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Biomedical subjects

N T Cable

Publications and source records attributed to N T Cable.

27 records · Page 2Linked to original sources
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↗
PubMed1994

Modification of forearm resistance vessels by exercise training in young men.

The aim of this study was to determine whether a 4-wk handgrip training program would elicit changes in endothelium-dependent and endothelium-independent vasodilatation in resistance vessels of the human forearm. Minimum vascular resistance after a 10-min ischemic stimulus, an index of peak vasodilator capacity, was also determined. Forearm blood flow response to the endothelium-dependent vasodilator methacholine chloride did not change over the 4-wk-intervention period either in the group undertaking training (n = 11) or in control subjects (n = 6). Similarly, the response to sodium nitroprusside was not influenced by the handgrip training program. Peak vasodilator capacity of the trained forearms significantly increased, whereas no change was evident in the untrained limbs. These results suggest that 4 wk of forearm exercise training enhances peak vasodilator capacity of the vasculature without influencing stimulated activity of the nitric oxide dilator system.

Adult↗
PubMed1993

The influence of thermoregulatory mechanisms on post-exercise hypotension in humans.

1. To examine the influence of the rate of heat loss on the magnitude of post-exercise hypotension, subjects were exposed to three different environmental conditions during recovery from bicycle exercise. 2. When subjects recovered in warm conditions both core temperature (measured in the external auditory meatus) and mean skin temperature were significantly elevated 60 min after the cessation of exercise. This attenuation of heat loss was associated with a significant reduction in post-exercise mean arterial pressure. 3. In contrast, when subjects recovered in neutral or cool conditions both core temperature and mean arterial pressure had returned to baseline levels 60 min after exercise. 4. These results indicate that persistence of peripheral vasodilatation during recovery from exercise, and therefore the magnitude of post-exercise hypotension, is dependent upon thermoregulatory-induced changes in skin blood flow.

Adult↗
PubMed1990

The influence of bicycle exercise, with or without hand immersion in cold water, on forearm sweating in young and middle-aged women.

Forearm sweat production rate (SPR) and external auditory meatal temperature (TEAM) were examined in five young and five middle-aged women in response to intermittent exercise, on three separate occasions. The first experiment was a control study, while in the second study the left hand was immersed in cold water at the onset of sweating during each exercise bout, and in the third study this immersion was accompanied by venous occlusion of the upper left arm. TEAM increased by 0.5 degrees C during exercise with no significant differences between the groups on any occasion. The young women displayed a greater peak SPR during exercise in the control than the middle-aged women (52.5 +/- 23.9 vs. 16.7 +/- 6.5 mg cm2 h-1, P less than 0.001). With hand immersion, peak SPR was depressed to 14.0 +/- 4.6 mg cm2 h-1 (P less than 0.001) in the young women and to 13.1 +/- 4.5 mg cm2 h-1 in the middle-aged (P less than 0.05). With hand immersion and venous occlusion the peak SPR in young women increased (43.0 +/- 9.2 mg cm2 h-1). In the older women SPR was 14.9 +/- 6.1 mg cm2 h-1, which was not different from either control or cold-immersed values. Thus, forearm SPR during low-intensity intermittent exercise is greater in young compared with middle-aged women, despite similar changes in TEAM. The response to hand immersion in cold water was more marked in the young subjects.

Adult↗
PubMed1990

Heart rate and oxygen consumption during walking on land and in deep water.

Oxygen consumption and heart rate were measured during treadmill walking and during walking in deep water in a group of women and in a group of men. In both groups predicted maximum oxygen uptakes were similar on land as in the water. However, there were obvious individual differences in the responses to land versus water exercise. These differences suggest that if deep water walking is used for training, the intensity of work should be assessed from preliminary fitness tests in water and not on land.

Adult↗
PubMedDate not supplied

Health professionals' perspectives in exercise referral: implications for the referral process.

The number of exercise referral schemes expanded rapidly across the UK during the 1990s. Health professionals are thought to be one of the most credible sources of health advice for patients and, hence, are thought to have a pivotal role to play in exercise referral schemes. The aim of the study was to investigate the exercise referral process from the health professional's perspective, specifically examining perceived barriers to referral, priority given to an exercise referral scheme in day-to-day consultations, perceived importance of their role in the process and referring practices. Quantitative and qualitative research methods were utilized with 49% (n = 71) of general practitioners and practice nurses (collectively referred to as health professionals throughout), in a large North West borough (population size approximately 287,000) responding to a postal survey and 11 health professionals (general practitioners n = 9 and practice nurses n = 2) volunteering to take part in a semi-structured interview. Barriers to the referral of patients included lack of time, lack of feedback regarding the patients referred, medico-legal responsibility, a feeling that patients may not take exercise advice given and the belief that physical activity promotion is not a priority during routine consultations. Health professionals refer individuals to an exercise referral scheme on an unsystematic basis and express mixed opinions regarding their perceived role in patient physical activity behaviour change. This study calls for closer partnership working, involving training for promoting physical activity in general practice. Also, greater feedback with regard to patient benefits is needed, in order to overcome some of the practical and perceived barriers for health professionals when referring patients to an exercise referral scheme.

Attitude of Health Personnel↗
PubMedDate not supplied

Influence of environmental temperature on duathlon performance.

The aim of this study was to evaluate the physiological, metabolic and performance responses to duathlon performance under a range of ambient temperatures. Ten male recreational athletes performed three self-paced duathlon time trials consisting of a 5 km run (R1), a 30 km cycle and a 5 km run (R2) at 10 degrees C, 20 degrees C and 30 degrees C and a relative humidity of 50%. Performance times, heart rate (HR), rating of perceived exertion (RPE), core temperature (Tc) and skin temperature (Tsk) were measured every kilometre. Carbohydrate and fat oxidation rates were calculated via expired gas analysis at the first and fourth kilometres during both running stages. Blood samples were taken before and after exercise for the determination of prolactin concentration.Overall performance was significantly faster at 10 degrees C (100.76+/-5.32 min) than at 30 degrees C (105.38 +/- 4.28 min). Significantly higher Tc was noted in the 30 degrees C trial than in the 10 degrees C trial, with concomitant elevations in prolactin after exercise (19.88 +/- 6.48 ng/ml at 30 degrees C; 13.10 +/- 8.75 ng/ml at 10 degrees C). The rates of carbohydrate oxidation did not differ between conditions, although fat oxidation rates were highest at 10 degrees C. Elevated ambient temperature has a negative effect on duathlon performance. This effect may be reflected in increased Tc and prolactin concentration.

Body Temperature↗
PubMedDate not supplied

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↗