Genetics Fitness & Exercise

Genetics Fitness & Exercise

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Science is now starting to realise our DNA affects every single one of our body processes.

This means we inherit previously unimagined individualities in the ways we respond to outside stimuli.

Our bodies are primed to function slightly differently, depending on the cocktail of genes we are born with.

While it’s common knowledge genes effect our outward appearance, hair colour and height, it’s now apparent genes effect how our bodies function on a cellular level.

A myriad of complex variations determines how our bodies are primed to react to any circumstance you could choose to mention.

The reason for this is DNA directs the construction and activity of proteins.

Enzymes, which speed up chemical reactions, are a type of protein.

Protein and enzyme activity are important for everything that goes on in the body.

Exercise and fitness are no exception.

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The Difference is in the SNP

Your genes possess variants known as SNPs which can increase or decrease the activity of the genes and therefore their effects.

Genes are strings of components which can be ‘read’, a bit like letters in a word.

A change in the order of one of these letters is much like a SNP.

Think of the difference between a relatively short word like ‘fat’.

Change the ‘a’ for an ‘i’ and it has a totally different meaning!

Each SNP exerts its effects through a multitude of pathways with potentially differing outcomes.

The unique genetic code you have inherited from your parents and grandparents influences how you’re likely to respond to a particular type of exercise.

This knowledge can help you to maximise your training and can even help your recovery.

Imagine being able to choose which type of exercise suits you best according to your genes?

In this article, we’ll delve a bit deeper into this fascinating subject.

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Hate Exercising? It Could be Your Genes 

As it happens, genetics may partly be the reason why one person is a gym addict while the next person dreads any type of exercise.

One study looked at pairs of identical twins while they performed low intensity and vigorous workouts.

Their perception of how they felt while exercising, their emotions and how much energy they believed they were putting in was then assessed and compared to other, unrelated people.

The identical twins had statistically similar feelings about doing the exercise.

Unsurprisingly, people who enjoyed fitness did more exercise (1).

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Genes and How we Respond to Exercise

Rather than concluding you simply hate exercise, next time you’re at the gym and you think you’re just not cut out for it – maybe it’s the type of exercise you’re trying to do that is jarring with your genes.

We know some aspects of how we respond to training are determined in part by genetics (2).

If each of us did exactly the same amount and type of exercise, we wouldn’t all become athletes, regardless of how much effort we put in.

If I trained forever, I’d never become the new Serena Williams and I doubt you would end up as the new Sally Gunnell.

This is due in part to our genetic differences.

We have genes which influence our muscle strength, our aerobic capacity, and how we respond to training.

Genes can have several variants, which are called polymorphisms.

One gene called the ACE gene has variants associated with improvements in performance and exercise duration.

Some variants favour endurance exercises such as triathlons, yet others favour strength and power, such as competitive swimming.

Other variants in this gene cause some people to respond better than others to exercise in terms of changes in their heart or skeletal muscle.

Finally, different variations may influence metabolic efficiency.

This has been seen in people who are high altitude climbers (3).

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Genes and Cardiovascular Health

Exercise places a higher demand on our cardiovascular system because active muscles need more oxygen and nutrients than when they’re resting.

In endurance sports, our heart’s ability to deliver enough oxygen via the bloodstream to the skeletal muscles is a limiting factor to how well we can compete.

Our cardiovascular system can adapt to this to a lesser or greater degree.

This is influenced in part by genetics, which determines which type of exercise suits us best.

If cardiac output – the amount of blood pumped by the heart - is elevated, we’ll be best at high-intensity sports like sprinting or weight lifting.


  • Genes and Blood Pressure

Genetic variations can influence our blood pressure via a system known as ‘RAAS’.

A group of related hormones act together to regulate our blood pressure over the long term.

Renin, angiotensin and aldosterone work to constrict blood vessels and alter how much fluid is retained by the kidneys.

These functions all receive their instructions from our genes and depend on enzymes.

Differences in how this system operates determines how our blood pressure responds to exercise.

If our genes cause our RAAS activity to be elevated, our blood pressure will tend to be higher.

The flipside of this is we tend to have better muscle growth and cardiac function. This is seen in elite athletes.

When we exercise our blood is diverted to the skeletal muscle into tiny blood vessels called capillaries.

The body responds to this by actually growing new capillaries, so more blood, oxygen and nutrients can reach the muscles (4).

In addition, although the density of our capillaries naturally declines with age, regular exercise can prevent this decline.

Some of us are born with better circulation than others, and again this is related to our genes.

Other genes instruct the release of a substance called nitric oxide, which relaxes blood vessels and improves circulation.

If our genes are enthusiastic at doing this, it means our blood pressure will have a tendency to remain low.

If this is the case we will be better at endurance sports.


  • Genes and Energy Generation

The second major area which can be influenced by genetics is that of energy production.

One limitation to how successful we are at some types of exercise is how effectively our muscles can use the oxygen and create energy in the form of ATP. ATP is the fuel which is needed for muscular function.

