According to Yale Medicine the facts about running and injury look bleak:
"at least 50 percent of regular runners get hurt each year—some estimates put the percentage even higher—sometimes from trauma, such as a fall, but more often from overuse."
I have definitely heard of the percentages running (pardon the pun) even higher than this, and have experienced the pains of running for myself.
A Personal Story
All through my childhood, teenage years and early adulthood I played lots of sport, and from the age of about 18, I did quite a bit of running as well. Even at this tender age I found that my hips would be very stiff afterwards, but I was young and did lots of training, so I saw the stiffness as all being part of the burn.
Looking back at my early-twenties, when I was playing quite a high level of squash and training hard, it now makes me cringe what I was doing to my poor body. By the age of 23, I was already suffering from sciatic pain, and I remember vividly not being able to sit on my local squash club's bar stool without pain shooting down my leg. Yet still, I'd push on through it.
How much of this pain was down to running is difficult to tell, as I was doing a lot of other activities and training at the time, but by the time I left England to teach English in South Korea in my mid-twenties, my hips were so tight that even rotating my foot outwards would be very painful.
Luckily though, Korea gave me a break from the old routine. I did some martial arts and the kicking seemed to help a bit. I did however, continue to run and completed my first marathon in Korea. The trouble is that after the training and the marathon itself, my hips, lower back, and ankles were so painful (I was sore for about 2 months after the race), I wondered whether I'd do any runs over any distance ever again.
About 6 months later, a number of friends were reading a book many of you will be familiar with, "Born to Run" by Christopher McDougall. The book tells the story of the author's experiences with a Mexican tribe called the Tarahumara, who run the equivalent of ultramarathons on most days wearing sandals made of tyres and string. Amazingly, they seem not to get injured from this volume of running.
In my desperation to keep running, I bought some sandals along with some of my friends. I say sandals, but they actually came as a flat piece of thin rubber that you had to cut to the shape of your foot and then thread a thick piece of string through and wrap around your ankles. It was the closest thing possible to running barefoot.
I began by running around the car park for 2 minutes and then gradually increased the time and distance over the next 6 months until I built-up to running another marathon. Incredibly, I ran about the same time (about 3hrs 50mins, 3hrs 45mins in normal running shoes), and apart from some slightly stiff calves that lasted for about two days, I had no ill effects after running at all and even completed a 78Km mountain ultramarathon in 2016. I'd cracked it, I thought.
However, as the years went by I started to have some trouble with my ankles. No where near as serious as before, but bad enough to cut my distances. In the last couple of years I have managed to change my gait through biomechanics (gait and posture) training and I now run pain-free, and am thinking of running marathons again.
What Causes Injury When Running?
You might be surprised to find out that science has little to say on this (I feel like this is a common theme on this blog). Studies on diet and exercise suffer from the same problems; it is difficult to study humans over long periods of time and control all the variables of people's lives to give reliable results, and studies of animals aren't very useful as animal diets and biomechanics are quite different from our own.
In my experience, the worst I felt when running was when I was heel-striking. One of the things you notice when you run barefoot is that you can't run while heel striking, and if you do the force with which you land is very noticeable. As soon as you take the cushions off your feet you run more towards your forefoot or mid-foot and this engages much more musculature in absorbing the force of your foot impact on the ground. To me, this is basic and obvious; heel-striking while running over the long-term is going to get you injured.
Forefoot striking will help, but it isn't the end of the story. If you run with poor posture or joint alignment, basic physics will infer that you will be putting pressure on certain areas and not absorbing impact efficiently through your body. For example, if you run with a lordosis in your lower back, you'll likely suffer back pain; if you run with an anterior pelvic shift, you'll likely suffer from knee and foot pain; and with both you'll likely make it harder to engage your glutes efficiently, leading to increased pressure on calves and hamstrings. Running with good posture is absolutely essential to engage muscles optimally and keep the joints in proper alignment, but it is harder than it sounds and requires training and practice.
What are the Best Shoes to Wear?
A few years ago, just at the time when the book, "Born to Run" was at the height of it's popularity, Vibram brought-out its famous, "Five Fingers", shoe and made the claim that wearing them could help runners reduce the risk of injury. Subsequently, people started wearing them and got injured and sued Vibram for misleading advertising. Vibram was the leading minimalist shoe maker on the market, so this must mean that minimalist shoes are just a bunch of hokum, right?
A lot of podiatrist's agreed with those suing Vibram as they noted an uptick in patients coming to them with stress fractures of the foot and Achilles tendon injuries. I am not sure that this is the end of the story, though.
The problem with those getting injured was that they were transitioning from running in normal padded shoes to no padding without working slowly into it first. If they usually ran 10Km, they'd just go running for 10Km straight-away in their new shoes. Vibram stupidly never mentioned building-up distances slowly or running with the correct technique (probably because they don't know what good technique is), so they deservedly got sued.
You cannot run the same distances right-away wearing minimalist shoes or barefoot running. Although we have evolved to run barefoot, we haven't lived the life of our ancestors. A life in shoes has prepared us poorly for running with no support (not to mention our lack of activity in general), but that doesn't mean we can't rediscover what we lost. The major strength of minimalist shoes is that the lack of cushioning helps us run properly. We feel the ground (and the sharp stones!) and that means we mitigate force through our musculature, not our joints.
That said, if you run with good posture and form already, normal running shoes will obviously pose less risk, as you'll be more protected from sharp stones and rocks. It is easy, however, to slip back into bad running habits if you aren't one of those lucky ones with good natural running technique.
Posture and Gait
Controversial as it may sound, it is my opinion that there is no form of injury prevention that works besides improving your posture and gait. Unless you are improving the way you stand, walk, and run, you will not prevent injuries, period. I see a lot of isolation exercises being done in the gym in the name of injury prevention, but I have never seen them work in anyone. I have been training a wide range of different clients for years and their situation never gets better if they do these exercises - and this includes various static stretches.
The false assumption everyone makes is that injury is just unfortunate or an inevitable consequence of age. Sure, luck and age play a role, but it is fundamentally your posture and the way you move that contributes to chronic injury and, to a lesser extent, acute injury. This is never more important than in the way you run.
If you run with good posture and understand the basics of an efficient gait cycle, you stand considerably less chance of getting injured. I'm planning on some videos to highlight this in more detail, but for now the correct gait cycle should include the following:
Running on the balls of your feet.
Having a neutral spine throughout the running stride.
Landing your feet hip width apart.
Having a neutral foot position as it hits the ground and as it pushes off.
Engagement of the gluteus maximus.
Rotation of the upper body at the thoracic spine.
Minimal rotation of the hips and no shifting of the hips.
Alignment of the hips, knees, and ankles throughout the running stride.
If you can achieve all of these, you'll likely run without much pain, and you'll probably run faster too. If you pay attention to yourself in the mirror and how you run, you'll notice, however, that these things are easier said than done. The best runners do these things naturally and are probably just fortunate to have developed the ideal gait and have had a lifestyle that hasn't compromised their posture too much. Lucky devils, some of us have to work on it. Put the time and effort in, however, and you won't just improve your running, you'll feel great too.