Most of us think that fitness and good posture are two unrelated things. Not so and now science can tell us why.
At the University of Michigan, reseachers explain why we swing our arms when we walk. Swinging the arms reduces the torques or twisting movements required to counter the inertia of our legs. In turn this reduces the energy needed to walk and the twisting forces on the knee joints. Experimental subjects used about 10% more energy to walk without swinging their arms than when they swung their arms normally. So to get the most from all those hours on the treadmill, allow your arms to swing naturally. That way you won’t wear yourself out before you’ve exercised enough to get fit.
‘Physical World’, volume 23, no. 1; January 2010 pp. 28-30