Cardiac Autonomic Control and Neural Arousal as Indexes of Fatigue in Professional Bus Drivers

Background: Bus driving is a mentally demanding activity that requires prolonged attention to ensure safety. The aim of the study was to assess mental fatigue caused by driving a public bus and to find a profile of workers at higher risk. Methods: We evaluated changes of critical flicker fusion (CFF) (index of central arousal) and heart rate variability (HRV) (index of autonomic balance) in a 6-hour driving shift on a real route, in 31 professional bus drivers, and we tested the influence of personal factors such as sleep quality, BMI, and age. Paired t test was used to test differences of CFF and HRV between both initial and final phase of driving, while multiple linear regression tested the influence of personal variables on the indexes of mental fatigue. Results: Results showed that CFF significantly decreased after 6 hours of bus driving (41.91 Hz, sd 3.31 vs. 41.15 Hz, sd 3.15; p = 0.041), and heart rate significantly decreased in the final phase of driving, with respect to the initial phase (85 vs. 78 bpm, p = 0.027). Increasing age (beta =-0.729, p = 0.022), risk of obstructive sleep apnea syndrome (beta =-0.530, p = 0.04), and diurnal sleepiness (beta =-0.406, p = 0.017) showed a significant effect on influencing mental fatigue. Conclusion: Elderly drivers at higher risk of sleep disorders are more prone to mental fatigue, when exposed to driving activity. Monitoring indexes of central arousal and autonomic balance, coupled with the use of structured questionnaires can represent a useful strategy to detect profile of workers at higher risk of mental fatigue in such duty

Influence of Two Exercise Programs on Heart Rate Variability, Body Temperature, Central Nervous System Fatigue, and Cortical Arousal after a Heart Attack

Cardiovascular diseases (CVD) are the leading cause of death globally. Cardiac rehabilitation (CR) programs’ benefits are overall consensual; however, during exercise, progressive physiological effects have not been studied yet in cardiac patients. Our study aims to analyze physiological parameters of thermography, heart rate variability (HRV), blood pressure, central nervous system (CNS) fatigue, and cortical arousal in heart attack patients (HAP) who belong to CR programs of High-Intensity Interval Training (HIIT) and Moderate-intensity Continuous Training (MICT) compared to healthy participants. In this case control study, two HAP patients (both male, age 35 and 48, respectively) and two healthy people (both male, age 38 and 46, respectively) were randomly assigned in a 1:1:1:1 allocation ratio to one of four groups: cardiac MICT, cardiac HIIT, control MICT, and control HIIT. The HIIT at _85–95% of peak heart rate (HR) was followed by a one-minute recovery interval at 40% peakHR, and MICT at _70–75% of peakHR. Outcome measurements included thermography, HRV, blood pressure, CNS fatigue, and cortical arousal; The HAP presents more than twice the CNS fatigue in MICT than control participants, but HIIT has almost the same CNS fatigue in HAP and control. In addition, both of the HAP groups presented higher temperatures in the chest. The HIIT protocol showed better physiological responses during exercise, compared to MICT in HAP

The effect of acute, moderate intensity indoor cycling on the temporal resolution of human vision system, measured by critical fusion frequency

Critical fusion frequency (CFF) reflects the basic temporal function of the visual system and therefore is a good measure of its performance. CFF has been implemented in psychological and pharmacological studies to evaluate cognitive functions. The influence of abnormal environmental conditions, such as physical exercise, has been recently explored. Previous studies have presented alterations of cognitive processes due to acute exercise. However, the duration of the effect after the end of exercise has not been investigated. This evaluation is important especially in reference to long-term conclusions on the effect of training on CFF as an improvement of cognition. The main goal of this study was to check whether a stimulatory effect of acute submaximal physical exercise on CFF among non-experienced cyclists persists over time. Moreover, we asked whether this effect differs between areas of visual field. CFF thresholds from 15 volunteers were measured by means of an automated medical perimeter PTS 910 (Bogdani) before, immediately after the end, and 30 min after the end of two sessions (training and rest). During rest, CFF did not change significantly, but we observed an increased CFF immediately after training. Interestingly, this increase was maintained 30 min after the end of exercise in fovea. A greater decrease of CFF during rest was observed for lower than for upper hemifield. Our results suggest that an acute, moderate-intensity cycling improved CFF in non-experienced cyclists, with the duration of the effect depending on eccentricity. The possible visual hemifield asymmetries of CFF changes over time will be further investigated

