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Introduction to your body

Introduction to your body
This introduction to your body article has been written to help you understand about genetics, your body type, your skeletal muscles and the way they work and types of muscle fibres our bodies have.


Our genes are passed down to us from our parents and make us who we are. They govern how we are put together and then how we will be maintained. Although it should also be noted that the genetics from our parents can be passed to us in varying percentages. As far as our exercise performance and potential are concerned, they can have either a small or big impact on their outcome. It can affect your fitness and performance level, body fat, body shape, size and strength potential and even your motivation and thought process. This is why two people can follow the same workout routine and even diet and one of the trainers could end up stronger and fitter than the other. However very few people realise their ‘full potential’ and those with the willpower and determination can often excel and even outperform those with better genetics than them at their chosen sport or physical activity.

Body types

There are three basic forms of body type, although in truth many people are a combination of more than one. Your body type may also have an effect on which type of training is best suited to you. It’s also interesting to note that as we get older some aspects of our body type often changes from the leaner skinnier type to the more larger fatter type. Here are the body types as denoted by science:


EctomorphAn ectomorph generally has a skinny thin build, long limbs, less muscle, small joints and bones and a fast metabolism. They have mostly stringy fast twitch muscle fibres and are often unable to pack on muscle mass or even weight, but tends to burn calories much more easily and therefore are more lean. They can also be more hyperactive.

Type of training: Ideally to put on more muscle mass, they require short intense weight training routines (30-45 minutes per session) and minimum (if any) cardio. They should use mostly big compound exercises and workout 3-4 times a week, doing 1-2 exercises per muscle group in the 6-12 rep range most of the time. Getting enough from their diet can be a problem, so possibly will need supplements to add calories and protein.


MesomorphA mesomorph generally has a muscular, athletic and strong build with small/medium joints and bones and a fast metabolism. They tend to gain muscle more easily, but often still have a lean physique.

Type of training: A mesomorph if required can do cardio for their fitness needs, but it may not be necessary for fat loss purposes due to their fast metabolism. Both strength training and hypertrophy workouts can show great results. Weight training can be done 4-5 times a week with mixed rep range sessions, some low rep sessions 4-10 reps, some higher 12-15 reps. Use of Creatine supplements tend to work well to maximise performance.


EndomorphAn Endomorph has generally a big build, with a pear or round shaped body, short limbs, high body fat, medium to large joints and bones and a slow metabolism. They also find it difficult to reduce waist size and can store energy very easily. They can be lethargic and often hungry.

Type of training: If new to training and out of shape physically, then it is best to start off with low to moderate intensity cardio (depending on your fitness/health level and medical advice should be taken before if in doubt) – even walking can be a good start for many. Add to this, moderate weight training sessions, if physically able. Work your way up at a steady pace to a more HIIT (High intensity interval training) style training to shift more body fat and progressive weight training (only when your fitness and health level has improved enough). Work at your own pace if you are overweight and don’t push yourself too hard to begin with until you are more familiar with your body and health status. Do 2-3 exercises per muscle group with mixed rep range sessions, some low rep sessions 6-10 reps, some higher 12-20 reps. Do cardio 2-3 times a week, weights 2-4 times a week. Being more active and sorting your nutrition is key with this group.

Before moving on, I’d like to say that the suggested workouts/rep ranges mentioned above for each body type are a guide, as most people fall into more than one category and will have different goals that require a modified approach. Therefore you need to use the above as a guide only for your own goals and body type.

Skeletal muscles of the human body

It helps to know what are the main skeletal muscles of the human body and how they correspond to movements you make. These muscles are attached to your bones via tendons and when the muscles contract, they shorten their length and along with your joints help make movements that lift or pull as a lever system. Note: some muscles work in unison to stabilise a movement or contraction, so in some instances they can overlap or assist and work synergistically.

Here is a very basic rundown of the main muscle groups:

Pectoral (Chest)

The pecs are a popular muscle for men to work and mainly consist of the pectoralis major and the pectoralis minor, it is activated when throwing a ball for instance, rotating the arm inward and helps in moving the arm forward, downward and upward (especially across the body).

