Table 2.

Postganglionic sympathetic action potentials and action potential clusters detected at rest and during maximal breath-holding for each participant

	Baseline		Maximal activity
Subject	Action potentials/burst	Active clusters/burst	Action potentials/burst	Active clusters/burst	Total detected clusters
1	19	6	46	12	14
2	7	3	37	12	16
3	23	6	54	16	24
4	13	4	39	14	22
5	8	3	23	9	11
Mean ±s.d.	14 ± 7	4 ± 2	40 ± 12*	13 ± 3*	17 ± 5†

Total detected clusters indicate the number of clusters identified throughout the entire protocol. The difference between the total detected clusters and the number of clusters present during maximal activity at the end of breath-holding indicates that not all clusters are recruited at one time.

^*Significantly different from baseline, P < 0.01.

^†Significantly different from action potential clusters per burst during maximal activity, P < 0.05.