Does running really ruin your knees?#

A lot of people have probably heard that “running ruins your knees”

Running does put repeated load on the knee joint, but that doesn’t mean running itself damages your knees

In fact, the knee isn’t a mechanical part that only wears down and can never adapt to movement

Appropriate exercise helps maintain joint function, and strengthening the muscles around the knee — the quadriceps and hamstrings, for example — also helps the knee handle the load

A 2017 systematic review and meta-analysis published in the Journal of Orthopaedic & Sports Physical Therapy included more than 120,000 study participants

Pooling the studies, the prevalence of hip and knee osteoarthritis was about 3.5% in recreational runners, about 10.2% in non-runner controls, and about 13.3% in competitive runners

Of course, these figures come from observational studies and can’t directly prove that running prevents osteoarthritis. But at the very least they help us re-examine the claim that “running definitely ruins your knees”

For most people, what matters more is whether the amount of exercise suits your body and condition, whether you have a previous injury, and whether you’re giving your body enough time to recover

If you’re just starting out, you can absolutely begin with brisk walking, jogging, or a mix of running and walking. There’s no need to run five kilometres on day one

As for running form, it’s worth learning some basics early on, but everyone’s body structure and running habits differ. You don’t have to force yourself to imitate some “perfect running form” — finding what feels most comfortable is usually enough

References:

• Systematic review of running and hip/knee osteoarthritis (2017)
• AAOS: knee strength training

Does sweating more burn more fat?#

Some people like to wear thick clothes while exercising, believing that the more they sweat, the faster fat burns

In reality, sweating is mainly the body’s way of regulating temperature

You sweat even sitting still in a hot environment, and that obviously doesn’t mean you’re doing high-intensity training

The temporary drop in weight after exercise may also be mostly lost water — once you rehydrate, that weight can come back

One of the core factors behind long-term fat loss is the relationship between energy intake and expenditure over a period of time

So there’s no need to deliberately chase being drenched in sweat, and do remember to drink water

References: Cleveland Clinic: sweating and calorie burn

Do you have to run every day to lose weight?#

Of course not. In fact you don’t even necessarily need running to lose weight — people with a higher body weight can lose weight purely by adjusting their diet reasonably, though combining it with appropriate exercise is usually better

Because from the perspective of energy balance, the basic principle of weight loss comes down to one sentence:

Over a period of time, the calories you take in are less than the calories you burn

And exercise helps increase daily energy expenditure

However, here we need to distinguish between “losing weight” and “losing fat”

What we usually want to reduce is excess fat, not simply to chase a number on the scale

Through a reasonable energy deficit, combined with strength training, adequate protein intake and recovery, we can help maintain as much muscle as possible during weight loss

Running is a very convenient form of aerobic exercise, but it isn’t the only option

Brisk walking, cycling, stair climbing, swimming, dancing — all can be part of daily activity. Strength training also helps improve fitness and build or maintain muscle

In addition, training needs to account for recovery. Beginners especially don’t need to ignore obvious fatigue and discomfort just to tick off a so-called daily task

Exercise can absolutely start with a few sessions a week and gradually become a habit

References: Systematic review of strength training’s effect on body composition during weight loss (2025)

Aerobic exercise#

Aerobic exercise usually means activity you can sustain for a while and that relies mainly on aerobic metabolism for energy

For example:

• Brisk walking, jogging and long-distance running

• Cycling

• Swimming

• Dancing and some aerobics classes

• Stair climbing

These activities help improve cardiorespiratory endurance, and they’re also the form most people come into contact with first when they start exercising

Here, more intensity isn’t always better

There’s a simple way to judge your intensity: the talk test

If your breathing speeds up during exercise but you can still talk normally and just find it hard to sing, you’re usually in the moderate-intensity range; if you can barely say a few words in a row, the intensity is probably higher

For someone just starting out, choosing an intensity that suits you and that you can stick to is good enough

References: CDC: how to measure physical activity intensity

Anaerobic exercise and strength training#

In daily life, many people lump lifting weights, squats and push-ups together as “anaerobic exercise”

But anaerobic exercise is classified by how energy is supplied, while strength training is classified by training purpose and form — the two aren’t exactly the same thing

Strength training works muscles against resistance to improve strength, muscle mass and physical function

Common forms include:

• Bodyweight training such as push-ups and squats

• Dumbbell and barbell training

• Fixed machines at the gym

• Resistance band training

You might wonder: do you have to go to a gym to do these?

Actually you can start entirely at home — simple squats, wall push-ups, or training with resistance bands

For most people, both aerobic exercise and strength training are worth including; there’s no need to pick only one

How much exercise do you actually need?#

The World Health Organization recommends that adults aged 18 to 64 do 150–300 minutes of moderate-intensity aerobic activity per week, or 75–150 minutes of vigorous-intensity aerobic activity, and do muscle-strengthening activities involving major muscle groups on at least two days a week

Seeing that number for the first time, you might feel it’s a lot

But it’s a long-term goal you can approach gradually — you don’t have to complete all of it in your first week

You can start with a few sessions a week, ten-odd minutes each

More important than how much you exercise on day one is gradually building a habit that suits you

References: WHO: physical activity recommendations

好人松松 (Haoren Songsong)#

• The complete training handbook for fitness beginners, Bilibili edition

• Covers training frameworks, muscle gain and fat loss, and nutrition knowledge — suited to beginners who want to learn systematically

凯圣王 (Kai Sheng Wang)#

• Beginner muscle-building series

• Plenty of movement instruction, explanations of training terminology and training programming — suited to people about to start strength training

跑步的子章老师 (Zizhang, on running)#

• Running your first 5K: this one secret is enough

• Part of Zizhang’s running fundamentals series, suited to readers who want to start with running and gradually build endurance

Other references#

If you want to go further into exercise science, these sites are also worth a look:

• World Health Organization (WHO): basic physical activity recommendations

• American College of Sports Medicine (ACSM): research and public education in exercise science, training and health

• MuscleWiki: look up strength exercises by muscle group

• E3 Rehab: knowledge about rehabilitation, pain and training