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Summary

Introduction

This study aims to test the feasibility and explore the effects of training in cardiac coherence of people who have with intellectual disabilities in conjunction with their work in sheltered workshops. People with intellectual disability may have difficulties in managing stressful and emotional events. Training in heart coherence has been proved beneficial for different populations.

Our main hypothesis is that the practice of respiratory sinus arrhythmia (RSA) improves responsiveness to external stimuli by developing the capacity to respond to them. The physiological indices for parasympathetic activity will increase in post-test as well as perceived stress.

Materials and Methods

Training in heart coherence was tested on 17 volunteers with mild intellectual disability working in sheltered workshops. Training in cardiac coherence was implemented during two consecutive weeks. It corresponded to a period of 30 minutes of introduction to breathing control delivered before the start of each working half-day. The evaluation of the effectiveness of these exercises was performed by recording the variability of heart rate and the Perceived Stress Scale (PSS) during the week before and the week following the training period. Data on cardiac variability was recorded live at a high esolution (4.1 ms sampling; 250 Hz) with a recording box arranged in the pocket of a shirt with integrated sensors.

Results

The approximate length of ECG recordings was 4.3 °æ 2 hours at pre-test and 3.4 °æ 2 hours at post-test. On the PSS after training, an average decrease of 1.5 points was measured between the pre-test and the post-test, but this did not reach statistical significance.

Ten of the 17 participants improved their score on the PSS. Pre-test versus post-test differences for the RMSSD physiological variables (_2(1.16) = 4.76, P < 0.03) and LF (_2(1.16) = 4.5, P < 0.04), as well as a marginal effect for pNN50 (_2(1.16) = 2.88, P = 0.089) were noted. It is noteworthy that the largest increase between post- and pre-test was observed for pNN50 indices (+79%) and SDNN (+30%) with a particularly large variance. The reasonably expected mean values of our participants were low: SDNN approximately 60 ms for 100—250 ms expected, RMSSD approximately 20 ms for 20—60 ms expected, and pNN50 between 3 and 5% for 5 to 25% expected. The relationship between physiological and psychological variables was studied by the differences between the pre-test and the post one calculated for RMSSD, pNN50 and perceived stress.

Linear regression analysis revealed that RMSSD and pNN50 indices maintained a strong link in their increase (F(1.16) = 7.67, P = 0.014; R2 = 0.34; 0.58 correlation), but that only physiological index RMSSD was significantly associated with a decrease of perceived stress (F(1.16) = 8.8, P < 0.001; coefficient of determination R2 = 0.37; 0.61 correlation). This predictive link was not found between perceived stress and pNN50 (F(1.16) = 18; P = 0.68; R2 = 0.011).

Discussion

The benefits of training in cardiac coherence affect the entirety of our study participants: they are psychological (reduction of perceived stress: n = 10), physiological (increased RMSSD: n = 11; increased pNN50: n = 11; increase pNN50 and RMSSD: n = 9) or both combined (n = 5). Together, our results indicate that the population with intellectual disabilities seems particularly receptive to learning cardiac coherence and are also sensitive to its benefits. Their subjective perception of stress is particularly related to the strengthening of inhibitory activity of the parasympathetic autonomic nervous system. Thus, our results allow us to confirm the possible effect of the introduction to cardiac coherence for subjects with intellectual disability.

© 2015 Association franc¸aise de thérapie comportementale et cognitive.