Warming up and your cartilage – Knowledge

1. What this article is about

Before sport, many people hear the same sentence: warm up, or your cartilage will suffer. Behind it sits a particular picture. The joint gets warm, the joint fluid gets thinner, and the cartilage is lubricated as a result.

This article checks that picture against the measurements. It answers four questions:

• What actually gets warm when you warm up?
• How does cartilage respond to load, and when during a session does it respond?
• What has been measured at the warmed-up joint itself?
• What is proven to help your cartilage?

Two points up front. Warming up acts on performance, and that is well documented. The route runs through the muscle and the nervous system. For cartilage there is a possible detour, and it runs through injuries that do not happen. What that detour looks like is in section 10.

One note: this article does not replace a personal examination. What your doctor decides for your case takes precedence.

How a warm-up is built and what role stretching plays in it is covered in detail in our guide Stretching. This article is about the joint.

2. What gets warm when you warm up

What gets warm is mainly the muscle. In 25 footballers, the temperature in the thigh muscle was measured during two matches [5]. At rest it was 36.0 degrees. After the warm-up, shortly before kick-off, it was 39.4 degrees. It stayed at that value through the first half.

The rise of just over three degrees is a pronounced and well-documented effect of warming up. It comes from the work of the muscles themselves.

2.1 What the warmth does to the muscle

A warm muscle produces more force in a short time. In a study with four people, the legs were placed in water baths of different temperatures for 45 minutes [6]. A 20-second sprint on a cycle ergometer followed. The highest power reached was measured.

• After the bath at 44 degrees, muscle temperature was 39.3 degrees. Peak power was about 11 per cent above the resting value [6].
• After the bath at 18 degrees, muscle temperature was 31.9 degrees. Peak power was about 12 per cent below it [6].
• After the bath at 12 degrees, muscle temperature was 29.0 degrees. Peak power was about 21 per cent below it [6].

How strongly the warmth acts depends on the speed. At a slow pedalling rate, each degree brought about 2 per cent more peak power. At a fast pedalling rate it was about 10 per cent per degree [6].

Four people are few. This study dates from 1987. Its direction has since been confirmed in review articles [2], [3].

That warming up improves performance is well studied. A summary of 32 studies analysed every performance measure recorded in them. In 79 out of 100 of those measures, the studies reported an improvement [4]. The authors found little evidence of any worsening.

The measures come from very different studies and sports. This figure therefore describes the results reported, not your prospect of a better performance.

A warm-up that is too long or too hard can also lower performance. Warming up to the point of fatigue, or waiting a long time afterwards, gives the gain away again [3].

Alongside the warmth, other processes act. Oxygen turnover rises before the actual effort, blood flow through the muscles increases, and nerve conduction becomes faster [2], [3].

2.2 What is known about the inside of the joint

On the temperature inside the knee joint during a warm-up, we found no measurement in humans in the medical database Europe PMC. Joint temperature has so far been measured in the operating theatre and during cold treatments.

There is a calculation. A model of the knee joint reproduced what happens during repeated loading and unloading [7]. The result of the calculation: the cartilage warms from within, because part of the loading energy turns into heat. The flowing joint fluid carries away only a small part of that heat.

So if the joint does warm up during a warm-up, it happens through the movement itself. That is a calculation, not a measurement in a living knee [7].

3. How cartilage feeds itself

Articular cartilage has no blood vessels of its own and no nerves. Its cells sit in a mesh of fibres and sugar proteins that binds a great deal of water.

Supply runs through the joint fluid. Nutrients travel from the joint fluid into the cartilage by spreading out through the tissue water. Specialists call this diffusion. It is the main route [32].

Alongside that, loading moves fluid through the tissue. When you load a joint, the pressure squeezes fluid out of the cartilage. When you unload it, the cartilage takes fluid back in. A sponge behaves in a similar way.

This alternation of loading and unloading has been measured. Seven volunteers performed 100 knee bends. During recovery, fluid flowed back into the cartilage behind the kneecap, at 1.1 to 3.5 cubic millimetres per minute [10]. Those who had given off a lot of fluid also took a lot back up.

How much this pumping contributes to nutrition has been tested directly. Pieces of cartilage from human femoral heads were loaded in the laboratory with a simulated walking rhythm [32]. For small solutes, pumping did not change transport measurably. Glucose and oxygen are small solutes. For one large protein, release rose by 30 to 100 per cent [32].

