How Muscle Fatigue Hits During Workouts and Easy Ways to Fight It Back
A Resilient Insight with our highly-regarded Exercise Physiologist Liana Paparella on How Muscle Fatigue Hits During Workouts And Easy Ways To Fight It Back.
If you have ever pushed through a challenging workout only to feel your muscles shaking, burning, or simply refusing to cooperate - you have experienced muscle fatigue. It is a normal response to physical exertion, but understanding why it happens (and how to recover) is key to training smarter, not harder.
“As Exercise Physiologists at Resilient Health Group, we see firsthand how fatigue affects performance, motivation, and daily function, and how it can slow progress within your exercise program. The good news? With the right strategies, you can reduce fatigue, enhance recovery, and build lasting resilience in your body.”
What Is Muscle Fatigue?
“Muscle fatigue occurs when your muscles lose the ability to generate force. It is not just about feeling “tired” – it is a complex process that happens on a cellular level when the body can no longer produce enough energy to sustain activity, or when waste products (i.e. lactic acid) accumulate at a faster rate than they can be cleared.”
“In simple terms, muscle fatigue is your body’s way of saying “I need a break.”
The Science - What Causes Muscle Fatigue During Exercise?
“Several factors contribute to fatigue during workouts:
Energy depletion: Your muscles rely on glycogen (stored carbohydrates) to fuel movement and exercise. When these stores run low, performance dips.
Lactic acid accumulation: Lactic acid (C₆H₁₂O₆) is produced when glucose is broken down anaerobically - that is, without enough oxygen - during high-intensity exercise. The hydrogen ions then dissociate (H⁺), build up in the body, and create a more acidic environment that makes it harder for the muscles to contract. This leads to the burning sensation we are all familiar with!
Neural fatigue: The communication between your brain and muscles weakens, reducing coordination and strength output. Neural fatigue is influenced by factors such as neurotransmitter depletion (particularly acetylcholine and dopamine), central nervous system stress, and mental fatigue.
Poor recovery or sleep: During deep sleep stages, the body releases growth hormone and other anabolic hormones essential for tissue recovery, muscle repair, and glycogen replenishment. Insufficient or poor-quality sleep disrupts these processes, leading to slower recovery, reduced energy availability, and higher levels of cortisol (a stress hormone that can break down muscle tissue over time).
Dehydration: Even a 2% loss of body weight through fluid loss can impair performance. Water and electrolytes (especially sodium, potassium, magnesium, and calcium) are critical for nerve conduction and muscle contraction. Your blood volume also decreases when you are dehydrated, which in turn reduces oxygen and nutrient delivery to working muscles.
So before blaming your workout, check your water bottle, lunch box, and your bedtime routine!”
Why Do Muscles Shake When Fatigued?
“That shakiness after the final set on the leg extension machine or plank hold is not a sign of weakness… it is a signal from your nervous system. When your muscles are fatigued, the communication between your brain and muscle fibers becomes less efficient. Your body recruits extra motor units to keep up and maintain force; however, these fire in a chaotic nature that is out of sync – leading to the familiar shaky feeling.”
Do Tight Muscles Cause Fatigue?
“Absolutely. When muscles are tight or restricted, blood flow and oxygen delivery are reduced, making it harder for the muscle to contract efficiently. Over time, this creates a repetitive cycle where fatigue leads to tension, and tension leads to more fatigue. Regular stretching, mobility work, and remedial exercise can help break that cycle – which our multidisciplinary team at Resilient can help with.”
How Long Can Muscle Fatigue Last?
“Mild fatigue may ease within a few hours, but deeper muscle fatigue after heavy resistance training or endurance work can last between 24 to 72 hours. Persistent fatigue beyond this may signal overtraining or inadequate nutrition and should be reviewed by an Exercise Physiologist or allied health professional.”
Is Muscle Fatigue Good or Bad After a Workout?
“A little post-workout soreness or fatigue can be a positive sign of adaptation - your body is rebuilding stronger muscle tissue,”
“We often get asked, “Is it still a good workout if I don’t feel it in my muscles the next day?”
The answer is yes! You do not have to feel sore for your workout to be effective. Muscle soreness is certainly not the best indicator of progress - it just means your muscles experienced something new or different. What really matters is consistency, good form, and gradual overload over time,”
“However, chronic fatigue, prolonged soreness, or reduced performance indicate that recovery systems are not keeping up with training demands,”
“The key is balance: enough challenge to stimulate growth, but enough recovery to allow it.”
How to Combat Muscle Fatigue
“Fighting muscle fatigue is not just about resting. It is about supporting your body holistically:
Fuel your training: Eat balanced meals rich in carbohydrates, lean protein, and healthy fats.
Stay hydrated: Aim for steady fluid intake throughout the day, not just during exercise.
Prioritise sleep: Seven to nine hours per night supports muscle repair and hormonal balance.
Incorporate active recovery: Light movement, stretching, and hydrotherapy can promote circulation and reduce stiffness.
Manage training load: Alternate high-intensity days with lighter sessions to avoid overtraining.
Seek professional support: An Exercise Physiologist can assess muscle function, identify imbalances, and design a tailored program to enhance endurance and recovery.”
When to See an Exercise Physiologist
“If you are constantly feeling run-down, struggling to recover, or unsure how to train safely, consulting an Exercise Physiologist can make all the difference. At Resilient Health Group, we combine evidence-based exercise science with personalised care to help you move better, recover faster, and achieve sustainable strength,”
“Whether you are an athlete chasing performance, an injured worker striving for a safe to return to the workforce, or an everyday mover looking to build exercise consistency for general health and wellbeing, our goal is to help your body work with you and not against you!”