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Biomedical subjects

R Eston

Publications and source records attributed to R Eston.

15 recordsLinked to original sources
PubMed2005

Changes in performance, skinfold thicknesses, and fat patterning after three years of intense athletic conditioning in high level runners.

OBJECTIVES: To determine if the changes in specific skinfold sites induced by intense athletic conditioning over a three year period were associated with changes in running performance in high level athletes. METHODS: Thirty seven top class runners (eight male and five female sprint trained, 16 male and eight female endurance trained) volunteered to participate in the study. The athletes were divided into class A (n = 18) and class B (n = 17), with class A having the best performance. Biceps, triceps, subscapular, pectoral, iliac crest, abdominal, front thigh, and medial calf skinfold thickness and the best running performance were recorded at the beginning and after one, two, and three years of training. A one way analysis of variance and a linear regression analysis were conducted to determine changes and association between performance and skinfold thicknesses. Analyses were controlled for sex, sprint event or endurance event, and class. RESULTS: Training resulted in a significant increase in performance and decreases in sum of six skinfolds, abdominal, front thigh, and medial calf skinfolds, and the ratio of extremity to trunk skinfolds (E/T, Sigmatriceps, front thigh, medial calf/Sigmasubscapular, iliac crest, abdominal). There were no significant differences in body weight. Except for the abdominal skinfold, there was no significant difference in trunk skinfolds. Significant differences in these changes were observed by sex for E/T, which decreased and increased in male and female runners respectively, and by class. Class B runners significantly improved performance, with decreased skinfold thicknesses in the lower limb. There were no significant changes in performance or skinfold thicknesses in class A runners. Improvements in performance were consistently associated with a decrease in the lower limb skinfolds. CONCLUSIONS: On the basis of these findings, anthropometric assessment of top class athletes should include an evaluation of all skinfolds. The loss of body fat appears to be specific to the muscular groups used during training. The lower limb skinfolds may be particularly useful predictors of running performance.

Adipose Tissue↗
PubMed2003

Effects of prior concentric training on eccentric exercise induced muscle damage.

BACKGROUND: Exercise induced muscle damage (EIMD) from strenuous unaccustomed eccentric exercise is well documented. So too is the observation that a prior bout of eccentric exercise reduces the severity of symptoms of EIMD. This has been attributed to an increase in sarcomeres in series. Recent studies have suggested that prior concentric training increases the susceptibility of muscle to EIMD following eccentric exercise. This has been attributed to a reduction of sarcomeres in series, which decreases muscle compliance and changes the length-tension relation of muscle contraction. OBJECTIVE: To assess the effects of prior concentric training on the severity of EIMD. METHODS: Four men and four women (mean (SD) age 21.1 (0.8) years) followed a four week concentric training programme. The elbow flexor musculature of the non-dominant arm was trained at 60% of one repetition maximum dynamic concentric strength performance, three times a week, increasing to 70% by week 3. After three days of rest, participants performed 50 maximal isokinetic eccentric contractions on both arms. All participants gave written informed consent before taking part in this study, which was approved by the school ethics committee. Strength, relaxed arm angle (RAA), arm circumference, and soreness on active extension and flexion were recorded immediately before eccentric exercise, one hour after, and at 24 hour intervals for three days. Data were analysed with fully repeated measures analyses of variance. RESULTS: Strength retention was significantly (p<0.01) greater in the control arm than the trained arm (84.0 (13.7)%, 90.4 (14.7)%, 95.2 (10.5)%, 103.5 (7.6)% v 75.5 (11.3)%, 77.6 (15.3)%, 80.1 (13.9)%, 80.9 (12.5)%) at one, 24, 48, and 72 hours respectively. Similarly, soreness was greater in the trained arm (0.7 (0.6), 3.1 (1.4), 3.0 (1.5), 1.9 (2.3)) than in the untrained arm (0 (0.2), 1.6 (1.3), 1.4 (0.6), 0.6 (0.4)) at one, 24, 48, and 72 hours respectively (p<0.05). Concentric training induced a significant reduction in RAA (165.2 (6.7) degrees v 157.3 (4.9) degrees ) before the eccentric exercise bout (p<0.01). This was further reduced and remained lower in the trained arm at all time points after the eccentric exercise (p<0.01). The arm circumference of the concentrically trained arm was significantly greater than baseline (p<0.05) at 72 hours (30.3 (2.9) v 29.8 (3.3) cm). CONCLUSIONS: These findings extend the understanding of the effects of prior concentric training in increasing the severity of EIMD to an upper limb exercise model. The inclusion of concentric conditioning in rehabilitation programmes tends to exacerbate the severity of EIMD in subsequent unaccustomed exercise. However, where concentric conditioning is indicated clinically, the net effect of conditioning outcome and EIMD may still confer enhanced strength performance and capability to dynamically stabilise a joint system.

