There are so many rumors and myths in running that are either not backed up by science or proven to be incorrect. Yet many of these are still touted as fact by either nonrunners or those in the health and exercise field who should know better.

It was actually hard to pick just five running injury myths, but here are the biggest offenders on a regular basis:

1. Running is bad for your knees

This is a common view among nonrunners, which on the whole is untrue. Several studies are available that show no link between runners (including both high level, competitive runners and recreational runners) and an increased development of osteoarthritis or any other degenerative knee condition.

I think where this misconception stems from is the frequency of knee injuries in runners and the number of runners who stop running due to knee injury. In most cases, the cause of injury is not degeneration of the articular cartilage within the joint (osteoarthritis) but is more commonly patellofemoral dysfunction or meniscal cartilage damage.

This type of pain, however, has nothing to do with the repeated impact that pounding the pavements incurs. It has more to do with faulty biomechanics — the movements patterns we adopt to compensate for muscular imbalances and structural abnormalities.

In fact, weight-bearing exercise actually strengthens the articular cartilage in the same way that exercise can strengthen muscles and tendons. Articular cartilage responds to exercise when cells known as chondrocytes (found within the cartilage) sense an increased load. At this point they increase the production of components required to repair and remodel the tissue in response to the increased stress levels.

So, while running can cause knee injuries when abnormal joint stresses occur, in a healthily functioning knee joint, runners are at no greater risk of developing degenerative injury than anyone else.

2. A low arch equals overpronation

Pretty much anyone who has ever done any running will have heard the term "overpronation." They may have even had a gait analysis and been told they need motion control shoes, neutral shoes or cushioned shoes.

Pronation is a necessary part of the foot's movement when walking and running, but it has long been accepted that excess (and also insufficient) pronation is a risk factor for injury in runners.

Many runners, therapists and running shoe salespeople mistakenly believe that simply looking at the foot in a static standing position can indicate if the runner pronates excessively. But this is simply not true. A lot of the time those with a low arch do overpronate, but this is not set in stone.

And even less reliable is the thought that someone with what appears to be a neutral arch, does not overpronate. Even a "normal" looking arch, once subjected to full body weight, movement dysfunctions and muscle imbalances from above can pronate excessively or too rapidly. The only way to tell if this is the case is to observe the foot in motion.

3. Barefoot running reduces injuries

The last point brings us on nicely to the most current of all running injury topics — the barefoot (or minimalist shoe) craze. The notion of running barefoot or in shoes that mimic barefoot movement patterns has really taken the running world by storm. Many hail barefoot running as the answer to all running problems — allowing you to run faster and with fewer injuries.

The reason for the proposed reduction in injury rates is that barefoot running promotes a forefoot strike, as opposed to a heel strike. The benefits of this are thought to be better shock absorption through the foot and ankle joint and a shorter stride length, which reduces knee hyperextension and patellofemoral joint forces.

This is likely to reduce the occurrence of knee injuries such as patella maltracking issues and IT band syndrome, as well as stress-related injuries such as stress fractures and medial tibial stress syndrome.

However, reduce one force and you increase another, as landing on the forefoot then raises the stress on the calf muscles and particularly the achilles tendon. Forefoot striking has been shown to increase the chances of developing achilles tendinopathies and overworking the calf muscles, which can contribute to the development of conditions including plantar fasciitis.

4. Running strengthens your legs sufficiently, so strengthening is not necessary

When studying exercise and fitness we are all told about the specificity principle. For anyone who's not aware of this, it basically means training in the sport in which you are competing. For example, to compete at the top level of soccer, your training should consist of playing soccer. The same applies to running — to run a marathon, for example, you need to run lots of long runs.

This is true, but there is far more to it than this, and I'm not just talking about cross-training or swimming to give your legs a bit of a rest. Many runners make the mistake of thinking that with the amount of running they are putting in to their training, their legs are developing the strength they need to perform the activity at hand. But this is not true.

In order to perform at your best and to avoid injuries, additional leg strengthening exercises should be included. This is largely because the motion of running occurs in one plane — forward. And that's great, as long as that is what happens.

In many runners, injury happens when rotational and sideways movements come in to play. These may happen due to muscle imbalances or fatigue, but either way they can be reduced with a good strengthening program.

Great examples include the clam exercise, which strengthens the hip abductor muscles and reduces that knock-kneed appearance that affects knee alignment. Similarly, hip hitching or step-down exercises help to train our muscles to keep the pelvis level as we transition from one foot to the other.

The glutes are also often overlooked, yet vitally important in propelling us forward with every step. A weak butt equals not only reduced performance, but also increased stress on the hamstrings and calf muscles, which can contribute to many running ailments.

I read a great analogy on this point recently that really stuck with me: "You can’t let your engine outpace your chassis." This means cardio fitness-wise you can be as fit as you like, but your body must be able to keep up, too.

5. Stretching before running reduces injury

To stretch or not to stretch. This is a common dilemma among all sports people. History has had us warming up with a light pulse-raising exercise, followed by static stretching. Recent research has shown that static stretching actually has no effect on preventing overuse injury (the type most often sustained by runners). Even worse, it may actually decrease performance by reducing muscle strength and power immediately post-stretch.

If the subject is distance running, where there are no sudden changes in direction or explosive movements that can cause acute injuries such as muscle tears, then prerun static stretching isn't usually necessary.

So should runners stop stretching altogether? That depends on a few variables. If you have a history of injury and subsequent restrictions in flexibility, then static stretching has been shown to increase range of motion and so could be beneficial and at worst will do no harm to the distance runner as power is not a key requirement.

If you are one of these athletes who has always stretched prior to running, then the advice is don't stop now. If it works for you, keep doing it.

So there you have it — some common running injury myths debunked!