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Biomedical subjects

T Reilly

Publications and source records attributed to T Reilly.

187 records · Page 11Linked to original sources
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Influence of time of day and partial sleep loss on muscle strength in eumenorrheic females.

Disrupted sleep is the most common form of sleep deprivation in travellers, shift workers, athletes the night before important competitions and among parents of infants. The influence of partial sleep loss on muscle strength might differ according to the time of testing on the following day. This study was therefore designed to assess the interaction between the effects of partial sleep loss and time of day on muscle strength in females. Eight sedentary eumenorrheic females (mean +/- SD; age 30 +/- 6 years, height 1.62 +/- 0.06 m and body mass 67 +/- 5.0 kg) took part in the study, in a counterbalanced design. Measurements of muscle strength were carried out at 06:00 and 18:00 hours after the one control night (no sleep loss) and the one night of partial sleep loss, during menses. Muscle strength measures included isokinetic (at 1.05, 3.14 rad s(-1); 90 degrees range of motion) and isometric peak torque (at 60 degrees of knee flexion) of knee extensors and flexors (dominant leg). In addition, isometric force of knee extensors with super-imposed electrical twitches (50 Hz, 250 V, 200 mus pulse width) was measured using the same procedure in order to control for motivation. Rectal temperature was measured during the 30 min before muscle strength measurements. Partial sleep loss consisted of allowing 2.5 h sleep (between 03:00 and 05:30 h), whilst in the control condition (no sleep loss) subjects retired between 22:30 and 23:30 h, rising at 05:30 hours. All measurements were conducted at just one phase of the menstrual cycle (menses) to prevent any masking effect due to different phases of the menstrual cycle. In both conditions (with and without partial sleep loss) a diurnal variation was observed in peak torque of knee flexors at 1.05 (F(1,7) = 5.5, p < 0.05) and 3.14 rad s(-1) (F(1,7) = 8.0, p < 0.05); values at 18:00 hours were 4.5 and 5.9% higher than at 06:00 hours, respectively. No significant diurnal variation was observed for the other muscle strength measures. No significant effect of partial sleep loss or interaction effect (sleep x time of day) was observed for muscle strength measures. However, the performance rhythms were in phase with the circadian rhythm in rectal temperature. Partial sleep deprivation over one night did not have any adverse effect on maximal muscle strength, nor on diurnal variations of muscle strength indices. As the effect of time of day was observed with some of the muscle strength measures, it is suggested that, in designing future studies using females, the control of time of day is essential.

Adult↗
PubMedDate not supplied

A comparison of circadian rhythms in work performance between physically active and inactive subjects.

This study compared circadian rhythms in physiological, subjective, and performance measures between groups exhibiting different levels of habitual physical activity. Fourteen male subjects, aged 19-29 years, were assigned to a physically active (group I, n = 7) or a physically inactive (group II, n = 7) group on the basis of leisure-time physical activity. Rectal temperature, oral temperature, resting pulse rate, subjective arousal and sleepiness were measured at 02:00, 06:00, 10:00, 14:00, 18:00 and 22:00 in a counter-balanced sequence for each subject. Whole-body flexibility, back and leg strength, grip strength (right and left), flight time in a vertical jump, PWC150, and self-chosen work-rate were also recorded at each time point. At least 8h separated each test session. Subjects avoided exercise 48h prior to, and during the experiment. Data were subjected to the group cosinor method. Group I evidenced 1.5-2.5 times greater rhythm amplitudes than Group II for oral temperature, subjective arousal, sleepiness, flexibility, left and right grip strength, submaximal heart rate, and self-chosen work-rate (p < 0.05). Oral temperature and arousal for Group I were lower than Group II only at 06:00. Early morning troughs in most of the performance measures were significantly greater for Group I (p < 0.05). The groups did not differ with respect to phasing of the rhythms (p < 0.05). These results confirm with physical performance measures that rhythm amplitudes are higher for physically fit subjects. This could be attributed to greater early-morning troughs in the measures for active individuals. Since the subjects were sedentary immediately prior to testing, it is plausible that these findings are training effects of physical activity.

Adult↗
PubMedDate not supplied

Medi-Cal managed care.

