What is Muscle Tiredness?

Muscle tiredness is not uncommon for even the most avid athlete. As our bodies use energy in order to exercise, we lose energy and eventually have to stop exercising; this can get in the way of your goals, whether you’re playing a team based game, or exercising alone, and obviously that’s counter productive.


We need energy to contract our muscles. The largest source of energy we gain is obtained by our food. Carbohydrates are the kings (and queens) of energy; eating a carbohydrate rich meal a couple of hours before exercising is important to provide your body with sugars like glucose, which our bodies use as fuel for energy; any glucose not immediately needed is stored in our muscles and liver as glycogen, ready to provide energy later. Click here for our suggestions of preparations for different types of exercise.

When muscle tiredness commences, it will feel like you have hit a wall, and that you can no longer progress. It is easily noticeable during weight training, for example some trainers may easily be able to lift 8 reps, yet when muscle tiredness sets in, they struggle to reach 5. Other long, stamina based exercise also get affected by muscle tiredness, for instance a swimmer may noticeably be taking longer to do laps, or a runner may not be able to carry on running during muscle fatigue.


Electrolytes like calcium, sodium and potassium play a big role in the contraction of muscles. All three are needed for a contraction, and electrolyte levels change with the bodies’ water levels, so hydration is also really important to keep in mind when talking about muscle fatigue.

Muscle fatigue will prevent you from tapping into the strength you need to progress, so the intent of this article is to offer insight into what causes muscle tiredness, and to explore how to overcome muscle fatigue. It will affect the muscles you are trying to train, and if it gets in the way of your training, looking at the causes of muscle tiredness may be a first step to fighting it.

What causes muscle fatigue:

Neural fatigue:

Neural fatigue strikes when muscle contractions are needed, which closely match the amount of strength that the body can exert, for example trying to curl a dumbbell which is much heavier than you can lift. When the contractions push the body to as hard as it should go, the nerve’s signal reduces in frequency, and less force is produced. The cause of this is unclear, and it appears that during neural fatigue, that no aches or pains are produced, the tired muscle simply stops responding, and halts movement.

It appears to be a case of mind over matter in most instances; the mind begins to challenge the workload being set out, and seeks an easier alternative: not doing it at all. In very serious cases it can point to neural problems, which require medical attention, but neural fatigue should be nothing to worry about, and come the next training session no problems should persist. If the fatigue is persistent, consult your doctor.

With strength trainers and weight lifters, part of the process of the sport is to combat neural fatigue, by training on how much force the muscles can work with, and train the nerve’s power to create strong, high frequency signals. This is a long process, which happens over time, with plenty of practice.

It’s easy to shrug this off, but listen to your body. It’s telling you that you’ve pushed yourself, maybe a bit too hard, and that you shouldn’t continue. The determination and drive to out perform yourself is common in the gym, but it’s important to take into account things like your natural strength, how recently you have used your muscles and your training methods.

Muscles need to rest after being used, and should not be trained excessively without a chance to rest. During these resting periods, it’s important to refuel appropriately, with a diet abundant of carbohydrates for energy, and protein to repair muscles.

Hydration is very important; O.R.S Hydration Tablets provide your drinking water with minerals and electrolytes, like glucose, sodium and potassium, which would not otherwise be present. By mixing drinking water with two tablets, athletes can aim to provide their body with minerals and electrolytes needed to persevere.


Metabolic fatigue

Metabolic fatigue occurs when we lose fuel (substrates) to carry on exercising, or after the production of substances (metabolites) which hinder the bodies ability to release calcium, which affects its ability to contract.

The shortage of fuel happens naturally, as we use substrates like glucose, ATP and creatine phosphate during exercise to contract our muscles. Metabolic muscle fatigue therefore can be easily fixed, by gaining more energy through food and supplements, or by

Eating a light portion of carbohydrates during exercise, like a large banana, or oats, can offer glucose during the workout, but it is much more effective to eat a meal chockfull of carbohydrates before exercise.

Water and bananas hydrate you and supply potassium in order to lift such heavy weights and exercise like the athlete you are

As mentioned before, hydration is very important, and by using O.R.S Hydration tablets you can supply minerals and electrolytes to your body, which aid in energising the body, as well as maintaining fluids needed during muscle contractions in order to avoid cramps.

Muscle tiredness can also be instigated by the presence of metabolites, which are usually waste products as a result of muscle contraction. They’re perfectly natural, and slow down the same process which creates them.

Intracellular Chloride is a big culprit, as it sends false alarms to the muscles, signalling them to contract when you don’t actually need them to. However, the body is smart, and can detect when these false alarms are sent, and when you actually need to contract the muscles.

Very high levels of potassium also causes muscle deficiency, and can lead to cramps and muscle tiredness. It should be noted, that whilst the article promotes the use of comestibles like O.R.S Hydration Tablets and bananas, you would have to consume a very large amount of these in order for the results to cause cramps and muscle tiredness. Think “everything in moderation” and you will be fine.

Lactic acid builds up naturally after anaerobic respiration. Lactic acid produces a burning effect in the muscles, which is an easy symptom to identify during training, however the effects of lactic acid and muscle fatigue is ambiguous. It both restricts and promotes the release of calcium, meaning it both aids and hinders muscle fatigue. Ultimately, it’s too uncertain to claim lactic acid helps or hurts the training process.

Muscle fatigue should not be confused with delayed onset muscle soreness (DOMS). DOMS is usually present after a workout, whereas muscle fatigue is present during. Delayed onset muscle soreness is what causes the aches and pains to occur after exercise, and was for a while thought to be linked to lactic acid build up. As lactic acid is washed through the system within approximately 30 minutes, it is unlikely that lactic acid build up causes DOMS. DOMS can very well put athletes off training, but it is not muscle fatigue. Stretching is a very easy way to combat delayed onset muscle soreness, as is allowing yourself plenty of rest. You’ve worked hard, so go ahead and relax for a while – you deserve it.