The present study evaluates the cardiovascular effects of reflexology in a healthy sample. Forty-one participants were randomly assigned to one of three experimental groups: reflexology (n=15), non-professional foot massage (n=14), and a waiting time control group (n=12). Dependent variables were systolic, diastolic and mean blood pressure, inter-beat interval, heart rate variability and baroreceptor reflex sensitivity measured pre- and post- interventions. The study was performed during three 40-min sessions separated by weekly intervals. Results show that the three manipulations produce similar increases in inter-beat interval, heart rate variability and baroreceptor reflex sensitivity. Reflexology specifically produces an increase in blood pressure, which increases gradually over the three sessions. The parallel increase in heart rate variability and baroreceptor reflex sensitivity together with the increase in blood pressure suggest that reflexology is associated with a co-activation of both sympathetic and parasympathetic branches of the Autonomic Nervous System. These changes could be helpful in optimizing homeostatic activity, promoting the healing process and increasing the human organism’s capacity to respond adaptively to internal and external challenges. Finally, the observed physiological changes in the waiting-time control group shows the relevance of habituation processes and suggests the need for addition of waiting-time control groups in future studies.
The capture of exogenous attention by negative stimuli has been interpreted as adaptive for survival in a diverse and changing environment. In the present paper, we investigate the neural responses towards two discrete negative emotions with different biological meanings, disgust and fear, and its potential relationships with heart rate variability (HRV) as an index of emotional regulation. With that aim, 30 participants performed a digit categorization task while fear, disgust and neutral distractor pictures were presented. Resting HRV at baseline, behavioral responses, and event-related potentials were recorded. Whereas P1 amplitudes were highest to fear distractors, the disgust stimulation led to augmented P2 amplitudes compared to the rest of distractors. Interestingly, increased N2 amplitudes were also found to disgust distractors, but only in high HRV participants. Neural source estimation data point to the involvement of the insula in this exogenous attentional response to disgust. Additionally, disgust distractors provoked longer reaction times than fear and neutral distractors in the high HRV group. Present findings are interpreted in evolutionary terms suggesting that exogenous attention is captured by negative stimuli following a different time course for fear and disgust. Possible HRV influences on neural mechanisms underlying exogenous attention are discussed considering the potential important role of this variable in emotional regulation processes.