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Biomedical subjects

T Reilly

Publications and source records attributed to T Reilly.

At least 163 records · Page 9Linked to original sources
PubMed1987

A potent hypotensive factor in chicken left ventricle.

Chicken artria and ventricles both have membrane-bound granules which resemble those containing atriopeptin (ANP) in mammals. However, nothing is known about the contents of the avian granules. A previous study in chickens showed that although extracts of whole chicken heart or synthetic rat ANP both caused profound hypotension, ANP caused both natriuresis and diuresis, while chicken heart extract did not. The present study sought to locate the region(s) of chicken heart containing the hypotensive activity, and to observe the effect on sodium and water excretion and blood pressure in rats. Acid extracts of either atrium, either ventricle, ventricular septum, skeletal muscle, and liver were identically prepared from chickens and rats. Extracts were adjusted to the same protein concentration and injected (0.15 ml/kg) into anesthetized Single Comb White Leghorn roosters. Mean arterial pressure (MAP) and the time for recovery were measured. The most potent extract from chicken hearts was from the left ventricle (-38 +/- 1 mm Hg, 149 +/- 9 sec to recover). All other extracts (including right ventricle) produced only small (10-20 mm Hg), short-lived (20-30 sec) decreases in MAP. In contrast, only rat atrial extracts evoked long-lasting hypotension (greater than 40 mm Hg, recovery time greater than 200 sec). A 30-min infusion of the most potent chicken extract (left ventricle, CLV) into rats produced a small but significant natriuresis and diuresis compared to the vehicle time control (P less than 0.05) and the hypotensive response to bolus injection was about one-third that seen in the chicken. The location of potent spasmolytic activity primarily in chicken left ventricle, the different avian renal responses to chicken heart extract and synthetic rat ANP (5), and the weak diuretic, natriuretic, and hypotensive effects of CLV extract in rats all suggest that the chicken heart substance may be different from mammalian ANP.

Animals↗
PubMed1986

Exercise and the circadian variation in body temperature measures.

This study examined the existence of circadian rhythms in rectal temperature (Tr) and selected skin temperatures at rest and during light (82 W) and medium (147 W) exercise on a cycle ergometer. Each intensity was sustained for 5 min and then followed by a graded exercise test to exhaustion. The Tr and skin temperatures were also measured on cessation of exercise and 4 min post-exercise. Fifteen males participated, measurements covering six interspersed times of day. The mean exercise time to exhaustion of 19.83 min was independent of the time of day and caused a constant rise of 0.7 degree C in Tr. Significant rhythms were observed in Tr, Tc (chest), and Ta (arm) under all conditions: findings for Tl (leg) were nonsignificant at maximal exercise and post-exercise (P greater than 0.05). The crest time for Tl had a significant lead over that of Tr and the other skin sites which were in phase concordance, mean difference in crest times being 4.73 h at rest and 4.42 h during submaximal exercise. The results demonstrated constancy with time of day in the thermal load imposed by fixed exercise. This was reinforced when mean skin and mean body temperatures were computed. The general pattern did not apply to the exercised limb, the pre-exercise rhythm disappearing after 10 min exercise. Differential heat conductances according to skin sites are implicated in the phase differences between the leg and the other temperature sites.

Adult↗
PubMed1986

Spinal loading during circuit weight-training and running.

Spinal shrinkage was used as an indicant of loading on the spine in circuit weight-training and running regimes. The loss of stature during two sets of a circuit of weight-training (n = 10), a 6 km run by novices (n = 9) and a 25 km run by trained runners (n = 7) was assessed in male subjects. Shrinkage was not significantly different between the weight-training regime and the 6 km run by novices, mean losses being 5.4 and 3.25 mm respectively. The rate of height loss in the experienced runners was 2.35 mm over 6 km run at 12.2 km.h-1, representing 0.4 mm.km-1 over the 6 km run, this shrinkage rate being continued over the last 19 km run at 14.7 km.h-1. The loss of height could not be predicted from a set of covariates. The magnitude of the circadian variation, mean 14.4 mm, exceeded the change in height during the 25 km run. The diurnal variation conformed to a cosine function, though a better fit was obtained with a power function equation. A marked diurnal pattern was also observed in lumbar extension. Though reversal of spinal shrinkage was observed during a night's sleep, no significant recovery occurred during a 20 min resting period immediately following the exercise regimes. These results have implications for the warm-up and timing of exercise regimes that impose significant loading on the spine.

Adolescent↗
PubMed1985

Circadian variation in stature and the effects of spinal loading.