The sentence "movement feeds cartilage" therefore falls short. More precisely: nutrients arrive mainly by diffusion, and movement additionally supports the transport of larger molecules.

How a joint is lubricated and which substances take part is covered in our guide Osteoarthritis.

4. How much cartilage deforms under load

Since the 1990s, cartilage volume can be measured in a magnetic resonance scanner. People are scanned before and after an activity, and the difference shows how far the cartilage has deformed.

A Munich study with 12 volunteers compared five activities [9]. The cartilage behind the kneecap lost volume:

• 5.9 per cent after knee bends
• 5.0 per cent after running
• 4.7 per cent after squatting
• 4.5 per cent after cycling
• 2.8 per cent after ordinary walking

At the shin bone, the deformation was smaller. It reached 7 per cent during jumping and stayed small for all other activities [9].

These figures are smaller than many people expect. Under heavy load, cartilage gives off a few per cent of its volume. The order follows the range of movement: the further the knee bends, the more surface comes under pressure [9].

A different method produced the same picture. In 25 healthy people, cartilage thickness at the inner thigh bone was measured by ultrasound [11]. Measurements were taken before and after 30 minutes each of walking, running and sitting. Walking and running deformed the cartilage more than sitting did. Between walking and running there was no difference.

At the ankle, the deformation is larger. After 30 double-leg knee bends, the cartilage on the talus in 12 volunteers lost 10.4 per cent of its volume [12].

The blood shows a response as well. After 30 minutes of running, a protein from cartilage, cartilage oligomeric matrix protein, rose by 30.7 per cent in 14 adults. After 100 drop landings from a 73-centimetre platform it rose by 32.3 per cent [14]. What this rise means for the health of the cartilage is open.

4.1 The first minutes deform it most

For the question about warming up, the timing is what matters. Seven volunteers performed 50 knee bends and were then scanned [10]. The deformation lay between 2.4 and 8.6 per cent. After 100 knee bends it lay between 2.4 and 8.5 per cent, so at the same level.

Then came the informative part. The volunteers repeated the knee bends at 15-minute intervals. The cartilage deformed no further [10].

The same pattern appeared in runners. 48 knees of male athletes were scanned before and after runs of 5, 10 and 20 kilometres [13]. After 5 kilometres, the loss of volume at kneecap, shin bone and menisci was already measurable. A further loss after 10 and 20 kilometres showed only at the medial meniscus.

It follows that what cartilage does mechanically under load, it does early. After the first minutes it reaches the state in which it stays.

Whether any benefit of warming up follows from this is open. That cartilage deforms early and then stays put shows a mechanical response. Whether that response prepares the joint for what is coming has never been tested. Neither study examined warming up at all.

4.2 How long recovery takes

After 100 knee bends, the cartilage behind the kneecap needed more than 90 minutes to regain its starting volume [10]. At the talus it went faster. There, the deformation was no longer detectable after 30 minutes [12].

For your everyday life this means: after a training session, the cartilage is in a different state than before it for a good hour. Scans of the knee should therefore be taken after a period of rest [8].

5. Why movement keeps friction low

A healthy joint glides with very little friction. How this is achieved was measured in the laboratory on bovine cartilage.

In the first experiment, a piece of cartilage was pressed against glass under steady pressure and slid back and forth [16]. Over time, friction rose from 0.010 to 0.243. At the same time, the share of the load carried by the fluid pressure inside the cartilage fell from 88.8 to 8.7 per cent. The two were closely linked.

As long as the fluid inside the cartilage is under pressure, it carries the load and friction stays low. Once the pressure has slowly squeezed the fluid out, the fibre network takes over the load and friction rises.

In the second experiment, the point of pressure was moved instead of held in one place [17]. Friction then stayed low for at least an hour. The same experiment also compared the effect of the joint fluid:

• The joint fluid lowered friction by about one and a half times compared with a saline solution [17].
• The fluid pressure inside the cartilage itself lowered it by about sixty times [17].

In this experimental set-up, the pressure inside the tissue therefore weighed far more heavily than the switch from saline to joint fluid. That pressure is maintained by the travelling point of contact, which is to say by movement [17].