Adult↗
PubMed2001

The relationship between torque and joint angle during knee extension in boys and men.

The length-tension relationship of muscle contraction is well documented in adults. However, research on this relationship in children has been limited. The aim of this study was to compare differences in the torque-joint angle relationship of the quadriceps muscle in children and adults. Eight boys aged 8-10 years and eight men aged 20-26 years performed two maximal voluntary isometric contractions at six knee joint angles (20 degrees, 40 degrees, 60 degrees, 80 degrees, 90 degrees, 100 degrees). The mean of the two trials was used as the performance measure. Both groups demonstrated an expected increase in relative torque as the joint angle increased (P< 0.05). The men produced significantly greater relative torque at 20 degrees, 40 degrees and 60 degrees knee flexion (P < 0.05). The percentage of maximal torque at these angles for the men and boys respectively were: 35.2+/-4.3 vs 15.2+/-12%, 63.6+/-9.1 vs 51.8+/-16.8% and 93.6+/-6.5 vs 84.4+/-14.4%. There were no group differences at 80 degrees or 90 degrees. Peak torque was attained at 80 degrees in men, but decreased significantly (P< 0.05) at 90 degrees and 100 degrees. For boys, peak torque was attained at joint angles of 80 degrees and 90 degrees. The reduction in peak torque at 100 degrees was not statistically significant, but the relative torque at this angle was lower in men than in boys (77.9+/-13.7 vs 87.1+/-10.4%; P< 0.05). In conclusion, the relationship between torque and joint angle appears to be affected by age.

Adult↗
PubMed1999

Effects of cold water immersion on the symptoms of exercise-induced muscle damage.

Cryotherapy is an effective treatment for acute sports injury to soft tissue, although the effect of cryotherapy on exercise-induced muscle damage is unclear. The aim of this study was to assess the effects of cold water immersion on the symptoms of exercise-induced muscle damage following strenuous eccentric exercise. After performing a bout of damage-inducing eccentric exercise (eight sets of five maximal reciprocal contractions at 0.58 rad x s(-1)) of the elbow flexors on an isokinetic dynamometer, 15 females aged 22.0+/-2.0 years (mean +/- s) were allocated to a control group (no treatment, n = 7) or a cryotherapy group (n = 8). Subjects in the cryotherapy group immersed their exercised arm in cold water (15 degrees C) for 15 min immediately after eccentric exercise and then every 12 h for 15 min for a total of seven sessions. Muscle tenderness, plasma creatine kinase activity, relaxed elbow angle, isometric strength and swelling (upper arm circumference) were measured immediately before and for 3 days after eccentric exercise. Analysis of variance revealed significant (P < 0.05) main effects for time for all variables, with increases in muscle tenderness, creatine kinase activity and upper arm circumference, and decreases in isometric strength and relaxed elbow angle. There were significant interactions (P<0.05) of group x time for relaxed elbow angle and creatine kinase activity. Relaxed elbow angle was greater and creatine kinase activity lower for the cryotherapy group than the controls on days 2 and 3 following the eccentric exercise. We conclude that although cold water immersion may reduce muscle stiffness and the amount of post-exercise damage after strenuous eccentric activity, there appears to be no effect on the perception of tenderness and strength loss, which is characteristic after this form of activity.

