Does entrained breathing improve the economy of rowing?

A previous study has shown that subjects who entrain breathing during cycling exhibit a lower oxygen consumption (VO2) compared with random breathing. We sought to investigate the hypothesis that entrainment of breathing during rowing improved biomechanical economy (reduced VO2) compared with spontaneous breathing. A secondary hypothesis was that perceptual ratings of breathing difficulty would be lower with entrained breathing. Sixteen physically active male subjects (mean +/- SD age: 21 +/- 5 yr) with no previous rowing experience received instruction in rowing and then performed progressive incremental exercise on the variable-resistance rowing ergometer (Concept II, Morrisville, VT). Peak VO2 was 53.1 +/- 5.4 ml.kg-1.min-1. At three subsequent visits subjects rowed at power productions of 50% and 75% of peak VO2 for 6 min each. At each visit they were randomized to a specific pattern of breathing: inspire during drive, expire during recovery; expire during drive, inspire during recovery; or spontaneous breathing. At the end of each session subjects rated "breathing difficulty" using the 0-10 category-ratio scale. Analysis of variance revealed no significant differences in VO2, VO2/power production, or perceptual ratings at either intensity of exercise for the three different breathing patterns. Although our results do not support either the primary or secondary hypothesis, it is possible that any physiologic and/or perceptual benefits of locomotor-respiratory coupling might be specific for exercise mode or might require months to years of training.