Marines who received MMFT showed greater reactivity ( heart rate [ d = 0.43 ] ) and enhanced recovery ( heart rate [ d = 0.67 ] , breathing rate [ d = 0.93 ] ) after stressful training ; lower plasma neuropeptide Y concentration after stressful training ( d = 0.38 ) ; and attenuated blood-oxygen-level-dependent signal in the right insula and anterior cingulate .