Exercise Improves Insulin Sensitivity in the Absence of Changes in Cytokines.

PURPOSE: The benefits of aerobic exercise training on insulin sensitivity in subjects with the metabolic syndrome (MetS) are, at least in part, associated with changes in cytokines. Recent studies identified novel cytokines (e.g. fractalkine, omentin and osteopontin) that are strongly involved in glucose homeostasis and therefore potentially contribute in the exercise-induced changes in insulin sensitivity. Therefore, we aim to examine changes in skeletal muscle RNA expression and plasma levels of novel cytokines after exercise training, and correlate these changes to the exercise-induced changes in insulin sensitivity. METHODS: Women with the metabolic syndrome (MetS, n=11) and healthy women (n=10) participated in a 6-month aerobic exercise training intervention (3/week, 45min per session at 65%-85% of individual heart rate reserve). Before and after training, we examined insulin sensitivity (M-value during hyperinsulinemic euglycaemic clamp), circulating blood levels of cytokines (venous blood sample; leptin, adiponectin, omentin, fraktalkin, osteopontin). Skeletal muscle RNA-expression of these cytokines (muscle biopsy) was examined in two subgroups (MetS n=6; healthy women n=6). RESULTS: At baseline, plasma levels of omentin (85.8±26.2ng/ml) and adiponectin (5.0±1.7μg/ml) levels were significantly higher in controls compared to MetS (51.1±27.1; 3.6±1.1 respectively), and leptin levels were lower in controls (18.7±11.5ng/ml vs 53.0±23.5). M-value was significantly higher in controls (8.1±1.9mg/kg/min) than in MetS (4.0±1.7). Exercise training significantly improved M-values in both groups (P0.05). CONCLUSION: Whilst exercise training successfully improves insulin sensitivity in MetS and healthy women, we found no change in plasma and mRNA expression levels of novel cytokines

Exercise in Women with the Metabolic Syndrome. Molecular mechanisms of exercise-induced changes in insulin resistance and vascular structure

Contains fulltext : 131643.pdf (publisher's version ) (Open Access)Radboud Universiteit Nijmegen, 21 november 2014Promotores : Hopman, M.T.E., Tack, C.J.J. Co-promotor : Lammers, G

Counteracting venous stasis during acute lower leg immobilization.

Contains fulltext : 51030.pdf (publisher's version ) (Closed access) Contains fulltext : 51030thijssen.pdf (publisher's version ) (Open Access)AIM: During lower limb immobilization, patients are at risk to develop deep venous thrombosis. Recently, a water-pad was developed that should counteract venous stasis. The water-pad, located under the plaster, mobilizes water from the foot to the calf during weight bearing and, thereby, imitates muscle pump function. The purpose of this study was to assess the effect of the water-pad on venous pump function in healthy individuals. METHODS: In 21 healthy subjects (10 men and 11 women) both legs were plastered. Venous pump function was assessed by plethysmography measuring lower leg venous ejection fraction and volume. Subjects were tilted from the supine position to upright standing to determine total venous volume. Hereafter, stepping was performed to measure venous ejection fraction and volume under different filling conditions of the water-pad (0, 50, 100, 150, 200, 250 and 300 mL). Different sizes of water-pads (small, medium and large) were applied to each plastered leg in order to test the effectiveness and to relate optimum size to anthropometrical data. RESULTS: The venous ejection fraction increased significantly from 30 +/- 17% to a maximum of 42 +/- 19% during stepping with increasing filling condition (RM anova; P = 0.009). Ejection volume also enhanced significantly during stepping with increasing filling condition from 1.3 +/- 0.7 to 1.9 +/- 0.9 mL (100 mL)(-1) (RM ANOVA; P = 0.006). The optimal filling condition of the water-pad depended on the water-pad size, while body height was the best predictive value for the water-pad size (Pearson's R = 0.72, P < 0.001). CONCLUSION: The filled water-pad markedly increased the venous ejection fraction and volume of the lower leg during stepping, hereby counteracting stasis of venous blood in the immobilized lower leg. Therefore, the water-pad seems to be a promising tool to prevent deep venous thrombosis during periods of lower leg immobilization

Letter by Poelkens et al regarding article, "Aerobic interval training versus continuous moderate exercise as a treatment for the metabolic syndrome: a pilot study".

Contains fulltext : 79983.pdf (publisher's version ) (Closed access

Preserved flow-mediated dilation in the inactive legs of spinal cord-injured individuals.

