Priming Cardiac Function with Voluntary Respiratory Maneuvers and Effect on Early Exercise Oxygen Uptake

Putting back respiration into respiratory sinus arrhythmia or high-frequency heart rate variability: Implications for interpretation, respiratory rhythmicity, and health

Research on respiratory sinus arrhythmia, or high-frequency heart rate variability (its frequency-domain equivalent), has been popular in psychology and the behavioral sciences for some time. It is typically interpreted as an indicator of cardiac vagal activity. However, as research has shown for decades, the respiratory pattern can influence the amplitude of these noninvasive measures substantially, without necessarily reflecting changes in tonic cardiac vagal activity. Although changes in respiration are systematically associated with experiential and behavioral states, this potential confound in the interpretation of RSA, or HF-HRV, is rarely considered. Interpretations of within-individual changes in these parameters are therefore only conclusive if undertaken relative to the breathing pattern. The interpretation of absolute levels of these parameters between individuals is additionally burdened with the problem of residual inspiratory cardiac vagal activity in humans. Furthermore, multiple demographic, anthropometric, life-style, health, and medication variables can act as relevant third variables that might explain associations of RSA or HF-HRV with experiential and behavioral variables. Because vagal activity measured by these parameters only represents the portion of cardiac vagal outflow that is modulated by the respiratory rhythm, alternative interpretations beyond cardiac vagal activity should be considered. Accumulating research shows that activity of multiple populations of neurons in the brain and the periphery, and with that organ activity and function, are modulated rhythmically by respiratory activity. Thus, observable health benefits ascribed to the cardiac vagal system through RSA or HF-HRV may actually reflect beneficial effects of respiratory modulation. Respiratory rhythmicity may ultimately provide the mechanism that integrates central, autonomic, and visceral activities.

Women's Respiratory Movements during Spontaneous Breathing and Physical Fitness: A Cross-Sectional, Correlational Study

BACKGROUND

Abdominal/diaphragmatic breathing exercises are popular worldwide and have been proven to be beneficial for physical performance. Is abdominal motion (AM) during spontaneous breathing correlated with physical fitness? The present study aimed to answer this question.

METHODS

434 women (aged 20-59) were enrolled and participated in respiration tests using two respiration belts (one was tied at the height of the xiphoid and another at the navel) to detect AM and thoracic motion (TM). They also performed physical fitness tests to measure body size, muscular strength, muscular power, muscular endurance, balance, flexibility, reaction time, and cardiorespiratory endurance.

RESULTS

All the correlation coefficients between respiratory movements (AM, TM, AM + TM, AM/(AM + TM)) and physical fitness outcomes were less than 0.4/-0.4. Only AM and muscular power (countermovement jump height) had a weak correlation, with a correlation coefficient close to 0.4 in the 20-29-year age group (r_s = 0.398, p = 0.011, n = 40).

CONCLUSIONS

Women's respiratory movements during spontaneous breathing were not correlated with physical fitness. Future studies may focus on the relationship between AM and countermovement jump height in young women with a larger sample size and using ultrasound to directly test the excursion of the diaphragm.