In recent years, there’s been a noticeable rise in doctor-influencers — i.e., medical professionals with large social media followings who offer advice on everything from diet to training regimens. On the surface, we may be saying to ourselves: Finally, health information from “credible” sources instead of anecdotal tales from random internet personalities.

While doctors bring essential medical training to the table, many are not specialists in sports science, exercise physiology, or endurance coaching. And when these physician-influencers deliver sweeping statements like “running is bad for your knees” or “you should stop running if you have arthritis,” they can be just as misleading as fitness influencers chasing views. This is called authoritative dogmatism — the tendency to state universal rules without allowing for individual variability or updated science.

Moreover, the nature of social media requires the influencer to “hook” the reader by condensing the message into as few words as possible. And then follow up this hook with simplified language. So the issue isn’t necessarily about qualifications or skill — it’s oversimplification. Many of these claims sound authoritative but lack nuance, individualization, or updated evidence. They often fail to distinguish between general health recommendations and what’s appropriate for runners or active individuals who understand training variables like load, recovery, and adaptation.

In this post, we unpack six of the most persistent running myths that often come from authority figures — including doctors. Each one is carefully refuted using current sports medicine and exercise science, aimed at helping runners and coaches think more critically and contextually about running and movement.

Myth 1: Running is bad for your knees

Correction

Running is not inherently bad for healthy knees. It doesn’t damage your knees. On average, it does not increase your risk of knee osteoarthritis. In fact, studies show that runners often have healthier knees than non-runners, likely because running strengthens the muscles around the knee and helps keep a healthy weight. The notion that every stride “wears out” your knee is a misconception – our joints adapt and can even become more resilient with regular running.

Scientific Evidence & Explanation

Many studies have debunked the idea that running wrecks your knees. A large survey found that recreational runners tend to have a lower prevalence of knee and hip osteoarthritis compared to sedentary people. Regular running can increase cartilage nourishment and bone density, bolstering joint health. Of course, proper progression and technique matter – sudden large increases in mileage or poor form can cause knee pain, but running itself, done correctly and in moderation, does not wreck your knees. Nonetheless, it should be noted that the survey also showed high-volume or high-intensity running are linked to hip or knee osteoarthritis but there is no conclusion “whether these associations were causative or confounded by other risk factors, such as previous injury.”

Myth 2: You must stop running if you have arthritis.

Correction

Having arthritis does not automatically mean your running era is over. Understandably, severe arthritis may require some activity modifications, but if you have mild to moderate arthritis, you can continue to run safely and even improve your symptoms. Exercise is actually one of the best treatments for arthritis. Staying active, as long as it’s within comfort limits, helps maintain joint function and relieves stiffness. In contrast, completely stopping can worsen pain and weaken the joint.

But as always, individualization is important — a person with advanced osteoarthritis or acute joint inflammation might opt for lower-impact activities like cycling, swimming, or brisk walking during those flare-up moments. But telling every arthritis patient to stop all running is an over-generalization. Often, a better approach is to adjust — i.e., run shorter distances on softer surfaces and perform strengthening exercises to support the joint. By staying active in a sensible way, arthritis sufferers can often maintain their running routine and joint health rather than deteriorating with inactivity.

Scientific Evidence & Explanation

Blanket statements to “never run” with arthritis are outdated. Research and clinical guidelines favor exercise for arthritis management because movement nourishes the joints and strengthens supporting muscles. According to the Arthritis Foundation, regular exercise — including activities like running — can help lubricate joints, reduce inflammation, strengthen surrounding muscles, and improve mobility, making it a beneficial part of arthritis management. In studies, exercise (including walking and controlled running) has been shown to reduce pain and improve function in arthritis patients.

Myth 3: You should only run if you’re young or athletic.

Correction

There is no age limit or athletic requirement to start running. People of all ages – including middle-aged and seniors – can run and benefit from it, as long as they progress gradually and listen to their bodies. You don’t need to be a born athlete to run. In fact, older adults who run often experience improved health and longevity, disproving the idea that running is only for the young and fit.

Naturally, someone who is older or currently inactive should start slowly to allow their joints, muscles, and cardiovascular system to adapt. But there is nothing inherently unsafe about running for older adults. We have programs and run-walk training plans that have helped inactive or non-athletic people to become runners. You’re never “too old” or “too unathletic” to start running. The key is gradual progression, consistency, and good guidance — not youth or athletic background.

Scientific Evidence & Explanation

Research tracking adults over age 50 found that senior runners had fewer disabilities and lived more active, longer lives than non-runners. Regular running appears to slow aspects of aging and halve the risk of early death in older individuals. Experts are now even encouraging more endurance exercise in healthy older adults to increase lifespan and vitality.

