-wraps, sleeves and bands are helpful for the heaviest sets in some exercises
-external protection should not be applied all the time as it would weaken the joints
Some exercises are so strenuous for joints that some sort of mechanical support should be considered. Almost all weight lifters use wraps or sleeves for squats. Squats are definitely one of the most dangerous exercises (especially if done in wrong position) and the cause of many knee and back injuries.
Protective belts should be used for dead lift – another exercise that a beginner or person with lower back problems should avoid at all.
If you experience pain in wrist joints or elbow joints for more than 2 weeks you should definitely consider wraps or sleeves too – and visit a medical practitioner as soon as possible.
You can see the supportive sleeves and bands as additional tendons. From this point of view they are definitely beneficial.
The problem with every external joint support is that the connective tissue gets “used” to it – it doesn’t get stronger at the same pace as the muscles.
Therefore the best way to do very strenuous exercises is to make the first sets (with smaller weight) without sleeves/bands and only the heaviest ones with them.
If this is not possible (because your joints are already injured or weak), the exercise should be done first with such weights that you are still able to lift without pain. These “easy” sets may not increase your muscle mass but they are a very good workout to strengthen the joints.
The rule of thumb is to use knee-bands for squats with over 80% of your one-time personal maximum.
Do not use very elastic bands. They will give you only a false feeling of safety but tightly applied elastic material does not protect the joint.
Good bands are solid and long and should be wrapped several times around the joint (usually knee).