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Biomedical subjects

K L Lamb

Publications and source records attributed to K L Lamb.

17 recordsLinked to original sources
PubMed2005

The effects of a high carbohydrate diet on cortisol and salivary immunoglobulin A (s-IgA) during a period of increase exercise workload amongst Olympic and Ironman triathletes.

The present study observed the effects of a 6-day high carbohydrate (H-CHO) diet on salivary cortisol and IgA during a period of increased exercise workload. Thirty-two competitively trained male triathletes were randomly allocated into a self-selected (SS), or an H-CHO (12 g CHO kgbm (-1) . day (-1)) dietary group. In addition to their training regimes, all subjects performed a 1-hour running exercise bout at 70 % V.O (2max) . d (-1), for six days. Saliva samples were taken pre, immediately post, and morning post-exercise bout on days 1, 4, and 6. The concentrations of s-IgA and cortisol were determined by ELISA assays. There was a significant (p < 0.001) interaction between Group x Time for cortisol, with a marked increase in concentrations occurring in the SS dietary group pre to post exercise, and pre to morning post-exercise (p < 0.01). Conversely, a significant (p = 0.009) Group x Time interaction reflected higher post exercise s-IgA concentrations (p < 0.005) than pre exercise in the H-CHO diet group. Blood glucose concentration decreased pre to post exercise in the SS diet group (p < 0.01), whilst remaining stable in the H-CHO group. It is concluded that the consumption of a high CHO diet throughout a 6-day period of overtraining had a favourable effect on markers of immune activity and thereby reduced the susceptibility of these endurance athletes to upper respiratory tract infection URTI.

Adult↗
PubMed2004

The reproducibility of perceptually regulated exercise responses during short-term cycle ergometry.

The purpose of this study was to assess the reproducibility over four trials of perceptually regulated exercise intensity during short-term cycle ergometry. Recent research has suggested that an improvement in the reproducibility (better agreement) of the exercise output would be observed with a repeated practice using regulatory tools such as Borg's 6 - 20 rating of perceived exertion (RPE) scale. Eighteen healthy active volunteers (nine males, mean age (+/- SD) 24.7 +/- 3.4 yr, and nine females 27.6 +/- 5.4 yr) completed four identical intermittent effort production trials on a cycle ergometer over a period of two - three weeks, with all trials being between three and five days apart. After warm-up, the volunteers were asked to produce four x three-minute bouts of exercise at RPE levels: 13, 15, 9, and 17 (in this order). Power output (W), percentage maximum heart rate reserve (%MHRR), and oxygen consumption (VO(2); ml x kg(-1) x min(-1)) were recorded in the final minute of each bout. Analysis revealed that the 95 % limits of agreement (LoA) between repeated trials did not decrease for the objective markers of exercise intensity, remaining wide throughout. In the worst case comparisons the LoA represented changes (expressed as a proportion of the mean of two trials) of up to 58.3 % in power output (T2 vs. T3 at RPE 9), 65.5 % in % MHRR (T1 vs. T2 at RPE 13) and 36.5 % in VO(2) (T3 vs. T4 at RPE 17). These findings question the use of ratings of perceived exertion to regulate exercise effort. That the reproducibility of effort is also not seen to improve with practice raises doubts about the validity of using the RPE scale to provide training intensities for this type of exercise.

Adult↗
PubMed2004

The effect of experiential anchoring on the reproducibility of exercise regulation in adolescent children.

