My physiotherapist wife always tells me that sitting cross
legged (on a chair or sofa) is not good as it weakens the gluteal muscles.
As a cardiologist, I have one more reason to advise against
sitting cross legged on a chair i.e., thigh of one leg over the thigh of the
other leg or ankle of one leg over the knee of the other leg (see pics).
This is because, sitting cross legged in these ways can raise
your systolic (the upper number) blood pressure by 8 to 10 points (mm of Hg).
Carefully done studies in which participants were randomly
assigned, using a crossover design, consisted of having seated blood pressures
measured with their legs in three different postures:
Feet flat on the floor and legs uncrossed
Legs crossed, method 1: popliteal fossa of the dominant leg over
the suprapatellar bursa of the non-dominant leg
Legs crossed, method 2: lateral malleolus of the dominant leg
over the suprapatellar bursa of the non-dominant leg
The person measuring BP was ‘blinded’ by a screen from knowing
the posture of subjects whose BP was being measured.
Results showed that systolic blood pressure in patients with
hypertension increased by 8 mm Hg by method 1 leg crossing and 10 mm Hg by
method 2.
Another study demonstrated that although crossing the legs at
the knees influenced blood pressure, crossing them at the ankles had no effect.
Hence it is not a good idea to sit cross legged in general, especially
if you have hypertension or are getting your BP measured.