Biomedical subjects

Lesley J White

Publications and source records attributed to Lesley J White.

12 recordsLinked to original sources

PubMed2006

Cardiovascular/non-insulin-dependent diabetes mellitus risk factors and intramyocellular lipid in healthy subjects: a sex comparison.

Little is known about the relationship between intramyocellular lipid (IMCL) and coronary artery disease (CAD)/non-insulin-dependent diabetes mellitus risk factors. The aim of the study was to examine the relationship between IMCL and CAD/non-insulin-dependent diabetes mellitus risk factors in healthy male (n = 9) and female (n = 10) subjects with similar norm-based aerobic fitness and body composition. Nineteen volunteers (21-36 years) completed health and physical activity questionnaires, cardiovascular and body composition evaluation, and assessment of thigh IMCL using proton magnetic resonance spectroscopy. Outcome measures were blood pressure, total cholesterol, high-density lipoprotein cholesterol, C-reactive protein, interleukin 6, tumor necrosis factor alpha (TNF-alpha), homocysteine, insulin resistance (IR), percentage of body fat, waist-to-hip ratio, physical activity levels, and cardiovascular fitness. Analysis of variance was used for group comparisons. Correlation analyses were used to determine association between variables, and stepwise regression was used to determine predictive variables of IR. Women had 2-fold higher IMCL and greater IR than men (P < .05). Men had greater plasma homocysteine and interleukin 6 concentration (P < .05) as well as stronger correlations with CAD risk factors than female subjects. Correlation analyses using all subjects revealed a significant relationship between IMCL and waist-to-hip ratio, body weight, percentage of body fat, and IR. In the regression analysis, age, IMCL, and TNF-alpha were the strongest predictors of IR (R2 = 0.62, P < .01). Our results suggest that female subjects, matched for age and fitness, have higher IMCL compared with their male counterparts. IMCL was correlated with several CAD and prediabetes markers in both male and female subjects. In the final regression model, age, IMCL, and TNF-alpha were the strongest predictors of IR. Future studies with larger sample sizes are warranted.

Adult↗

PubMed2006

Cytokine responses to resistance training in people with multiple sclerosis.

Exercise for individuals with multiple sclerosis (MS) has been shown to improve cardiovascular function, increase strength and endurance, and reduce fatigue. The impact of exercise on immune function in the disease, however, remains mostly unexplored. Ten female MS patients participated in an 8 week programme of twice-weekly progressive resistance training, with pre- and post-training assessment of serum concentrations of cytokines IL-2, IL-4, IL-6, IL-10, CRP, TNF-alpha and IFN-gamma. After training, IL-4, IL-10, CRP and IFN-gamma showed statistically reduced resting concentrations in blood, while TNF-alpha showed non-significant reductions and IL-2 and IL-6 remained unchanged. These results suggest that progressive resistance training may have an impact on cytokine concentrations in individuals with MS and should be confirmed in studies with stronger statistical power. The impact of these changes on overall immune function in MS and on disease status and prognosis remains to be determined.

Adult↗

PubMed2005

Effect of resistance exercise on skeletal muscle myopathy in heart transplant recipients.

The purpose of this study was to determine the efficacy of resistance exercise in reversing skeletal muscle myopathy in heart transplant recipients. Myopathy, engendered by both heart failure and immunosuppression with glucocorticoids, is a post-transplant complication. The sequelae of myopathic disease includes fiber-type shifts and deficits in aerobic metabolic capability. We randomly assigned patients to either 6 months of resistance exercise (training group; n = 8) or a control (control group; n = 7) group. Exercise was initiated at 2 months after transplant. Biopsy of the right vastus lateralis was performed before and after the 6-month intervention. Myosin heavy chain (MHC) composition was assessed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Biochemical assays were performed to determine citrate synthase, 3-hydroxyacyl-CoA-dehydrogenase, and lactate dehydrogenase activity. There were no group differences (p >or=0.05) in MHC composition and enzymatic reserve at baseline. Improvements in the training group for citrate cynthase (+40%), 3-hydroxyacyl-CoA-dehydrogenase (+10%), and lactate dehydrogenase activity (+48%) were significantly greater (p <or=0.05) than in the control group (+10%, -15%, and +20%, respectively). Oxidative type 1 MHC isoform concentration increased significantly in the training group (+73%, p <or=0.05) but decreased in the control group (-28%; p <or=0.05). Glycolytic type 2x MHC isoform increased significantly (17%; p <or=0.05) in the control group but decreased (-33%; p <or=0.05) in the training group. This is the first study to demonstrate that resistance training elicits myofibrillar shifts from less oxidative type II fibers to more oxidative fatigue-resistant type I fibers in heart transplant recipients. Resistance exercise initiated early in the post-transplant period is efficacious in changing skeletal muscle phenotype through increases in enzymatic reserve and shifts in fiber morphology.

