Autonomic nervous system dysfunction and abnormal heart rate recovery

AbstractAutonomic nervous system dysfunction (ANSD) is a significant cause of mortality in tetanus. Currently diagnosis relies on non-specific clinical signs. Heart rate variability (HRV) may indicate underlying autonomic nervous system activity and represents a potentially valuable non-invasive tool for ANSD diagnosis in tetanus. HRV was measured from 3 5-minute ECG recordings during a 24-hour period in a cohort patients with severe tetanus, all receiving mechanical ventilation. HRV measurements from all subjects - 5 with ANSD (Ablett Grade 4) and 4 patients without ANSD (Ablett Grade 3) - showed HRV was lower than reported ranges for healthy individuals. Comparing different severities of tetanus, raw data for both time and frequency measurements of HRV were reduced in those with ANSD compared to those without. Differences were statistically significant in all except root mean square standard deviation RMSSD (p=0.07) indicating HRV may be a valuable tool in ANSD diagnosis.

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The Heart of an Endurance Athlete: Impact of and Recovery After an Ultra-Endurance Event.

10.21203/rs.3.rs-639854/v1 ◽

2021 ◽

Author(s):

Anton Swart ◽

Demitri Constantinou

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Nervous System ◽

Autonomic Nervous System ◽

The Body ◽

Mountain Biking ◽

Vagal Activity ◽

Autonomic Nervous System Dysfunction ◽

Autonomic Nervous ◽

Ultra Endurance

Abstract Background: Acute bouts of ultra-endurance exercise may cause an acute reduction in cardiac function, causing a physiological cascade which releases cardiac biomarkers. This study set out to determine the cardiac stress and recovery of participation in a three-day ultra-endurance mountain biking event of athletes using heart rate variability (HRV) as an outcome measure. Sixteen healthy participants (male and female) participating in a three-day ultra-endurance mountain biking event underwent a five-minute resting electrocardiography (ECG) recording in a supine position. Heart rate variability measurements were recorded two days before the race (baseline testing), after each race day, and at 24-hour post-event (recovery). Results: Time-domain and frequency domain measures showed significant (p≤0.05) changes from baseline in HRV parameters after each race day. The significant changes in HRV parameters reflected an increase in sympathetic activity after each day of the event. Our data revealed that the mean HR and RR variability variables did not return to baseline value after 24-hours of recovery, reflecting autonomic nervous system dysfunction, and that changes persisted for at least 24-hours post-event.Conclusion: Our study shows that competing in an ultra-endurance mountain bike event led to diminished vagal activity and a decrease in HRV throughout the event and persisted for at least 24-hours post-event. The body was under continuous sympathetic dominance during rest as well as during each day of racing, implying each race day can be considered a physiological stress. This may, in turn, cause a disturbance in homeostasis and an increase in autonomic nervous system dysfunction. This has implications for further research, including dysrhythmia risk, and monitoring of athletes in advising a return to strenuous activity.

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The heart of an endurance athlete: impact of and recovery after an ultra-endurance event.

10.1101/2020.07.16.20155127 ◽

2020 ◽

Author(s):

Anton Swart ◽

Demitri Constantinou

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Nervous System ◽

Autonomic Nervous System ◽

The Body ◽

Mountain Biking ◽

Vagal Activity ◽

Autonomic Nervous System Dysfunction ◽

Autonomic Nervous ◽

Ultra Endurance

Objectives Our study set out to determine the cardiac stress and recovery of participation in a three-day ultra-endurance mountain biking event of athletes using heart rate variability (HRV) as an outcome measure. Methods Sixteen healthy participants (male and female) participating in a three-day ultra-endurance mountain biking event underwent a five-minute resting ECG recording in a supine position. Heart rate variability measurements were recorded two days before the race (baseline testing), after each race day, and at 24-hour post-event (recovery). Results Time-domain and frequency domain measures showed significant (p≤0.05) changes from baseline in HRV parameters after each race day. Our study found significant changes in HRV parameters, all of which reflected an increase in sympathetic activity after each day of the event. These data also revealed that the mean HR and RR variability variables did not return to baseline value after 24-hours of recovery, reflecting autonomic nervous system dysfunction, and that changes persisted for at least 24-hours post-event. Conclusion Our study shows that competing in an ultra-endurance mountain bike event led to diminished vagal activity and a decrease in HRV throughout the event and persisted for at least 24 hours post-event. The body was under continuous sympathetic dominance during rest as well as during each day of racing, implying each race day can be considered a physiological stress. This may, in turn, cause a disturbance in homeostasis and an increase in autonomic nervous system dysfunction. This has implications for further research, including dysrhythmia risk, and monitoring of athletes in advising a return to strenuous activity.

Download Full-text