Contains fulltext : 57370.pdf (publisher's version ) (Closed access)The aim of the study was to assess endothelial function, measured by flow-mediated dilation (FMD), in an inactive extremity (leg) and chronically active extremity (arm) within one subject. Eleven male spinal cord-injured (SCI) individuals and eleven male controls (C) were included. Echo Doppler measurements were performed to measure FMD responses after 10 and 5 min of arterial occlusion of the leg (superficial femoral artery, SFA) and the arm (brachial artery, BA), respectively. A nitroglycerine spray was administered to determine the endothelium independent vasodilatation in the SFA. In the SFA, relative changes in FMD were significantly enhanced in SCI compared with C (SCI: 14.1 +/- 1.3%; C: 9.2 +/- 2.3%), whereas no differences were found in the BA (SCI: 12.5 +/- 2.9%; C: 14.2 +/- 3.3%). Because the FMD response is directly proportional to the magnitude of the stimulus, the FMD response was also expressed relative to the shear rate. No differences between the groups were found for the FMD-to-shear rate ratio in the SFA (SCI:0.061 +/- 0.023%/s(-1); C: 0.049 +/- 0.024%/s(-1)), whereas the FMD-to-shear rate ratio was significantly decreased in the BA of SCI individuals (SCI: 0.037 +/- 0.01%/s(-1); C: 0.061 +/- 0.027%/s(-1)). The relative dilatory response to nitroglycerine did not differ between the groups. (SCI: 15.6 +/- 2.0%; C: 13.4 +/- 2.3%). In conclusion, our results indicate that SCI individuals have a preserved endothelial function in the inactive legs and possibly an attenuated endothelial function in the active arms compared with controls

Leg intravenous pressure during head-up tilt.

Contains fulltext : 69520.pdf (publisher's version ) (Closed access)Leg vascular resistance is calculated as the arterial-venous pressure gradient divided by blood flow. During orthostatic challenges it is assumed that the hydrostatic pressure contributes equally to leg arterial, as well as to leg venous pressure. Because of venous valves, one may question whether, during orthostatic challenges, a continuous hydrostatic column is formed and if leg venous pressure is equal to the hydrostatic pressure. The purpose of this study was, therefore, to measure intravenous pressure in the great saphenous vein of 12 healthy individuals during 30 degrees and 70 degrees head-up tilt and compare this with the calculated hydrostatic pressure. The height difference between the heart and the right medial malleolus level represented the hydrostatic column. The results demonstrate that there were no differences between the measured intravenous pressure and the calculated hydrostatic pressure during 30 degrees (47.2 +/- 1.0 and 46.9 +/- 1.5 mmHg, respectively) and 70 degrees head-up tilt (83.9 +/- 0.9 and 85.1 +/- 1.2 mmHg, respectively). Steady-state levels of intravenous pressure were reached after 95 +/- 12 s during 30 degrees and 161 +/- 15 s during 70 degrees head-up tilt. In conclusion, the measured leg venous pressure is similar to the calculated hydrostatic pressure during orthostatic challenges. Therefore, the assumption that hydrostatic pressure contributes equally to leg arterial as well as to leg venous pressure during orthostatic challenges can be made

Effect of unilateral resistance training on arterial compliance in elderly men.

Item does not contain fulltextAn increase in age coincides with a decrease in arterial compliance, which is related to a higher risk for cardiovascular accidents. Evidence regarding the effects of resistance training on arterial compliance is conflicting. Currently, little information is available about the effect of resistance training on arterial compliance in elderly men. We assessed the impact of 10 weeks of unilateral arm and leg resistance training on carotid, brachial, and femoral arterial compliance in 12 healthy elderly men (mean age +/- SD, 71 +/- 7 y). Arterial compliance was evaluated before, after 4 weeks, and after 10 weeks of unilateral resistance training by simultaneously measuring arterial diameter and blood pressure in each artery. There were no significant differences in arterial compliance or stiffness index in any of the arteries examined after 10 weeks of training. However, after 10 weeks of resistance training, resting heart rate decreased from 76 +/- 4 beats/min to 61 +/- 3 beats/min (p < 0.05), plasma glucose decreased from 6.0 +/- 0.9 to 5.1 +/- 0.9 mmol/L (mean +/- SE) (p < 0.05), and carotid artery peak blood flow increased from 1831 mL/min to 2245 mL/min (p < 0.05). There were no significant changes in resting arterial blood pressure. Unilateral resistance training for 10 weeks does not alter peripheral and central arterial compliance elderly men

Vascular adaptation to 4 weeks of deconditioning by unilateral lower limb suspension.

