Bellows action is one of the most effective mechanisms to exchange air and heat inside clothing. The effect of bellows action on heat transfer in clothing system has been investigated with experimental model. The effect of bellows action on heat transfer has been expected being affected by both air permeability of clothing material and the size of air space in clothing. Contrary to our expectation, the effect of air permeability was small. On the other hand, the effect of size of air space was remarkable. When the size of air space "s" was set 5mm, the effect of bellows action on heat transfer in clothing was largest. The larger or the smaller "s" was, the smaller the effect of bellows action was. On contrary to other size of space, when "s" was 20mm, bellows action does not always increase heat transfer.

DESCENTE SPORTS SCIENCE Vol.20/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE