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Biomedical subjects

T Reilly

Publications and source records attributed to T Reilly.

At least 91 records · Page 5Linked to original sources
PubMed1998

Heart rate response to "off-road" running events in female athletes.

INTRODUCTION: Despite the growing popularity of off-road running events, little information is available about the physiological stress of such activities. The demands of such events are unique in terms of the rough surface of the terrain encountered as well as the underfoot vegetation and the gradient. OBJECTIVES: The aim of this study was to investigate the physiological response of female athletes, as measured by heart rate, to three common off-road running events: cross country running (n = 15), fell running (n = 20), and orienteering (n = 25). METHODS: Heart rate responses were recorded during cross country and fell races, and orienteering by means of short range radiotelemetry. Road running (n = 21) was also studied as a reference. RESULTS: The mean heart rates for each event varied with the differing demands of the terrain. The highest (182 (10) beats/minute; mean (SD)) was for road running and the lowest (172 (10) beats/minute) for orienteering. Orienteering evoked a significantly more variable response than all other events (F4,100 = 112.4; p<0.01), with a range of 44 beats/minute (142-186 beats/minute) in the heart rate. This may be due to both the variability of the terrain and the additional technical aspect of this sport. There was a positive trend in the slope of the regression lines of heart rate against time for both road and cross country running, which was not evident in the fell runners or the orienteers. The latter events demonstrated no consistent pattern. CONCLUSIONS: It is concluded that running off-road elicits a heart rate response that varies with the altering demands of surface, vegetation, and gradient.

Adult↗
PubMed1998

Effects of deep and shallow water running on spinal shrinkage.

OBJECTIVES: Running in water has the potential to decrease the compressive forces on the spine as the body is supported. The aim of the study was to determine the magnitude of this loss in stature compared with running on land. METHODS: Fourteen runners completed three 30 minute runs on separate days in deep water, shallow water, and on a motor driven treadmill. During the three conditions, runners exercised at 80% of their exercise mode specific peak oxygen consumption. Subjects rested in the Fowler position for 20 minutes before and after exercise. Measurements of changes in stature were taken before resting, before running, after 15 minutes of running, after 30 minutes of running, and after the post-exercise rest in the Fowler position. Changes in stature were recorded using a stadiometer accurate to 0.01 mm. RESULTS: Loss of stature values were 4.59 (1.48), 5.51 (2.18), and 2.92 (1.7) mm (means (SD)) for running on the treadmill, and in shallow and deep water respectively. Running in deep water caused significantly lower creep than in the other trials (p<0.05), with no difference between the shallow water and treadmill conditions. Loss of stature was greater in the first half of the run for all conditions (p<0.05). Ratings of perceived exertion did not differ between the three exercise conditions. CONCLUSION: Results support the use of deep water running for decreasing the compressive load on the spine.

Adult↗
PubMed1998

Metabolic and performance responses during endurance exercise after high-fat and high-carbohydrate meals.

We studied the effects of preexercise meal composition on metabolic and performance-related variables during endurance exercise. Eight well-trained cyclists (maximal oxygen uptake 65.0 to 83.5 ml . kg-1 . min-1) were studied on three occasions after an overnight fast. They were given isoenergetic meals containing carbohydrate (CHO), protein (P), and fat (F) in the following amounts (g/70 kg body wt): high-carbohydrate meal, 215 CHO, 26 P, 3 F; high-fat meal, 50 CHO, 14 P, 80 F. On the third occasion subjects were studied after an overnight fast. Four hours after consumption of the meal, subjects started exercise for 90 min at 70% of their maximal oxygen uptake, followed by a 10-km time trial. The high-carbohydrate meal compared with the high-fat meal resulted in significant decreases (P < 0.05) in blood glucose, plasma nonesterified fatty acids, plasma glycerol, plasma chylomicron-triacylglycerol, and plasma 3-hydroxybutyrate concentrations during exercise. This was accompanied by an increase in plasma insulin (P < 0.01 vs. no meal), plasma epinephrine, and plasma growth hormone concentrations (each P < 0.05 vs. either of the other conditions) during exercise. Despite these large differences in substrate and hormone concentrations in plasma, substrate oxidation during the 90-min exercise period was similar in the three trials, and there were no differences in performance on the time trial. These results suggest that, although the availability of fatty acids and other substrates in plasma can be markedly altered by dietary means, the pattern of substrate oxidation during endurance exercise is remarkably resistant to alteration.

