but are more resistant to fatigue and are best for lengthy aerobic exercise; fast twitch fibres have a relatively fast firing rate but are more easily fatigued and are better for explosive or anaerobic exercise. Fast twitch fibres have the potential to be bigger in size than slow twitch fibres.
All muscles contain both fast twitch and slow twitch muscle fibres and the overall mix between the two varies between people. Top sprinters have a greater proportion of fast twitch fibres in their muscles than most people whereas the best endurance runners have a greater proportion of slow twitch fibres than others.
What is less generally understood is that whatever the activity, the order of muscle fibre recruitment through the motor units is the same: the slowest motor units are recruited first. If greater force is required, more and faster motor units have to be recruited. The better you are at recruiting motor units the more force you can exert but full activation of motor units within a muscle is very difficult to achieve. The higher threshold motor units can only be stimulated with heavy resistance training, so if you never lift heavy weights, you don’t have much chance of being able to recruit those faster muscle fibres.
Women have fewer muscle fibres than men and the fibres are smaller in terms of cross-sectional area. Interestingly, most women (around 75% of untrained women) start off with larger slow twitch fibres than fast twitch fibres, even though it is the fast twitch fibres which have the greater potential for size and strength.
This means that untrained women have enormous potential for strength gains – greater than men, in many ways. However the fast twitch fibres and high threshold motor units that are the key to strength require heavy resistance in order to be stimulated. Exercising with light weights will not make the slightest difference to these elements and the unfortunate trainee will remain weak.
Moreover heavy resistance training is required to improve the strength of connective tissue (tendons, ligaments) and bones, which is useful for all sports including endurance events. Without heavy weight training, this improvement is foregone.
In fairness, it is not just women who are reluctant to train with heavy weights and thus miss out on all these important benefits. Many men who are interested in endurance sports or need to remain fairly light weight shy away from heavy weight training through a misconception that it will make them much bigger and heavier, but as the Jonathan Edwards example (above) shows this is not necessarily the case.
Strength isn’t just about size, it is also to do with the ability of the nervous system to recruit enough motor units to complete the task without damaging the body. This will improve over time with training.
Most strength sports involve relative strength where the objective is not to increase bodyweight but to increase strength and/or power relative to bodyweight. Nobody should be afraid that if they lift weights they will gain significant amounts of muscle or body weight as this is merely a subset of the many types of weight training that exist.
Women have huge potential for strength gains because they start off at a disadvantage, with less muscle mass, smaller and fewer muscle fibres. But with heavy resistance training, strength can grow considerably without increases in size. Men are also missing out on strength benefits by avoiding heavy weights, since more weight on the bar does not necessarily result in significant gains in bodyweight.
Strength seems not to be so prized in modern times as it once was. But when the emphasis is so much on the appearance of strength for aesthetic reasons, what gets forgotten are the many health benefits of decent strength. It’s not just about looking good naked, it is about having healthy bones and tissues, efficient muscles, good posture and flexibility and reducing the effects of ageing (never mind those wrinkles, what if you fall over and break your leg?). In the UK the biggest cause of time off work is back pain – something that strength training can genuinely help with.
I believe that sooner or later people will realise that strength is vital even with all the conveniences of modern life and modern medicine and that by picking up heavy stuff every once in a while we’ll all be better off.
- Strength standards for women
- Types of strength
- Types of weight training
- The toning problem: why women are missing out when it comes to weight training
- Why do most women avoid the free weights room?
- Define strength by Chip Conrad on EliteFTS
- Strength from Brianmac
- Your body is a barbell by Alwyn Cosgrove
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