Fact checked by Elizabeth GallStrengthening the muscles around the knee is important for functional movements.Credit: andreswd / Getty ImagesKey TakeawaysSit-to-stands are a simple functional exercise that strengthens the hips, quads, and hamstrings and improves balance.Side-lying clamshells target hip and glute strength, which helps prevent inward knee collapse and reduces stress on the knee joint.Stretching the calves with a standing calf stre…