How everyday movements load the knee
The forces acting on the knee differ considerably by movement. Walking on the level sits at the lower end, stair climbing clearly above it, descending usually above ascending, and deep flexion such as squatting at the top.
That order explains why symptoms often show up first during particular activities while ordinary walking still feels fine.
The graphic in text form
From lower to higher load: walking on the level, going up stairs, going down stairs, rising from a low seat, deep squatting, jumping and landing. Duration adds to this: a moderate load for hours can be more demanding than a high load for seconds.
Body weight acts as a multiplier throughout. That is why reducing excess weight has an immediate effect on joint load that no supplement replaces.
What follows practically
Avoiding load entirely is rarely sensible, because joints need movement. What is sensible is spreading peaks: use the lift for several floors, kneel instead of squatting deeply, break long loads into sections.
Strengthening the thigh and hip muscles raises the load you tolerate. It is therefore the single most effective measure on this list.
Limits of this presentation
The relationships named are orders of magnitude from biomechanical research, not individual measurements. They depend on technique, muscle strength, joint condition and body weight.
This page does not replace an examination. With swelling, locking, instability or symptoms after an accident, the knee needs medical assessment.