What happens to your body when you run?
WHETHER you're a seasoned marathon runner or a rookie at pounding the pavement, understanding the physiological effects running has on your body is vital.
Here's a breakdown.
Stomach pain or cramping is a common problem for runners. This is because our body drives blood towards our muscles and away from the gut. As a result, digestion of food begins to slow and is exactly why a big meal before a run is never a good idea.
While it's essential to fuel your body pre-run, always opt for something small and light like a piece of fruit or sandwich.
The "runner's high" is not a myth. When you run long distances it triggers the release of endorphins, brain chemicals that produce feelings of euphoria, and can even go so far as to numb the body from physical pain.
Other neurotransmitters include dopamine, which stimulates feelings of pleasure, and serotonin, which plays a role in mood-regulation. These factors all likely contribute to the immediate mood-boosting effects of running, as well as reduce symptoms of stress, anxiety, and depression.
Generally speaking, the amount of energy "in" versus the energy "out" is what determines our weight, and running can create a calorie deficit and promote fat loss through energy expenditure.
According to Bupa's Energy Burned tool, if you weigh 65kg, and you set a pace of 6.5km/h, you could burn around 130 calories (544 kJ) in just 20 minutes. That's equivalent to roughly one slice (55g) of sourdough bread.
Along with endurance, running also strengthens bones and muscles and bolsters metabolism, however at a certain point, lean muscle will not continue to increase with running, as the repetitive nature of running only requires a certain level of muscle recruitment for sustainability.
Therefore, running combined with resistant training is recommended to achieve a desirable level of fat versus muscle.
HEART AND LUNGS
When we pick up the pace, so do our heart and lungs. It's their co-task to flow oxygen-rich blood to our muscles in order to keep them firing. Just like other muscles, our heart experiences fatigue.
So it's just as important to "train" our ticker to endure long distances as it is to train our legs. Each time you run, the idea is to increase your "maximal oxygen uptake" (aka VO2 max), which measures how efficient you are at using oxygen. This measure is considered to be one of the best indicators of cardiovascular fitness, and a higher oxygen uptake in turn allows your muscles to increase their capacity to efficiently create energy.
It seems like a no-brainer that our body temperature increases as we run, particularly the case in hot weather, however your sweat (which is different in everyone) can actually decrease the core body temperature, especially in colder climates, and in some cases cause hypothermia.
The key is to dress appropriately and wear layers that can be added or removed as necessary to protect from cold or hot weather injury.
Yes, there are some downsides to running. Mainly in the way of injury. As running is a repetitive-strain activity, your joints and muscles undergo significant stress. That's why it's common for runners to experience joint tendinitis (swelling), shin splints, muscle tears and even heart stress.
"Around 40 per cent of running injuries start in the knees, which can be avoided with a balance of strength training and consistent stretching after running, and in combination with a good shoe" says Pip Taylor, professional triathlete and author of the Athlete's Fix.
Preparation is key. Build up, train your muscles and joints for endurance to allow optimal adaptation, and, as always, properly fuel your body before and after for the long run, with adequate recovery periods in between.
Kathleen Alleaume is an exercise and nutrition scientist and founder of The Right Balance. Follow her @therightbalance