In this study, we examined whether a preparatory perceptual 'anchoring' technique would enhance the reproducibility (test-retest reliability) of adolescent children in their ability to self-regulate their exercise output on the basis of their effort perceptions. Forty-one adolescents aged 12.6 +/- 0.7 years (mean +/- s), randomly assigned to either an anchor or non-anchor group, undertook two identical production trials (three 3-min cycle ergometer bouts at levels 3, 6 and 8 of the Children's Effort Rating Table) over 8 days. Before each trial, the anchor group received an experiential (exercise) trial intended to provide a frame of reference for their perceived exertions. The test-retest reproducibility of the heart rates and power outputs produced during the production trials was assessed using intraclass correlation coefficients and 95% limits of agreement analysis. For the anchor group, the intraclass correlation coefficients ranged from 0.68 to 0.81 for heart rate and from 0.39 to 0.86 for power output. For the non-anchor group, they were generally higher: 0.86 to 0.93 and 0.81 to 0.95 for heart rate and power output, respectively. The 95% limits of agreement indicated no marked differences between the two groups in the amount of bias and within-subject error. The results suggest that among these adolescents, the implementation of an experiential anchoring protocol had no positive effect on the reproducibility of their exercise regulation during prescribed cycling.

Adolescent↗
PubMed2001

Statistical analyses in the physiology of exercise and kinanthropometry.

Research into the physiology of exercise and kinanthropometry is intended to improve our understanding of how the body responds and adapts to exercise. If such studies are to be meaningful, they have to be well designed and analysed. Advances in personal computing have made available statistical analyses that were previously the preserve of elaborate mainframe systems and have increased opportunities for investigation. However, the ease with which analyses can be performed can mask underlying philosophical and epistemological shortcomings. The aim of this review is to examine the use of four techniques that are especially relevant to physiological studies: (1) bivariate correlation and linear and non-linear regression, (2) multiple regression, (3) repeated-measures analysis of variance and (4) multi-level modelling. The importance of adhering to underlying statistical assumptions is emphasized and ways to accommodate violations of these assumptions are identified.

Adaptation, Physiological↗
PubMed1999

Reliability of ratings of perceived exertion during progressive treadmill exercise.

OBJECTIVE: To assess the test-retest reliability (repeatability) of Borg's 6-20 rating of perceived exertion (RPE) scale using a more appropriate statistical technique than has been employed in previous investigations. The RPE scale is used widely in exercise science and sports medicine to monitor and/or prescribe levels of exercise intensity. The "95% limits of agreement" technique has recently been advocated as a better means of assessing within-subject (trial to trial) agreement than traditional indicators such as Pearson and intraclass correlation coefficients. METHODS: Sixteen male athletes (mean (SD) age 23.6 (5.1) years) completed two identical multistage (incremental) treadmill running protocols over a period of two to five days. RPEs were requested and recorded during the final 15 seconds of each three minute stage. All subjects successfully completed at least four stages in each trial, allowing the reliability of RPE responses to be examined at each stage. RESULTS: The 95% limits of agreement (bias +/- 1.96 x SDdiff) were found to widen as exercise intensity increased: 0.88 (2.02) RPE units (stage 1), 0.25 (2.53) RPE units (stage 2), -0.13 (2.86) RPE units (stage 3), and -0.13 (2.94) RPE units (stage 4). Pearson correlations (0.81, 0.72, 0.65, and 0.60) and intraclass correlations (0.82, 0.80, 0.77, and 0.75) decreased as exercise intensity increased. CONCLUSIONS: These findings question the test-retest reliability of the RPE scale when used to monitor subjective estimates of exercise intensity in progressive (or graded) exercise tests.

Adolescent↗
PubMed1997

Effort perception in children.

Studies addressing children's perceptions of exercise effort have appeared steadily in the scientific literature over the last 20 years, though they have been relatively sparse in number. With little or no regard for their suitability, researchers initially applied to children the methods and applications of the rating of perceived exertion (RPE) notion established amongst adults. Whilst some success was claimed, findings were inconclusive, possibly because of the use of an inappropriate measurement scale. More recently, the development of the child-specific Children's Effort Rating Table (CERT) has advanced research in this domain and helped to focus attention on the numerous problems of applying this psychophysical concept to such immature subjects. Accordingly, the scope for further research in this discipline is now far broader than ever before.

Child↗
PubMed1996

The use of ratings of perceived exertion for regulating exercise levels in rowing ergometry.

