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Fighting Fatigue: Unlocking Performance Potential for Hybrid Athletes


Understanding the whys and hows of fatigue is crucial for every athlete, especially if you're a hybrid or Hyrox athlete striving to maximise performance in both strength and endurance. Fatigue isn't just about feeling tired; it's a complex state influenced by various factors from cardiovascular function to muscle trauma and even motivation. It's the body's natural response to exertion, a multifaceted phenomenon that can impact how you perform and recover.

But, rather than seeing fatigue as an obstacle, consider it a valuable feedback mechanism. The more you understand about what contributes to your fatigue, the better equipped you are to plan your training and recovery strategies, tailor your nutrition, and ultimately, push your boundaries without risking overtraining or injury. In this blog post, we're going to delve into the weeds of why hybrid athletes experience fatigue, exploring each major factor, and most importantly, provide practical advice on what you can do about it.

Let's demystify fatigue and turn it into a tool for better performance!

1. Cardiovascular Factors:

Cardiovascular endurance is a cornerstone of hybrid athlete performance. Fatigue can occur when the cardiovascular system cannot deliver oxygen to working muscles fast enough to meet demand. This can be due to decreased cardiac output, compromised blood flow or inadequate oxygen uptake by the muscles. These factors can all contribute to cardiovascular fatigue, which manifests as a decrease in performance over time.

Oxygen Delivery and Fatigue

The cardiovascular system, consisting of the heart, blood, and blood vessels, is responsible for delivering oxygen and nutrients to working muscles during exercise. Oxygen is vital for the process of aerobic respiration, where your body creates energy for muscle contraction.

When you're exerting yourself, your muscles demand more oxygen to maintain this energy production. However, there is a limit to how much oxygen your body can deliver to the working muscles. This maximum capacity is largely determined by your cardiovascular fitness and is often measured as VO2max, the maximum volume of oxygen your body can utilise during intense exercise.

If your muscles aren't getting enough oxygen, they can't produce energy efficiently, and the rate of aerobic metabolism decreases. Instead, your body starts to rely more heavily on anaerobic metabolism, which is less efficient and leads to the production of lactate. If lactate and hydrogen ions accumulates faster than your body's ability to clear it, it can contribute to muscle fatigue, leading to a decrease in muscle force generation and exercise performance.

Waste Product Removal and Fatigue

Another crucial role of the cardiovascular system is removing waste products generated by muscle metabolism during exercise. Some of these waste products include carbon dioxide, a byproduct of aerobic metabolism, and lactate, which is produced during high-intensity, anaerobic exercise.

Carbon dioxide needs to be transported back to the lungs, where it is expelled from the body during exhalation. High levels of carbon dioxide can lead to an increase in the acidity of the blood (a condition known as acidosis), which can interfere with the function of muscles and nerves and contribute to fatigue.

Lactate, on the other hand, can be used as an energy source by various tissues, including muscle, but when produced rapidly and in large quantities (as during high-intensity exercise), it can accumulate in the muscles and blood, contributing to muscle fatigue.

The faster and more efficiently your cardiovascular system can deliver oxygen and remove waste products, the better you can perform and the longer you can stave off fatigue. However, when the demand for oxygen and the production of waste products exceed your cardiovascular system's capacity to deliver and remove them, fatigue sets in, and performance decreases.

Therefore, improving cardiovascular fitness – through endurance training, for instance – is key for enhancing oxygen delivery and waste product removal, delaying the onset of fatigue, and improving performance.

Solution: Improve Cardiovascular Fitness

Boosting your cardiovascular fitness calls for a balanced approach that combines low-intensity, high-volume training with high-intensity workouts. Spending a significant amount of your training time in Zone 2 (60-70% of your max heart rate), often referred to as the 'aerobic' or 'endurance' zone, can help develop your body's capacity to transport and utilise oxygen efficiently, strengthening your heart and lungs. This type of training often involves longer, steady-state cardio workouts, like distance running or cycling, where you can maintain a conversation without feeling overly out of breath.

On the other hand, incorporating high-intensity workouts (Zone 5, 90-100% of max heart rate), such as interval training or sprinting, pushes your body to its limits, promoting adaptations that improve your body's ability to handle intense bouts of work and recover quickly. This blend of training methodologies can yield optimal improvements in cardiovascular fitness, helping you perform better across a wide range of activities, both endurance-based and high-intensity. Remember, though, that balance is key, and recovery is just as crucial as the workouts themselves for your body to adapt and improve.