Using a method comparable with that of Eklund and Corlett (1984) stature was measured with an accuracy of I mm in eight young adults. The mean circadian variation was 19.3 mm (1.1% of stature). Fifty-four percent of the diurnal loss in stature occurred in the first hour after rising. Approximately 70% was regained during the first half of the night. With static shoulder loads (2.5-40 kg), increases in the rate of shrinkage with increasing weight were nonlinear. Repetitive lifting led to greater shrinkage than with equivalent static loading. Rest in Fowler's position gave more rapid regains in stature than post-exercise recovery in standing positions. The technique is therefore suitable for assessment of the effects of manual work with both occupational and therapeutic applications.

Adult↗
PubMed1984

Exercise and sports equipment: some ergonomics aspects.

Sports equipment encompasses a gamut of devices used in laboratory, training and competitive contexts and these form the content of this paper. Ergometers range in sophistication from friction braked stationary bicycles to computer controlled simulators which incorporate exercise modes specific to the athletic user. These are now used in training, as experimental devices and in some instances for competition purposes. Training equipment exhibits a similar emphasis on exercise specificity, safety being an important aspect of its use. Design of projectiles for sporting activities has mainly reflected their traditional modes of use, the introduction of synthetic materials having some ergonomics implications. Similarly, materials science and design technology have contributed innovations in equipment for racquet sports and hitting implements. The changes have tended to be associated with availability of new materials for product construction and have implications for safety and skill in the transition to using the new products. Ski equipment design illustrates ergonomics factors in interfacing the performer with the sporting environment and how equipment has progressed by regenerative design processes. Enhancement of performance in some sports must be accompanied by an awareness of safety requirements: where appropriate, risks to participants should be reduced by use of protective clothing and equipment. Enforced validation of protective equipment is recommended to raise safety levels in certain sports and the safety of spectators must not be neglected. Human factors criteria can then be applied in monitoring, officiating and spectating at sporting events.

Journal Article↗
PubMed1984

Some circulatory responses to exercise at different times of day.

Circadian rhythms in heart rate were examined at rest, immediately pre-exercise, during submaximal and maximal exercise on a cycle ergometer, and during recovery post-exercise (N = 10). Observations were made under controlled conditions at 0300, 0900, 1500, and 2100 hours. A significant circadian rhythm was found for resting heart rate lying supine and sitting pre-exercise (P less than 0.05), peak values being measured at 1500 hours. The acrophase in the oral temperature rhythm at 1739 hours was not significantly out of phase with that of resting heart rate (P greater than 0.05). The rhythm in heart rate persisted during submaximal exercise (150 W) and at the maximal rate (P less than 0.05); the amplitude of the rhythm was attenuated at maximum. Ratings of perceived exertion at submaximal and maximal exercise intensities, and time of day (P greater than 0.05). The increment of 0.2 degrees C in oral temperature during exercise did not exhibit circadian variation (P greater than 0.05). A significant rhythm was found for recovery heart rates in minutes 2, 3, 4, and 5 post-exercise (P less than 0.05). Observations of systolic and diastolic pressures pre- and post-exercise were inconclusive. Therefore, the circadian rhythm in heart rate responses to exercise should be considered when a heart rate variable is used as a criterion in fitness testing or as an index of physiological strain.

Adult↗
PubMed1984

Circadian variation in human stature.

The aim of this study was to monitor the creep in stature due to compression and its recovery over 24 hr in eight adult males. Measurements of stature were made at nine times during the 24-hr cycle using a purpose built metal frame tilted 5 degrees to the vertical. Accessories for standardization of posture and prevention of unwanted muscular tension included a series of microswitches on the frame, cross-beams for controlling spinal curvatures, slit spectacles used in conjunction with a mirror for proper head alignment. A dead load BAYE micrometer recorded stature to 0.01 mm. A significant circadian rhythm was established, the trough to peak variation being 19.3 mm or 1.1% of overall stature. Peak stature was measured at 0730 on awakening and the trough occurred at midnight before assuming a recumbent posture for sleep. Altogether 71% of the height gained during the night was achieved in the first half of the night's sleep. Over 50% of the height loss in a day was lost within the first hour of rising, 80% being lost within 3 hr of arising: the rate of creep decelerated throughout the remainder of the waking day. It is concluded that the rate of change in creep throughout the day varies, being greatest in the morning whilst distension is most pronounced in the early hours of sleep.

Adult↗
PubMed1983

Investigation of biorhythms in female athletic performance.

