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Alan Nevill

Publications and source records attributed to Alan Nevill.

14 recordsLinked to original sources
PubMed2006

Performance of soccer passing skills under moderate and high-intensity localized muscle fatigue.

Despite the acknowledged importance of fatigue on performance, ecologically sound studies investigating fatigue and its effects on sport-specific skills are surprisingly limited. The aim of this study was to investigate the effects of moderate and high-intensity localized muscle fatigue on passing performance in soccer. Twenty physically active male college students (age, 22.9 +/- 5.3 years) participated in this study. Subjects performed the modified Loughborough Soccer Passing Test under the following three conditions: rest, moderate fatigue, and high-intensity fatigue. Fatigue intensity was established using a percentage of the maximal number of alternate split squats performed by the subject in 1 minute. Results revealed a significant difference between performance at rest and performance following high-intensity, localized muscle fatigue. The results suggest the need for trainers and coaches to incorporate high-intensity exercise drills into training plans to help players better cope with the demands of the game on the pitch.

Adult↗
PubMed2005

Further assessments of the relationship between jet lag and some of its symptoms.

The disruption of circadian rhythms following time-zone transitions gives rise to the syndrome of jet lag. The power of some of the symptoms of jet lag to predict the amount of jet lag measured at the same and at different times of the day has been investigated. Eleven healthy subjects were studied in an Isolation Unit for two days after a simulated flight from the UK to Beijing (8 time zones to the east). At six time-points (08:30, 11:00, 14:00, 17:00, 20:00, and 23:00 h), the subjects recorded their jet lag, and the differences from "normal" (that is, from days in which there is no jet lag) of alertness, hunger, indigestion, concentration, motivation, and irritability. They recorded at 08:30 h the type of food they had eaten since rising at 08:00h and, at the other times, the type of food eaten in the last three hours. Assessments were made by visual analogue scales or, in the case of type of food, by a nominal scale. Following the time-zone transition, the adjustment of meals appeared to be complete almost immediately. Jet lag and its symptoms were present during both experimental days. Jet lag tended to rise during the course of the daytime, accompanied by falls in alertness, motivation, and concentration. Correlation matrices between jet lag and each of the other variables were produced, using lags between the variable (from up to 5 time-points before the assessment of jet lag to 5 time-points afterwards) and pooling the results from both days. These matrices indicated that significant correlations existed only between jet lag and alertness, concentration, and motivation, and then only when these other variables were assessed at the same time as jet lag or 1 or 2 time-points earlier. Jet lag was then treated as the dependent variable and the symptoms as covariates in analysis of covariances (ANCOVAs), with the days treated as a random effect. This analysis enabled the significance of potential predictors of jet lag, together with their beta-coefficients (the relationship between a unit change of each significant predictor and the change in jet lag), to be calculated. Falls in alertness and motivation were significant predictors of increased jet lag, provided that they were measured at the same time, when they accounted for about 50% of the jet lag; when measured at other time-points, they did not act as significant predictors. It is concluded that the amount of jet lag varies during the course of the day and that it can be predicted from contemporaneous assessments of alertness and motivation-but not from assessments made at other times of the day, nor from other variables that are symptoms of jet lag, even though these other variables are significantly increased. In considering the results of this and our previous study, we reiterate the view that the exact meaning of "jet lag" is complex and that the particular combination of factors that contribute to it might vary with the time of day that the assessment is made. Inferences about any decrements due to time-zone transitions cannot be made reliably at times of the day that differ from the time when jet lag is assessed.

Adult↗
PubMed2004

The effects of 60 minutes of brisk walking per week, accumulated in two different patterns, on cardiovascular risk.