Adult↗
PubMed1996

The use of ratings of perceived exertion for exercise prescription in patients receiving beta-blocker therapy.

The ratings of perceived exertion (RPE) scale has received widespread acceptance for gaining a subjective estimate of work intensity and as a means of monitoring and regulating exercise intensity across a variety of populations. The original premise for the use of the scale was its high correlation with heart rate (HR). Although individual correlations between HR and RPE in individuals on beta-blocker therapy are probably as high as in untreated individuals, there is evidence to suggest that the RPE response is mediated at a given work rate, particularly at higher absolute work rates. The variation in the RPE response appears to be mediated by the type of beta-blocker therapy administered. In the interests of safety it is necessary for the exercise specialist to develop at least a basic understanding of the mechanism and effects of beta-blocker therapy as they relate to exercise prescription. beta-Blocking drugs cause a decrease in HR and cardiac output at rest and during exercise, a decrease in myocardial contractility and a decrease in coronary and muscle blood flow. These effects can initiate premature fatigue and apprehension in the exercising patient. In the light of these responses, the RPE scale provides important information and may be used to increase the accuracy of monitoring and the prescription of exercise intensity in the cardiac population. While results regarding the use and accuracy of the scale during beta-blocker treatment are equivocal, this appears to be due mainly to variations in dosage of the drug, the mode, intensity and duration of exercise and the health status of the individuals used. Overall, the RPE scale appears to be an appropriate monitoring tool, particularly when it is used after a learning period. It is concluded that nonselective beta-blockade therapy increases RPE, particularly localised RPE. This could be attributed to a decreased blood flow and oxygen delivery to the muscle and altered glycolytic metabolism, which increases local muscle fatigue. There is no evidence to suggest a decrease in the total level of oxygen consumption at given work rates. However, as beta-blocker therapy reduces the maximal oxygen consumption (VO2max) attainable, this serves to increase the exercise intensity at all work rates. Thus, for a given absolute work rate, the RPE response is higher. However, when the work rate is expressed as a proportion of the VO2max attainable during beta-blockade, the differences in RPE are minimised or disappear. Although the evidence is not conclusive, it appears that cardioselective beta-blocker therapy does not have such profound effects on the RPE response, compared with nonselective beta-blocker therapy, when this is expressed as a proportion of VO2max. However, localised RPE tends to be higher for nonselective beta-blocker therapy. Thus, the evidence indicates that RPE can be used to estimate exercise intensity, provided the specific effects of the type of beta-blocker therapy on local and central fatigue (and local and central RPE) are taken into account. Studies which have examined the effects of an endurance training programme during beta-blocker therapy have shown that RPE are decreased at given work rates after training. This has been observed for cardioselective and nonselective beta-blocker therapy, and local and central RPE. There is also some evidence to suggest that the RPE can be used as the controlling variable to regulate the exercise response. Patients on cardioselective beta-blocker therapy produce similar exercise intensities to other cardiac patients who are not receiving beta-blocker treatment.

Adrenergic beta-Antagonists↗
PubMed1996

Psychological affect at different ratings of perceived exertion in high- and low-active women: a study using a production protocol.

The purpose of this study was to examine psychological affect at different ratings of perceived exertion (RPE) in 15 high- and 15 low-active women. Both groups performed three steady-state exercise bouts on a cycle ergometer at RPEs 9, 13, and 17 and reported their affect in the last 20 sec. of and 5 min. after each work rate. There were no differences between groups in percentage of maximal oxygen uptake (% VO2max) at each RPE. Low-active women reported feeling significantly more negative at RPE 17 than RPE 9 and less positive than the high-active women at RPEs 9, 13, and 17. In addition, all subjects reported more positive feelings 5 min. postexercise than in the last 20 sec. of exercising, especially at RPE 17. These results have implications for exercise prescription in groups differing in habitual activity levels.

Adolescent↗
PubMed1996

A method of detecting the muscle pain threshold using an objective software-mediated technique.