Implications for sports performance and athletic injury occurrence have been forcefully insinuated by proponents of a biorhythm theory based on date of birth. The theory postulates that variations in human abilities are governed by three consistently recurring cycles of 23, 28 and 33 day lengths. This study assessed the validity of biorhythms by analysing best performances in 610 top ranked European female track and field specialists over a single competitive season. Chi-square analysis of data found no significant influence of the computed physical, emotional or intellectual cycles on peak performances. It concluded that 'biorhythms' theory has no basis to justify its application to strenuous exercise.

Journal Article↗
PubMed1983

Trait and state anxiety in male and female cross-country runners.

The purpose of this study was to explore the relationships between state/trait anxiety and competitive cross-country performance for males and females. A-trait and A-state pre- and post-competition were monitored in 38 females and 26 males at major meetings. The females' A-trait was correlated with pre-race A-state (p less than .05) which was itself correlated significantly with race performance (p less than .05). A significant post-race A-state reduction occurred only with the better runners. The correlation between A-trait and pre-race A-state was also found in the male athletes (p less than .05) while A-trait significantly correlated with race performance (p less than .05). A-state was significantly reduced post-race, the greatest decrease being observed in the top performers. It is concluded that trait as well as transient dispositions are relevant when psychological determinants of performance are considered.

Adolescent↗
PubMed1983

Influence of time of day on all-out swimming.

The effect of time of day on all-out swim performances was examined. Fourteen subjects performed maximal front crawl swim tests on separate days over 100 m. and 400 m. at 5 different times of day between 06.30 h. and 22.00 h. Performance showed a significant linear trend with time of day in close though not exact association with the circadian rhythm in oral temperature: a goodness of fit test confirmed that the values predicted from linear trend analysis coincided with the measured values (p less than 0.05). The steady improvement throughout the day was 3.5% for 100 m. and 2.5% for 400 m. swims. Trunk flexibility displayed a time of day variation with a trough in the morning and a peak in the afternoon. No significant rhythm was observed in ankle and shoulder flexibility, grip strength or peak expiratory flow rate (p greater than 0.05). It was concluded that maximal swimming trials are best scheduled for the evening and worst in the early morning. Specific fitness factors cannot clearly account for the higher exercise capability in the evening which is strongly related to the circadian curve in body temperature.

Adolescent↗
PubMed1983

Influence of time of day on reactions to cycling at a fixed high intensity.

The circadian cycle in all-out competitive performance may be due to changes in motivational drive to tolerate strenuous exercise rather than to rhythms in maximal physiological functions. This experiment explored the hypothesis that a fixed relative loading of high intensity aerobic effort could be sustained for longer in the evening compared with the morning. Eight females cycled to exhaustion at 95% VO2 max at 06.30 h. and at 22.00 h. after a 5 min, moderate load of 40% VO2 max. Oral temperature was 0.4 degrees C higher at 22.00 h. compared with the earlier time. Perceived exertion showed no significant effect of time of day at either work load but exercise tolerance time, total work done and peak lactate production were significantly greater at 22.00 h. (p = 0.05). Perceived exertion at the high load was significantly related to endurance time (r = -0.77) and to the rating at the low work level (r = 0.75). Peak lactate was not significantly correlated with the time to exhaustion (p less than 0.05). It was concluded that superior exercise performance in the evening may be attributed to a greater tolerance for high intensity exercise which is closely associated with the acrophase in body temperature.

Adult↗
PubMed1983

The freely-chosen swimming stroke rate in a maximal swim and on a biokinetic swim bench.

The purpose of this study was to investigate the significance of the freely-chosen stroke rate (S) in swimming to attain maximum velocity. Seven club swimmers swam five 366-m freestyle trials, the first three at low to maximum velocities and the next two at higher stroke rates in an attempt to increase velocity further. A clear "inverted U" pattern was observed, the optimal stroke rate (Sopt) being the median rate of 45.8 (range 42-49) S X min-1. Each subject then performed a maximal experimental test on five separate occasions, simulating the freestyle arm action on a biokinetic swim bench. Stroke rate was manipulated according to the five rates used by each subject in the swim trials. The mean VO2peak on the biokinetic bench also varied as an "inverted U" curvilinear function of S, with the correlation between Sopt and the S at the highest VO2peak being 0.98 (P less than 0.001). Peak values for VO2, VE, and heart rate in simulated swimming were, respectively, 73%, 52%, and 85% of the maximal rates determined on a cycle ergometer. Maximum swimming velocity was not significantly correlated with VO2max or with VO2peak on the swim bench (P greater than 0.05). Results confirm that freely-chosen S produces the top performance in swimming to attain maximum velocity and the highest peak VO2 values in simulated swimming on a biokinetic bench.

Adolescent↗