BACKGROUND: Current ACSM guidelines recommend that adults should exercise for 20-60 min on 3-5 days.week(-1) (M.L. Pollock, et al., The recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness, and flexibility in healthy adults. Medicine and Science in Sports and Exercise, 30 (6) (1998) 975-991.). For individuals constrained by a busy lifestyle, an exercise prescription that delivers benefits with the minimum investment of time is attractive. The purpose of the present study, therefore, was to examine the effect of instructing sedentary individuals to undertake 20 min of brisk walking, in two different patterns, 3 days per week, on fitness and other cardiovascular disease (CVD) risk factors. METHODS: Forty-eight subjects (31 women) mean (+/-SD) age 45.7 +/- 9.4 year were randomly assigned to either one 20-min walk (single bout), two 10-min walks (accumulated bouts) 3 days week(-1) for 12-week, or no training (control). Oxygen consumption (VO2), heart rate (HR), and ratings of perceived exertion (RPE) were measured during a 4-stage treadmill test at pre- and post-intervention. Body composition, resting blood pressure and fasting lipoproteins were also assessed. Thirty-two subjects completed the study. RESULTS: There was a significant difference between single-bout and accumulated-bout walkers in the reduction of HR at stages 2 and 3 of the treadmill test from pre- to post-intervention (P < 0.05). There were no differences between groups for changes in VO2 or RPE from pre- to post-intervention. There were also no changes in body mass, adiposity, blood pressure, waist and hip circumferences, or lipid/lipoproteins. CONCLUSION: Brisk walking for 20 min on 3 days of the week fails to alter cardiovascular disease risk factors in previously sedentary adults.

Adult↗
PubMed2004

Scaling or normalising maximum oxygen uptake to predict 1-mile run time in boys.

There is still considerable debate and some confusion as to the most appropriate method of scaling or normalizing maximum oxygen uptake (VO2max) for differences in body mass (m) in both adults and children. Previous studies on adult populations have demonstrated that although the traditional ratio standard VO2max (ml kg(-1) min(-1)) fails to render VO2max independent of body mass, the ratio standard is still the best predictor of running performance. However, no such evidence exists in children. Hence, the purpose of the present study was to investigate whether the ratio standard is still the most appropriate method of normalising VO2max to predict 1-mile run speed in a group of 12-year-old children (n=36). Using a power function model and log-linear regression, the best predictor of 1-mile run speed was given by: speed (m s(-1))=55.1 VO2max(0.986) m(-0.96). With both the VO2max and body mass exponents being close to unity but with opposite signs, the model suggest the best predictor of 1-mile run speed is almost exactly the traditional ratio standard recorded in the units (ml kg(-1) min(-1)). Clearly, reporting the traditional ratio standard VO2max, recorded in the units (ml kg(-1) min(-1)), still has an important place in publishing the results of studies investigating cardiovascular fitness of both children and adults.

Algorithms↗
PubMed2004

Do sporting activities convey benefits to bone mass throughout the skeleton?

It is well known that sport and exercise play an important role in stimulating site-specific bone mineral density (BMD). However, what is less well understood is how these benefits dissipate throughout the body. Hence, the aim of the present study was to compare the BMD (recorded at nine sites throughout the skeleton) of 106 male athletes (from nine sports) with that of 15 male non-exercising age-matched controls. Given that BMD is known to increase with body mass and peak with age, multivariate and univariate analyses of covariance were performed to compare the BMD of the nine sports groups with controls (at all sites) using body mass and age as covariates. Our results confirmed a greater adjusted BMD in the arms of the upper-body athletes, the right arm of racket players and the legs of runners (compared with controls), supporting the site-specific nature (i.e. specific to the externally loaded site) of the bone remodelling response (all P <0.01). However, evidence that bone mass acquisition is not just site-specific comes from the results of the rugby players, strength athletes, triathletes and racket players. The rugby players' adjusted BMD was the greatest of all sports groups and greater than controls at all nine sites (all P <0.01), with differences ranging from 8% greater in the left arm to 21% in the lumbar spine. Similarly, the strength athletes' adjusted BMD was superior to that of controls at all sites (P <0.05) except the legs. The adjusted BMD of the triathletes was significantly greater than that of the controls in both the arms and the legs as well as the thoracic and lumbar spine. The racket players not only had significantly greater right arm BMD compared with the controls but also a greater BMD of the lumbar spine, the pelvis and legs. In contrast, the low-strain, low-impact activities of keep-fit, cycling and rowing failed to benefit BMD compared with the age-matched controls. These results suggest that sporting activities involving high impact, physical contact and/or rotational forces or strains are likely to convey significant benefits not only to the loaded sites, but also to other unloaded peripheral and axial sites throughout the skeleton.

