I did a nice long and hilly ride yesterday, and when I was 'in the zone' and honking up hills, two things occurred to me: 1) If sitting, I sometimes (on the hardest bits of the hills) move my upper body side to side. 2) If standing, I sometimes move the bike from side to side underneath me. Questions: 1) Why is it that either of these side to side motions makes the uphill struggle feel easier? 2) Is it an inefficient way of cycling? I would assume so, but I don't understand what principles are behind this. Any ideas folks?