This is a response to the statement: “tight muscles in legs after sitting”
Usually, after driving in one of those newfangled low driver’s seat without back support, one’s legs would feel weak, the lower back would feel stiff, and one would find it very difficult to stand up straight after getting out of the car. Therefore, I would think that “tight muscles in legs after sitting” would involve sitting in a bad “ergonomic” chair for a long time, say 2 to 4 hours on end.
Tight muscles in the legs after sitting would most likely occur if the leg muscles have to support a sustained posture for long periods. Being overweight worsens the situation and would make the leg muscles even tighter. The usual culprit that tightens the muscles in the legs, both the hamstrings, side muscles of the thighs and the back muscles of the lower legs, may likely be due to a protruding beer belly. In one sense, the legs have to not only sustain the body weight, but also maintain the center of gravity of the body. And if the “ergonomic” chair is tilting the center of gravity off kilter, then the legs have to do extra work to sustain all that body weight in a bad posture since the “chair” is providing no support.
The beer belly would shift the body weight off center, and one possibility is that the “chair” is not supporting the body weight. Instead, the body weight is supported by the legs while one sits for a long time.
One’s physique may also play a role. More endowed women with thicker thighs and legs sometimes feel that the leg muscles get tight rather easily. Women of South American aboriginal origin are top heavy with thin legs. Their leg muscles do not seem to tighten up that much.