Managed care programs may give California communities a cost effective way to provide health care to a growing Medi-Cal population. In this issue California Hospitals explores the benefits and risks of these programs.

Arizona↗
PubMedDate not supplied

Some chronobiological considerations related to physical exercise.

Variables associated with physical activity show circadian rhythms in resting subjects; these rhythms have both exogenous (due to the individual's lifestyle and environment) and endogenous (due to the "body clock") components. During exercise, many of the rhythms persist, even though some show decreasing amplitude with increasing severity of exercise. Whilst the value of physical fitness is not disputed (for elite athletes, for individuals who just want to be physically fit, or for patients undertaking physical rehabilitation regimens), there are certain times of the day when special care is needed. These times are soon after waking--when there is the possibility of an increased risk of cardiovascular morbidity and damage to the spine--and late in the day--when there is an increased risk of respiratory difficulties. Since physical exercise is inextricably linked with thermoregulation, there are special considerations to bear in mind when exercise takes place in cold or hot environments. Further, due to the effects of the body clock, exercise and activity during night work and after time-zone transitions presents problems peculiar to these circumstances. In addition, the menstrual cycle affects physical performance, and these circatrigintan rhythms interact with the circadian ones. Bearing in mind these factors, advice that is based upon knowledge of circadian and circatrigintan rhythms can be given to all those contemplating physical activity. Chronobiologically, there is advantage in undertaking physical activity programmes towards the middle of the waking day and not at times when a sleep or nap has just been taken.

Chronobiology Phenomena↗
PubMedDate not supplied

Metabolic production of carbon dioxide in simulated sea states: relevance for hyperbaric escape systems.

Hyperbaric Escape Systems (HES) are used when saturation diving bells have to be evacuated and divers transported to safety. The aim of the present investigation was to determine the levels of metabolic CO2 production expected from the occupants of an HES in different wave states, and from this, to recommend a reasonable and safe requirement for scrubbing CO2 within an HES. The CO2 production and heart rate of 20 male subjects representing saturation divers were collected while they were seated in an HES seat, fixed to an inflatable rescue vessel. The vessel was tethered in a wave pool and longitudinal (L), perpendicular (P), and calm (C) sea conditions were reproduced. Heart rate did not differ between conditions (P=0.33) the mean (SD) heart rates (b x min(-1)) were: C: 71 (8.5); L: 74 (9); P: 75 (9). Carbon dioxide production was significantly higher (P=0.005) with the boat orientated perpendicular to the waves compared to the calm condition. The mean (plus 99% confidence interval) carbon dioxide production for each of the conditions was C = 319mL x min(-1) + (41mL x min(-1)) = maximum of 360mL x min(-1); L=374mL x min(-1) + (46mL x min(-1)) = maximum of 420mL x min(-1); P = 409mL x min(-1) + (57mL x min(-1)) = maximum of 466mL x min(-1). It is therefore recommended that a 12 person HES should be capable of scrubbing at least 8,053L of carbon dioxide in 24 hours. Thus, the current requirement for 8,415L in 24h is reasonable.

Adult↗
PubMedDate not supplied

Analysis of the reasons for the high turnover of clinicians in neighborhood health centers.

A high rate of turnover of professional personnel in a clinic is disruptive to patient care and organizational stability as well as to the individual clinician. The turnover rate for clinicians (physicians, nurse practitioners, and physician assistants) working in neighborhood health centers (NHCs) is considerably higher than that for clinicians in other forms of practices. All 10 of the neighborhood health centers in HEW (Department of Health, Education, and Welfare--now the Department of Health and Human Services) Region X (Alaska, Idaho, Washington, and Oregon) that offered a full range of medical services provided information about the clinicians that they had employed since their inception. One hundred and one clinicians were surveyed about their work experience. The vast majority of those clinicians who had left a neighborhood health center remained in the community; they cited organizational issues as being at the heart of their dissatisfaction with the centers. Clinicians who began work during the initiation of a clinic remained significantly longer. The results suggest the immediate need for a strategy directed at the smooth organizational evolution of each NHC right from its inception.

Community Health Centers↗