We know it sheds kilos like no other exercise can. We know it makes us hangry and stiff. We know that on a training day we fall asleep within 20 seconds after our heads have been placed on our pillows. But what really happens to our bodies when we run and how does it affect our brains? What is the science behind running and how can we perform better?

Today at Marathon Grit we get nerdy and explore the physiology of running. Read on for the full scoop.

Let’s start with your muscles. When you run your muscles are contracting at a fast rate. This is hard work and requires energy.

Your bloodstream carries oxygen to your muscles and this oxygen converts glucose into ATP (the energy required to do the work). When you are running your muscles require more oxygen. This is why your heart rate increases and you become out of breath.

The more your workout demands, the more oxygen your muscles crave. Therefore, you are more out of breath and your heart rate is higher when running intervals as opposed to running at an easy pace.

Caroline’s Top Tip: If you want to explore different types of training sessions this article is a good place to start: Running Training The Different Types.

LACTIC ACID

No one (not even Eluid Kipoge) has an unlimited source of oxygen in their body and unfortunately, we all get depleted somewhere during our training run. When our system cannot deliver oxygen quickly enough our muscles take glucose and convert it into lactic acid. This is when you start feeling fatigued towards the end of a run or during an intensity session. If you have a high VO2 Max your body can utilize a lot of oxygen in your muscles. You, therefore, do not get tired as quickly and can perform better. Your VO2 Max is a good indicator of your performance ability.

LACTATE THRESHOLD

Your lactate threshold is the point at which, during training, lactate acid starts to accumulate in your muscles. When you have a lactate build-up in your muscles they are hindered and cannot contract. The lower your blood lactate, the higher your power and output. Every person’s lactate threshold is individual to them. Many elite runners can clear lactate from their bloodstream quicker than others, this allows them to keep a fast pace for longer.

To burn fat there is little that compares to running. Losing weight requires you to burn more calories than you consume. According to a Harvard University study, a 155-pound (70-kg) person could burn 372 calories in 30 minutes running at a moderate pace of 6 miles per hour (10 km per hour). There are few exercise alternatives that can burn this many calories in only half an hour.

Additionally, certain sessions like interval training, hill sprints, and tempo runs can continue to burn calories throughout the day due to a phenomenon called the “afterburn effect”. When you stop training your body needs to use oxygen for a few processes required to get you back into a resting state.

This includes replenishing ATP, creatine, and oxygen stores, removing lactic acid from the muscles, and repairing muscle cells. Lucky for you, the oxygen consumption needed for these processes burns calories and so when you are chilling on your couch after a thought session, your body is still burning fat.

What happens to your brain when you run? According to the Journal of Sports Medicine and Physical Fitness, running is a natural anti-depressant. Running lowers your anxiety levels, due to increased levels of tryptophan. Additionally, it releases endocannabinoids in the brain, which promote feelings of calm. A runner’s high or feelings of euphoria are linked to the endorphin release that running at a comfortably hard effort typically triggers in the brain. This is why you feel a rush of happiness as your step out of your post-run shower.

Want to sleep like a baby? Running may be the key. After 4 months of consistent running, you’ll start to notice that you fall asleep a lot quicker and sleep much deeper through the night. Studies have proven that exercise increases the time you spend in deep sleep. This is because exercise triggers the release of hormones (as mentioned above) that can help to stabilize your mood and decompress your mind. This, in turn, makes you fall asleep quicker and keeps you in deep sleep for longer.

Have you ever experienced a strong urgency to get to the toilet during a run? When you run blood flow that is usually allocated to the digestive system is redirected to your cardiovascular system. This can cause irritation in your bowl and can lead to runner’s gut. Diarrhea is not uncommon in runners because the irritation in the bowel causes it to expel whatever is inside.

Caroline’s Top Tip: Experiment with your pre, during, and post-run nutrition to ensure you are eating foods that don’t trigger runner’s gut. Here is an article from Marathon Grit on the subject – Marathon Training Nutrition: Where to start and how to maintain healthy eating habits.

From your muscles to your gut and all the way up to your brain running has a scientific effect on the entire system. The body adapts over time and handles the physiological effects of running better, therefore after a period of running consistently, it starts feeling easier, more comfortable, and later, enjoyable. After reading this we hope you will understand some of your body’s natural responses to your new training regime a little better. Keep at it! It gets easier.

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