We’ve all dealt with fatigue either in the gym or out it’s something that every extremely active person is going to face. We typically feel fatigue when performing repetitions in the gym. A repetition may seem simple on the surface, moving an object from position A to B. But there is so much more going on behind the scenes, all from the central nervous system to the brain. The more advanced or elite athletes have developed a better central drive through years of learning to recruit more muscle fibres through this neural canal.

How Fatigue Can be Caused

sleep and testosterone

Fatigue can be seen in two different dimensions: physiological and psychological. Think back to some of your heaviest deadlift or squat sets, the intensity and fatigue of those last 2-3 reps is something you can’t explain they have to be experienced. The power of the mind can not be underestimated in the state of immense fatigue. The fatigue we face is most likely a cause of both physiological and psychological. 

Cause 1: Hypoglycemia

This is a result of low blood glucose levels in the body. Glucose is the body’s main fuel source. There is a reason a lot of people conflate a low carb diet with fatigue. The idea of low carb means low energy is mainly a psychological cause of fatigue, although that isn’t entirely accurate. Carbohydrates are stored in the body as glucose so limiting the amount of carbohydrates will naturally limit the amount of glucose in the body as a result. 

A depleted state is considered to be less than 200mmol/kg, a range in which performance would most definitely be hindered. This doesn’t necessarily mean that the body can’t handle training in a low glycogen state, it’s just not as efficient. The body is, however, fairly efficient and accustomed to producing ATP (the body’s energy) through other pathways and using other fuel sources. 

Glucose is stored in 3 subcellular localizations: intermyofibrillar glycogen, located between the myofibrils and close to SR and mitochondria. Intramyofibrillar glycogen, located within the myofibrils and most often in the I-band of the sarcomere. Subsarcolemmal glycogen, located beneath the sarcolemma and primarily next to mitochondria, lipids and nuclei. Approximately 75% of the body’s total glycogen reserves are stored in the cells as intermyofibrillar glycogen.

Click Here To Check Out a Bodybuilding Course Put Together by The Author

The intermyofibrillar glucose stores have been proven to be the most influential to fatigue. This is due to the relationship between this store and bioavailability of calcium. Put more simply, the body needs Calcium in order to generate muscular contraction due to the binding of actin to myosin.

Cause 2: Phosphocreatine Depletion

fatigue in the gym
Fatigue in the gym

Phosphocreatine levels in the body are also very important. Pcr’s primary utility in the body is maintaining and recycling ATP for muscular use – in our case – for repetitions. If the rate of ATP utilization is not higher than the rate of production by mitochondrial respiration, ATP homeostasis is thrown off and energy levels plummet. This can be avoided with the supplementation of creatine. 

Cause 3: ORM Deficiency – Orosomucoid is an acute-phase protein whose carbohydrate content is very high at 45%. ORM is mainly synthesized in the liver but under extreme bouts of exercise and stress other extrahepatic tissues have been known to also produce ORM. When the body becomes fatigued ORM has been shown to increase in the serum, liver, and skeletal muscle. Exogenous ORM can increase muscle glycogen and enhance muscle endurance. On the other hand a deficiency of ORM can result in decreased muscle endurance. This shows that ORM is an endogenous anti-fatigue protein and necessary to combat fatigue.

There are many more causes of fatigue, some very obvious like lack of sleep or poor nutrition, and some more nuanced and complicated like the generation of ORM in the body. One thing will always be true though, and that is that for as long as we are putting new stress on our muscle tissue we will be enduring fatigue. The key is how we can aid in the recovery of fatigue and limit how the fatigue prohibits us from action.

What to Do

So with these causes of fatigue what can we do to help mitigate or at a minimum learn how to deal with our fatigue?

  • Keep body fat in check. ORM is most deficient when body fat percentage is too high
  • Utilise mini cuts when body fat gets too high
  • Utilise carbohydrates pre and post workout for increased glycogen stores to avoid hypoglycemia 
  • Stay hydrated 
  • Sleep as much as possible
  • Supplement with creatine and beta alanine to ensure glycogen stores are sufficient 

Click here to amp up your mind with caffeine-free natural nootropics


Don’t hesitate to email us at [email protected] for personalized coaching and a client questionnaire if you’d like DEDICATED tailor-made personal training on strength training, building muscle, losing fat, developing athleticism, and more — all to your liking, lifestyle, habits, and taste!

Otherwise, don’t forget to claim your FREE eBook detailing how to lose 20lb of fat while building muscle in 12 weeks! You can claim it here.

Alternatively, you can pick up a FREE eBook on fundamental strength principles offering an introductory workout program.