It does not follow that the joint fluid is unimportant. The two routes complement each other and act under different conditions. Lubricin and the other substances at the surface take over where the pressure inside the tissue falls away [17].

5.1 What that means for long periods of sitting

These experiments were done on bovine cartilage in a laboratory. Whether the figures hold for a living human knee is open. The direction of the finding is still useful in practice.

If you stay in the same position for a long time, the pressure rests on the same spot. Change position, and the point of pressure travels. So when sitting for long stretches, stand up briefly now and then and take a few steps.

We suggest every 30 to 45 minutes for this. That interval is a practical recommendation from our practice. No threshold can be derived from the two laboratory experiments.

The same holds for the start of a training session. A few minutes of easy movement through the full range spread the pressure across the joint surface before the heavy load arrives.

6. Whether movement increases the lubricants

On the cartilage surface sits a protein called lubricin. It makes the surface glide. Movement acts on how it is produced.

In mice, running increased the production of lubricin in the top layer of cartilage [18]. The researchers also showed the route: the flowing fluid exerts a shear force on the cells, and that force switches production on.

In ageing rats, regular running kept the amount of lubricin in the cartilage higher than in rats without exercise [19].

Both studies come from animal experiments. Whether the same route runs in humans, we do not know for certain. How uncertain the evidence on lubricin is overall is set out in our guide Osteoarthritis.

For warming up, the time frame matters as well. These processes take hours to days, because cells have to manufacture proteins for them. Ten minutes before training is too short for that.

7. What has been measured at the warmed-up joint

On the question of what a warm-up does at the joint itself, we found a single measurement in Europe PMC.

17 healthy, physically active people with a mean age of 25.7 years took part in a study with two appointments [20]. At one appointment they sat on a chair. At the other they walked on a treadmill and then performed a fatiguing exercise. Before and after each part, microphones on the knee recorded the sounds made while standing up.

The result: after the warm-up, the sounds at the inner shin bone became louder. Mean signal amplitude rose by 1.51 decibels, while at the control appointment it fell by 1.28 decibels [20]. After the fatiguing exercise there was no difference.

The authors discuss higher load and higher friction in the joint as a possible explanation [20]. What they measured were sounds. Friction inside the joint cannot be determined from them.

The widespread story that a warm-up makes a joint smoother and quieter still finds no support in this measurement.

17 people are few, and joint sounds say little about the health of a knee. What this study mainly establishes is that the question is barely researched.

Two further studies measured joint position sense, that is, the ability to hit a knee angle without looking:

• 14 footballers hit the target angle more accurately after a 25-minute warm-up than at rest. After a 90-minute match they hit it less accurately [21].
• 32 sprinters also hit the target angle more accurately after the warm-up, and they jumped higher. After a hard jumping programme, both values worsened [22].

Both groups were small. Both studies measure the nervous system, not the cartilage.

8. Does loading harm cartilage?

Behind the worry about cartilage sits another question: does the joint wear out through loading? There are figures on this.

A systematic review brought together nine studies [23]. In them, people at raised risk of osteoarthritis, or with knee osteoarthritis, exercised. Their cartilage was measured in a magnetic resonance scanner. Of the 14 comparisons in people with osteoarthritis, six found no change in cartilage thickness, cartilage volume or cartilage defects. For the building blocks of cartilage, the results were mixed.

The review's conclusion: loading exercise appears to do no harm to articular cartilage. The certainty of the evidence is low [23].

On running, there is a summary of 25 studies with 125,810 people [24]. Hip or knee osteoarthritis was found in:

• 3.5 out of 100 recreational runners
• 10.2 out of 100 people who moved little
• 13.3 out of 100 competitive runners

Whether running itself causes these differences cannot be derived from these data. People who already have pain run less. Earlier injuries play their part as well [24].

What running means when osteoarthritis is already present is covered in our guide Osteoarthritis.

9. What regular warm-up programmes are proven to do

One effect is well documented: warm-up programmes carried out regularly lower the number of certain injuries. What is meant are programmes with strength, balance, jumping, landing and change-of-direction drills.

The difference from easy jogging matters. In every analysis named below, the programme ran for months, before every session. That design cannot separate two things: the effect in the minutes before sport and the effect of the training that adds up across a season. The second is favoured by the fact that strength and movement control take weeks.

