Heart rate variability (HRV) and muscular system activity (EMG) in cases of crash threat during simulated driving of a passenger car

Neuromuscular fatigue profiles depends on seat feature during long duration driving on a static simulator

Prolonged driving could induce neuromuscular fatigue and discomfort since drivers have little opportunity to adjust their position. However, better car seat design could play a major role in limiting these effects. This study compared the effect of two different seats (S - soft and F - firm) on neuromuscular fatigue and driver's perceived discomfort during prolonged driving, also assessing the effect of different road types on neuromuscular activity. Twenty participants performed two 3-h driving sessions, one for each seat, on a static simulator. Every 20 min, participants self-evaluated their level of whole-body and individual body-area discomfort. Surface electromyography (sEMG) was recorded for eight muscles including Trapezius descendens (TD), Erector spinae longissimus (ESL), Multifidus (MF), Vastus lateralis (VL) and Tibialis anterior (TA) throughout the driving sessions. Moreover, an endurance static test (EST) was performed prior to and after each driving session. Whole-body discomfort increased with time with both seats, but no difference in discomfort scores was observed between seats throughout the driving sessions. The highest discomfort scores were for neck and lower back areas with both seats. Neuromuscular fatigue was revealed by a shorter endurance time in post-driving EST for both seats. EMG recordings showed different neuromuscular fatigue profiles for the two seats, with earlier onset of fatigue for S. Despite the lack of difference in perceived discomfort level, the two seats have different impacts: the softness of S induces greater activity of the lower back muscles, while F offers greater support for the lower back.

Impact of exercise in high-humidity on heart rate variability and salivary oxidative stress in obese and lightweight asthmatic children

BACKGROUND

Asthma and obesity are becoming increasingly common among children. Such conditions are known to negatively affect both cardiac autonomic function and oxidative stress. We therefore investigated the heart rate variability (HRV) and oxidative (malondialdehyde, MDA) response to exercise within a high humidity environment (~65%) in obese and lightweight asthmatic children.

METHODS

Forty-two children participated in this study and were categorized into four groups: obese asthmatic (OA, N.=10), obese non-asthmatic (ONA, N.=15), lightweight asthmatic (LA, N.=10), and lightweight non-asthmatic (LNA, N.=7). Time-domain and nonlinear indices of HRV were assessed at rest, during, and immediately after exercise. Further, saliva samples were collected immediately before and after exercise and analyzed for the determination of MDA.

RESULTS

HRV significantly decreased during and after exercise compared to baseline (P<0.05) with short-term fractal scaling exponent (α1) for the LNA group significantly smaller than the OA group after exercise (P<0.05). In contrast, the long-term fractal scaling exponent (α2) was greater after exercise compared to baseline and during exercise for all groups (P<0.05). MDA significantly decreased after exercise compared to baseline (P<0.05). We also found significant correlations after exercise between salivary levels of MDA with HRV components (i.e., RMSSD, SD1, and α2) in asthmatic groups (all P<0.05).

CONCLUSIONS

Our findings showed that exercise in high humidity environment does not significantly differentiate the autonomic response among children with various conditions (i.e., obese, asthmatic and healthy). However, a significant relationship was found between HRV and MDA in asthmatic children after exercise, highlighting the inter-relationship between oxidative stress markers and autonomic function in asthmatic children.

Wireless Patrol Sign-In System with Mental Fatigue Detection

Current sign-in methods of patrolling security guards mainly comprise signature, image identification, and fingerprint identification; notably, none of these methods indicate the physical and mental conditions of such guards. In particular, when patrolling security guards perform their duties consecutively for a long period of time, adequate attention should be directed toward their levels of mental fatigue. When a handwriting sign-in system is adopted, security guards may not record their sign-in time accurately, or they may fake signatures during long shifts. In addition, image identification systems cannot comprehensively reflect the physical and mental statuses of on-duty security guards, particularly their levels of fatigue. Monitor fatigue in patrolling security guards is important to avoid burnout and stress in the workplace. Therefore, in this study, a patrolling sign-in system that integrates physiological signals and images was designed. A thermometer, hand dynamometer, and electromyography sensor were combined to measure physiological signals. Results showed that hand grip strength and the median frequency of electromyography signals gradually reduced when muscle fatigue occurred. The system determined whether a security guard had signed in punctually and whether this person should stay on duty. Overall, this system was verified to operate effectively, and it is therefore applicable for monitoring the sign-in of patrolling security guards who work long shifts. This case series study proposed a conceptual prototype of the system; large-scale testing should be performed in subsequent research.