2. Energy (glycogen depletion)

2. 1 Energy Availability:

Glycogen, stored in the muscles and liver, is the body's main source of energy during intense physical activity. However, glycogen stores are finite and can become depleted during prolonged or high-intensity training, leading to muscle fatigue. This is often referred to as 'hitting the wall' or 'bonking', which is primarily a factor of inadequate energy availability.

ATP (Adenosine Triphosphate) and Fatigue

ATP is the primary energy currency of cells, providing the energy needed for many processes, including muscle contraction. During exercise, the demand for ATP in muscle cells increases dramatically. To meet this demand, your body has several systems to produce ATP, which can be broadly classified into aerobic (requires oxygen) and anaerobic (does not require oxygen) metabolism.

However, each ATP-producing system has its limitations and can contribute to fatigue when its capacity is exceeded:

  1. Phosphocreatine system: This is the most immediate source of ATP, but it is also rapidly depleted – typically within 10 to 20 seconds of high-intensity effort. Once depleted, it takes time to replenish, and its exhaustion can contribute to short-term, high-intensity exercise fatigue.

  2. Glycolysis: This anaerobic process breaks down glucose (from blood glucose or muscle glycogen) to produce ATP. However, it also produces lactate, which can contribute to fatigue when it accumulates faster than it can be removed.

  3. Oxidative phosphorylation: This is the primary method of ATP production during moderate to low-intensity exercise. It uses oxygen to convert nutrients (carbohydrates, fats, and to a lesser extent, proteins) into ATP. But, as previously discussed, this system is limited by the cardiovascular system's ability to deliver sufficient oxygen to working muscles.

Glycogen and Fatigue

Glycogen is the stored form of glucose in our muscles and liver, and it's another crucial factor for fatigue. During exercise, particularly high-intensity exercise, your body relies heavily on glycogen for energy production. As the glycogen stores in your muscles get depleted, your muscles' ability to produce ATP decreases, which can lead to fatigue. This is often a significant factor in long-duration events like marathons where 'hitting the wall' is a common experience when muscle glycogen stores are exhausted.

Furthermore, low glycogen levels have been shown to impair the nervous system's ability to stimulate muscle contraction, further contributing to fatigue.

So, the supply and usage of ATP and glycogen are critical in understanding exercise fatigue. Strategies for managing fatigue often involve maximising the efficiency and capacity of these energy systems through training, diet, and other interventions.

Solution: Proper Nutrition and Hydration

When your body runs out of glycogen (the body's primary source of energy during exercise), you start to feel fatigued. This can be mitigated by ensuring you're getting adequate nutrition, particularly carbohydrates, before, during, and after workouts.

Prior to a workout, especially a long or intense one, it can be beneficial to eat a meal rich in complex carbohydrates to top up your glycogen stores. We recommend aiming for around 1g per kg of bodyweight, of carbohydrates (if you have weight to lose, use target body weight). For example, if your goal weight is 86kg, you should have around 86g of carbohydrates. During prolonged exercise (90 minutes or more), consuming a source of quick-release carbohydrates like a sports drink, gel, or bar can provide a valuable boost of energy.

Want to dive deeper into how the right supplements can help combat fatigue and boost your performance? Don't miss out on our FREE 'Supplement Guide for Hybrid Athletes'. This comprehensive guide will walk you through the best supplements to support your hybrid training, from fueling your workouts to aiding recovery. Click the link below to get your FREE guide now!"

3. Neuromuscular Fatigue:

Neuromuscular fatigue refers to a decrease in muscular performance usually characterised by an inability to maintain or generate a specific force. This type of fatigue occurs when your nervous system can no longer adequately send signals to your muscles to contract effectively.

This fatigue can be peripheral, originating from the muscles themselves, or central, originating from the nervous system.

  1. Peripheral Fatigue: This occurs due to changes at or beyond the neuromuscular junction. It can be the result of an accumulation of metabolic byproducts within the muscle, such as hydrogen ions from lactic acid production, or the failure of the muscle contractile machinery itself. It can also be caused by the depletion of muscle glycogen stores and the failure of the calcium ion transport system, which is crucial for muscle contraction.

