Sport Science: The Brain-Body Connection Mark D. Stephenson, MS, ATC, CSCS,*D, TSAC-F tacfit@live.com

Brain-Body Axis Interoception Influences Autonomic regulation Processing of visceral-afferent neural signals by the CNS (Schulz, & Vögele, 2015) Involved in homeostasis & self-regulation Influences Autonomic regulation Autonomic Nervous System (ANS) Heart Rate Variability

Brain-Body Axis Vagus Nerve Parasympathetic influence of the SA node Efferent & Afferent pathway Parasympathetic innervation of the heart, lungs, gastrointestinal tract (other abdominal visceral organs) Parasympathetic influence of the SA node Vagal stimulation decreases HR Sympathetic stimulation increases HR

Interoception Insula Cortex Processing of internal bodily signals Integration of mental map and sensory information to create sense of self

Response to perceived threat Perception Brain’s response to a perceived threat Sensory input Visual Auditory Environmental Touch/sensation Emotional Sensory Input Perception of threat Response to perceived threat

Autonomic Nervous System (ANS) Vagal (Parasympathetic) Decreases Heart Rate Inhibit sympathetic nerve activity Vagal Inhibition (Sympathetic) Increase sympathetic outflow to SA node Increases heart rate Parasympathetic response inhibits sympathetic nerve activity necessary for responding to threat (Fight or flight). Sympathetic activation relases norepinephrine (NE) and decrease K leakage while slowing Ca and Na uptake.

Electrophysiology P wave QRS Complex R-S segment R-R Action potential (depolarization) QRS Complex Repolarization of ventricles R-S segment Indicator of immune dysfunction R-R Time (ms) between the peak of R to the peak of the next R (HRV)

Heart Rate Variability (HRV) Measure of Vagal Function Link between physiological and cognitive function Prefrontal neural function High Variability – Recovery Low Variability - Stress

HRV Calculated 972ms – 888ms = Δ 84ms HRV = 84 Average of last 300 consecutive beats = HRV HRV average changes with each beat

HRV Frequency Domains

HRV Frequency Domains High Frequency (HF) – 0.15 - 0.40 Hz Governed exclusively by Parasympathetic effects Driven by respiration (specific to depth of respiration) Low Frequency (LF) – 0.04 - 0.15 Hz Both sympathetic and Parasympathetic modulation Predominately Sympathetic Very Low Frequency (VLF) – 0.01 – 0.04 Hz Governed exclusively by Sympathetic effects LF/HF Ratio Metric of sympathetic-parasympathetic balance

HRV Frequency Domains Parasympathetic Dominance Sympathetic Dominance

Cognitive Function Prefrontal Cortex Motor Cortex Dorsal Lateral Pre-Frontal Cortex (DLPFC) Motor Cortex

Direct Current (DC) Potential DC Potential – Signaling from cell-to-cell (mV) Relaxed – (+) voltage Stress – (-) Voltage Strength of signal Chronic Stress – Long-term decrease in voltage Acute stress – Temporary decrease in voltage Dimmer Switch Theory Increase time to shift from (+) to (-) DC potential is a shift after receiving stimulus to a negative voltage Chronic stress results in an increase in time to shift to a negative voltage.

Cellular DC Potential

Stress Reaction

HPA Axis Hypothalamus-Pituitary-Adrenal Axis Maintain Homeostasis (endocrine balance) Response to stress CRF regulates HPA axis Regulated at the level of the hypothalamus Glucocorticoids released from adrenal gland Mediated by ANS Sympathetic-parasympathetic

HPA Axis

Brain-Body Connection Stimulus Efferent-Afferent signal Exteroceptive -Interoceptive Vagus Nerve Parasympathetic Sympathetic DC Potential (+) mV RELAXED (-) mV STRESS HPA Increase Endocrine response Decrease Endocrine response

Monitoring Zephyr, Haldago Omegawave, BioForce, ithlete, Biofeedback Smart Phone Apps

Summary Brain-Body Connection HRV + DC Potential = State of Readiness Recovery = Optimal State of Readiness The brain and body cannot be separated Both must be monitored

Mark D. Stephenson, MS, ATC, CSCS,*D, TSAC-F Questions? Mark D. Stephenson, MS, ATC, CSCS,*D, TSAC-F tacfit@live.com