Absorptiometry, Photon↗
PubMed2004

Thermoregulation during mild exercise at different circadian times.

Eight healthy subjects exercised at 90watts on a cycle ergometer on four occasions, at times close to the minimum, maximum rate of rise, maximum, and maximum rate of fall of their resting core temperature. The duration of exercise was determined by the time taken for the core (rectal) temperature to reach an equilibrium value. Forearm skin blood flow and temperature were measured regularly during the exercise, as were heart rate and ratings of perceived exertion. Sweat loss was calculated by weighing the subjects nude before and after the exercise. The rise of heart rate was not significantly different at the four times of exercise, though the rating of perceived exertion was greatest at 05:00 h. Resting core temperatures showed a significant circadian rhythm at rest (the timing of which confirmed that exercise was being performed at the required times), but the amplitude of this rhythm was decreased significantly by the exercise. The initial rate of rise of core temperature, and the total rise from the resting to the equilibrium value, were both inversely proportional to resting temperature. The time-course of the rise was accurately described by a negative-exponential model, but this model gave no evidence that the kinetics of the equilibration process depended upon the time of day. The thermoregulatory responses to the rise in core temperature--the amount of total sweat loss and rises in forearm skin blood flow and temperature--differed according to the time of exercise. In general, the responses were significantly greater at 17:00h compared with 05:00h, and at 23:00 h compared with 11:00 h. The results accord with predictions made on the basis of previous work by us in which core temperature rhythms have been separated into components due to the endogenous body clock and due to the direct effects of spontaneous activity. The results are discussed in terms of the ecological implications of the differing capabilities of humans to deal with heat loads produced by spontaneous activity or mild exercise at different phases of the circadian rhythm of resting core temperature.

Adult↗
PubMed2004

Lack of evidence for a marked endogenous component determining food intake in humans during forced desynchrony.

In an attempt to investigate the relative importance of endogenous and exogenous factors in determining food intake, 14 healthy subjects were studied while living in an Isolation Unit (where external time cues were absent) for eighteen 28 h "days" (equal to 21 solar days). The subjects were free to spend their waking time as they chose, and they had a free choice of what they ate and when they ate it. The only restrictions were that no naps were allowed in the "daytime," that some time was required to perform a variety of tests at regular intervals throughout the 18.67 h waking periods, and that any food preparation had to be performed by the subjects themselves. Core (rectal) temperature and activity were monitored throughout, and the subjects answered a questionnaire on their eating habits at 3 h intervals during the waking periods. The questionnaire investigated reasons for eating or not eating a meal during the previous 3 h and, if a meal had been eaten, its type, the factors influencing that choice, and the subjects' subjective responses (hunger before, enjoyment during, and satiety after) to it. The results were analyzed (two-way ANOVA) in terms of both the imposed day length (the exogenous component) and the free-running period of the temperature rhythm (the endogenous component). Results indicated that by far the main reason for eating/not eating was hunger/lack of hunger rather than factors such as food availability and time-pressure. There were statistically significant effects of time within the imposed waking periods upon the type of meal eaten--"breakfast" tending to be a snack, "lunch" a small hot meal, and the "evening meal" a large hot meal. Hot meals (whether small or large) were associated with more hunger before the meal, more enjoyment of the meal, and a greater degree of satiety afterward than were cold meals. These effects suggest that the individuals adjusted their eating habits to fit in with the imposed wake times. By contrast, the effect of circadian phase upon food intake, the type of meal eaten, and subjective responses to the meal was much weaker, and either statistically nonsignificant (P > 0.10) or only marginally so (0.10 > P > 0.05). For example, a large hot meal was chosen as readily for an "evening meal," and subjective responses to it were the same, at whatever circadian phase it was eaten. We conclude that food intake during forced desynchronization is dominated by the waking schedule rather than by circadian influences; some of the implications of these findings when eating habits and the metabolism of food are concerned, particularly in night workers, are considered briefly.

Adolescent↗
PubMed2004

The effect of 6 months training on leg power, balance, and functional mobility of independently living adults over 70 years old.