Contains fulltext : 48213.pdf (publisher's version ) (Closed access)Physical inactivity or deconditioning is an independent risk factor for atherosclerosis and cardiovascular disease. In contrast to exercise, the vascular changes that occur as a result of deconditioning have not been characterized. We used 4 wk of unilateral lower limb suspension (ULLS) to study arterial and venous adaptations to deconditioning. In contrast to previous studies, this model is not confounded by denervation or microgravity. Seven healthy subjects participated in the study. Arterial and venous characteristics of the legs were assessed by echo Doppler ultrasound and venous occlusion plethysmography. The diameter of the common and superficial femoral artery decreased by 12% after 4 wk of ULLS. Baseline calf blood flow, as measured by plethysmography, decreased from 2.1 +/- 0.2 to 1.6 +/- 0.2 ml.min(-1).dl tissue(-1). Both arterial diameter and calf blood flow returned to baseline values after 4 wk of recovery. There was no indication of a decrease in flow-mediated dilation of the superficial femoral artery after ULLS deconditioning. This means that functional adaptations to inactivity are not simply the inverse of adaptations to exercise. The venous pressure-volume curve is shifted downward after ULLS, without any effect on compliance. In conclusion, deconditioning by 4 wk of ULLS causes significant changes in both the arterial and the venous system

[Physical risks whilst walking the Nijmegen Four Days Marches in 2007: electrolyte imbalance in 1 in 5 walkers]

Contains fulltext : 69287thijssen.pdf (publisher's version ) (Closed access)OBJECTIVE: To determine the physiological impact and health risks for walkers during the Nijmegen (the Netherlands) Four Days Marches in 2007, the largest walking event in the world with more than 45,000 participants. DESIGN: Observational study. METHODS: 66 volunteers were randomly selected and counterbalanced for distance walked and gender in this observational study. Subjects walked 30 km (n = 20; 10 men), 40 km (n = 25; 14 men) or 50 km (n = 21; 10 men) per day, for 4 consecutive days. Core body temperature, fluid intake, changes in body weight, plasma sodium concentrations and energy usage were measured before and after the marches. RESULTS: During this event, ambient temperatures ranged from 11.0 degrees C to a maximum 25.4 degrees C expressed as 'wet bulb globe temperature' (WBGT). Heart rate (+38 beats per minute) and core body temperature (+0.8 degree C) significantly increased in all subjects during each day (about 9 hours walking per day at an average of 4.6 km/h), but hyperthermia was not diagnosed (definition: > 39.0 degrees C). Average fluid intake varied between 2.6 and 3.3 l/d with a range of 0.3-12 l/d. The relative change in body weight associated with this was -3.1 to +4.3%. Mean plasma sodium concentration decreased from 142.4 to 140.6 mmol/l over each walking day. The plasma sodium correlated negatively with fluid intake (r = -0.32; p < o.001), change in body weight (r = -0.13; p < 0.05), and walking time (r = -0.37; p < 0.001). A high prevalence of hyponatraemia (5%) and hypernatraemia (16%) was observed; extrapolating these findings to the entire field a large group (about 10,000) would have been at risk with this electrolyte imbalance. CONCLUSION: This study showed that walking the Four Days Marches in Nijmegen with mild ambient conditions led to one in five participants incurring disturbances in fluid and electrolyte balance. Nonetheless, the participants were well able to keep their increasing core temperature within safe limits. Apart from the frequent electrolyte imbalance, the fluid intake varied strongly between individuals

[Unexplained pain in the ankle and foot. Consider transient osteoporosis]

Item does not contain fulltextTransient osteoporosis is an increasingly recognized condition that causes severe pain in weight-bearing joints and is characterized by otherwise unexplained bone-marrow oedema on MRI. We present two patients, a 40-year-old man and a 60-year-old woman, with longstanding severe pain in the foot and ankle. Both had invalidating pain with only mild swelling of the foot or ankle. Laboratory investigation was unremarkable, and conventional X-ray showed osteopenia of the bones involved. In both cases, consecutive MRIs showed migrating bone marrow oedema. The patients were treated with analgesics, immobilization of the body parts concerned and an intravenous bisphosphonate