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Biomedical subjects

W J Wilkinson

Publications and source records attributed to W J Wilkinson.

6 recordsLinked to original sources
PubMed2005

Obesity, macrophage migration inhibitory factor, and weight loss.

OBJECTIVE: Elevated macrophage migration inhibitory factor (MIF) has been implicated as a causal mechanism in a number of disease conditions including cardiovascular disease (CVD), diabetes, and cancer. Excess body fat is associated with an increased risk of numerous health conditions including CVD, diabetes, and cancer. To our knowledge, the association between MIF and obesity status and the effect of weight loss on serum MIF concentrations have not been reported. In this study, we examined the effects of participation in a behavior-based weight loss program on MIF concentrations in obese individuals. SUBJECTS: Study participants were 71 men and women enrolled in The Cooper Institute Weight Management Program. Participants were predominantly female (68%, n=48), middle-aged (46.5+/-9.8 y), and severely obese (BMI=43.0+/-8.6). METHOD: Plasma MIF concentrations and other standard risk factors were measured before and after participation in a diet and physical activity based weight management program. RESULTS: The mean follow-up was 8.5+/-3.0 months with an average weight loss of 14.4 kg (P<0.001). The majority of clinical risk factors significantly improved at follow-up. Median levels of plasma MIF concentration were significantly lower at follow-up (median [IQR]; 5.1[3.6-10.3]) compared to baseline (8.4 [4.3-48.8]; P=0.0005). The percentage of participants with plasma MIF concentration > or =19.5 mg/nl (highest tertile at baseline) decreased from 33.8 to 5.6% (P<0.001). Further, elevated baseline plasma MIF concentration was associated with markers of beta-cell dysfunction and reductions in MIF were associated with improvements in beta-cell function. CONCLUSIONS: Circulating MIF concentrations are elevated in obese but otherwise healthy individuals; however, this elevation in MIF is not uniform across individuals. In obese individuals with elevated circulating MIF concentrations, participation in physical activity and a dietary-focused weight management program resulted in substantial reduction in MIF.

Adult↗
PubMed2001

Evaluating the reproducibility and validity of the Aerobic Adaptation Test.

PURPOSE: To examine the reproducibility and validity of a new submaximal, ramped cycle ergometer testing methodology known as the Aerobic Adaptation Test (AAT), which attempts to detect changes in submaximal work capacity and minimize participant discomfort. METHODS: 36 sedentary men (mean age = 48.1 +/- 10.2 yr [SD]) and 22 sedentary women (mean age = 51.9 +/- 10.2 yr [SD]) participated in the study. To test reproducibility, participants were tested twice with an average of 20 d between tests (+/-15 d). To test validity, participants were tested before and after a 6-month physical activity intervention, and outcomes were compared with standard measures of fitness (exercise time and oxygen consumption at 70% max heart rate). The main outcome variable of the AAT was work output (W) over a period of 3 min after reaching 70% maximal heart rate. RESULTS: The average work output at 70% HRmax was highly reproducible, with a test-retest reliability of rho = 0.85 (P < 0.001). Average work output at 70% HRmax significantly increased after 6 months of physical activity intervention (87.8 +/- 32.9 W vs 95.5 +/- 37.9 W, P = 0.002), and changes in average work output at 70% HRmax correlated with changes in exercise time to elicit 70% HRmax (r = 0.87, P < 0.001) as well as changes in VO2 at 70% HRmax (r = 0.75, P < 0.001). Thus, the AAT appears to be a valid measure of submaximal work capacity. CONCLUSIONS: The AAT is a reproducible and valid measure of submaximal work capacity that can serve as an effective means to evaluate physical activity interventions.

Adaptation, Physiological↗
PubMed1990

Exercise and mild essential hypertension. Recommendations for adults.

Chronic essential hypertension is a major public health problem afflicting an estimated 15 to 30% of persons from most Western industrialised countries. Persons with mild hypertension (diastolic blood pressure between 90 and 104mm Hg and/or systolic blood pressure between 140 and 159mm Hg) represent the overwhelming majority of hypertensive individuals in the general population. The achievement of long term blood pressure control in these individuals is of central strategic concern in the prevention of hypertension-related morbidity and mortality. Epidemiological studies suggest that regular participation in physical activity may be beneficial in preventing hypertension. The findings of epidemiological studies are supported by a recent meta-analysis of 25 longitudinal aerobic training studies, in which the average sample-size-weighted reductions in resting systolic and diastolic blood pressures were 10.8mm Hg and 8.2mm Hg, respectively. Moreover, preliminary analyses from our centre suggest that cardiorespiratory fitness and, by inference, aerobic exercise training may be of benefit in reducing mortality rates in hypertensive patients. When compiling an exercise prescription with the intention of reducing an elevated blood pressure and attenuating the risk for coronary artery disease, several factors must be considered in order to optimise the likelihood of a safe and effective response. Specifically, the 5 basic components of the exercise prescription for patients with mild hypertension are safety aspects, the type of exercise to be performed, and the frequency, intensity and duration of exercise training. For those patients who require pharmacotherapy, the interaction between the specific antihypertensive agent and exercise responses must also be considered. We recommend that aerobic exercise training be performed at an intensity corresponding to 60 to 85% of the maximal heart rate and that the duration and frequency be modulated to achieve a weekly energy expenditure of between 14 and 20 kcal/kg of bodyweight.

Adult↗