The knee is the joint most often complained about in the fitness centre – and the one about which a suspicion is voiced fastest that should not be voiced at all. “That is bound to be the meniscus” is not an assessment but a diagnosis, and that is not yours to make. What is yours, and what you have to be able to do: know the common clinical pictures, recognise their typical signs, adapt the training accordingly and refer on in good time. This article works through the most common knee complaints – with the eye of the trainer, not that of the therapist.
Knee pain is not a diagnosis
Very different things can lie behind the same pain. Arthritis is initially only an inflammation of the joint – through infections, rheumatological diseases or other non-infectious causes – and shows pain, redness, swelling and raised temperature. Osteoarthritis, by contrast, is a degenerative joint disorder caused by a mismatch between the load and the load capacity of the joint cartilage. It often has no or a very weak inflammatory component and makes itself felt above all through position- and load-dependent pain.
For the training the difference is decisive, and for the classification an assessment is needed. In general the following applies: gentle, pressure-free and pain-free movements as well as strengthening of the musculature close to the joint make sense and have a positive effect on the course. That is your line – not the question of which tissue is affected.
Axial deviation: when the load is distributed unevenly
An axial deviation is present when the physiological joint axis differs from the one actually present. At the knee this is particularly easy to see, because the distance between the knee joints changes. With knock knees the axis deviates inwards, the distance between the knees in a parallel stance with the feet touching becomes smaller, and the lateral part of the knee joint is loaded more heavily – which can lead to lateral partial osteoarthritis. With bow legs the axis deviates outwards, the distance becomes larger, and the medial part is loaded more heavily, with the risk of medial partial osteoarthritis.
What matters is the classification: many knee joints with a weakly pronounced axial deviation never cause problems, which is why an axial deviation on its own is not an indication for surgery. It may, however, be the case that the deviation produces an unequal distribution of forces and that degenerative changes subsequently take place which in turn lead to pain. In training, a surprisingly relaxed principle applies here: training should be carried out normally, with joint-friendly activities being preferred. With incipient osteoarthritis, strengthening the knee-stabilising muscles and stretching the muscles that tend to shorten can bring an improvement. If you want to keep the leg axis in view, the article Proprioceptive training offers the right building block for it.
When the cartilage suffers
Gonarthrosis
Osteoarthritis of the knee joint is mostly caused by injuries or deformities – axial deviations, fractures, ligament ruptures, meniscus lesions. But there are also knee osteoarthritides that are due merely to inferior cartilage. Typical are load- and position-dependent pain, a general feeling of tension in the knee, pain at night and restrictions of mobility. Characteristic is the start-up pain: pain directly after getting up, which decreases after some movement.
Fundamentally, the load has to be reduced. Conservative options are cold for acute irritation and warmth for chronic conditions; occasionally injections help – all of this is symptomatic and does not fight the osteoarthritis at its cause. For the training area, the sentence that describes your role remains: training the knee-stabilising muscles and length training of the musculature that tends to shorten can improve the situation somewhat in the longer term. And: the patient has to be instructed in how to deal with an osteoarthritic knee, what is allowed and what is not. That instruction comes from medicine; you work within it.
Chondropathia patellae
It occurs rather frequently and describes a softening of the cartilage tissue beneath the kneecap. Typically there is a malformation of the joint between the thigh bone and the kneecap, with the kneecap coming to lie rather laterally. The characteristic sign is easy to observe in the gym: a spontaneous pain on strong flexion of the knee, in particular when climbing stairs or when performing squats.
Conservative work is done by avoiding deep squats and other movements with a flexed knee in order to prevent pressure on the kneecap. In addition, active build-up training of the vastus medialis of the quadriceps is recommended in order to counteract the lateralisation. This is one of the few points at which your craft connects directly – provided the assessment has taken place.
When the kneecap slips out
In a dislocation of the kneecap the patella slips away to the side, usually outwards. Behind it there is usually a congenital weakness of the connective tissue or a kneecap that is too flat. A dislocation is very painful and often results in overstretching of the ligaments and the capsule. With repeated dislocation and failed conservative therapy an operation is necessary; this brings an improvement, but consistent strength training is required in order to prevent relapses. The focus is then on strengthening the entire leg musculature and on training the leg axis, that is, the position of foot, knee and hip in relation to one another.
Meniscus and cruciate ligament
The meniscus has a shock-absorbing function in the knee joint and is also responsible for control and stability. It is mostly damaged by movements in which the thigh bone presses on the meniscus and the meniscus is pinched; usually the inner meniscus is affected, because it is fused with the medial collateral ligament and the capsule and therefore has almost no way of giving way. A damaged meniscus can block the knee partially or completely depending on the damage; frequently a wandering pain occurs at the level of the joint space.
A look at the diagnostics shows how little there is to be gained on the training floor: there are at least ten different manual tests for meniscus lesions, but none of them is really reliable. That is why an MRI is often carried out today – although it also shows damage that is not yet causing any complaints. When even the specialist world is cautious, a suspicion from the gym is all the less a basis.