The best-known study followed 1,892 female footballers aged 13 to 17 from 125 Norwegian clubs over a season of eight months [25]. Half the clubs warmed up with a set programme. The injury rates were compared:

• All injuries: 32 per cent fewer in the programme group (rate ratio 0.68; 95% confidence interval 0.48 to 0.98)
• Overuse injuries: 53 per cent fewer (0.47; 0.26 to 0.85)
• Severe injuries: 45 per cent fewer (0.55; 0.36 to 0.83)

One limitation belongs with this. The question the study set out to answer concerned injuries to the leg. On that question, the result missed statistical significance (0.71; 0.49 to 1.03) [25]. The figures above come from analyses that followed.

A summary of 15 studies in children and adolescents arrived at a rate ratio of 0.64, so 36 per cent fewer injuries (95% confidence interval 0.54 to 0.75) [26]. After a correction for the preferential publication of favourable results, the value was 0.70.

This figure has a wide spread. The authors state that a single new study could produce a result between 0.34 and 1.19 [26]. The upper value means: no effect.

For the cruciate ligament there is a separate summary. Eight randomised studies were analysed [27]. Under a prevention programme, the number of cruciate ligament tears fell by 53 per cent (rate ratio 0.47; 95% confidence interval 0.30 to 0.73).

For a single easy jog, no protection has been shown. A review from 2006 examined exactly that question. Of five studies, three found fewer injuries and two found no difference [28]. Larger studies of the programmes have appeared since, but not of plain jogging.

10. Why fewer injuries protect your cartilage

Here the circle closes back to the cartilage. The strongest known route to knee osteoarthritis at a young age is a knee injury.

A systematic review analysed 41 studies of people ten years or more after a cruciate ligament tear [29]. At inclusion, participants were between 23 and 38 years old; at follow-up, between 31 and 51.

The proportion with signs of osteoarthritis on X-ray ranged from 0 to 100 out of 100 people. That span mainly shows how differently the studies measured [29]. Only two studies distinguished between the X-ray finding and the symptoms:

• 35 out of 100 people had symptomatic osteoarthritis between thigh bone and shin bone (one study)
• 15 out of 100 people had symptomatic osteoarthritis behind the kneecap (one study)

The only consistent risk factor was the removal of meniscal tissue [29].

This lets the chain be stated. A regular warm-up programme lowers the number of cruciate ligament tears by 53 per cent [27]. A cruciate ligament tear raises the probability of knee osteoarthritis in the following decades [29]. Such programmes could therefore protect your cartilage in the long run, through the injury that does not happen.

This chain is assembled from parts, and the conditional is deliberate. No study has tested whether people who used a warm-up programme have less osteoarthritis twenty years later. What is documented is the two links individually.

More on the cruciate ligament is in our guide Osteoarthritis, more on the meniscus under Meniscus.

11. What long unloading does to cartilage

The counter-test to loading is complete unloading over months. It is well studied, and its effect is clear.

In people with a complete spinal cord injury, knee joint cartilage was measured at 6, 12 and 24 months [30]. It was compared with the cartilage of nine healthy young people. Six months after the injury, the cartilage was thinner:

• 10 per cent thinner behind the kneecap
• 16 per cent thinner at the inner shin bone

The loss continued over the two years [30]. The groups were small, with 9 people at 6 months and 6 people at 24 months.

A review by the same group summarised the animal experiments on this [31]. After immobilisation, cartilage becomes softer, loses sugar proteins and becomes thinner. Part of these changes reverses once loading resumes, and part remains.

These figures apply to complete paralysis over months. Muscle work and control by the nervous system are absent at the same time. They do not carry over to a two-week training break or to a few days of taking it easy. Whether short rest changes cartilage measurably is open.

Age changes cartilage as well. 30 symptom-free people aged 50 to 78 were examined [15]. In the women, the cartilage behind the kneecap was 12 per cent thinner than in 95 young comparison participants. At the same time, the cartilage of the older participants deformed less under the same load.

12. What warming up does not do

Three expectations of a warm-up do not hold up against the measurements.

First: training makes cartilage thicker. The Munich study compared seven weight lifters, seven sprinters and 14 untrained people [9]. Deformation after knee bends was the same in all three groups. A review summarises that elite athletes have no thicker cartilage than other people [8].