The purpose of this study was to examine the validity of the use of ratings of perceived exertion (RPE) to estimate and regulate exercise intensity during rowing ergometry. Nine competitive male rowers [mean age 28.6 years, (SD 6.3)] completed two rowing trials on an ergometer. The first trial (estimation) consisted of an incremental protocol designed to elicit a range of work outputs (WO) and heart rates (HR). The subjects indicated their perception of effort using a 15-point scale at each intensity level. In the second trial (production), 7-14 days later, the subjects were asked to produce exercise intensities corresponding to five levels of RPE: 15, 11, 17, 13, and 19. Data analysis revealed high Pearson correlation coefficients between HR and RPE (r = 0.95, P < 0.01) and WO and RPE (r = 0.96, P < 0.01) during the estimation trial. In addition, significant correlations (P < 0.01) were obtained between the estimation and production trials for HR (r = 0.82) and WO (r = 0.84). Posthoc analysis of variance revealed that the observed differences in mean HR were not significant (P > 0.05) at three of the five intensity levels (RPE 15, 17 and 19), but were at the two lowest RPE levels (11 and 13). Significant mean differences in WO were seen at all but RPE 17. These data support the validity of the RPE scale as a measure of physiological strain among competitive male rowers, and offer support for its use as a method of regulating the intensity of rowing ergometry, especially at higher levels.

Adult↗
PubMed1994

Validity of a perceived exertion scale for children: a pilot study.

The purpose of this study was to examine the validity of a recently developed rating scale of perceived exertion, the Children's Effort Rating Table (CERT), for controlling exercise intensity in young children. 16 children (M age = 9.9 yr., SD = 1.2) performed three separate exercise tests on a mechanically braked cycle ergometer. Stage I (response protocol) consisted of a graded test with heart rate and perceived effort rating recorded in response to specified steady-state work outputs. Stage II (production protocol) examined subjects' ability to produce work outputs corresponding to levels 5, 7, and 9 of the CERT. This protocol was repeated on a further occasion (Stage III) to assess the reliability of the findings. Pearson correlations between ratings and heart rate (0.76) and ratings and work output (0.75) highlight the potential of the scale as a valid measure of exercise intensity. Also, the work rates produced by subjects in Stage II correlated 0.89 with those predicted from Stage I; however, analysis of variance showed that work output was significantly lower in Stage II than predicted. Finally, an intraclass correlation of 0.91 between Stages II and III suggests that the scale gave a reliable estimate of exercise intensity of children. The findings from this pilot study suggest that children's perceptions of effort might be used to guide intensity of exercise during structured activity classes.

Attitude↗
PubMed1993

Leisure-time physical activity as a determinant of self-perceived fitness.

This paper examined the extent to which a reliable measure of leisure-time physical activity is predictive of self-perceived fitness among 40 British university students (mean age = 20.6 yr.). Spearman's rank-order correlations indicated that self-perceived fitness, on an ordinal scale of 1 through 5, was positively correlated 0.48 with Total activity score and 0.54 with one of its subfractions, Very Hard activity. An additional association of 0.52 with an estimate of cardiorespiratory endurance capacity meant that 35.4% of the variation in self-perceived fitness was accounted for by leisure-time physical activity and fitness variables (R = 0.60). These findings provide support that notions of perceived fitness are not inaccurate and are influenced by the amount and types of leisure-time physical activity undertaken.

Adolescent↗
PubMed1992

Effect of very low calorie diet on body composition and exercise response in sedentary women.

