Why do you get Puffed During Sprint Training?
Sprinting. It’s a term that can invoke intrigue, fear and excitement all at the same time. An intense workout for the whole body that is over in a short amount of time, sprint training offers health benefits no other form of running can quite match.
This should all sound like a great idea; and if we’re honest, it is! But why do we get ‘puffed’ when we do sprints? As we should all know, sprints are an ‘anaerobic’ form of exercise or, effectively, the energy for sprinting is provided without the need for oxygen. So why do we puff, pant and struggle off the track at the end of each sprint? It’s all a bit more complicated than it seems, so let’s explore the science of why we get puffed when we do sprint training.
The 3 Energy Systems:
The body has 2 different ways of producing energy anaerobically (without oxygen); what we call the lactic acid system and the ATP-PCR (or alactic) system. Furthermore, everyone’s favourite energy system is there to back it all up; our aerobic energy system. To understand why we get puffed after sprints, we first have to understand how the energy systems work individually and then together as a unit.
When we need to produce ‘explosive’ movements, such as a shot-put, 100m running sprint or long jump, we rely mostly on the ATP-PCR system. This involves rapid energy assembly utilising substrates available in the muscle bellies. The ATP-PCR system provides energy at a fast rate and has no bi-products – the downside is, however, that these substrates (the PCR) run out after 6-10 seconds of energy production. After this point, we rely more heavily on the Lactic Acid System.
Lactic Acid System:
As our ATP-PCR system tires and we push past 10 seconds of high intensity exercise, our lactic acid system is working hard to become the predominant energy system. Any high intensity activity greater than 10 seconds through to around 60 to 90 seconds (like a 100m swim, 400m run) relies heavily on the lactic acid system to produce energy quickly. The lactic acid system is so called due to the production of our favourite bo-product: lactic acid. Lactic acid (or, more correctly, lactate and hydrogen) occurs as blood glucose and stored muscle glucose (glycogen) are broken down to produce energy, and in the process shed hydrogen ions. These hydrogen ions make up the ‘acid’ in lactic acid, and slowly start to accumulate in the muscle. When the production of ‘lactic acid’ is faster than the removal, we start to see lactic accumulation. This is where our muscle burn comes from (review this by clicking here).
Aerobic Energy System:
After 60 to 90 seconds of exercise, the aerobic energy system becomes the predominant source of energy for exercise. Our aerobic energy system utilises the oxygen that we breathe to literally ‘burn’ the energy we eat. This energy system has many benefits, namely that it can utilise fats and proteins (as well as our carbohydrates) to produce energy, and the system is so efficient at producing energy that it can continue for long periods of time. The only down-side is that aerobic function takes place in our ‘slow twitch’ (red) muscle fibres, and hence limits our ability to perform higher intensity work over long durations.
So we have three separate energy systems, all working in unison to keep us functioning as we live, breathe and exercise. Each system has its own unique characteristics that make it better for a certain speed and intensity of exercise. It makes sense then that they would work together to provide optimal function during exercise, but how exactly does this work?
How the energy systems work together:
We’ve explored the three very different energy systems, but how do they all fit together? The most important thing to visualise when thinking about ‘energy burning’ during exercise is that all 3 of our energy systems are working together at all times. Each energy system is contributing a different level of energy production during exercise, but we talk about the predominant source of energy production as being the energy system providing the most energy. In the case of sprint training, the ATP-PCR and lactic acid system provide the majority of energy for work. But these don’t require oxygen – so why do we get puffed and heave in oxygen if our aerobic energy system isn’t playing a starring role during sprints?
Intermittent exercise and recovery:
Probably the best bit about sprint training is the rests we have in between repetitions. Due to the extremely high intensity nature of sprint training, we require rest between reps to allow the body to adequately recover and replenish energy stores. Our ATP-PCR stores deplete during each sprint, and we require time to shift lactate and hydrogen accumulation from the muscle, to the blood, to the kidneys and beyond. During our rest we often start to feel puffed out, despite resting and standing still. This is the beauty of sprints, where we get to work all three energy systems in the space of a 20 minute session. To replenish and recover our anaerobic systems, we require the help of our aerobic system. And after such a high intensity workload, there is a lot of recovery to be done. The aerobic energy system starts working over-time to rest the already fatigued anaerobic energy systems, and in the process requires large quantities of oxygen. Hence, we increase ventilation in an effort to match the increased oxygen demand. This is often called our ‘O2 debt’, during which our aerobic system attempts to makes up for the lack of involvement during the sprinting activity. This leads us to the other major benefit of sprint training, known as EPOC. Excess post-exercise oxidative consumption occurs after high intensity interval and sprint sessions, as our body attempts to restore our heart rate and energy levels back to resting state.
So, basically, if you’ve done sprint training you’ve just worked all 3 energy systems, stimulated serious muscle activity AND spent more energy than if you’d just done a straight up 20 minute run (or stayed sitting on the couch). The benefits of sprint training are numerous and affect almost every part of your physiology, making high intensity sprint training the ideal method of training to get you moving, improve your fitness and keep those stubborn kilos off.
Need help starting up with some sprint training, or just getting more active in general? For more information, or to join up, get in contact and let one of our expert team help you on your way to achieving your health and fitness goals.
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