Purpose: Sleep loss and its concomitant fatigue and risk are ubiquitous in today's fastpaced soci... more Purpose: Sleep loss and its concomitant fatigue and risk are ubiquitous in today's fastpaced society. A bio-mathematical model that succeeds in describing performance during extended wakefulness would have practical utility in operational environments, and could help elucidate the physiological basis of sleep loss effects.
Repeated exposure to low-level blast is a characteristic of a few select occupations and there is... more Repeated exposure to low-level blast is a characteristic of a few select occupations and there is concern that such occupational exposures present risk for traumatic brain injury. These occupations include specialized military and law enforcement units that employ controlled detonation of explosive charges for the purpose of tactical entry into secured structures. The concern for negative effects from blast exposure is based on rates of operator self-reported headache, sleep disturbance, working memory impairment, and other concussion-like symptoms. A challenge in research on this topic has been the need for improved assessment tools to empirically evaluate the risk associated with repeated exposure to blast overpressure levels commonly considered to be too low in magnitude to cause acute injury. Evaluation of serum-based neurotrauma biomarkers provides an objective measure that is logistically feasible for use in field training environments. Among candidate biomarkers, ubiquitin ca...
Current military missions occasionally require combat readiness of soldiers who might be experien... more Current military missions occasionally require combat readiness of soldiers who might be experiencing a sustained period of activity without sleep. Strategies to overcome the debilitating effects of sleep deprivation include the ingestion of caffeine. Unknown is the efficacy of caffeine use on specific elements of target detection and marksmanship following a modest period of sustained wakefulness. There were 20 subjects (mean +/- SD of 26.7 +/- 7.2 yr of age, 179 +/- 6 cm in height, and 84.5 +/- 10.8 kg in weight) who participated in double-blind caffeine and placebo trials where each trial involved a 24-h control period (with sleep) followed by 22 h of mixed mental and physical activity with no sleep. At the end of this period, subjects engaged in a 1-h rifle-shooting task. Subjects ingested 400, 100, and 100 mg of caffeine or placebo at 7.5, 3, and 0 h, respectively, prior to shooting. Measures of shooting performance included target engagement time (between target appearance and...
Sleep loss, as well as concomitant fatigue and risk, is ubiquitous in today's fast-paced soci... more Sleep loss, as well as concomitant fatigue and risk, is ubiquitous in today's fast-paced society. A biomathematical model that succeeds in describing performance during extended wakefulness would have practical utility in operational environments and could help elucidate the physiological basis of sleep loss effects. Eighteen subjects (14 males, 4 females; age 25.8 +/- 4.3 years) with low levels of habitual caffeine consumption (<300 mg/day) participated. On night 1, subjects slept for 8 h (2300-0700 h), followed by 77 h of continuous wakefulness. They were assigned randomly to receive placebo or caffeine (200 mg, i.e., two sticks of Stay Alert gum) at 0100, 0300, 0500, and 0700 during nights 2, 3, and 4. The psychomotor vigilance test (PVT) was administered periodically over the 77-h period of continuous wakefulness. Statistical analysis reveals lognormality in each PVT, allowing for closed-form median calculation. An iterative parameter estimation algorithm, which takes adv...
The purpose of this study examined the changes in heart rate (HR), catecholamines (NE, EPI) and p... more The purpose of this study examined the changes in heart rate (HR), catecholamines (NE, EPI) and percentages of blood lymphocyte subsets (CD3+ T cells, CD3+ CD4+ helper T cells, CD3+ CD8+ cytotoxic T cells, CD3− CD56+ NK cells, CD4/CD8 ratio, CD19+ B cells, and total lymphocytes [NK cells+ T cells + B cells]) in firefighters exposed to a computerized firefighting strategies and tactics decision-making challenge while participating in moderate intensity exercise. Furthermore, this study also examined the possible relationships between catecholamines (NE and EPI) and blood lymphocyte subsets following combined mental and physical challenge. Ten professional male firefighters participated in two counterbalanced exercise conditions on a cycle ergometer: (1) 37 min of cycle ergometry at 60% VO 2max (exercise alone condition; EAC) and (2) 37 min of cycle ergometry at 60% VO 2max along with 20 min of a computerized firefighting strategies and tactics decision-making challenge (firefighting strategies condition; FSC). FSC elicited significantly greater HR, NE, and EPI when compared to EAC. Both EAC and FSC elicited increases in CD3− CD56+ NK cells. The percentages of CD3+ T cells, CD3+ CD4+ helper T cells, CD4/CD8 ratio, CD19+ B cells, and total lymphocytes were lower immediately following both conditions. Following dual challenge NE AUC was negatively correlated with percentage of CD19+ B cells immediately post challenge, and HR was negatively associated with the percent change in the CD4/CD8 ratio from pre to post challenge. These elevations in NE and heart rate simultaneously in response to the dual challenge suggest greater sympathetic activation that in turn would possibly explain the alteration in the distribution of lymphocyte subsets.