This paper describes the reliability of a new procedure of applying force to a muscle site using a computer-mediated myometric procedure to measure a discomfort-pain threshold. 24 female subjects were divided into four groups. Each group was tested on three occasions (trial) at four muscle sites (site) repeated daily over four days (day). Each group received one of four different rates of force application (ramp). Analysis of variance (ramp by day by site by trial) showed a significant main effect for trials and discomfort-pain threshold at different muscle sites, but no significant main effect for days or ramps. Intraclass correlations for each muscle site were in the range of R = 0.73 to 0.98. This procedure appears to be a valid, reliable and nonintrusive means of assessing the muscle discomfort-pain threshold.

Adult↗
PubMed1995

Changes in ratings of perceived exertion and psychological affect in the early stages of exercise.

The purpose of this study was to examine differences in the rating of perceived exertion (RPE) and affect, as assessed by a bipolar feeling scale (FS) during cycle ergometry in a steady-state and a nonsteady-state condition in active and inactive individuals. 71 subjects completed a self-report questionnaire on physical activity and were assigned to two groups, a low-active group of 16 men and 18 women and a high-active group of 18 men and 19 women. On Day 1 all subjects completed a sub-maximal exercise test to predict maximum oxygen uptake (VO2max) from which work rates corresponding to 60% and 90% VO2max were calculated. On Day 2 half of the subjects completed a work rate equivalent to 60% VO2max whilst the other half completed a 90% VO2max work rate. On Day 3 alternative work rates were completed. RPE and FS were recorded after 2 and 4 min, at each work rate on both days. Mixed-model, 4-factor (gender x group x work rate x time) analyses of variance with repeated measures on work rate and time were conducted on the FS and RPE data. RPE was higher after 4 min, at both intensities, and there was a greater increase in RPE between 2 and 4 min, at the 90% than the 60% work rate. Rated feeling was more positive at the 60% work rate, high-active subjects were more positive than low-active subjects and rated feeling was lower in Minute 4 for both groups. The following interactions were observed: rated feeling was more negative after 4 min. for the low-active group compared to the high-active group at 2 and 4 min. and the low-active group reported more negative feeling at the 90% work rate compared to the 60% work rate while the high-active group did not change significantly. Timing of the RPE is important if used to prescribe exercise intensity. Further, low-active subjects should be encouraged to exercise at moderate intensities and discouraged from focusing on how they feel immediately before they finish a session.

Adult↗
PubMed1994

Estimation of body composition in Chinese and British men by ultrasonographic assessment of segmental adipose tissue volume.

It has been shown that ultrasonographic measurements can be used to predict body composition in adults. The purpose of this study was to assess the relationship between ultrasonograph and caliper (SKF) measurements of subcutaneous adipose tissue thickness in athletic Caucasian (English, E) and Asian (Chinese, C) men against estimates of body composition determined from hydrodensitometry (HYD). The usefulness of a proposed ultrasonographic method of estimating lean and fat proportions in the upper and lower limbs was also evaluated as a potential method of predicting body composition. Ultrasonography (US) was used to measure adipose and skin thickness at the following sites: biceps, triceps, subscapular, suprailiac, abdominal, pectoral, thigh and calf. Caliper measurements were also made at the above sites. Subcutaneous fat thickness and segmental radius were measured directly from the display screen of the ultrasonic scanner (Aloka 500 SD). By applying the geometry of a cone, the proximal and distal radii of the upper arm and upper leg were used to calculate the proportionate volumes of adipose tissue. The best correlations for US and SKF were obtained at the quadriceps, subscapular and pectoral sites for E (r = 0.96, 0.93 and 0.90, respectively) and at the quadriceps, calf and abdominal sites for C (r = 0.90, 0.81 and 0.75, respectively). The best ultrasonographic predictor of the percentage fat in both groups was the percentage adipose tissue volume in the upper leg (r = 0.83 and 0.79 for C and E, respectively). Stepwise multiple regression analysis indicated that the prediction of percentage fat was improved by the addition of the ultrasonographic abdomen measurement in both groups: Chinese sample: %fat = %fat(leg) (0.491) + US abdomen (0.337) + 0.95 ( R = 0.89, s.e.e. = 1.9%); English sample: %fat = %fat(leg) (0.435) + US abdomen (0.230) - 0.765 ( R = 0.80, s.e.e. = 3.6%). It is concluded that ultrasonographic measurements of subcutaneous adipose tissue and volumetric assessment of percentage adipose tissue in the thigh are useful estimates of body composition in athletic English and Chinese males.