  2. Central Fatigue: This is related to the nervous system, from the brain down to the motor neuron. The theory is that during prolonged exercise, certain neurotransmitters in the brain (like serotonin) increase and can lead to feelings of tiredness and lethargy, reducing the drive to exercise. In essence, it's thought that the brain starts to protect the body from over-exertion, reducing the motor signals to the muscles.

While the mechanisms behind neuromuscular fatigue are not entirely understood, one practical implication is clear: proper rest and recovery are essential to allow both the nervous system and the muscles to recover from strenuous exercise. Adequate nutrition (including electrolyte balance), hydration, sleep, and stress management all play crucial roles in managing neuromuscular fatigue.

Training can also be a potent tool in managing neuromuscular fatigue. For example, endurance training can enhance the body's ability to clear metabolic byproducts, and resistance training can improve the efficiency of the neuromuscular system and the durability of the muscle fibres themselves. Therefore, a well-rounded training program is crucial for hybrid athletes to perform at their best and manage fatigue effectively.

Solution: Regular Strength Training and Proper Rest

Neuromuscular fatigue happens when your muscles and nerves fail to produce maximal force. Regular strength training can help to improve neuromuscular efficiency, reducing the onset of neuromuscular fatigue. In addition, getting enough rest and recovery between training sessions is essential to prevent neuromuscular fatigue.

5. Biomechanical Factors:

Biomechanical fatigue is a type of fatigue that can occur due to the repetitive nature of certain movements in endurance and strength sports. Over time, these repetitive movements can result in changes in form or technique, which can decrease performance and potentially lead to injuries.

This type of fatigue can be managed by incorporating a variety of training modalities into your routine.

A major factor in this is running economy. Running economy refers to the amount of energy you expend to maintain a certain speed. If you have good running economy, you use less energy to run at a particular pace, which means you can run further or faster before fatigue sets in. On the other hand, poor running economy, which can be caused by factors like improper form or inefficient movement patterns, can lead to faster fatigue because you're expending more energy than necessary.

Movement efficiency is closely related to running economy, but it applies to all types of physical activity, not just running. Efficient movement means your body is moving in a way that maximises performance while minimising energy expenditure and injury risk. When your movement is inefficient, your muscles have to work harder to perform the same task, which can lead to quicker fatigue.

Solution: Improve Technique and mechanical efficiency

To combat biomechanical fatigue related to running economy and movement efficiency, it's crucial to focus on proper form and technique in all exercises, not just running. For runners, this could mean working with a running coach or physiotherapist to improve form. Strength and conditioning exercises that target the specific muscles used in running can also enhance running economy and overall movement efficiency. Similarly, for activities like weightlifting, proper form is crucial to ensure you're lifting as efficiently as possible and not wasting energy or risking injury.

For example, incorporating different types of resistance training can help strengthen muscles and connective tissues, reducing the likelihood of injury from repetitive strain. Also, practising good technique in your specific sport can help ensure that your movements are as efficient as possible, reducing unnecessary strain and conserving energy.

Improving running economy and mechanical efficiency involves a combination of training techniques, body conditioning, and form adjustments. Here are several strategies to consider:

  1. Strength Training: Specific strength and conditioning exercises, particularly for your core and lower body, can help improve your running efficiency. This might involve gym workouts, hill sprints, or plyometric exercises.

  2. Form Drills: Drills that focus on your running form can help you develop a more efficient stride. This might involve high knees, butt kicks, or bounding drills.

  3. Flexibility and Mobility Work: Regular stretching and mobility exercises can help ensure that your joints move freely and your muscles function optimally. This can include both dynamic stretching before a run and static stretching afterwards, as well as regular yoga or Pilates sessions.

  4. Running Technique: Attention to your running technique can lead to significant improvements in running economy. This includes factors like maintaining a slight forward lean, keeping your arms relaxed and driving them forwards and backwards, ensuring your foot strikes under your center of gravity, and aiming for a quick, light stride.

  5. Footwear: The right running shoes can also make a difference to running economy. Everyone's needs are different, so it's a good idea to get professional advice on the best type of running shoe for your particular foot shape and running style.

  6. Weight Management: Excess body weight can reduce running economy, so maintaining a healthy weight can lead to improvements in efficiency. This should always be achieved through a balanced diet and regular exercise rather than extreme diets or rapid weight loss.