With the cruciate ligament, the anterior rupture is the common sports injury: during a change of direction the foot stays put while the body moves on, and a medial collapse of the knee occurs. Afterwards an instability can develop in which the knee gives way under load – what is known as “giving way”. Whether surgery is performed is decided by the stability examination and function tests; roughly 30 per cent of all patients with cruciate ligament ruptures can continue their sport without an operation. Because this special case is a story of its own, you will find it in detail in the article Cruciate ligament rupture: can a torn cruciate ligament heal again without an operation?. Considerably rarer is the posterior cruciate ligament rupture, whose symptoms turn out to be far less serious for many of those affected.
What applies after a knee injury
The following points apply to training after a knee injury. They are orientation knowledge, so that you understand the time frame you are moving in – the binding clearance always comes from the doctor or physiotherapy and depends on the individual case.
- After a cruciate ligament rupture, muscle training in the fitness area is possible relatively early, from about the sixth week. What matters is strengthening all the muscles close to the knee.
- No leg extension exercises until at least 90 per cent of the strength has been restored – at the earliest three months after the operation, because the stability of the knee is not given before that.
- No contact sports and no skiing for at least six months; the re-rupture rate when sport is taken up before six months is high.
- After a partial meniscectomy it is advisable to relieve the knee for three days and to load it only slightly in the first week. From the second week, cycling, jogging on the treadmill and strength training within the limits of the complaints are possible again; exercises with strong knee flexion beyond 90 degrees should be avoided for six weeks.
- After a meniscus refixation, knee flexion is limited to a maximum of 60 degrees in the first six weeks, and during this time walking is only allowed with crutches. With squats up to 90 degrees you have to wait at least six weeks, deep squats are only permitted after three months, and jogging on the treadmill at the earliest eight weeks after the operation.
One point from strength training fits this phase remarkably well: strength training of the lower extremity with free weights is to be preferred to machine training – provided the client has a clean technique. It is helpful to build in technique and coordination schooling as a supplement to strength training. If you want to look at the trade-off between machine and dumbbell in general, the article Machines or free weights: which is better for your training? will help.
The swelling is your yardstick
If you remember a single sentence from this article, let it be this one: with all knee complaints, the swelling is an important indicator of load capacity, and if the swelling increases, the load has to be reduced immediately. That is a criterion you can observe without a diagnosis and one that works regardless of which clinical picture lies behind it.
Added to that are the limits of your role. The update Akademie trains trainers, not therapists. You do not make a tentative diagnosis, you do not test a knee joint manually and you do not set up a rehabilitation programme. You observe, adapt, document and refer on – in the case of blockages, sudden giving way, increasing swelling, pain at night. After that you shape the training within the medical clearance.
Training tip from the update Akademie: anyone who supports guests with a history of knee problems needs more than a repertoire of exercises – namely an understanding of load capacity, build-up and the interface with medicine. That is exactly what the course Fitness- und Bewegungstrainer Advanced goes deeper into; it builds on the Basic and deals with designing training for more demanding starting situations. Anyone who only wants to catch up on the clinical pictures themselves will find them in the workshop Die Pathophysiologie – an in-depth look at health limitations.
Frequently asked questions about knee pain in training
What is start-up pain in the knee?
Start-up pain is characteristic of gonarthrosis. What is meant is pain directly after getting up that decreases again after some movement. Typically it is accompanied by load- and position-dependent pain, a feeling of tension in the knee and restrictions of mobility.
Are knock knees or bow legs a reason not to train?
No. Many knee joints with a weakly pronounced axial deviation never cause problems, and an axial deviation on its own is not an indication for surgery. Training should be carried out normally, with joint-friendly activities being preferred. With incipient osteoarthritis, strengthening the knee-stabilising muscles can help.
Why does the knee hurt during deep squats?
A spontaneous pain on strong flexion, especially when climbing stairs or during squats, is typical of a chondropathia patellae, that is, a softening of the cartilage beneath the kneecap. The pain can also be provoked by tension on the quadriceps or by pressure on the kneecap. The assessment belongs in medical hands.
Can you get through a cruciate ligament tear without an operation?
Roughly 30 per cent of all patients with cruciate ligament ruptures can continue their sport without cruciate ligament surgery. Whether surgery is performed is decided by the examination of knee stability and by function tests. In sports with stop-and-go movements at a high level, as a rule only surgical replacement comes into question.
How do I recognise that the load was too high?
With all knee complaints, the swelling is an important indicator of load capacity. If the swelling increases, the load has to be reduced immediately. This criterion applies regardless of which clinical picture is present, and it does not replace a medical assessment.
Conclusion
Knee pain is a collective term for very different pictures: axial deviations, cartilage damage, an unstable kneecap, meniscus and ligament injuries. For the training they surprisingly often come down to the same measures – strengthen the knee-stabilising musculature, lengthen shortened musculature, build up in a joint-friendly way and keep the leg axis in view. The swelling remains your most reliable indication of load capacity. What is not part of your role is assigning the pain to a structure: diagnosis and treatment belong in medical and physiotherapeutic hands, and your training begins where their clearance stands.