Adipose Tissue↗
PubMed1994

CERT: a perceived exertion scale for young children.

This paper describes the rationale for the Children's Effort Rating Table (CERT) designed for assessing perceived exertion by children aged 6 to 9 years. This device is similar to Borg's Rating of Perceived Exertion (RPE) which is internationally recognized and currently used in conjunction with standard metabolic measures in a wide range of settings where exercise is prescribed and the intensity of various forms of physical activity is regulated by adults. We devised CERT for use in our research on the development of perception of effort by younger children. Some validation research on CERT has been completed.

Arousal↗
PubMed1993

Prediction and measurement of frame size in young adult males.

The assessment of frame size is a problematic and ambiguous area. The purpose of this study was to assess the level of agreement between various techniques of assessing frame size in a group of 27 healthy and active men aged 18-24 years, and also to assess which anthropometric variables were best associated with a measure of actual frame size (AFS) which is proposed in this study. Actual frame size was measured by the summation of a series of bone breadths, lengths and depths on a sub-sample of 17 men. The results of the study revealed substantial discordance between methods of assessing frame size. The variables which correlated most highly with AFS (P < 0.01) were body mass, ankle breadth, hand length and chest breadth, respectively. These variables were also positively correlated (P < 0.01) with fat-free mass (FFM), with no significant correlation with fat mass in either case. Of the various documented methods used to assess frame size, the 'HAT' technique, which incorporates biacromial and bitrochanteric breadths, was more highly correlated with AFS than both elbow breadth (currently used in height-weight insurance tables) and the height/wrist circumference index. The latter measure was not highly correlated with AFS, body mass and FFM in this study. It was concluded that ankle breadth and hand length may be better predictors of frame size in young men than other bone dimensions. In addition, the results of this preliminary investigation have substantiated the potential viability of an AFS model. Future research using this technique is recommended to determine true indicators of frame size in a larger and more heterogeneous population.

Adipose Tissue↗
PubMed1989

Restoration to normal body composition by VLCD: a comparison of post obese and lean subjects questions BMI 25 as diet limit.

Body composition was assessed in naturally lean female subjects who never had need to diet. At BMI 21-22 their body weight distribution of 75 per cent FFM and 25 per cent fat was compared with subjects who had dieted below BMI 25 by various conventional self-selected diets; subjects who had dieted to BMI 21-22 by VLCD and subjects who were dieting with VLCD but were still above BMI 25. These body composition studies support values of BMI 22-22 as a better estimate of desirable weight in women than BMI 25. At BMI 21-22 the distribution of body weight between fat and FFM of post VLCD dieters matches that of normal lean women.

Body Composition↗
PubMedDate not supplied

Changes in body fat: measurements by neutron activation, densitometry and dual energy X-ray absorptiometry.

The measurement of body fat in ten subjects (BMI from 22 to 43 kg/m2), and in particular the changes arising from a ketogenic diet, by the techniques of in vivo neutron activation analysis (NAA), densitometry (using two- and four-compartment models) by under water weighing (UWW) and dual energy X-ray absorptiometry (DXA) was compared. The association between techniques for the fat changes was generally high (r = 0.70 to 0.98) and significant (p < 0.05). Assessment of agreement between DXA and the other techniques revealed discrepancies with significant slope and high association (r = -0.81 and -0.64). Whilst NAA and UWW appeared to measure similar changes, DXA underestimated small changes.

Absorptiometry, Photon↗