657 Reasons Your Muscles Are Amazing

OK, so there are only 23 reasons here. Point being, your body is made up of 657 muscles, each intrinsic to everything you do every day. That’s 657 reasons to be thankful and 657 reasons to make sure you keep them healthy. Here, we shine a light on these miracle workers and provide you with some handy anatomy ammo to impress upon your mates.

Get in touch to submit your favourite muscle fact. We’re all ears, in fact that’s where you’ll find the smallest muscles in your body.

22,680 kg

If all 657 skeletal muscles in your body contracted and pulled in the same direction, you could lift over 22 tonnes of resistance – equivalent to two Baird’s beaked whales, four and a half African elephants or 22 walruses.

30 years old

Our muscle mass starts to decrease after we hit 30 at a rate of roughly 1% per year. But you can slow the decline with exercise and good nutrition.

Further reading: 5 Easy Steps For Healthy Muscles

2–3 months

Muscles regenerate at a rate of 1–2% per day, meaning you grow a completely new pair of biceps every two to three months. Skin, by comparison, renews every two to three weeks, and your stomach manufactures a new lining every three days to avoid digesting itself.

The fittest

The ultimate endurance muscle is your heart — a single muscle. Each heartbeat pumps 71g of blood, a minimum of 2,500 gallons [11,365 litres] per day, has the ability to contract over 3 billion times over a lifetime and will have pumped enough claret to fill 13 oil super tankers.

Further reading: Whey: What Is It Good For?

The keenest

The most powerful muscles in relation to the job they have to do is the external muscles of the eye which are 100 times stronger than they need to be in relation to the small size and weight of the eyeball.

The smallest

The tensor tympani in the ear is your most minuscule muscle. It primarily dampens the noise of chewing by tensing to reduce the amplitude of sounds coming from your mouth. A small portion of the population can voluntarily control their tensor tympani muscle, causing a low rumble in the ear.

The strongest

Pound for pound the masseter in the jaw is your strongest muscle. It’s one of a number responsible for mastication and can become enlarged in those who habitually clench or grind their teeth (known as bruxism) or in those who constantly chew gum. Special mentions also to the powerful myometrium muscle in the uterus, used in childbirth.


The masseter is particularly powerful in herbivores to aid chomping plants. As a point of reference, an adult man has an average measured bite force of 150–200 psi (pound per square inch) compared with 3,700 psi for the saltwater crocodile, the strongest measured bite force in the animal kingdom — or as much as 7,700 psi if you scale up for the biggest crocs on record.

Further reading: 657: It’s The Magic Number


Increasing your muscle mass will speed up your basal metabolic rate (BMR), helping you burn more calories at rest. It tends to naturally peak at around 16 or 17 before starting to steadily decline.


Muscle is 18% heavier and more dense than fat, hence why it can be misleading to only track your bodyweight as a measure of exercise progress. Your total muscle mass percentage can vary wildly from one person to another but on average it is around 40–45% for men and 30–35% for women.


Your body is constantly breaking down and rebuilding muscle — even if you don’t exercise. However, during deep rapid eye movement (REM) sleep your body releases androgenic hormones like testosterone that significantly aid in recovery and muscle protein synthesis.

Further reading: Let’s Drink To Your Muscle Health

Pull your weight

Muscles contract and relax, meaning they can only pull, not push. That’s why muscles are often arranged in pairs that pull bones in opposite directions. For example, pushing something, like a door or pressing a weight off your chest, requires contraction of the triceps and pectorals.


You can’t grow new muscle fibres, you can only increase their size. In other words, we’re born with our full complement of muscle fibres, meaning we own the same number of muscle fibres as bodybuilding overlord Arnold Schwarzenegger.


It takes half as long to gain muscle as it does to lose it.

Hypnic jerk

Find yourself jolting out of bed moments after falling asleep or jumping out of your seat when you nod off on your commute? That’s called a hypnic jerk. This twitching of the limbs is caused by the brain’s misinterpretation of relaxed muscles as falling. The brain then sends signals to your arm and leg muscles in an attempt to regain balance.


Your muscles create at least 85 percent of your total body heat. This is why you shiver when cold — your muscles are rapidly contracting and relaxing to generate heat.


Despite the dexterity required by your hands there aren’t any muscles in your fingers. They’re made up of ligaments, tendons and three bones (the proximal, intermediate and distal phalanges). The flexor digitorum superficialis and profoundus and the extensor digitorum muscles in your forearm pull on these tendons to move your digits.


Each muscle fibre is thinner than a human hair and can support up to 1,000 times its weight.

Weak grip

Ever woken to find your grip is so feeble you can barely squeeze the toothpaste out the tube? One possible cause is you’ve pinched a nerve while sleeping, causing numbness and occasionally pins and needles. It tends to take anywhere from 10–60 minutes to shake off.

Further reading: 10 Protein Commandments To Live By


If we were capable of hearing frequencies lower than 20 Hz we would hear our muscles moving.


In the UK, more than 70,000 people have muscular dystrophy or a related condition. This group of inherited genetic conditions gradually cause the muscles to weaken, leading to increasing levels of disability. There is no cure or treatment to reverse the deterioration. It robs sufferers of their mobility, independence and, for those with the most severe form, ultimately their lives.

100 per year

Duchenne muscular dystrophy (DMD) is the most common type, primarily affecting boys. In the UK, about 100 boys are born with it every year and about 2,500 boys are living with the condition at any one time.

11 years old

Most affected individuals with DMD are wheelchair-bound by around 11 years old. Despite improved technology and drug interventions, few live beyond their late 20s to early 30s due to breathing complications and disease of the heart muscle, known as cardiomyopathy.

Remember, Every Muscle Matters. Join our community and tag your posts with #fuel657

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