Adult↗

PubMed2005

Resistance training improves gait kinematics in persons with multiple sclerosis.

OBJECTIVE: To evaluate the effects of an 8-week lower-body resistance-training program on walking mechanics in persons with multiple sclerosis (MS). DESIGN: Repeated-measures design, evaluating gait kinematics before and after an 8-week progressive resistance-training intervention. SETTING: Biomechanics laboratory and fitness center (with conventional, commercially available resistance-training equipment). PARTICIPANTS: Eight ambulatory subjects with MS (age, 46.0+/-11.5 y) with Expanded Disability Status Scale scores ranging from 2.5 to 5.5. INTERVENTION: An 8-week progressive resistance-training program. MAIN OUTCOME MEASURES: Kinematic gait parameters including knee range of motion, duration of stance, swing, and double-support phases in seconds and as percentages of the stride time, percentage of stride time spent in stance, swing, and double-support phases, step length, foot angle, stride length, velocity, step width, and toe clearance for both the more affected and less affected lower limbs. Isometric strength, 3-minute stepping, fatigue, and self-reported disability were also measured. RESULTS: After 2 months of resistance training, there were significant increases (P<.05) in percentage of stride time in the swing phase, step length, stride length, and foot angle; and significant decreases (P<.05) in percentage of stride time in the stance and double-support phases, duration of the double-support phase, and toe clearance. Isometric leg strength improved (P<.05) in 2 of the 4 muscle groups tested. Fatigue indices decreased (P=.04), whereas self-reported disability tended to decrease (P=.07) following the training program. Three-minute stepping increased by 8.7%. CONCLUSIONS: Resistance training may be an effective intervention strategy for improving walking and functional ability in moderately disabled persons with MS.

Adult↗

PubMed2005

Increased caloric intake soon after exercise in cold water.

We examined the acute effect of cold-water temperature on post-exercise energy intake (EI) for 1 h. In a randomized, crossover design, 11 men (25.6 +/- 5 y) exercised for 45 min on a submersed cycle ergometer at 60 +/- 2% VO2max in 33 degrees C (neutral) and 20 degrees (cold) water temperatures, and also rested for 45 min (control). Energy expenditure (EE) was determined using indirect calorimetry before, during, and after each condition. Following exercise or rest, subjects had free access to a standard assortment of food items of known caloric value. EE was similar for the cold and neutral water conditions, averaging 505 +/- 22 (+/- standard deviation) and 517 +/- 42 kcal, respectively (P = NS). EI after the cold condition averaged 877 +/- 457 kcal, 44% and 41% higher (P < 0.05) than for the neutral and resting conditions, respectively. Cold-water temperature thus stimulated post-exercise EI. Water temperature warrants consideration in aquatic programs designed for weight loss.

Adult↗

PubMed2005

Factors limiting maximal oxygen uptake in exertional monoparesis.

Strength and maximal oxygen uptake (VO2max) for each leg were compared in a trained multiple sclerosis (MS) patient with exertional left monoparesis. Left quadriceps strength and left leg VO2max were 22% and 30% lower, respectively, compared to the right (control) leg. Because the same O2 delivery system served each leg during exercise, VO2max of the paretic leg was not limited by cardiorespiratory factors but rather by strength and/or muscle oxidative capacity. However, training with monoparesis likely enhanced O2 extraction and aerobic work capacity of the right leg.

