The trick to injecting quad is to go high and outside. If you are standing up let your arms hang down by your side. Right about where your finger rest against your thigh is where you inject. At first it seems weird but the higher and more to the outside of the wuad you inject the less the muscle stretched and contracts while walking etc. If you inject a hands distance away from the knee with painful gear like BD you won't be able to bend your knee for a week or so and will end up walking around like a vietnam vet with a fused knee