Relation between pedalling- and breathing rhythm.

The relationship between pedalling- and breathing rhythm was studied in 34 medical students (non-cyclists") and 10 racing cyclists on an electromagnetic bicycle-ergometer, the effective work load of which (50 W, 100 W, 150 W, 200 W) was independent of the pedalling rate. The criteria used were integer p/b ratios (pedalling rate being a multiple of breathing frequency) and phase coupling (the breathing phases starting preferentially at a certain angle of the pedalling cycle). Unconsciously occurring coordination of pedalling and breathing rhythm was found in the majority of the test persons; 70%-100% of the racing cyclists, 50%-63% of the regularly breathing and 25%-33% of the decreased with increasing work load. Phase coupling was even more frequent than integer p/b ratios and was not affected by increasing work load. The majority of racing cyclists (unlike the non-cyclists) coupled the inspiration-onset with the onset of either the left or the right leg movement. Expiratory phase coupling, however, was analogous in all groups; expiration began preferentially at mid-contraction of either leg. The results are discussed in terms of relative (nervous) coordination. It is concluded that the tendency to coordination between pedalling- and breathing rhythm increases with pedalling training and with regularity of breathing.