Where strength training has been used in conjunction with functional-task training in older people, not only have there been improvements in leg strength but also improved function has been measured (e.g., Skelton & McLaughlin, 1996). Many studies use participants from care homes rather than community dwellers. We investigated changes in leg power, balance, and functional mobility in community-dwelling sedentary men and women over 70 years of age (n = 6 for training group [TR]; n = 10 for control group [CN]). Progressive training took place over 24 weeks using seated and nonseated exercise. For TR, leg power increased 40%, from 108 +/- 40 to 141 +/- 53 W (p < .01); dynamic balance increased 48%, from 22.3 +/- 7.9 to 33.1 +/- 6.1 cm (p < .01; functional reach); and functional mobility increased 12%, from 7.46 +/- 1.32 to 6.54 +/- 1.41 s (p < .05; timed walk). CN showed no significant change. In conclusion, a community-based exercise program led to large improvements in leg-extensor power, dynamic balance, and functional mobility.

Adaptation, Physiological↗
PubMed2003

The relationship between assessments of jet lag and some of its symptoms.

The power of the symptoms of jet lag in predicting the amount of jet lag measured at the same and different times of the day has been investigated. A total of 85 subjects was studied for 6 days after a flight from the UK to Australia (10 time zones to the east). At 08:00, 12:00, 16:00, 20:00, and 24:00 h, the subjects recorded their jet lag and fatigue. At 08:00 h, they also assessed their sleep. At 12:00 and 16:00 h, they assessed their attitude to a meal, as well as their motivation, commitment, and irritability. On retiring, they recorded bowel activity. Assessments were by visual analog scales. Jet lag was treated as the dependent variable and the symptoms as covariates in ANCOVAs. Fatigue was a powerful predictor of jet lag, provided it was measured at the same time, and some aspects of sleep predicted jet lag measured on retiring or rising. The other symptoms predicted jet lag less powerfully and/or at a wider range of times. It is concluded that, even though jet lag at any time of the day can be predicted from contemporaneous assessments of fatigue and that it can be predicted on retiring or rising from some aspects of changed sleep, jet lag is predicted less reliably from other symptoms, including aspects of mental performance. These findings question exactly what causes jet lag at a particular time of day, and so are relevant to studies which use this measurement to investigate the problems associated with time-zone transitions, and ways to ameliorate them.

Affect↗
PubMed2002

Accumulating brisk walking for fitness, cardiovascular risk, and psychological health.

PURPOSE: To compare the effects of different patterns of regular brisk walking on fitness, risk factors for cardiovascular disease, and psychological well-being in previously sedentary adults. METHODS: Twenty-one subjects (14 women), aged 44.5 +/- 6.1 yr (mean +/- SD) were randomly assigned to two different, 6-wk programs of brisk walking in a cross-over design, with an interval of 2 wk. One program comprised one 30-min walk per day, 5 d.wk(-1) (long bout) and the other three 10-min walks per day, also 5 d.wk(-1) (short bouts). All walking was at 70-80% of predicted maximal heart rate. Maximal oxygen uptake ((.)VO(2max)), body composition, resting arterial blood pressure, fasting plasma lipoprotein variables, and psychological parameters were assessed before and after each program. RESULTS: Overall, subjects completed 88.2 +/- 1.1% and 91.3 +/- 4.1% of prescribed total walking time in the short- and long-bout programs, respectively. Both programs increased plasma concentrations of high-density lipoprotein cholesterol, and decreased concentrations of triacylglycerol and total cholesterol (all < 0.05). There were no changes in body mass, but the sum of four skinfolds, waist circumference, and hip circumference were decreased after both walking programs (all P<0.05). Predicted (.)VO(2max) increased with both programs ( P<0.05), but this increase was greater with the program based on short bouts (P<0.05). Both walking patterns resulted in similar decreases in tension/anxiety (P<0.05). CONCLUSION: These findings suggest that three short bouts (10 min) of brisk walking accumulated throughout the day are at least as effective as one continuous bout of equal total duration in reducing cardiovascular risk and improving aspects of mood in previously sedentary individuals.

Adult↗