Adult↗

PubMed2004

Exercise and multiple sclerosis.

The pathophysiology of multiple sclerosis (MS) is characterised by fatigue, motor weakness, spasticity, poor balance, heat sensitivity and mental depression. Also, MS symptoms may lead to physical inactivity associated with the development of secondary diseases. Persons with MS are thus challenged by their disability when attempting to pursue an active lifestyle compatible with health-related fitness. Although exercise prescription is gaining favour as a therapeutic strategy to minimise the loss of functional capacity in chronic diseases, it remains under-utilised as an intervention strategy in the MS population. However, a growing number of studies indicate that exercise in patients with mild-to-moderate MS provides similar fitness and psychological benefits as it does in healthy controls. We reviewed numerous studies describing the responses of selected MS patients to acute and chronic exercise compared with healthy controls. All training studies reported positive outcomes that outweighed potential adverse effects of the exercise intervention. Based on our review, this article highlights the role of exercise prescription in the multidisciplinary approach to MS disease management for improving and maintaining functional capacity. Despite the often unpredictable clinical course of MS, exercise programmes designed to increase cardiorespiratory fitness, muscle strength and mobility provide benefits that enhance lifestyle activity and quality of life while reducing risk of secondary disorders. Recommendations for the evaluation of cardiorespiratory fitness, muscle performance and flexibility are presented as well as basic guidelines for individualised exercise testing and training in MS. Special considerations for exercise, including medical management concerns, programme modifications and supervision, in the MS population are discussed.

Exercise↗

PubMed2003

Plasma adiponectin response to acute exercise in healthy subjects.

Adipose tissue secretes adiponectin, an adipocytokine that is involved in the regulation of insulin sensitivity. Following acute exercise, insulin sensitivity has been shown to increase. Increased adiponectin following exercise may be related to the change in insulin sensitivity. The purpose of the present study was to characterize the effect of a single cycle exercise session on adiponectin and to compare the exercise effects between healthy male and female subjects. Plasma concentrations of adiponectin, tissue necrosis factor-alpha (TNF-alpha), insulin, glucose, and leptin were assessed before and immediately after a 60-minute stationary cycle ergometry session at 65% of Vdot;O(2max). Male and female subjects were matched for cardiorespiratory fitness and body composition and dietary intake was controlled for the three days prior to the exercise trial. At rest, adiponectin concentration was not associated with percentage body fat, body mass index (BMI), fitness, or resting plasma variables ( P>0.05). Following exercise, neither male nor female subjects exhibited changes in adiponectin or leptin concentrations ( P>0.05). TNF-alpha exhibited a time main effect increase with exercise ( P<0.05), but there were no gender differences. These results suggest that plasma adiponectin concentrations do not change with exercise in healthy male or female subjects. Results are given as mean (SE).

Adiponectin↗

PubMed2003

Effects of intermittent cycle exercise on intramyocellular lipid use and recovery.

The purpose of this investigation was to compare intramyocellular lipid (IMCL) changes in skeletal muscle in nine moderately trained subjects after 45 min of interval cycling and through 1 h of recovery. The exercise session was continuous with alternating cycling intensity achieving 50 (3 min) and 110% (2 min) of ventilatory threshold. Spectra from the vastus lateralis were acquired before, immediately after, and 60 min following exercise using a 1.5 T Signa whole-body magnet (point-resolved spectroscopy sequence, echo time 60 ms, transverse relaxation time 2000 ms, 128 acquisitions, and 20 mm3 voxel). Immediately following exercise, IMCL concentration decreased 38% compared to pre-exercise levels (P < 0.05). Fitness level and baseline IMCL were not correlated with changes in IMCL following exercise (P > 0.05). In the 60-min recovery, IMCL was reduced 30% compared to baseline (P < 0.05) and did not recover. In contrast, a nonexercising control group showed no change in IMCL. Our results suggest that IMCL decreased significantly following 45 min of interval cycling, with little recovery in the hour following.

