Coordination between breathing and forearm movements during sinusoidal tracking

Time relationships (coordination) between breathing and rhythmical limb mov ements were analyzed during sinusoidal tracking movements of the forearm in 11 healthy subjects. The tracking rate was varied systematically between 0 .1 and 1.0 Hz in 0.1-Hz steps. The aim of the study was to elucidate whethe r rhythmical tracking movements can entrain breathing, and whether this ent rainment depends upon the movement rate. Subjects exhibited coordination be tween tracking movements and breathing at various rate ratios (1:1, 1:2, 1. 3). At tracking rates of between 0.2 and 0.6 Hz, 1:1 coordination occurred with a maximum at 0.3 Hz; this rate range was called the 1:1 entrainment ba nd. Coordination of 1.3 occurred at between 0.5 and 1.0 Hz (the 1:2 coordin ation band) with a maximum at 0.7 Hz. Coordination of 1:3 could be detected at between 0.5 and 1.0 Hz. Different subjects showed 1:n entrainment bands at similar locations but different widths of the rate range studied. The b reathing rate during tracking was significantly higher than at rest, and it was correlated positively with tracking rate. This correlation, however, d epended upon the width of the entrainment bands. Breathing rates varied bet ween 0.2 and 0.6 Hz for all coordination patterns. We conclude that the occ urrence of fixed time relationships is an expression of the strength of cen tral nervous system coupling between the two processes. The frequency of co ordination between breathing and rhythmical tracking movements depends crit ically upon the movement rate.