Restricting dietary sodium reduces plasma sodium response to exercise in the heat.

Exercise-associated hyponatremia can be life-threatening. Excessive hypotonic fluid ingestion is the primary etiological factor but does not explain all variability. Possible effects of chronic sodium intake are unknown. The aim of this study was to determine whether dietary sodium affects plasma sodium concentration [Na+ ] during exercise in the heat, when water intake nearly matches mass loss. Endurance-trained men (n = 9) participated in this crossover experiment. Each followed a low-sodium (lowNa) or high-sodium (highNa) diet for 9 days with 24-h fluid intakes and urine outputs measured before experimental trials (day 10). The trials were ≥2 week apart. Trials comprised 3 h (or if not possible to complete, to exhaustion) cycling (55% VO2max ; 34 °C, 65% RH) with water intake approximating mass loss. Plasma [Na+ ], hematocrit, sweat and urine [Na+ ], heart rate, core temperature, and subjective perceptions were monitored. Urine [Na+ ] was lower on lowNa 24 h prior to (31 ± 24, 76 ± 30 mmol/L, P = 0.027) and during trials (10 ± 10, 52 ± 32 mmol/L, P = 0.004). Body mass was lower on lowNa (79.6 ± 8.5, 80.5 ± 8.9, P = 0.03). Plasma [Na+ ] was lower on lowNa before (137 ± 2, 140 ± 3, P = 0.007) and throughout exercise (P = 0.001). Sweat [Na+ ] was unaffected by diet (54.5 ± 40, 54.5 ± 23 mmol/L, P = 0.99). Heart rate and core temperature were higher on lowNa (P ≤ 0.001). Despite decreased urinary sodium losses, plasma sodium was lower on lowNa, with decreased mass indicating (extracellular) water may have been less, explaining greater heart rate and core temperature. General population health recommendations to lower salt intake may not be appropriate for endurance athletes, particularly those training in the heat.

[Universal Dutch guideline on 'Venous disease']. / Overkoepelende richtlijn 'Veneuze pathologie'.

- The Dutch guideline on 'Venous disease' comprises four parts: two revised guidelines ('Varicose veins' and 'Venous leg ulcer') and two new guidelines ('Deep venous disease' and 'Compression therapy').- These guidelines were drawn up by a working party made up of representatives from the Dutch Association of Surgeons, the Dutch Society of Vascular Surgery and the Dutch Society of Dermatology and Venereology.- We will discuss the most important parts of the guideline here.

Changes in the pressure and the dynamic stiffness index of medical elastic compression stockings after having been worn for eight hours: a pilot study.

OBJECTIVES: There is no data available at present on the changes in the exerted pressure together with the dynamic stiffness index (DSI) of medical elastic compression stockings (MECS). The objective of this pilot study was to measure the pressure and calculate the DSI of 12 different brands of MECS before and after having been worn for eight hours. METHODS: In all, 12 different commercially available brands of MECS that were divided into two categories (class I round-knitted and class II flat-knitted MECS) were tested. The pressure was measured, and the DSI of the MECS was first calculated at the B1 level before wearing in the morning and again eight hours after they had been worn. All laboratory measurements were performed using a newly developed dynamic leg-segment model. RESULTS: The pressure at the B1 level dropped significantly in all 12 brands of MECS after having been worn for eight hours, whereas the DSI remained unchanged. CONCLUSION: The DSI of MECS reflects an important and particularly consistent therapeutic effect. As the pressure drops during the day, the pressure amplitude or pulsations remain the same. The pressure drop may be due to fatigue of the elastic material. The DSI would therefore form a valuable indicator for prescribing the most effective MECS for the patient.

Variation in the dynamic stiffness index of different types of medical elastic compression stockings.

OBJECTIVES: To calculate the dynamic stiffness index (DSI) of 18 different brands of medical elastic compression stockings (MECS). METHODS: In all, 18 different brands of MECS that were divided into five categories (class II round-knitted, class II flat-knitted, class III round-knitted, class III flat-knitted and class IV flat-knitted MECS) were tested. The static pressure and dynamic pressure pulsations at the B1 level were measured with a newly developed dynamic pressure-determining device. The DSI was calculated. RESULTS: The DSI of all 18 brands of MECS showed higher values compared with the static stiffness. A wide range of dynamic stiffness indices was observed not only between all brands of MECS, but also within the five categories. CONCLUSIONS: The DSI of MECS is independent of the compression class and the type of knit. The variation in the DSIs between MECS is not because of any measurement error and would indicate that different therapeutic effectiveness may be expected within one compression class. Therefore, a refinement in the current classification system for MECS with other characteristics such as the DSI is warranted.

A method for measuring the dynamic behavior of medical compression hosiery during walking.

BACKGROUND: . Compression therapy is effective in patients suffering from venous disease. This therapy has proven to be especially effective in the ambulant patient. Therefore, the dynamic behavior of the medical compression hosiery (MCH) is more important than the static one in the treatment of patients. OBJECTIVE: . The objective of this study was to develop a method for investigating the dynamic behavior of MCH during walking. METHODS: . The changes in the circumference of the lower leg equipped with a MCH are registered on a treadmill. The dynamic movement is then exactly simulated using an artificial leg-segment model equipped with the same MCH. The dynamic behavior of the MCH can thus be investigated using this artificial leg-segment model. The dynamic stiffness index can be calculated from the dynamic pressure and circumference signals. RESULTS: The expansion of the MCH was only limited to the area underlying the expanding muscles and did not spread circularly. This resulted in relatively high pressure exerted by the MCH on the underlying tissues during walking. Insertion of nonelastic material into the MCH overlying the expanding muscles increased the dynamic pressure. CONCLUSIONS: The active behavior of the MCH during normal walking differed considerably from its passive behavior. We defined a new characteristic of the MCH: the dynamic stiffness index based on the dynamic pressure profile. Insertion of nonelastic materials into the MCH covering overlying the expanding muscles increased the dynamic stiffness index.