Adult↗
PubMed1998

The effect of one night's sleep deprivation on temperature, mood, and physical performance in subjects with different amounts of habitual physical activity.

Eleven healthy males were studied twice. On one occasion (control, C), they slept (night 1) and then underwent a battery of tests at 4 h intervals from 06:00 day 1 to 02:00 day 2; then, after a normal sleep (night 2), they were tested from 10:00 to 22:00 on day 2. On the second occasion (sleep deprivation, SD), the subjects remained awake during night 1. Each battery of tests consisted of measurements of tympanic membrane temperature, profile of mood states (POMS), muscle strength, self-chosen work rate (SCWR), perceived exertion, and heart rate (HR) while exercising on a stationary cycle ergometer. Subjects also kept a diary of their activities during the two days and answered a questionnaire about their habitual physical activity. Results showed a significant negative effect of sleep deprivation on most mood states on day 1, but no effect on the other variables. By day 2, mood had tended to recover, though muscle strength tended to be worse in both control and sleep-deprivation experiments. There was also a more general tendency for negative effects to be present at the end of day 1 (02:00) or at the beginning of day 2 (10:00). There was limited support for the view that subjects who were habitually more active showed less negative effects after sleep deprivation and responded less adversely to the poor sleep achieved on the university premises (night 2). These results stress the considerable interindividual variation in the responses to sleep loss and, therefore, the difficulty associated with giving general advice to individuals about work or training capability after sleep loss.

Adult↗
PubMed1998

Training and injuries amongst elite female orienteers.

BACKGROUND: A study was carried out on the patterns of injury amongst elite female orienteers. METHODS: A retrospective questionnaire was administered which contained questions pertaining to training practices such as quality, quantity and type. This was followed by a section investigating general to specific injury problems, regarding their occurrence and effect on training. Members of various national orienteering squads (elite group; n = 19) and competitors of an elite level in Great Britain (sub-elite group; n = 9) completed these questionnaires. As this was a descriptive study, no intervention was carried out. RESULTS: The sub-elite orienteers trained less than the elite during the off-season (p < 0.01) but there was no significant difference in the distribution and/or likely cause of injuries between the groups. Only 32% of the subjects did their training predominantly on the road while the others ran on either off-road terrain or a mixture. Injuries occurred in 68% of the respondents. Only 4% of them suffered upper body injuries. Ankle injuries were the most common injuries. The proportion of injuries to the knee (16%) and ankle (43%) in orienteers was the reverse of what is normally found in runners. CONCLUSIONS: Orienteers suffer certain sport specific injuries such as ankle sprain. This is likely to be related to their training predominantly on rough surfaces.

Ankle Injuries↗
PubMed1997

Jet-lag.

Explore the source record for details and available documents.

Circadian Rhythm↗
PubMed1997

Effects of acute changes in oestrogen on muscle function of the first dorsal interosseus muscle in humans.

1. To investigate the effect of the female reproductive hormones on muscle function, patients undergoing in vitro fertilization were tested during two phases of treatment. The first was following the downregulation of pituitary gonadotrophin releasing hormone (GnRH) receptors and the second after 9 days of gonadotrophin injections. 2. Maximal strength and fatiguability of the first dorsal interosseus muscle were assessed when oestrogen and progesterone were low, and less than 2 weeks later when oestrogen production reached supraphysiological levels. 3. There were no significant changes in either strength or fatigue resistance during acute, massive fluctuations in oestrogen. These results occurred at a time when progesterone levels remained relatively low. 4. Contrary to previous work, the present results suggest that oestrogen does not affect muscle strength.

Adult↗
PubMed1997

Metabolic responses to isoenergetic meals containing different proportions of carbohydrate and fat.

The purpose of the present study was to investigate the interrelationship between carbohydrate and fat metabolism at rest after isoenergetic meals of varying proportions of carbohydrate and fat. Eight physically-active subjects (BMI 18.1-23.4 kg/m2) were studied at rest on three occasions after an overnight fast. In a balanced design they were given meals containing carbohydrate, protein and fat in the following amounts respectively (g/70 kg body weight): meal 1 121, 16, 48; meal 2 70, 16, 70; meal 3 50, 14, 80. All meals were isoenergetic, containing 4.0 MJ/70 kg body weight, and were of similar appearance. In addition, on a fourth occasion five of the eight subjects consumed meal 4 (g/70 kg body weight): carbohydrate 0, protein 0, fat 108. Blood samples were taken before eating the meal and at intervals following the meal to determine metabolic and hormonal responses. Energy expenditure and substrate oxidation were measured by indirect calorimetry and balance was calculated over the 5 h postprandial period. The incremental areas under the time curves for fat oxidation were greatest after meals 3 and 4 (P < 0.05), whereas incremental areas under the carbohydrate oxidation v. time curves were relatively reduced after these two meals (P < 0.05). This was accompanied by lesser suppression of plasma non-esterified fatty acid concentrations (P < 0.001) and reduced plasma insulin concentrations (P < 0.001) following these meals. Energy balance was almost identical after the three isoenergetic meals. In contrast, there was an inverse relationship between carbohydrate and fat balance following these meals, with carbohydrate balance decreasing as carbohydrate intake decreased and fat balance increasing as fat intake increased. We conclude that there is a close interrelationship between carbohydrate and fat metabolism following isoenergetic meals in resting subjects.

