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Running is good (even for your knees). If you take it slowly

Science says that running reinforces the joints. But why do so many runners get hurt? Because they don’t take it slowly. And it’s not a matter of speed…

Very few, among the non-runners, resist the temptation of explaining to those who grind kilometers with enthusiasm, that “running does more harm than good”. A sentence that is very irritating (especially if pronounced by those who think the word marathon is solely associated with movies). But that is also false.

(cover photo: Julia Hawkins, 101 years old, winning the World’s Seniors 100 meters in 2017, ph. Brit Hackabay)

When it comes to running, everything is relative

«Any absolute statement, when it comes to running, should not be taken seriously», says Carlo Selmi, head of Rheumatology and Clinical Immunology at the Humanitas Clinic in Milan. «Because scientific data support different theories on running. But the analysis to gauge if it has a positive or negative impact on our health often depends on the attitude that those who interpret them have towards the discipline».

Photos from Pacers Running Festival Half Marathon and 5k in Arington, VA. May 10, 2009.

Running and early arthrosis

An example? «The age-old discussion about running and early arthrosis. We have data (from Professor Jeffrey B. Driban of the Boston Hospital) that compare 80km per week runners with non runners. 4.4% of the former had early osteoarthritis. However, one element is missing: also 1.3% of sedentary patients had it. It therefore makes sense to say that early osteoarthritis is a risk for serious runners, and that this risk is 3% higher than in sedentary people. Yet it also makes sense to underline that the risk is very low (as a matter of fact, arthrosis also hits 1.3% of non runners). And that, in the light of proven cardiovascular benefits, running is definitely worth it. Which is exactly what I think».


It is better to run than to be sedentary

We understood this when Selmi revealed, when we started out chat, that he had run the Florence Marathon a few days earlier with the West Milan group. Under a torrential rain. «If we talk about healthy people (the micro-traumas caused by running aggravate the chronic situation in progress in those suffering from arthrosis), running is with no doubt much healthier than sedentary life. The latter, truly has a nefarious impact on our body», says Selmi. Dr Driban must be a runner too. The title of article with which he will present the results of the research we mentioned (to be published in November 2018) is Most Runners Are Not At Greater Risk of Ostheo-Arthritis (source: US National Library of Medicine).

Is running bad for your knees?

The work cited by Selmi is just one of the most recent studies that are reviewing the assumption that “running is bad for your knees”. In a document published in the European Journal of Applied Physiology, researchers of the Brigham Young University have demonstrated that the bio-mechanical stress associated with runner’s stroke has a local anti-inflammatory effect.

Stretching before and after running is fundamental. See box below

Inflammation decreases

«They measured the levels of inflammation markers in the synovial fluid of the knees after 30 minutes of running. They found out that – after a temporary increase during the exercise – they had fallen to lower levels than before the run», explains Selmi. «These are surveys carried out on a small group of individuals. Yet, if repeated on a larger scale, they would lead to thinking that running not only does not harm knees. But it also has a chondroprotective effect: which means, it helps to preserve cartilages».

Any benefits for the spine?

Other studies also indicate that running could make the spine stronger. Researchers at Deakin University in Australia Working have been analysing people who have been runing 30 to 40 km a week for more than 5 years. And they were able to prove that what was already been tested on rodents (vertebral discs grow bigger and are better hydrated through running) is also true for humas.

Why do runners get hurt then?

But if running strengthens the body and even joints, how is it possible that most runners get injured? Because statistics are pitiless: 50% of those who run are forced at least once a year to stop for at least a week due to pain or accidents.
According to Lorenzo Boldrini, sports doctor at the Isokinetic orthopedic and sports rehabilitation center in Milan, there are two causes: lack of adequate sports preparation and rush.

GRAND BARA DESERT, Djibouti (Dec. 8, 2011) A runner sprints for the finish line during the 29th annual Grand Bara 15K race in the Grand Bara Desert, Djibouti.  (U.S. Air Force photo by Staff Sgt. Jonathan Steffen/Released)

The enemy number 1 of runners: rush

Rushing into things, explains Boldrini, is the source of many problems related to overload. «Lack of time, too much enthusiasm or even the trivial desire to test oneself: there are many reasons why runners often do too much and too quickly. Most victims are beginners, ie those who have been running for less than three years. Joining a more trained group and keeping up the pace, or being able to run a marathon in the first 12 months is good for morale but increases risks. The body must adapt gradually to mechanical activities. In running, the mechanical act is a high impact one: at every step, we must be able to sustain our weight which, due to the “flight”, is 2.5 times more than it actually is».