The effect of very low calorie diet (VLCD) on fat-free mass (FFM) and physiological response to exercise is a topic of current interest. Ten moderately obese women (aged 23-57 years) received VLCD (1695 kJ.day-1) for 6 weeks. FFM, estimated by four conventional techniques, and heart rate (fc), blood lactate (la(b)), mean arterial pressure (MAP), respiratory exchange ratio (R) and rating of perceived exertion (RPE) were measured during a submaximal cycle ergometry test 1 week before, in the 2nd and 6th week, and 1 week after VLCD treatment. Strength and muscular endurance of the quadriceps and hamstrings were tested by isokinetic dynamometry. The 11.5-kg reduction in body mass was approximately 63% fat and 37% FFM. The latter was attributed largely to the loss of water associated with glycogen. Whilst exercise fc increased by 9-14 beats.min-1 (P < 0.01), there were substantial decreases (P < 0.01) in submaximal MAP (1.07-1.73 kPa), la(b) (0.75-1.00 mmol.l-1 and R (0.07-0.09) during VLCD. R and fc returned to normal levels after VLCD. Gross strength decreased (P < 0.01) by 9 and 13% at 1.05 rad.s-1 and 3.14 rad.s-1, respectively. Strength expressed relative to body mass (Nm.kg-1) increased (P < 0.01) at the lower contraction velocity, but there was no change at the faster velocity. Muscular endurance also decreased (P < 0.01) by 62 and 82% for the hamstrings and quadriceps, respectively. We concluded that the strength decrease was a natural adaptation to the reduction in body mass as the ratio of strength to FFM was maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Correlates of self-perceived fitness.

This paper reports the associations between two global measures of self-perceived fitness and numerous objective fitness and fitness-related measures among 118 British men and women (mean age = 37.9 yr.). Self-perceived fitness, indicated on both a semantic scale of excellent through very poor (I) and an ordinal scale of 1 through 5 (II), was significantly correlated with most fitness and fitness-related variables. For self-perceived fitness I and II, respectively, these included physical work capacity (rho = 0.48 and 0.51), percent body fat (rho = -0.27 and -0.39), grip strength (rho = 0.30 and 0.35), very hard leisure-time physical activity (rho = 0.47 and 0.35), and frequency of sweating (rho = 0.54 and 0.45). Stepwise regression analyses yielded Rs of 0.70 and 0.64 for self-perceived fitness I and II, respectively. A significant correlate of self-perceived fitness was self-perceived health (rho = 0.47), suggesting that people may perceive fitness and health in the same manner. The present data suggest the considerable scope for examining further how people interpret the concept of fitness.

Adolescent↗
PubMed1991

A comparison of selected health-related data from surveys of a general population and a sporting population.

This paper presents a comparison of health-related data from two surveys of British adults. Respondents from one survey formed a representative sample of the British population, whilst respondents from the other were characterised by their participation in sport. Statistical analysis revealed that sports participants had significantly lower body mass index values, lower blood pressures and lower resting pulse rates (P less than 0.05). In addition, sports participants possessed better self-perceived health and perceived themselves overall to be more active than members of the general population. When controls were introduced for gender and age, many of these differences remained, particularly among females. It is concluded that despite the cross-sectional nature of these data, evidence is provided that supports the health-promoting case for sport.

Adolescent↗
PubMed1991

Leisure-time physical activity as an estimate of physical fitness: a validation study.

This paper describes a new interview questionnaire for the assessment of leisure-time physical activity (LTPA), and its validation as an alternative estimate of physical fitness. British subjects (77 males, 41 females) provided details of their LTPA over a period of a "typical" 2 weeks, enabling the estimation of the energy expended. Physical fitness was assessed with a battery of measures, the optimal single measure being sub-maximal physical work capacity (PWC). The questionnaire showed LTPA to be stable following test-retest administration (r = 0.86; p less than 0.0001) for total LTPA energy expenditure. Total LTPA was found to be significantly related to PWC (r = 0.48, p less than 0.0001), as were very hard (r = 0.55; p less than 0.0001) and hard LTPA (r = 0.38; p less than 0.0001). Multiple regression analysis with PWC as the dependent variable yielded a multiple correlation of r = 0.87, with significant contributions from very hard and hard LTPA. It is concluded that whilst this questionnaire is both reliable and a valid estimate of physical fitness amongst a population consistent in their leisure-time physical activities, there is scope for its further use within larger populations, allowing for an analysis of the effects of age and gender on the associations so far observed.

Adolescent↗
PubMed1990

Self-perceived health among sports participants and non-sports participants.