Adult↗
PubMed1997

Changes in stature following plyometric drop-jump and pendulum exercises.

The aim of this study was to compare the changes in stature following the performance of plyometric exercises using drop-jumps and a pendulum swing. Eight male participants aged 21.7 +/- 1.8 years with experience of plyometric training gave their informed consent to act as participants. Participants undertook two exercise regimens and a 15-min standing test in a random order. The exercises entailed the performance of 50 drop-jumps from a height of 0.28 m or 50 pendulum rebounds. Participants were instructed to perform maximal jumps or rebounds using a 'bounce' style. Measurements of stature were performed after a 20-min period of standing (pre-exercise), 2-min after exercise (post-exercise) and after a 20-min standing recovery (recovery). Back pain and muscle soreness were assessed using an analogue-visual scale, at each of the above times and also 24 and 36 h after the test. Peak torque during isokinetic knee extension at 1.04 rads-1 was measured immediately before and after the exercise bouts, to assess the degree of muscular fatigue. Ground/wall reaction force data were recorded using a Kistler force platform mounted in the floor for drop-jumps and vertically on the rebound wall for pendulum exercises. Drop-jumps resulted in the greatest (p < 0.05) change in stature (-2.71 +/- 0.8 mm), compared to pendulum exercises (-1.77 +/- 0.7 mm) and standing (-0.39 +/- 0.2 mm). Both exercise regimens resulted in a significant (p < 0.01) decrease in stature when compared to the standing condition. Drop-jumps resulted in significantly greater peak impact forces (p < 0.05) than pendulum exercises (drop-jumps = 3.2 +/- 0.5 x body weight, pendulum = 2.6 +/- 0.5 x body weight). The two exercise conditions both invoked a small degree of muscle soreness but there were no significant differences between conditions. Both exercise regimens resulted in a non-significant decrease in peak torque indicating a similar degree of muscular fatigue. Based on the lower shrinkage resulted and lower peak forces, it can be concluded that pendulum exercises pose a lower injury potential to the lower back than drop-jumps performed from a height of 28 cm.

Adult↗
PubMed1997

Energetics of high-intensity exercise (soccer) with particular reference to fatigue.

Soccer entails intermittent exercise with bouts of short, intense activity punctuating longer periods of low-level, moderate-intensity exercise. High levels of blood lactate may sometimes be observed during a match but the active recovery periods at submaximal exercise levels allow for its removal on a continual basis. While anaerobic efforts are evident in activity with the ball and shadowing fast-moving opponents, the largest strain is placed on aerobic metabolism. On average, competitive soccer corresponds to an energy expenditure of about 75% maximal aerobic power. The energy expenditure varies with playing position, being highest among midfield players. Muscle glycogen levels can be reduced towards the end of a game, the level of reduction being reflected in a decrease in work rate. Blood glucose levels are generally well-maintained, although body temperature may rise by 2 degrees C even in temperate conditions. The distance covered by players tends to under-reflect the energy expended. Unorthodox modes of motion-running backwards and sideways, accelerating, decelerating and changing direction-accentuate the metabolic loading. These are compounded by the extra requirements for energy associated with dribbling the ball and contesting possession. The overall energy expended is extreme when players are required to play extra-time in tournaments. Training, nutritional and tactical strategies may be used to reduce the effects of fatigue that may occur late in the game.

Adult↗
PubMed1997

Travel fatigue and jet-lag.

Travel across multiple time zones is a common feature of the lifestyle of contemporary international sport competitors. This entails a disruption of the body's circadian timing mechanisms. Symptoms of 'jet-lag' persist until circadian rhythms re-tune into local time. Exercise performance may be impaired during the period of adjustment to the new time zone. Behavioural and pharmacological strategies are available to help accelerate the resynchronization of circadian rhythms. It is recommended that sports administrators should consider the consequences of jet-lag and the time needed to overcome it when planning the international itineraries of travelling athletes.