Deltoid (Shoulders)

The delts are made up of several muscle groups, but generally grouped as a set of three heads and referred to as the front (anterior), side (lateral) and rear (posterior) deltoids. The deltoids moves and stabilizes the shoulder joint and are also responsible for movement of the arm in a multiple of directions.

Trapezius (Traps)

The traps consist mainly of three muscles, its function is to help support, move and tilt the head and stabilise and move your shoulder blades (Scapula). It also pulls the shoulders up into a shrug position and helps support the weight of your arms.

Latissimus dorsi (Lats – largest muscle of the back)

The lats help to rotate and move the shoulders back and to pull them down. They also help to pull the arms back and down, such as in rowing and pull ups.


The biceps are made up of 2 (or more) muscle heads – it helps move the forearm and hand upwards and aids in the rotation of the forearm with the palm of the hand rotating upwards as well. They also help with shoulder and elbow movement.


The forearms are primarily made up of two main muscle groups (anterior and posterior). They aid in the movement and rotation of the wrist and hand and provide grip strength to the fingers.


The triceps are made up of 3 muscle heads, they help straighten the arm out and help in pushing movements. They also help stabilise the shoulder joint.


The abs are made up of several muscles (Rectus Abdominus, Oblique’s and Transverse Abdonimis) over three layers. They serve to protect internal organs, support the body’s trunk and stabilize the spine. They also allow the movement of the trunk, such as with rotation and bending forward or to the side.


The quads are made up of 4 large muscles, they help extend the knee and hip and straighten the leg. They also stabilize the knee.


Hamstring are made up of three large bicep muscles at the back of the leg which allows the leg to bend at the knee and extend the hip.


Calf muscles are made up of 3 muscles which helps flex the foot, especially for pushing your toes down and upwards. It also supports the ankle and aids stabilisation as well.

Note:  many of these major muscle groups have several heads and there are also many more smaller muscle groups – for more detailed information of these muscles and their function, please see the various exercises listed in the exercise section of the muscle development and strength gain page.

Muscle fibre types

If you didn’t already know, your skeletal muscles are made up of slow and fast twitch muscle fibres. Your genetic makeup will determine how much of each type you will have. Both of these types of fibre can be trained to increase in size and strength. For the most part, it really doesn’t matter, unless you are a competitive athlete or want to absolutely push your muscle gains to the max.

Slow twitch muscle fibres

Red Type I – These are essentially your endurance muscle fibres. They have less force/power and move slower than the fast twitch muscle fibres (hence the name). They are quite resistant to fatigue and last for hours. Used for low intensity activities, such as day to day chores, walking or endurance type exercises. Located mostly in the postural muscles such as the neck, back and legs for example.

Fast twitch muscle fibres

This is the fibre that is most prone to size increases and there are more of them in general. There are two types of fast twitch fibres:

Red Type IIA – These fibres are midway in terms of speed, but are also both aerobic and power fibres and can generate much more force than the slow twitch fibres. Used for a combination of speed and power with moderate weight and length of activity. Leg and shoulder muscles have lots of these fibres for example.

White Type IIB – These are power and speed fibres that can create much more force than the other two, but also activate much faster for more explosive power, but fatigue faster. Used for short bursts of near maximal power. Good for heavy weights. Muscles of the shoulders and arms have a lot of these fibres for example.

How your types of muscle fibres are activated and used

Your muscles get a signal from your brain to contract when necessary. Individual muscle motor units then contract with 100% effort. The unit type (muscle type) and number of units used will depend on the task required. As the task gets more difficult (heavier or longer) then more of the appropriate motor units are recruited as required. Interestingly it is the nerve system that signals which fibres and how many units activate and fire, and not all units will get recruited. In essence those with more efficient nervous systems will actually be able to perform better physically. Here’s another interesting point to note, those with more fast twitch fibres use more energy, this type of muscle fibre uses a lot of the bodies fuel and isn’t as efficient – see muscular people doing endurance activities and more than likely you will see them gas (unable to supply enough oxygen and fuel to their muscles).

You can train the body to become more efficient at using the necessary units and even training in a particular way can make changes to your muscle type. For example endurance training can convert Type IIB fibres to become Type IIA fibres, adding plyometric type training can build Type IIA fibres and sprinting or training heavy can increase the size of type IIB fibres. As you can see training in various ways can maximise your muscle growth/performance potential.