This paper examines and compares the self-perceived health (SPH) of a sample of sports participants (n = 1385) and a matched sample of non-participants (n = 292). Ratings of health were generally found to be favourable among both samples, but a non-parametric analysis of their distributions revealed that the SPH of sports participants was significantly (P less than 0.0001) better than that of the non-participants. SPH improved with age among both samples, but above the age of 34, the non-participants' perceived health ceased to be inferior to that of participants. Controlling for age and gender revealed no difference in SPH above 24 years among males and 34 years among females. SPH was related to a variety of additional health-related factors. Multiple regression analysis was used to identify the predictors of SPH for both samples, and highlighted marked differences between them in the type and number of contributory factors. It is suggested that participation in active sports may enhance health awareness, especially among the young, and that future studies of this kind among sports populations should take account of the levels of commitment (frequency, duration and intensity) to sport.

Activities of Daily Living↗
PubMed1990

The assessment of physical activity by leisure-time physical activity questionnaires.

The assessment of physical activity by questionnaire is currently the most popular and practical method of quantifying physical activity levels. Many questionnaires, past and present, have considered overall or habitual physical activity, which includes occupational (or nonleisure) activity. Others have focused specifically on leisure-time physical activity (LTPA) owing to the recognition of its dominating contribution to the total physical activity of developed populations. This review covers questionnaires that wholly or in part attend to LTPA levels. Typically, self-complete or interviewer-administered questionnaires record information on the types, frequency and duration of activities performed over a particular period of time. Activity-specific energy cost values, expressed in metabolic equivalents (METS) or kilocalories, are then commonly used to estimate the total energy expenditure from all activities and/or categories of activities. The validation of LTPA questionnaires has had to rely upon indirect methods, such as the assessment of cardiorespiratory fitness, body composition and activity diaries. The reporting of the reliability of questionnaires has frequently been ignored, although in cases where it has been reported, doubt exists as to whether the consistency of the questionnaire or the consistency of subjects' physical activity habits were being examined. LTPA questionnaires first appeared in the literature in the mid-1960s for use among specific, mainly middle-aged male population groups. Though they varied in their modes of scoring, periods of activity recall, and overall complexity, associations were universally observed between physical activity levels and chronic health conditions. However, it became apparent that different questionnaires did not yield the same results. In 1978, a questionnaire to assess only LTPA, the Minnesota LTPA Questionnaire, was published and despite its substantial limitations, has since established itself as the most popular option available. In recent years, shorter and simpler alternatives have been advocated, though most have yet to be adequately scrutinised. Associations have been found between LTPA and fitness levels, prompting the use of LTPA questionnaires in large-scale fitness surveys of both adults and children. Although LTPA has continued to be estimated in terms of energy expenditure, little attempt has been made to extend existing knowledge on the energy cost of physical activities. Existing values do not accommodate for individual intensities and inter-population activity variations. Consequently, standardised questionnaires are not yet viable. There exists considerable scope for further work with LTPA questionnaires, especially since the association between coronary heart disease and physical activity is now well recognised. Efforts ought to be directed at wider social groups for whom leisure-time activity may have distinct implications.

Humans↗
PubMed1988

Sports participation and health status: a preliminary analysis.

This paper presents fresh evidence which examines health in relation to age, sex, socio-economic status, sport type and frequency amongst indoor sports participants. The evidence is from 4441 self-completed questionnaires by representative samples of adult participants in seven indoor sports at 46 separate sports facilities, in six U.K. cities. Six indicators of the respondents' health were inter-related and, for purposes of this analysis, are combined into a six-point scale, Males and females in all age groups who were taking part in the more physically demanding sports recorded the highest health scores. In addition, individuals who were playing these demanding sports more than once per week scored higher than those participating in the same activities less often. Health score was also found to be associated with other health-promoting lifestyle practices, such as never smoking and moderate alcohol consumption. Longitudinal corroboration will be necessary to confirm sport as a causal factor in the health-sport relationship, though the cross-sectional evidence from this enquiry is encouraging. It suggests that all types of physically demanding sport, competitive or not, offer measurable health gains to men and women of all ages and whatever their broader ways of living.

Adolescent↗