Aircraft↗
PubMed1997

The quality of health data obtained in a new survey of elderly Americans: a validation study of the proposed Medicare Beneficiary Health Status Registry (MBHSR).

The Medicare Beneficiary Health Status Registry (MBHSR) is a proposed new survey program that would collect health status indicators annually from large probability samples of Medicine beneficiaries. For reasons of economy, the MBHSR would use mail survey procedures with telephone follow-up of nonrespondents. Because of concerns about response rates and the validity and reliability of the data obtained by such methods, a large-scale (N = 1,922) field test was conducted. The field test assessed the validity of MBHSR survey reports of past medical treatment and conditions by comparing those reports with Medicare claims data. It assessed the (internal) reliability of MBHSR survey responses by comparing responses with logically related survey questions from the MBHSR. Analyses indicate that the MBHSR survey procedures using a combination of mail data collection with telephone follow-up of nonrespondents produced relatively high levels of sensitivity and specificity in identifying medical treatments and procedures previously recorded in Medicare claims data. In addition, the MBHSR Field Test obtained, in general, relatively high levels of internal consistency in survey reports.

Aged↗
PubMed1997

Aging, rhythms of physical performance, and adjustment to changes in the sleep-activity cycle.

OBJECTIVES: Shiftwork causes disturbances of the normal sleep-wake cycle and circadian rhythm. There is concern that aging workers have more problems than younger counterparts when the human body clock is disrupted. This review considers issues relating to aging, the circadian body clock, and adjustment to altered sleep-wake schedules. METHODS: Reports on effects of aging on the human body clock were reviewed. Research concerned with adjustment to circadian phase shifts (as occurs in night work) was considered. RESULTS: With aging there is an increased tendency towards morningness which is linked with difficulties in sleeping. The peak time and amplitude of normal circadian rhythms are altered. Tolerance of shiftwork can be linked with social factors as well as adaptation of the body clock. CONCLUSIONS: People habituated to night work seem to have developed mechanisms which allow them to cope with disruptions to lifestyle and the endogenous body clock. Elderly people are more suited to phase advances, as occur in morning workshifts, than to phase delays such as nocturnal work.

Adult↗
PubMed1997

The effect of eumenorrheic menstrual cycle phase on physiological responses to a repeated lifting task.

Cyclic variations in physiological and endocrinological baselines are known to be consistent with the eumenorrheic (healthy) menstrual cycle. The aim of this study was to examine the interaction of these variations with the physiological responses to repeated lifting. Sixteen females visited the laboratory in each of five phases of their menstrual cycle. During each visit, subjects performed a repetitive lifting task, lifting a weighted box, from knee to shoulder height, at six repetitions per minute for 10 min. Oxygen consumption, minute ventilation, heart rate (HR), and perceived exertion were monitored throughout the task. The variation in physiological and subjective responses to lifting with menstrual cycle phase did not reach statistical significance (p > .05). However, the HR response to lifting was elevated by approximately 10 beats x min-1 in the postovulatory phases of the cycle (effect size > 0.61). Although the impact of the menstrual cycle upon lifting performance is minimal, alterations in HR must be taken into account in determining new international standards for manual handling.

Adolescent↗
PubMed1997

Physiological and biomechanical aspects of orienteering.

Orienteering is an endurance running event which differs from other running sports both in its cognitive element and in the type of terrain encountered. The demands of overcoming this terrain are not manifest in significant differences between orienteers and road runners in somatotype, though elite female orienteers have consistently been shown to have higher levels of adiposity (> 19%) than elite road runners. High aerobic power in orienteers (up to 63 and 76 ml/kg/min in women and men, respectively) is coupled with lower anaerobic performance. While leg strength is generally not high when compared with other athletic specialties, female orienteers have relatively good leg flexion strength. The energy cost of running is greatly increased in rough terrain. Oxygen cost was 26% higher while running in a forest when compared with road running. Biomechanical differences in stride pattern contribute towards this increased demand. Despite the high energy demands during competition, orienteers pace themselves such that their mean heart rate remains within the range of 167 to 172 beats/min, despite large fluctuations. The rough terrain encountered in orienteering results not only in a high energy cost but also in a higher incidence of sport-specific injuries, particularly to the ankle. Minor injuries such as cuts and bruises are common during competition.

Anthropometry↗