That statement concerns thickness and volume. Whether the composition of cartilage changes under training is left open by it. Two of the comparisons in the review of exercise in knee osteoarthritis found favourable values for collagen [23]. Muscle and bone gain mass under training. For cartilage, that has not been shown in adults.

Second: warming up prepares the cartilage for the load. This claim has never been tested. We found no study comparing a warm-up with no warm-up and measuring cartilage. What we do have is the finding that deformation happens early and then levels off [10], [13]. That yields a plausible thought, not a piece of evidence.

Third: warming up protects people with osteoarthritis. On this question we found no study. The research on warming up cited here was carried out mostly in young, sporting people. How a warm-up acts in a 70-year-old person with knee osteoarthritis, we do not know.

13. How to warm up

A well-established structure has three steps [1]. Depending on the sport and the intensity, it takes 13 to 25 minutes.

1. Raise your pulse. Five to ten minutes of easy walking, jogging, cycling or skipping. Until your breathing quickens and your skin is warm.
2. Move the joints and switch the muscles on. Leg swings, lunges, arm circles, hip openers, bodyweight squats. Take every joint through the range the coming activity asks for. Five to ten minutes.
3. Get fast and sport-specific. Accelerations, jumps, landings, changes of direction, passes, strokes. Build up close to the speed of what is coming. Three to five minutes.

The second step needs no maximal range. Choose the range your sport asks for and that you tolerate well.

The third step is the one most often left out. It is precisely what separates the programmes that prevented injuries from plain jogging [25], [27].

In strength training, the warm-up sets take on this role. Start each exercise with one or two light sets and build the weight up. Before heavy sets, many people need three or four steps.

13.1 When it is cold or early in the morning

In the cold, the muscle cools faster. After the bath in 12-degree water, peak power was about 21 per cent below the resting value [6]. So extend the first step and keep a layer of clothing on until you are warm.

Early in the morning, many joints feel stiff. On the question of how long a morning warm-up should last, we found no study. Take more time over the first step if it feels better.

13.2 If you have osteoarthritis

There are no studies on warming up in osteoarthritis (section 12). Something else is documented: exercise does no harm to cartilage in knee osteoarthritis [23], and it lowers pain.

What we do in practice and how we justify it:

• Start with unloaded movement. Five minutes of bending and straightening while sitting or lying, without resistance. The movement spreads the point of pressure across the joint surface [17].
• Raise the load afterwards. First your own body weight, then added weight.
• Judge it the next day. If the pain the following morning is at its usual level, the load was right.

This approach rests on experience and on the laboratory findings about friction. A study testing it does not exist.

13.3 After a break in the middle of sport

The effect of a warm-up does not last indefinitely. In the 25 footballers, muscle temperature fell during the 15-minute half-time break from 39.4 to 37.4 degrees [5].

That had consequences. Eight players rested during the break, eight moved gently. At the start of the second half, the resting players sprinted 2.4 per cent slower than before the break. In the players who kept moving, sprint performance stayed the same [5].

Eight people per group are few. Keep moving gently during longer breaks all the same, rather than sitting still.

14. For professionals: nine conclusions for practice

This section is addressed to colleagues in physiotherapy, sport and medicine. It summarises how we translate the evidence into our practice.

1. Justify the warm-up with the muscle and the nervous system. The temperature effects are measured [5], [6], and the performance gain is summarised [4]. On joint temperature in humans, no measurement exists.
2. Do not reduce joint lubrication to an "activation of the joint fluid". In one ex vivo set-up, interstitial fluid pressurisation lowered friction by a factor of 60, and the switch from saline to synovial fluid by a factor of 1.5 [17]. No unimportance of boundary lubrication follows from this; the two mechanisms complement each other.
3. Talk about the migrating contact area instead. Under a stationary contact area, the friction coefficient rises from 0.010 to 0.243; under a migrating one it stays low for over an hour [16], [17]. That carries the advice to change position and use the full range.
4. Use the deformation kinetics as an argument without overstating it. Deformation is complete after 50 knee bends and does not increase when repeated 15 minutes later [10]. In runners it appears after 5 km and changes little up to 20 km [13]. A test of warm-up versus no warm-up with a cartilage endpoint is missing.
5. Schedule imaging and measurements after a rest period. Recovery takes over 90 minutes at the patellar cartilage [10] and about 30 minutes at the talus [12].
6. Give weight to the third step of the warm-up. The effective programmes contained strength, jumping and landing components [25], [27]. Plain jogging was not tested in those studies.
7. Separate the acute effect from the training effect. The prevention trials delivered the programme across whole seasons. Their design does not allow the effect to be assigned to the state immediately before sport [25], [26], [27]. For the single warm-up, the evidence remains mixed [28].
8. State the uncertainty in the prevention figures. The primary endpoint of the largest single trial missed significance [25], and the prediction interval of the meta-analysis reaches 1.19 [26].
9. Transfer none of this untested to older people with osteoarthritis. The prevention studies cited here concern mostly young athletes. For older people, the documented sentence is this: therapeutic exercise does not change cartilage for the worse [23].