  7. Practise: Lastly, the most specific way to improve running economy is simply to run. The body becomes more efficient at movements it performs regularly, so consistent training over time will improve your running economy.

It's important to remember that everyone's body is different, and what works for one person might not work for another. It can be beneficial to work with a coach or physical therapist who can analyse your running form and give personalised advice on how to improve. It can also be helpful to have regular check-ins or assessments to monitor your progress and adjust your training plan as needed.

Thermoregulatory Factors:

Thermoregulatory fatigue is a type of fatigue that can occur due to the body's efforts to regulate its temperature. During intense exercise, your body generates heat, which can increase your core temperature. To prevent overheating, your body responds by sweating and increasing blood flow to the skin to dissipate heat.

However, these responses can put additional strain on the body, potentially leading to dehydration and reductions in blood flow to the muscles, which can result in decreased performance and feelings of fatigue.

Solution: Acclimate to Training Environment

Managing thermoregulatory fatigue involves proper hydration and, in some cases, cooling strategies. Drinking plenty of fluids before, during, and after exercise can help replace fluids lost through sweating and support overall hydration status. In addition, wearing lightweight, breathable clothing can help with heat dissipation. In hot conditions, using cooling strategies like cold towels or ice packs, or seeking shade when possible, can also help manage body temperature.

Furthermore, gradually acclimatising to hot conditions can improve the body's ability to manage heat stress, reducing the risk of thermoregulatory fatigue. This can be particularly relevant for hybrid athletes training in different environments or preparing for competitions in hot climates.


While often overlooked, motivation plays a crucial role in managing fatigue. Mental resilience and a positive mindset can help athletes push through perceived fatigue, enhancing performance despite the physical signs of fatigue.

Solution: Develop Mental Resilience and a Supportive Environment

Mental fatigue can be just as draining as physical fatigue. Developing mental resilience through practices like mindfulness, meditation, or working with a sports psychologist can help manage psychological fatigue. Having a supportive training environment and community can also boost motivation and energy levels.

Bringing it all together

In conclusion, fatigue in hybrid athletes is a multifaceted phenomenon, resulting from complex interactions among several factors including cardiovascular, energy supply, neuromuscular, biomechanical, thermoregulatory, and psychological aspects.

Optimising your training as a hybrid athlete involves addressing all these areas to increase your resistance to fatigue and improve performance. This requires a strategic approach that includes:

  1. Cardiovascular Training: Enhance your body's ability to deliver oxygen to muscles and remove waste products through regular cardiovascular training.

  2. Proper Nutrition: Ensure you're providing your body with the fuel it needs to produce energy and recover from workouts. This includes adequate intake of carbohydrates for energy, protein for muscle repair, and hydration for all physiological processes.

  3. Strength Training and Mobility Work: Maintain your muscle strength and mobility to reduce the risk of neuromuscular fatigue and muscle trauma.

  4. Focus on Form and Technique: Improve your running economy and overall movement efficiency through attention to form and technique in all exercises, potentially with the help of coaches or therapists.

  5. Temperature Management: Be mindful of training conditions and ensure you're prepared for the heat or cold, which can affect performance and fatigue.

  6. Psychological Strategies: Use mental strategies like goal setting, visualisation, and mindfulness to enhance your motivation and manage perceived fatigue.

Remember, every athlete is unique, and what works best for you might be different from what works for others. Experiment with different approaches, listen to your body, and don't be afraid to seek professional guidance to help you navigate your way to peak performance. The path to becoming a top-performing hybrid athlete is a marathon, not a sprint. It requires consistent effort, smart strategies, and a dedication to understanding and working with your body. With time, patience, and the right approach, you can maximise your potential and minimise fatigue

I hope you've found this insight into the various factors that contribute to fatigue in hybrid athletes useful. Remember, understanding why fatigue happens is just the first step. Taking action and applying this knowledge to your training is what will truly make the difference.

Are you ready to become a better Hybrid Athlete?

If you're ready to take the next step, why not check out our 'Box:Perform' program? We offer a comprehensive approach to training and nutrition that's designed specifically for hybrid athletes. You'll gain access to personalised plans, expert advice, and a community of like-minded athletes who are just as dedicated to improving performance as you are.

Want to find out more? to discover how Box:Perform can help you combat fatigue, improve your performance, and reach your full potential as a hybrid athlete. Don't just train hard, train smart with Box:Perform.


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