Runners are always looking for improved knowledge, but sometimes some things are misunderstood, writes Dr Jason Karp

Have you ever been told to stretch to prevent an injury? What about taking deeper breaths to take in more oxygen? There are so many myth conceptions about running and some things that you may not know that can unlock the doors to your success are listed here.

Stretching won’t prevent injuries

Have you ever run with a dog or watched a horse race? If you have, you probably noticed something interesting – none of these animals stretch before or after they run. Stretching before a workout seems to be something that only humans do. Whether stretching can prevent injuries depends on the type of activity you’re doing and the type of injury you’re trying to prevent.

If the activity includes explosive or bouncing movements, like those in volleyball, basketball, and plyometric exercises, research has shown that stretching can reduce injuries by increasing the compliance of your tendons and improving their ability to absorb energy. However, for low-intensity activities such as running, cycling, and swimming, research has shown that stretching doesn’t prevent injuries because you don’t need very compliant tendons for those type of activities.

In regard to the type of injury, stretching can prevent muscle injuries, such as sprains and strains, but not bone or joint injuries which are common among runners. These are caused by increasing the training load too much and too quickly. The only documented benefit of stretching is to improve the functional range of motion (flexibility), which is best accomplished when you stretch aside from the workout.

You need to run more

If you want to become a better runner, the first step is running more. The number of miles (or amount of time) you run each week, every week, is the most important part of becoming a better runner. I can’t emphasise this enough. More running stimulates many physiological, biochemical and molecular adaptations. It increases blood volume – a greater amount of blood circulating in your body means a greater number of red blood cells, which transport oxygen. Inside the red blood cells is a protein called haemoglobin, which carries oxygen to your working muscles. These changes to your blood improve your blood vessels’ ability to transport oxygen. It also promotes better fuel storage. Running lots of miles stimulates the storage of more fuel (glycogen) in your muscles and increases your body’s use of fat so that your muscles spare your reserved glycogen.

Running promotes more efficient transport of oxygen. When you run a lot, your body creates more capillaries surrounding your muscle fibres. More capillaries mean a more rapid diffusion of oxygen into your muscles. Running also improves the ability to produce energy. Through the complex activation of gene expression, running increases how many mitochondria you have in your muscles and the number of aerobic enzymes contained within them. That combination increases your muscles’ capacity to produce energy aerobically.

Running more also allows you to see and experience places and things you wouldn’t normally get to and gives you a chance to discover things about yourself, including discipline, courage and the ability to meet a new challenge. Always increase your running mileage systematically and with a rationale behind it. Be careful, because you can easily get injured if you increase your weekly mileage too quickly.

Injuries have little to do with shoes

Unless you’re wearing a shoe that is completely wrong for your foot type and running mechanics – for instance, wearing a cushioned shoe when you should be using a stability shoe, your shoes shouldn’t be the reason for an injury. The main reason why injuries happen is because the physical stress from running is too much for your body to handle at a particular stage of fitness.

The human body is great at adapting to stress, but only when you apply that stress in small doses. When you apply the stress too quickly for your body to adapt, something inevitably breaks down. Don’t train stupidly by training haphazardly or by increasing your mileage and intensity too quickly – if you train smartly, your chances of injury will be minimised.

Lung capacity has nothing to do with your ability to run

At first glance, distance running seems to have everything to do with strong lungs. After all, it’s through our lungs that we get oxygen. If the size of our lungs mattered, you would expect the best distance runners to have large lungs that can hold a lot of oxygen. However, the best distance runners in the world are quite small people, with characteristically small lungs. Total lung capacity – the maximal amount of air the lungs can hold – is primarily influenced by body size, with bigger people having larger lung capacities. There is no relationship between lung capacity and how fast you can run a 10km.

Studies show that the lungs don’t adapt to training or limit the ability to perform endurance exercise, especially in untrained people. That limitation rests on the shoulders of the cardiovascular and metabolic systems, with blood flow to and oxygen use by the muscles the major culprits. Apart from lung volume, there are other aspects of the pulmonary system that affect running performance, gas exchange being the most important. However, in healthy people, the lungs are more than adequate for this gas exchange to occur.

If you’ve been told to take deeper breaths when you run to get in more oxygen, don’t heed the advice! At sea level, your blood is nearly 100 per cent saturated with oxygen, even when running fast. Taking deeper breaths doesn’t get more oxygen from the lungs into the blood. At sea level, the main stimulus to breathe is the partial pressure of carbon dioxide and not oxygen. In some elite runners, there is a diffusion limitation between the alveolar wall and pulmonary capillaries because of a very high cardiac output, which leads to a desaturation of oxygen on haemoglobin. However, in nonelite runners without pulmonary pathology, the lungs do not limit exercise performance.

Muscle fibre type will dictate what you’re best at

Humans have three major muscle fibre types, with gradations between them, the proportions of which are genetically determined. If you have lots of slow-twitch aerobic muscle fibres, you’ll be better at long-distance races.

If you have a lot of fast-twitch anaerobic muscle fibres, you’ll be more adapt at sprints. However, if you have a 50/50 mix or 60/40 mix of slow-twitch and fast-twitch, middle-distance races will be your forte.

It’s impossible to know what your dominant fibre type is without getting a muscle biopsy – the only way you can gain some insight is by running many different races and doing different types of workouts over a number of years to see what you’re best at.

Once you know, though, train according to your fibre type. If you have 70% fast-twitch fibres and 30% slow-twitch fibres, you could get through a marathon if you really want to run it – however, it’s going to be a tough task!

» Dr Jason Karp holds a PhD in exercise physiology and is a prolific writer with more than 200 articles published in magazines as well as being the author of five books. He is also a frequent speaker at coaching conferences