To fuel your training or competition effectively, you need to understand how your body’s energy systems work. Without this knowledge, it’s challenging to fuel your sessions with confidence. This article is for everyone who exercises—regardless of age, fitness level, or goals! Let’s dive in!
Where does energy come from?
Energy comes from a small molecule with a big name – Adenosine Triphosphate (ATP). When one of its bonds breaks, energy is released. However, your muscles only store enough ATP for 2-3 seconds of work. After that, your body relies on its energy systems to replenish it.
Creatine Phosphate System
This system uses Creatine Phosphate as its fuel source. It can provide the highest power outputs, supporting short high-intensity efforts lasting up to 10 seconds. After a maximum effort, it takes about 30 seconds to 3-5 minutes of rest for your body to restore these levels. Creatine is the limiting factor of this energy system; therefore, supplementation can help increase creatine stores, potentially boosting performance.
Anaerobic Glycolysis
For activities lasting 5 to 30 seconds, especially with repeated bursts, your body relies on stored carbohydrates (glycogen) to generate energy, converting it to pyruvate. This process produces 2 ATP, and pyruvate is converted to lactate (or lactic acid – which is responsible for the familiar ‘burn’ you feel during intense exercise). Active recovery can help eliminate the waste products that accumulate, and supplements like beta-alanine or bicarbonate can help buffer the acid and ease that burning sensation. Be sure to consult an expert for guidance on using these supplements safely.
The Aerobic System
For longer efforts (beyond 30-60 seconds), your body uses oxygen to create energy (ATP). Pyruvate gets oxidised to carbon dioxide and water, instead of being broken down to lactate. This is a much slower process, but it generates a lot of energy that is essentially unlimited, and it can use carbohydrates, fats, and some proteins. During endurance exercise, eating and drinking can help keep the aerobic system functioning effectively.
Each athlete’s aerobic energy system generates different amounts of power. It is characterised by your VO2 max, which is influenced by your training level, genetics, gender, age, and body composition.
How this Translates in Energy Systems for Endurance Events
While long-distance events like marathons and triathlons mainly rely on the aerobic system, the anaerobic system steps in during intense moments like sprints or climbs. We are often bouncing between different energy systems.
While you can improve your body’s ability to utilise other fuels through training adaptations, carbohydrate stores (muscle glycogen) are crucial for those bursts of high power. This is why we focus on strategies that optimise this fuel at key times to maximise power output and performance.
How this Translates in Energy for Team Sports of Events with Repeated Efforts
In sports with repeated bursts of activity, the anaerobic system is key for powering through each effort, while the aerobic system helps you recover between efforts by replenishing ATP and clearing out lactate. Thus, we need to fuel both systems adequately for maximal energy and performance outcomes.
So What Next?
Knowing how your body’s energy systems work can help guide your fuelling choices before, during, and after your training or event.
Stay tuned for Part 2, where we’ll dive deeper into HOW to fuel for performance!
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