Understanding Energy Systems and Muscle Fibres in Sports Performance

As part of writing our regular blogs we try to address questions our clients regularly ask us. In this Blog, I try to explain as simply as I can energy production in our bodies and how some of us are born to be sprinters and some marathon runners. This question was set as one of my exam questions when I sat my Level 5 Soft Tissue therapist qualification so it feels significant to share. Near the end you will see how this is relevant to anyone under taking sports – not just athletes!


When it comes to sports and fitness, understanding how our bodies produce energy and the types of muscle fibres we have is key. Let’s break down the different energy systems and muscle fibres to help you grasp their significance in your training and athletic performance.

Energy Systems:

1. Phosphagen System

– Quick bursts of energy: This system is responsible for short, intense activities like sprinting or weightlifting.

– ATP Production: ATP (Adenosine Triphosphate) is like our body’s energy currency, and this system generates ATP for immediate energy use.

– Anaerobic Nature: It doesn’t rely on oxygen and is a part of the anaerobic energy system.

2. Anaerobic System:

– Moderate to high energy output: This system provides energy for activities requiring high to medium intensity.

– No Oxygen Required: ‘Anaerobic’ means it doesn’t need oxygen to produce energy.

3. Aerobic System:

– Endurance and sustained activities: This system powers low-intensity, long-duration exercises such as long-distance running or cycling.

– Relies on Oxygen: ‘Aerobic’ means it requires oxygen for energy production.

Muscle Fibres:

1. Slow Twitch Fibres (Slow Oxidative Fibres):

– Endurance Performers: These fibres are ideal for prolonged activities due to their ability to contract slowly and sustain efforts for longer durations.

– Benefits in Endurance: They are perfect for endurance athletes engaged in activities like marathons or long-distance cycling.

2. Fast Twitch Fibres (Fast Glycolytic Fibres):

– Speed and Power: These fibres are great for producing quick bursts of power and speed but fatigue faster compared to slow twitch fibres.

– Limited Endurance: They are not designed for prolonged activity but are excellent for activities requiring explosive movements like sprinting or weightlifting.

Significance in Sports:

The distribution of these fibres varies among individuals due to genetic factors. Some are naturally inclined towards certain activities. For instance:

– Sprinters: Born with a higher percentage of fast twitch fibres, enabling explosive speed.

– Marathon Runners: Possess more slow twitch fibres for improved endurance.

While genetics determine our natural fibre distribution, training can influence their performance. However, altering the fibre type drastically isn’t possible.

Understanding these energy systems and muscle fibres is crucial, especially for non-athletes diving into exercise. Tailoring workouts based on your body’s predisposition can optimise training results. For instance, someone with a high percentage of slow twitch fibres might benefit more from endurance-based workouts, while those with fast twitch fibres may excel in high-intensity activities.

Knowing your body’s tendencies helps in designing workouts that suit you best, leading to improved performance and overall fitness.

Remember, while genetics play a role, dedication and smart training can make a significant difference in achieving your fitness goals.

Keep moving forward with the right knowledge and enjoy your fitness journey to the fullest!

Remember our Sports Therapist in Truro Cornwall is here to help with sports massage and injury prevention/rehabilitation !