Objective.-This study investigated the effects of 2 potentially ''oxygen promoting'' dietary supp... more Objective.-This study investigated the effects of 2 potentially ''oxygen promoting'' dietary supplements on hypoxia and oxidative stress at a simulated altitude of 4600 m.
time of day effects on EEG spectral parameters. PHYSIOL BEHAV 54(2) 283-287, 1993.--Electroenceph... more time of day effects on EEG spectral parameters. PHYSIOL BEHAV 54(2) 283-287, 1993.--Electroencephalographic (EEG) recordings were obtained from nine male subjects at sea level and again following rapid ascent to high altitude (4300 meters) at 0900, 1600, and 1830 h. Electroencephalographic data were subjected to Fast Fourier Transformation and analyzed for beta, spindle, alpha, theta, delta, and total amplitudes. Total amplitude increased from baseline to altitude while relative theta (absolute theta/total amplitude) decreased from baseline to altitude. Amplitude for absolute and relative spindle and total amplitude increased across the day.
Purpose: 1) To examine the effect of a 12-wk endurance exercise training program on RMR and 2) to... more Purpose: 1) To examine the effect of a 12-wk endurance exercise training program on RMR and 2) to provide insight into the mechanisms responsible for alterations in RMR that may occur after exercise training. Methods: Male participants (19-32 yr) in an exercise group (EX; n = 9) performed jogging and/or running 3-4 dIwk j1 , 25-40 min per session, at 60%-80% V O 2max , whereas subjects in a control group (CON; n = 10) maintained their normal activity patterns. Body composition, V O 2max , RMR, epinephrine, norepinephrine, total thyroxine, free thyroxine, insulin, free fatty acids, and glucose were measured before and after the intervention. Results: Training resulted in a significant increase in V O 2max in EX (46.2 T 1.2 to 51.0 T 1.3 mLIkg j1 Imin j1 , P G 0.001). Absolute and relative values for RMR did not significantly change in EX after training. Mean values for epinephrine, norepinephrine, total thyroxine, insulin, and glucose did not significantly change in either group; however, free thyroxine decreased significantly after training in EX (P = 0.04). Training also resulted in a significant increase in free fatty acid concentration in EX (0.37 T 0.03 to 0.48 T 0.04 mmolIL j1 , P G 0.001). RMR in CON decreased significantly when expressed as an absolute value (P G 0.01) and relative to body weight (P G 0.01), fat-free mass (P G 0.01), and fat mass (P = 0.04). Conclusions: The mechanism for the decrease in CON is unknown, but it may be related to seasonal variations in RMR. Training may have prevented a similar decline in RMR in EX and may be related to a training-induced increase in fat oxidation.
Purpose: Sleep loss and its concomitant fatigue and risk are ubiquitous in today's fastpaced soci... more Purpose: Sleep loss and its concomitant fatigue and risk are ubiquitous in today's fastpaced society. A bio-mathematical model that succeeds in describing performance during extended wakefulness would have practical utility in operational environments, and could help elucidate the physiological basis of sleep loss effects.
Repeated exposure to low-level blast is a characteristic of a few select occupations and there is... more Repeated exposure to low-level blast is a characteristic of a few select occupations and there is concern that such occupational exposures present risk for traumatic brain injury. These occupations include specialized military and law enforcement units that employ controlled detonation of explosive charges for the purpose of tactical entry into secured structures. The concern for negative effects from blast exposure is based on rates of operator self-reported headache, sleep disturbance, working memory impairment, and other concussion-like symptoms. A challenge in research on this topic has been the need for improved assessment tools to empirically evaluate the risk associated with repeated exposure to blast overpressure levels commonly considered to be too low in magnitude to cause acute injury. Evaluation of serum-based neurotrauma biomarkers provides an objective measure that is logistically feasible for use in field training environments. Among candidate biomarkers, ubiquitin ca...
Current military missions occasionally require combat readiness of soldiers who might be experien... more Current military missions occasionally require combat readiness of soldiers who might be experiencing a sustained period of activity without sleep. Strategies to overcome the debilitating effects of sleep deprivation include the ingestion of caffeine. Unknown is the efficacy of caffeine use on specific elements of target detection and marksmanship following a modest period of sustained wakefulness. There were 20 subjects (mean +/- SD of 26.7 +/- 7.2 yr of age, 179 +/- 6 cm in height, and 84.5 +/- 10.8 kg in weight) who participated in double-blind caffeine and placebo trials where each trial involved a 24-h control period (with sleep) followed by 22 h of mixed mental and physical activity with no sleep. At the end of this period, subjects engaged in a 1-h rifle-shooting task. Subjects ingested 400, 100, and 100 mg of caffeine or placebo at 7.5, 3, and 0 h, respectively, prior to shooting. Measures of shooting performance included target engagement time (between target appearance and...
