Twenty two healthy school boys in the age group of 13-16 (14.5 ± 1.25, SEM) years who had received training in yoga for three months and were able to perform mukh bhastrika properly, were recruited for this study. They were briefed about the study protocol and informed consent was obtained from them as well as their parents. Recordings were taken in an air-conditioned laboratory (room temperature 27 ± 1°C) two hours after a light breakfast. To avoid the effect of lateralised stimulus, visual and auditory signals were given from the front of the subject who was instructed to use his dominant hand while responding to the signal (1, 15). RT was measured using a circuit that had a DC source, two tap keys, a magnetic time marker and visual/auditory signal source arranged in series. Signals obtained by operating the tap keys were recorded on RM 6000 polygraph (Nihon Kohden Corporation, Japan). Measurements were taken before and after nine rounds of mukh bhastrika by asking the subject to open as quickly as he could, a tap key that was connected alternatively to a light or sound source. Stimulus applied by completing the circuit was marked by upward deflection of the signal whereas subject’s response by breaking the circuit was marked as a downward deflection. RT was calculated as the time between these two deflections. The signals thus obtained were converted into digital format by analog-digital converter (Mi², USA) and analyzed with the help of data processing software (Bio Windows, Modular Instruments Inc. USA). With this software the RT was obtained with an accuracy of 1 ms. More than ten trials were recorded and mean of three similar observations was taken as a single value for statistical analysis (1). The data was analyzed using Student’s paired ‘ t’ test and P values less than 0.05 were accepted as indicating significant difference between the compared values.