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TRANSCRIPT
Sport Science: The Brain‐Body Connection
Mark D. Stephenson, MS, ATC, CSCS,*D, TSAC‐[email protected]
Brain‐Body Axis• Interoception
– 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– 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
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
Electrophysiology• P wave
– 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
HRV = 84
972ms – 888ms = Δ 84ms
Average of last 300 consecutive beats = HRVHRV average changes with each beat
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
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 (‐)
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
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
Summary
• Brain‐Body Connection• HRV + DC Potential = State of Readiness• Recovery = Optimal State of Readiness