Sleep loss, as well as concomitant fatigue and risk, is ubiquitous in today's fast-paced soci... more Sleep loss, as well as concomitant fatigue and risk, is ubiquitous in today's fast-paced society. A biomathematical model that succeeds in describing performance during extended wakefulness would have practical utility in operational environments and could help elucidate the physiological basis of sleep loss effects. Eighteen subjects (14 males, 4 females; age 25.8 +/- 4.3 years) with low levels of habitual caffeine consumption (<300 mg/day) participated. On night 1, subjects slept for 8 h (2300-0700 h), followed by 77 h of continuous wakefulness. They were assigned randomly to receive placebo or caffeine (200 mg, i.e., two sticks of Stay Alert gum) at 0100, 0300, 0500, and 0700 during nights 2, 3, and 4. The psychomotor vigilance test (PVT) was administered periodically over the 77-h period of continuous wakefulness. Statistical analysis reveals lognormality in each PVT, allowing for closed-form median calculation. An iterative parameter estimation algorithm, which takes adv...
The purpose of this study examined the changes in heart rate (HR), catecholamines (NE, EPI) and p... more The purpose of this study examined the changes in heart rate (HR), catecholamines (NE, EPI) and percentages of blood lymphocyte subsets (CD3+ T cells, CD3+ CD4+ helper T cells, CD3+ CD8+ cytotoxic T cells, CD3− CD56+ NK cells, CD4/CD8 ratio, CD19+ B cells, and total lymphocytes [NK cells+ T cells + B cells]) in firefighters exposed to a computerized firefighting strategies and tactics decision-making challenge while participating in moderate intensity exercise. Furthermore, this study also examined the possible relationships between catecholamines (NE and EPI) and blood lymphocyte subsets following combined mental and physical challenge. Ten professional male firefighters participated in two counterbalanced exercise conditions on a cycle ergometer: (1) 37 min of cycle ergometry at 60% VO 2max (exercise alone condition; EAC) and (2) 37 min of cycle ergometry at 60% VO 2max along with 20 min of a computerized firefighting strategies and tactics decision-making challenge (firefighting strategies condition; FSC). FSC elicited significantly greater HR, NE, and EPI when compared to EAC. Both EAC and FSC elicited increases in CD3− CD56+ NK cells. The percentages of CD3+ T cells, CD3+ CD4+ helper T cells, CD4/CD8 ratio, CD19+ B cells, and total lymphocytes were lower immediately following both conditions. Following dual challenge NE AUC was negatively correlated with percentage of CD19+ B cells immediately post challenge, and HR was negatively associated with the percent change in the CD4/CD8 ratio from pre to post challenge. These elevations in NE and heart rate simultaneously in response to the dual challenge suggest greater sympathetic activation that in turn would possibly explain the alteration in the distribution of lymphocyte subsets.
Objective.-This study investigated the effects of 2 potentially ''oxygen promoting'' dietary supp... more Objective.-This study investigated the effects of 2 potentially ''oxygen promoting'' dietary supplements on hypoxia and oxidative stress at a simulated altitude of 4600 m.
time of day effects on EEG spectral parameters. PHYSIOL BEHAV 54(2) 283-287, 1993.--Electroenceph... more time of day effects on EEG spectral parameters. PHYSIOL BEHAV 54(2) 283-287, 1993.--Electroencephalographic (EEG) recordings were obtained from nine male subjects at sea level and again following rapid ascent to high altitude (4300 meters) at 0900, 1600, and 1830 h. Electroencephalographic data were subjected to Fast Fourier Transformation and analyzed for beta, spindle, alpha, theta, delta, and total amplitudes. Total amplitude increased from baseline to altitude while relative theta (absolute theta/total amplitude) decreased from baseline to altitude. Amplitude for absolute and relative spindle and total amplitude increased across the day.
Purpose: 1) To examine the effect of a 12-wk endurance exercise training program on RMR and 2) to... more Purpose: 1) To examine the effect of a 12-wk endurance exercise training program on RMR and 2) to provide insight into the mechanisms responsible for alterations in RMR that may occur after exercise training. Methods: Male participants (19-32 yr) in an exercise group (EX; n = 9) performed jogging and/or running 3-4 dIwk j1 , 25-40 min per session, at 60%-80% V O 2max , whereas subjects in a control group (CON; n = 10) maintained their normal activity patterns. Body composition, V O 2max , RMR, epinephrine, norepinephrine, total thyroxine, free thyroxine, insulin, free fatty acids, and glucose were measured before and after the intervention. Results: Training resulted in a significant increase in V O 2max in EX (46.2 T 1.2 to 51.0 T 1.3 mLIkg j1 Imin j1 , P G 0.001). Absolute and relative values for RMR did not significantly change in EX after training. Mean values for epinephrine, norepinephrine, total thyroxine, insulin, and glucose did not significantly change in either group; however, free thyroxine decreased significantly after training in EX (P = 0.04). Training also resulted in a significant increase in free fatty acid concentration in EX (0.37 T 0.03 to 0.48 T 0.04 mmolIL j1 , P G 0.001). RMR in CON decreased significantly when expressed as an absolute value (P G 0.01) and relative to body weight (P G 0.01), fat-free mass (P G 0.01), and fat mass (P = 0.04). Conclusions: The mechanism for the decrease in CON is unknown, but it may be related to seasonal variations in RMR. Training may have prevented a similar decline in RMR in EX and may be related to a training-induced increase in fat oxidation.
Uploads
Papers by Gary Kamimori