On the state of the evidence: the basic work on cartilage mechanics is solid and comes largely from a handful of research groups. The link between warming up and cartilage has nowhere been measured directly. It rests on two individually documented links [27], [29].

15. What you should know about warming up and cartilage

• What gets warm is the muscle. Thigh temperature in footballers rose from 36.0 to 39.4 degrees [5]. On the temperature inside the joint, measurements in humans are missing.
• Cartilage is supplied mainly by diffusion. Movement additionally supports the transport of larger molecules [32].
• Under load, cartilage gives off a few per cent of its volume. After knee bends it was 5.9 per cent, after ordinary walking 2.8 per cent [9].
• This response happens in the first minutes. A second set of knee bends after 15 minutes deformed nothing further [10]. In runners, the loss showed after 5 kilometres already [13].
• Recovery takes over 90 minutes in the cartilage behind the kneecap [10].
• Movement keeps friction low. In one laboratory experiment, fluid pressure inside the cartilage lowered it sixtyfold, the joint fluid one-and-a-half-fold [17]. The two routes complement each other.
• When sitting for long stretches, change position regularly and stand up briefly now and then. Our suggestion of every 30 to 45 minutes is a practical recommendation [16], [17].
• Loading does no harm to cartilage. Under exercise, cartilage thickness and volume stayed unchanged in people with knee osteoarthritis [23].
• Regular warm-up programmes lower certain injuries. In young female footballers, severe injuries fell by 45 per cent [25], and across eight studies cruciate ligament tears fell by 53 per cent [27]. For a single easy jog this has not been shown [28].
• That is how such programmes could protect your cartilage in the long run. Ten years after a cruciate ligament tear, one in three people in one of the included studies had symptomatic knee osteoarthritis. Frequencies varied widely between studies [29].
• Long, complete unloading changes cartilage. Six months after a spinal cord injury it was 10 to 16 per cent thinner [30]. This does not carry over to short rest.
• That training makes cartilage thicker has not been shown in adults [8], [9]. Changes in its composition are possible [23].
• On warming up in osteoarthritis and in older age, studies are missing. What is written there rests on experience.

At your next session, start with five minutes of easy movement. Then take five minutes for the full range and three minutes for accelerations or jumps.

How a warm-up is built in detail and what stretching contributes to it is in our guide Stretching. Why movement helps in osteoarthritis is under Osteoarthritis.

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Transparency

• Authorship: Roger Hilfiker
• AI assistance: the literature search and the first draft were produced with Claude (Anthropic). Roger Hilfiker checked every statement, figure and source and revised the text.
• Written: 22 August 2026
• Last updated: 22 August 2026
• Sources: the 32 papers in the reference list. All DOIs were checked against the Crossref register.
• How the sources were found: systematic queries of the Europe PMC database in August 2026 on warming up, in vivo cartilage deformation, cartilage friction, immobilisation, injury prevention and osteoarthritis after cruciate ligament tear. Where this article states that no study exists on a question, that refers to this search.
• Conflicts of interest: our practice offers physiotherapy and training supervision and earns from it. This article names a documented benefit of warming up for injuries and says at the same time that its effect on cartilage has nowhere been measured directly.
• Funding: Physiotherapie Tschopp & Hilfiker, 3902 Glis. The practice funded this article from its own means.
• Next review: 28 August 2028. We also revise this article on an ongoing basis as new articles are added. That happens about every two months.