Knee-friendly exercises: strength and cardio that respect sore knees

When to see a doctor first

Knee pain is common and often settles with simple care. The NHS says it can often be treated at home and that you should start to feel better within a few days. Some situations, however, need a professional before you exercise.

Get urgent advice (in the UK, NHS 111) if your knee is very painful, you cannot move it or put weight on it, it is badly swollen or has changed shape, it locks, gives way or clicks painfully, or if you have a high temperature with redness or heat around the knee, which can be a sign of infection. See a GP if knee pain does not improve within a few weeks. Painless clicking is normal.

The NHS adds a clear piece of advice: do not self-diagnose. A sprain, a tendon problem, a meniscus tear and osteoarthritis do not call for the same exercises, so a diagnosis guides the plan.

What the evidence says about exercise and knees

For osteoarthritis, the message from NICE is unambiguous: offer therapeutic exercise tailored to each person, such as local muscle strengthening and general aerobic fitness, and consider supervised sessions. NICE explains that joint pain may increase when exercise starts, that regular and consistent exercise will still be beneficial, and that sticking with it over the long term increases the benefits. For people living with overweight, it adds that weight loss improves pain and function, and that losing 10% of body weight is likely to be better than 5%.

The NHS describes exercise as one of the most important treatments for osteoarthritis, whatever your age or fitness, combining strengthening and general fitness. It also warns that doing too much too quickly, or the wrong sort of exercise, may damage joints, which is why a plan from a GP or physiotherapist matters.

For healthy knees, the fear of deep bending is overstated. A review by Hartmann and colleagues found that deep squats do not add risk of injury to the knee's passive tissues, and Escamilla's review of knee biomechanics found that the parallel squat does not harm a healthy knee. Our squat form guide covers depth step by step.

Low-impact cardio

• Walking: the simplest start. Short walks on flat ground, several times a day, building up gradually.
• Cycling: a stationary bike lets you control the resistance and the range; set the saddle high enough that the knee stays slightly bent at the bottom.
• Swimming and water walking: the water carries part of the body weight. For knee osteoarthritis, the French health insurance service advises choosing swimming rather than running.
• Elliptical trainer: a smooth movement without landing impact.

These count towards the 150 minutes of moderate activity a week that the WHO recommends for adults. If your knee is sore after one type, try another rather than stopping altogether.

Six knee-friendly strength exercises

1. Sit-to-stand. Sit on the edge of a stable chair, feet hip-width apart, lean slightly forward and stand up using the legs, then sit down slowly. The NHS suggests five slow repetitions to start.
2. Mini-squat. Hands on the back of a chair, feet hip-width apart. Bend the knees only as far as is comfortable, keeping them facing forward over the feet, then stand while squeezing the glutes. This follows the NHS description.
3. Straight-leg raise. On your back, one knee bent, the other leg straight. Tighten the front of the thigh and lift the straight leg to the height of the other knee, hold two seconds, lower slowly. Ten per side.
4. Glute bridge. On your back, knees bent, lift the hips until knees, hips and shoulders line up. Strong hips help control the knee.
5. Step-up onto a low step. Start with a stair of 10 to 15 cm, push through the whole foot, lower slowly, keeping the knee in line with the foot.
6. Calf raise and side leg raise. Holding a chair, rise onto the toes, then lift each leg out to the side, as in the NHS home routine.

The calculator on this page counts the movement breaks in your working day. Standing up and walking for a minute or two at regular intervals is an easy habit for anyone who sits all day, and it fits the advice to stay active. The 20 to 30-minute rhythm used in the calculator comes from trials on sitting and blood sugar, such as one by Dunstan and colleagues, not from knee research.

How to progress without flaring the knee

• Start low: two sets of 8 to 10 repetitions, every other day, in a pain-free or mildly uncomfortable range.
• Use a simple pain rule: NICE expects some extra pain at the start. A practical coaching rule is that mild discomfort which settles by the next day is acceptable, while pain that is sharp, or worse the next morning, means doing less next time.
• Increase one thing at a time: first repetitions, then depth, then load, such as a backpack or dumbbell.
• Move to fuller exercises: squats to a lower chair, split squats, then our leg workout when the knee tolerates it.

Fransen's review found that the benefits of exercise lasted beyond the end of the programme, but the gains for pain and function were larger right after treatment. Exercise works best as a habit, not a course. Strong hips help too: see our glute workout.

This guide does not replace medical advice. If you have had knee surgery or an injury, a diagnosis of osteoarthritis or inflammatory arthritis, or a knee that swells, locks or gives way, ask your doctor or a physiotherapist which exercises suit you before starting. Stop any exercise that causes sharp pain or new swelling.

Keep your knees moving with Never Skip Club

Knees reward regularity: a little, often, for months. Once your doctor or physiotherapist agrees, Never Skip Club makes that rhythm easier. Choose the body area, the Easy level, 20, 30 or 45 minutes and where you train, with or without equipment, and the app builds a guided session of five or six animated exercises in about a minute, with your sets logged. Join a crew of three to seven friends with a sensible rhythm, such as three sessions a week; a session counts from 30 minutes, and the ranking rewards regularity, not extra effort. Create your free account, and if you would like a professional to adapt your exercises to your knees, find a coach from our network. Already a member? Sign in.