Our bodies use a combination of carbohydrates, protein and fat as sources of energy.

What is used at any one time depends on availability, how intensely we are exercising and also by our genetics.

Some people’s bodies are predisposed to produce energy by certain means rather than others.

Generally, carbohydrates are good for immediate energy as they are easily converted, so they’re used for high intensity exercise.

Fat is used for low to moderate intensity exercise as it takes longer to convert.

Protein provides energy when carbohydrates and fat are in short supply.

Glucose can be turned into energy either by using oxygen (aerobic) or without oxygen (anaerobic).

Energy tends to be produced anaerobically during strenuous exercise.

Genetic variants can determine how much glucose is available for energy production.

Initially, increased energy needs from exercise are fuelled by the energy stored as glycogen in our muscles.

After around two hours of intensive exercise, the body switches to producing energy aerobically from fat.

Our genes determine how easily we can use fat for energy.

If we can do this more readily we’ll be better at endurance sports such as long distance running or cycling.

When energy is in short supply, we are able to produce energy by recycling ATP, which uses an amino acid called creatine.

Some people can perform this process more easily than others, which allows them to produce energy more rapidly, but only for a short period of time.

These people are good at sports requiring short bursts of energy like sprinting.

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Genes and Body Structure and Strength

Our genetics can influence our muscle, connective tissue and bone structure.



  • Muscles

Muscle fibres can be what is known as fast or slow twitch types, and they differ by how they obtain energy.

Fast twitch muscles tire quickly but are great for rapid bursts of energy, while slow twitch fibres can work for a long time without tiring.

We tend to be genetically either fast or slow twitch dominant, which influences how our muscles respond to training. If you are fast twitch dominant, you may be better at sports which rely on short bursts of power like sprinting or weightlifting.

Although we can’t increase the number of the different types of muscle fibres we have, their strength can be improved by the right type of training.

For example, the strength and power of fast twitch fibres can be improved by strength training.

If you are slow twitch dominant you are suited to endurance sports like marathon running.


  • Connective Tissue

Our connective tissue makes up our tendons, ligaments and cartilage. It’s made from collagen.

Connective tissue repair is influenced by genes that control the speed of collagen synthesis.

This has an impact on how well our body can recover from an injury such as a sports injury.

Many different genes are associated with the production of collagen.

If you are genetically predisposed to repair collagen slowly, it’s a good idea to ensure you are eating foods containing sufficient nutrients for collagen synthesis, such as Vitamin C, E, manganese and zinc.


  • Bone Health

Bone health is influenced by genes which determine our ability to utilise Vitamin D and K.

If we can’t use these nutrients too well, it’s wise to be really careful we’re getting an adequate intake as our need for these nutrients may be higher than the next person.

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Genes and Exercise Recovery 

Our ability to recover from exercise is determined by our genes.

Any sports injury will result in the production of inflammatory molecules. Conversely, exercise has been shown to control inflammation.

Genes influence processes like the regulation of exercise induced inflammation, oxidative stress - and therefore our requirement for protective antioxidants - and our sleep/wake cycle.

If you are genetically predisposed to produce less exercise-induced inflammation, you may experience less muscle soreness after exercise and shorter recovery times.

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Exercise Can Change Genes 

Whatever genetic code you were gifted, exercise is always beneficial.

The neat thing is exercise itself can actually alter the expression of your genes.

One study found vigorous exercise, even if it was brief, led to structural and chemical changes in the DNA within muscles, although the underlying genetic code was not changed.

Scientists believe the gene activation was brought about by the muscle contractions.

Over time, this genetically reprogrammed the muscle for strength.

Some of the genes changed by exercise are those which play a role in the metabolism of fat.

Exercise, especially short burst of acute exercise increases the body’s production of proteins which break down fat (5).

Other changes involve alterations in the way our body stabilises blood sugar.

Endurance training appears to have other effects on gene expression. In a neat experiment, healthy volunteers were tasked with exercising on a bike only using one leg, for a period of three months.

The researchers then looked at metabolic changes in the exercising vs the non-exercising leg.

The researchers found over five thousand sites on the genes in the muscle cells showed changes in gene expression.

The changes related to energy metabolism, inflammation and insulin receptor sensitivity (6).

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Genetics are incredibly complicated – we still have a lot to learn.

In the future, this fascinating subject will no doubt tell us a great deal more about how we are influenced by – and how we ourselves can influence – the relationship between our DNA and exercise.

At Amchara we offer genetic tests which can provide an in-depth analysis of your genetic make-up and gene expression.

Such a test can tell you how your unique genetic tendencies could influence your reaction to exercise.

The results can allow you to tailor your exercise programme specifically to your genes, as well as making the right nutritional choices and lifestyle changes to align with your training programme.

A consultation with one of our trained naturopaths or nutritional therapists can also help to guide you through this process.


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By Cathy Robinson BScDipNutMed


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