The impact of nationality on the psychophysiological stress response and academic fulfilment in the final degree dissertation

The aims of this study were: i. to analyze the effect of nationality on the psychophysiological stress response of physiotherapy last year students in their final degree dissertations; and ii. to analyze the relationship between the stress response and academic results according to nationality. We evaluated the autonomic stress response, cortical arousal, distress subjective perception, and objective and subjective academic fulfilment in Spanish, Italian, and French physiotherapy students during their final degree dissertation. Results showed a large anticipatory anxiety response before the dissertation in the three student groups. Only the Spanish group showed an increased tendency in the habituation process, reducing the psychophysiological stress response during the dissertation, while the Italian and French groups maintained a large sympathetic activation until the end of the dissertation. Cortical arousal and subjective perception of distress were similar in the three nationalities. In addition, no correlation between academic fulfilment and autonomic modulation was found. We concluded that there was no nationality effect in the psychophysiological stress response of physiotherapy last year students in their final degree dissertation, all of them showing a large anticipatory anxiety response

Activación cortical y fatiga del sistema nervioso después de una maratón de montaña

Ultraendurance research has focused on the study of physiological parameters and body composition. The study of the influence on cognitive function and central nervous system (CNS) using the Critical Flicker Fusion Threshold (CFFT) has not been measured in this event. The objective of this study was to analyzed changes in CFFT before and after a mountain marathon. We analysed 26 athletes (22 men and 4 women, 66.9 ± 10.0 kg, 171.4 ± 7.1 cm, 37.8 ± 9.9 years). Before and after the event the mountain marathon runners performed a CFFT test, and for every test each subject performed the CFFT test three times. In addition, blood lactate concentration was analysed before and after the race as well as measuring heart rate during the race. The results found that the CFFT decreased after the event, with non-significance shown (p < 0.05). The mean heart rate was150.9 ± 7.9 bpm and final lactate concentration was 4.5 ± 1.2 mmol/l. The mountain marathon event was not therefore, found to affect the CNS, fatigue was caused by other peripheral causes.La investigación en pruebas de ultra resistencia se ha centrado en el estudio de parámetros fisiológicos y la composición corporal. El estudio de la influencia sobre la función cognitiva y el sistema nervioso central (SNC), utilizando el umbral de frecuencia crítica de fusión (UFCF), no ha sido medido en estas pruebas. El objetivo de este estudio fue analizar los cambios en el UFCF antes y después de una maratón de montaña. Se analizaron 26 atletas (22 hombres y 4 mujeres, 66.9 ± 10.0 kg, 171.4 ± 7.1 cm, 37.8 ± 9.9 años). Antes y después del maratón de montaña los corredores realizaron una prueba para analizar el UFCF, también se analizó la concentración de lactato en sangre antes y después de la carrera y la frecuencia cardíaca durante la carrera. Los resultados muestran que el UFCF disminuyó no significativamente (p < 0.05) después de la maratón de montaña. La media de la frecuencia cardíaca fue de 150.9 ± 7.9 lpm y la concentración de lactato sanguíneo final fue de 4.5 ± 1.2 mmol / l. Una maratón de montaña no afectó negativamente al sistema nervioso central, la fatiga fue causada por otras causas periféricasActividad Física y Deport

Influencia de la fatiga en la agudeza visual dinámica y frecuencia crítica de fusión en un grupo de motoristas de élite participantes de una prueba de resistencia de 24 horas