Adult↗

PubMed2003

Intramyocellular lipid changes in men and women during aerobic exercise: a (1)H-magnetic resonance spectroscopy study.

This study was designed to compare intramyocellular lipid (IMCL) changes during 60 min of submaximal exercise in men and women. Eighteen moderately active (18-38 yr) men (n = 9) and women (n = 9) were recruited. Maximum oxygen consumption (O(2)max) and body composition were used to match subjects for aerobic fitness and body composition. Subjects performed cycle ergometry for 1 h at 65% of O(2)max. Expired gases were collected throughout exercise to determine caloric expenditure and substrate use. Blood samples were collected before and after exercise to evaluate markers of lipid metabolism. Pre- and postexercise proton spectra were acquired from the vastus lateralis using a 3-T whole-body imaging system. Spectra were acquired from an 18-mm(3) region of interest (echo time = 45 msec; repetition time = 2000 msec) for IMCL evaluation. IMCL decreased significantly with exercise (11.5-28.5% for men and 17.1-21.7% for women) (P < 0.05); however, there were no significant differences between men and women. Although changes were found for many plasma variables [free fatty acids, glycerol, and norepinephrine (P < 0.05)], group differences were only evident for norepinephrine. In conclusion, a significant decrease in IMCL was observed during 60 min of cycling in matched men and women.

Adult↗

PubMed2003

Effectiveness of cycle cross-training between competitive seasons in female distance runners.

The purpose of this study was to examine whether substituting 50% of run training volume with cycling ("cross-training") would maintain 3,000-m race time and estimated Vo(2)max in competitive female distance runners during a 5-week recuperative phase. Eleven collegiate runners were randomly assigned to either the run training-only (R) group (n = 6) or the cycle training (R/C) group (n = 5), which cross-trained on alternate days. The groups trained daily at a reduced intensity (75-80% of maximum heart rate). Training volume was similar to the competitive season (40-50 mi x wk(-1)) except that cycling represented 50% of volume for the R/C group. On follow-up, 3,000-m time was 1.4% (9 seconds) slower in the R group and 3.4% (22 seconds) slower in the R/C group. No important change in estimated Vo(2)max was found for either group. It was concluded that cycle cross-training adequately maintained aerobic performance during the recuperative phase between the cross-country and track seasons, comparable to the primary sport of running.

Adult↗

PubMed2002

Maintenance of testosterone status in fitness joggers after increased training mileage.

The primary objective was to evaluate the early effect of increased training mileage on testosterone (T) status in recreational joggers. Serum total (T(tot)) and free (T(free)) concentrations at rest, overnight urinary T(tot) excretion, and the T(tot) and T(free) responses to maximal exercise were used as indicators of T status. A group of 13 male [mean (SD) age 24.5 (2.5) years] fitness joggers [maximal oxygen consumption, VO(2max), 52.9 (4.9) ml.kg(-1).min(-1)] qualified as subjects. The training intervention consisted of a 100% increase in the habitual distance run [12 (3) miles.week(-1)] for 2 consecutive weeks, while maintaining the customary training intensity. Blood samples were obtained at rest and after maximal exercise tests, at the beginning and end of a control week of habitual jogging (baseline) and also following the 1st and 2nd weeks of the intervention. The and treadmill exercise endurance time were unchanged across sampling times. Serum T(tot) and T(free) concentrations averaged 565 (62) and 24 (2.6) ng.dl(-1), respectively, at baseline and did not change significantly. Urinary T(tot) excretion averaged 1.5 (0.21) ng.min(-1) at baseline, and also remained unchanged during the intervention. Relative increases in T(tot) (23%) and T(free) (22%) were observed following maximal exercise compared to rest ( P<0.05). However, the exercise-related increases in serum T(tot) and T(free) were not evident after adjustment for the change in plasma volume. It was concluded, that the training intervention did not alter T status in these fitness joggers.

Adult↗