Myth 4: Walking is for the elderly, not real exercise.

Correction

Walking absolutely counts as real exercise. Dismissing walking as “just for old people” is misguided. In reality, walking is one of the most accessible and effective forms of aerobic exercise, proven to improve cardiovascular health, improve blood pressure, improve blood sugar control, improve mental health, aid weight management, and reduce disease risk. It may not be as intense as running but brisk walking provides substantial fitness and health benefits. In fact, many athletes — runners and weightlifters, for example — strategically incorporate walking into their training schedules.

Scientific Evidence & Explanation

Walking can elevate heart rate, improve circulation, and strengthen leg muscles. The U.S. CDC recommends at least 150 minutes of moderate aerobic activity (i.e., brisk walking) per week for adults of all ages. Research has shown that even a relatively modest amount of walking each day correlates with longer life. In other words, every step counts.

Myth 5: Fast food after a run is harmful

Correction

These myths reflect a rigid, moralized view of nutrition. Granted that a greasy burger and fries aren’t the ideal recovery meal, labeling it “harmful” is an exaggeration. In fact, your body is ready and craving to absorb nutrients post-run, and research has found that even fast foods can replenish glycogen and aid recovery similarly to typical sports foods.

Of course, regularly relying on high-fat, high-salt fast food isn’t optimal for overall health. Nutrient-dense foods (like lean protein, whole grains, fruits, veggies) are preferable for recovery because they provide vitamins, minerals, and less inflammation-promoting fats, but an occasional fast food stop post-run is not “toxic.”

Nobody eats a perfect diet 100% of the time, nor is it absolutely mandatory for health or performance. The idea of “eating healthy” without exception is a dogma that can lead to stress and disordered eating. Overall diet quality matters more than any single meal. Occasional treats or less-than-ideal foods won’t ruin your health or fitness, provided you mostly eat well. So, while you shouldn’t make fast food your every post-run ritual, you also don’t need to feel guilty if you occasionally grab a quick burger after a big run.

Scientific Evidence & Explanation

Surprisingly, studies have tested the effects of fast food vs. traditional sports nutrition after workouts. One randomized trial had athletes do a hard workout and then recover with either sports supplements or fast-food items containing equivalent carbs, protein, and calories. The result found no significant differences – the fast food meal was just as effective in restoring muscle glycogen and supporting subsequent performance. Blood glucose and insulin responses were similar in both conditions, and a cycling time trial after recovery was nearly identical between the fast-food and supplement groups. This evidence suggests that, metabolically, your body can make use of the carbs and protein from a fast-food meal to refuel muscles after exercise.

Myth 6: Don’t run unless you lose weight first.

Correction

Running itself is a great way to improve fitness and assist with weight management. And it’s correct that higher body weight can put more stress on joints and may increase injury risk if one does too much too soon. However, there is no rule that you cannot run until you slim down. By postponing running until weight is lost, individuals could miss out on these fitness benefits. So rather than prohibiting running, coaches and clinicians should instead emphasize “start low, go slow.” Maybe begin with brisk walking or run-walk intervals, follow conservative progression (maybe 5% increase weekly or even less), incorporate strength training to support your joints, allocate periods for recovery, and continuously listen for signs of pain. Many overweight or obese individuals have successfully started running programs and benefited greatly. There is absolutely no blanket requirement to lose weight first, and there is no magical number on the scale to begin running. Every body can run – it just needs to be done thoughtfully.

Scientific Evidence & Explanation

Research shows that obese novice runners can safely run. This study basically concluded that “obese persons can run for exercise, provided they follow conservative transitions and progression, schedule rest days, and heed onset of pain symptoms.” But there is truth to the thinking that obese individuals should be cautious when starting their running era — one study did that runners with a BMI > 30 had a higher injury rate when they ran more than 3 km in their first week of training. In other words, if you’re overweight, you should begin with short distances and gradually build up.

Final Thouhgts

Each of these myths contains a grain of truth—but taken as blanket rules, they do more harm than good. Movement is medicine, but the prescription must be personalized. Running, like any form of training, is highly individual. Even expert advice—whether from a doctor or influencer—must account for context, not cling to absolutes.

Training, recovery, and nutrition should reflect your body, your goals, and the latest evidence—not fear-based rules or outdated dogma. The real goal is sustainable, consistent activity. With sensible planning and self-awareness, running remains one of the safest, most effective paths to better health—regardless of age, size, or background

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References

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