Increase load and intensity slowly, 10% per week

«The percentage of increase, in terms of distance, loads and intensity, should never exceed 10% per week», continues Boldrini. «For beginngers, it is also better to distribute the mileage on more outputs. Going out 3 or 4 times per week with a gradual increase, rather only twice at a greater pace».

Strengthen muscles at the gym

The other determining factors for injuries are the lack of adequate muscles and wrong posture. «Reinforcing the right muscles and maintaining a correct position during the athletic gesture dampens the impact, allowing a gentle and uniform discharge. And thus impacting less on the joints». Boldrini is an expert on this issue: two years ago he created a RunningLab for biomechanical and postural analysis at Ortholabsport in Milan. Where, after an assessment of posture, flexibility and strength, he measures the distribution of forces during motion.

The correct posture for running

«Those who descend heel first, especially after a long stride (with a stretched out leg) andpoorly developed muscles, get a sudden high load impact. On the measurement charts it looks like a straight, almost vertical line going up. Ideally, this would be a bell-shaped curve, with forces distributed along all the 230 milliseconds of the return to the ground». Learning to run correctly, therefore, preparing yourself in terms of strength and stretching, reduces the risk of injury.

Proprioception: find your balance in motion

«Improving our ability to maintain balance during movement (proprioception) also decreases the risk of injuries» says Luca Dal Molin, physiotherapist at TakeCare in Milan where they organize Running Days workshops. «The more we are able to find our center of gravity during unexpected movements, the less we will be subjected to makeshift landings and potential sprains or injuries. The advice for those starting from scratch is working for a month with a personal trainer. You will start with preparatory exercises and increase distance and pace of running based on your muscles. Once you reach the desired level of fitness, you can continue on your own. Provided you never forget to do gymnastics and stretching in order to not lose the preparation you have acquired».

Is it a good idea to consider running to lose weight?

«To those who consider running to lose weight, especially at 45+, I would suggest a consultation with a nutritionist», continues Dal Molin. «This is in order to adjust the diet in the transition from a sedentary to an active life. And an orthopedic screening (which becomes mandatory if you have joint problems)».

«It’s not running that harms the body but the way you do it», concludes Boldrini. «Being in a hurry, in running just as in many other things in life, is the enemy we have to deal with».



Run at low cadence, with more frequent and small steps (180 per minute). Avoid the “big stride” that leads to stretch the knee in the support phase, with the foot that lands far away from the body. Keep the weight under the center of gravity (keeping the torso vertical, but slightly forwards).


A 10% increase per week (in terms of duration and intensity of the run) is useful to help the muscles get used to the effort and to keep high the control threshold. Athletes maintain an optimal posture even during the phases of acute fatigue. Amateurs’s posture, on the contrary, get worse with fatigue. By limiting oneself, it is easier to learn how to maintain the correct posture even under stress. It becomes natural.


The best exercises are those carried out without weights. The focus should be on the muscles that we use on the landing phase because strengthening protects the joints. These are: calf, mediogluteum and back muscles. Among the useful exercises. Get up on tiptoes and proceed slowly
in the descent. Squats and lunges (ensuring the knee never goes over the tip of the foot). Plank and abdominals to strengthen the core. Bipodalic bridge. They are simple exercises but only effective if done with precision: it is better to be guided to start with.


Warm up is essential to reduce the risk of accidents. You can do it with a light 5-10 minute jog, associated with dynamic stretching that starts slowly and then increases in extension and speed. In particular: swinging of the legs, walking on the spot, raising the knees towards the chest, step and side opening.


Thigh flexors, quadriceps, and hip flexors should be extended. Stretching should be practiced immediately after running, maintaining static positions for at least 30 seconds and performing 3 to 5 repetitions. If unable to do so immediately, at least the same evening.
Those with a deficit of elasticity should do stretching every day for at least 3 weeks in order to obtain visible results. 3 sessions a week after the sport are sufficient for maintenance.


Shoes condition the support. Those who have alterations in the axis of the foot benefit from a structured shoe (sometimes even a footbed). Those with better postural control can afford lighter shoes.

Cover photo: 101 years old runner, winner of the 2017 World Record for 100 meters for centenaries

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