1. Observar la evolución de la Agudeza Visual Dinámica en condiciones de alto y bajo contraste en un grupo de motociclistas de élite durante la realización de una competición de resistencia de 24 horas. 2. Analizar y relacionar mediante la evolución de la FCF los niveles de activación y/o fatiga del SNC de los pilotos en las distintas fases temporales de la prueba. 3. Valorar las posibles relaciones entre valores de FCF y AVD a lo largo de la prueba.La conducción deportiva requiere de unas óptimas capacidades perceptivomotoras. El objetivo de esta investigación fue evaluar el efecto que produce la fatiga en la capacidad visual de un grupo de motoristas de élite durante una competición de resistencia de 24 horas de motociclismo. Las variables estudiadas fueron la Agudeza visual dinámica (AVD), habilidad visual relacionada con una conducción eficaz, en alto y bajo contraste y la Frecuencia crítica de Fusión (FCF) para controlar el nivel de activación y fatiga del sistema nervioso central. Participaron 10 pilotos de categoría nacional e internacional con una edad media de 28 ±6 años. Los resultados no reflejaron diferencias significativas entre las diferentes mediciones realizadas para la AVD de alto y bajo contraste ni en la FCF durante la competición. A pesar de la dureza de la competición, la fatiga inducida no produjo una disminución de la AVD, tampoco supuso una reducción del nivel de activación del SNC tal y como reflejan los resultados en la FCF. Las ligeras variaciones observadas en la AVD pudieron deberse a distintos factores como la fatiga, condiciones ambientales, periodos de descanso,…El nivel de activación observado pudo deberse al adecuado nivel de reparación, descansos entre relevos, ingesta de bebidas energéticas,

Investigation of the effect of short duration breaks in delaying the onset of performance related fatigue during long distance monotonous driving at different times of the day

Road traffic accidents are a serious burden to the health systems of many countries especially in South Africa. Research aimed at reducing traffic related accidents is of importance as traffic crashes are rated as the second leading cause of fatalities in South Africa and ninth in the world. Despite the extensive efforts into research and development of new technology, driver fatigue still remains a cause of vehicle accidents worldwide. Fatigue plays a role in up to 20% of vehicle accidents with many being serious or fatal. Numerous coping behaviours are employed by drivers to counteract the negative effects of fatigue. The most common coping behaviours include taking short naps, talking to passengers, listening to the radio, opening windows and drinking stimulants. Driving breaks have long been identified as an effective countermeasure against fatigue. Most research done in driving breaks has investigated the duration of the breaks, activity undertaken during the break and the frequency of the breaks taken outside the vehicle. However limited literature is available on the effectiveness of breaks in counteracting the effects of fatigue. The objective of the current study was aimed at assessing whether short duration breaks are an effective countermeasure against fatigue. Physiological, neurophysiological, subjective and performance measures were used as indicators for fatigue. Additional focus of the research was determining whether breaks were more or less effective at counteracting the effects of fatigue at different times of day. Twelve participants were recruited for the study, six males and six females. The participants were required to perform a driving task on a simulator for 90 minutes. The study consisted of four independent conditions, namely driving during the day with breaks, driving during the day without breaks, driving during the night with breaks and driving during the night without breaks. The without breaks conditions were similar except that they occurred at different times of the day, one session at night and the other session during day time, as was the case for the conditions with breaks. The driving task used in the current study was a low fidelity simulator tracking task. The participants were required to follow a centre line displayed on a tracking path as accurately as possible. The measurements that were recorded in this study included physiological, performance, subjective and neurophysiological. Physiological measures included heart rate and heart rate variability (frequency domain) and core body temperature. The ascending threshold of the critical flicker fusion frequency was the only neurophysiological measurement included in the current investigation. Performance was quantified by mean deviation from a centre line participants were meant to track. Two rating scales were used: Karolinska sleepiness scale and the Wits sleepiness scale were used for the measurement of subjective sleepiness. Heart rate, heart rate variability and mean deviation were measured continuously throughout the 90 minute driving task. Critical flicker fusion frequency, temperature and the subjective scales were measured before and after the 90 minute driving task. The results indicated that the short duration breaks during day time had a positive effect on driving performance; however the breaks at night had a negative effect on driving performance. Heart rate was higher during the day compared to night time and the heart rate variability high frequency spectrum values were lower during the day condition, to show the activation of the sympathetic nervous system which is characteristic of day time. The night conditions had lower heart rate values and higher heart rate variability high frequency values, which show the activation of the parasympathetic nervous system which is dominant during periods of fatigue and night time. Subjective sleepiness levels were also higher at night compared to day time