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Outdoor Emissions
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
The autonomic nervous system impairment was most clearly demonstrated in the blunting of the normal rise in HF HRV at night. Because peripheral vagal baroreflex function was not significantly impaired, this abnormality of circadian variation in HF HRV suggests dysfunction in the CNS control of parasympathetic outflow just as Haley's study and ours showed. The sample size of this study was also sufficient to demonstrate significant, although more subtle, differences in HF HRV among the three syndrome groups during the day. Multivariable statistical analyses demonstrated that the objective findings of peripheral sudomotor neuropathy and impaired HF HRV were not explained by smoking, creatinine clearance, psychiatric comorbidity, diagnosis of heart disease, glycated hemoglobin level, officer rank during the war, indicators of deconditioning (BMI and resting pulse rate), or medications the participants were taking during the period of the study, including anticholinergic medications and tricyclic antidepressants.
Surface electromyographic assessment of low back pain
Published in Kumar Shrawan, Mital Anil, Electromyography in Ergonomics, 2017
Serge H. Roy, Carlo J. De Luca
The onset of pain invariably initiates neuromuscular and behavioral responses that, for the most part, likely represent efforts to prevent or reduce further pain or injury by either ‘splinting’ the spinal segment(s), as for instance by muscle spasm, or by repositioning the back or altering muscle tension to relieve mechanical impingement on nerves or other sensitive tissue. Sustained or recurring episodes of these musculoskeletal compensations may result in rapid structural and functional adaptations of the muscular tissue. Generalized physical inactivity related to prolonged bed-rest or pain avoidance behavior can precipitate a deconditioning of back muscles. Deconditioning may lead to specific physiological adaptations, such as muscle fiber atrophy and changes to the relative fiber type proportions of a muscle (Kraus and Rabb, 1961; Booth, 1987; Andersson et al., 1989).
Aerobic performance of Special Operations Forces personnel after a prolonged submarine deployment
Published in Thomas Reilly, Julie Greeves, Advances in Sport, Leisure and Ergonomics, 2003
In addition to the decrease in running performance, evidence of aerobic deconditioning in the DST is reflected in their change in the HR recovery profiles. Heart rate recovery is correspondingly faster in those individuals who have a higher aerobic capacity (Cardus and Spencer 1976, Hagberg et al. 1980, Kirby and Hartung 1980, Darr et al. 1988). Furthermore, endurance training results in a more rapid rate of recovery in HR following exercise (Hagberg et al. 1980). Consequently, in the present study, slower rates of heart rate recovery following exertion were attributed to a deconditioning effect. We provide two indices of HR recovery that may be useful to follow changes in the aerobic training status of an individual. The first index, HRrectime; provides a quick field-based estimate of aerobic training status that requires few calculations or knowledge about the characteristics of the HR recovery profile. This index includes both the initial fast component and a portion of the subsequent slow component of the exponential decline in HR following exercise (Imai et al. 1994). The time constant of the slow component of the HR recovery curve depends on the exercise workload (Imai et al. 1994), hence HRrectime will be somewhat sensitive to differences in the running speed between tests. Results of the present study indicate that the DST had a substantial increase in recovery time following the submarine deployment as measured by the HRrectime; index. This finding is tempered somewhat by the fact that the NDST also showed an increase in HRrectime, albeit a non-significant one.
Biodynamic human body model to assess the injury risk during space capsule landing
Published in International Journal of Crashworthiness, 2022
Rajesh Govindan, V. Huzur Saran, Suraj P. Harsha
During dynamic phases of spaceflight, i.e. liftoff, launch abort, landing, and parachute deployment, the crewmembers were exposed to dynamic loads, which most likely cause injury risk if it exceeds human tolerance. A space capsule to be considered human-rated is required to satisfy low injury risk criteria, i.e. likelihood of injury anywhere on the body to be less than 0.5% during any dynamic phase [1]. The occupants' dynamic response in a space capsule depends on various factors such as space capsule dynamics, design of crew seat, impact attenuation, and restraint system, occupants' age, gender, anthropometry, and spaceflight deconditioning [2]. Several methods have been employed to assess the dynamic response of the human body during dynamic events, including experimentation on human volunteers, human surrogates, and numerical models.