Relationship between gastro-intestinal complaints and endotoxaemia, cytokine release and acute phase reaction during and after a long-distance triathlon in highly trained men

The aim of the present study was to establish whether gastro-intestinal (GI) complaints observed during and after ultra-endurance exercise are related to gut ischaemia-associated leakage of endotoxins [lipopolysaccharide (LPS)] into the circulation and associated cytokine production. Therefore we collected blood samples from 29 athletes before, immediately after, and 1, 2 and 16 h after a long-distance triathlon for measurement of LPS, tumour necrosis factor-a and interleukin-6 (IL-6). As the cytokine response would trigger an acute-phase response, characteristic variables of these responses were also measured, along with creatine kinase (CK) to obtain an indicator of muscle damage. There was a high incidence (93 % of all participants) of GI symptoms; 45 % reported severe complaints and 7 % of the participants abandoned the race because of severe GI distress. Mild endotoxaemia (5-15 pg/ml) was evident in 68 % of the athletes immediately after the race, as also indicated by a reduction in IgG anti-LPS levels. In addition, we observed production of IL-6 (27-fold increase immediately after the race), leading to an acutephase response (20-fold increase in C-reactive protein and 12 % decrease in pre-albumin 16 h after the race). The extent of endotoxaemia was not correlated with the GI complaints or the IL-6 response, but did show a correlation with the elevation in C-reactive protein (r(s) 0.389; P = 0.037). Creatine kinase levels were increased significantly immediately post-race, and increased further in the follow-up period. Creatine kinase levels did not correlate with those of either IL-6 or C-reactive protein. It is therefore concluded that LPS does enter the circulation after ultra-endurance exercise and may, together with muscle damage, be responsible for the increased cytokine response and hence GI complaints in these athletes

Effects of energy restriction on acute adrenoceptor and metabolic responses to exercise in obese subjects

Effects of energy restriction on acute adrenoceptor and metabolic responses to exercise in obese subjects. Kempen KP, Saris WH, Senden JM, Menheere PP, Blaak EE, van Baak MA. Department of Human Biology, University of Limburg, Maastricht, The Netherlands. This study was intended to investigate the effects of energy restriction on the acute responses of platelet alpha 2- and lymphocyte beta 2-adrenoceptors to exercise in obese female subjects. Seven obese females were restricted to a low-energy formula diet (2.0 MJ/day) for 4 wk. As result of the diet, there was a 7.8-kg weight loss. No significant changes could be detected in sleeping and resting metabolic rate expressed per kilogram fat-free mass. Basal venous glucose, insulin, and norepinephrine levels decreased as a result of the diet, whereas free fatty acid values increased. Before the diet, 60 min of exercise (45% peak mechanical power) caused no alteration in the density of lymphocyte beta 2-adrenoceptors. At the end of 4 wk of dieting, the density was significantly increased in response to exercise, together with a higher thermogenic and lipolytic response and decreased venous insulin levels. Energy restriction resulted in an increased basal platelet alpha 2-adrenoceptor density, whereas exercise did not modify density and affinity of platelet alpha 2-adrenoceptors. The results indicate that adrenoceptor numbers can be modulated by energy restriction in obesity. Modulation of adrenoceptor density may play a role in increased exercise-induced lipolysis during energy restrictio

Post-exercise protein synthesis rates are only marginally higher in type I compared with type II muscle fibres following resistance-type exercise.

We examined the effect of an acute bout of resistance exercise on fractional muscle protein synthesis rates in human type I and type II muscle fibres. After a standardised breakfast (31 ± 1 kJ kg(−1) body weight, consisting of 52 Energy% (En%) carbohydrate, 34 En% protein and 14 En% fat), 9 untrained men completed a lower-limb resistance exercise bout (8 sets of 10 repetitions leg press and leg extension at 70% 1RM). A primed, continuous infusion of l-[ring-(13)C(6)]phenylalanine was combined with muscle biopsies collected from both legs immediately after exercise and after 6 h of post-exercise recovery. Single muscle fibres were dissected from freeze-dried biopsies and stained for ATPase activity with pre-incubation at a pH of 4.3. Type I and II fibres were separated under a light microscope and analysed for protein-bound l-[ring-(13)C(6)]phenylalanine labelling. Baseline (post-exercise) l-[ring-(13)C(6)]phenylalanine muscle tissue labelling, expressed as (∂(13)C/(12)C), averaged −32.09 ± 0.28, −32.53 ± 0.10 and −32.02 ± 0.16 in the type I and II muscle fibres and mixed muscle, respectively (P = 0.14). During post-exercise recovery, muscle protein synthesis rates were marginally (8 ± 2%) higher in the type I than type II muscle fibres, at 0.100 ± 0.005 versus 0.094 ± 0.005%/h, respectively (P < 0.05), whereby rates of mixed muscle protein were 0.091 ± 0.005%/h. Muscle protein synthesis rates following resistance-type exercise are only marginally higher in type I compared with type II muscle fibres

Urine color, osmolality and specific electrical conductance are not accurate measures of hydration status during postexercise rehydration.

Department of Human Biology, Maastricht University, The Netherlands. BACKGROUND: The aim of the study was to determine whether urine color, osmolality and specific electrical conductance (SEC) provide an accurate index of hydration status and of fluid requirements during the recovery phase after an acute exercise-induced dehydration. METHODS: Experimental design: eight well-trained healthy males were dehydrated about 3% of body mass, 3 times, by cycling in the heat. To rehydrate after exercise, three types of drinks frequently consumed by athletes postexercise, i.e. a caffeinated soft drink (CC), a mineral water (MW), or a carbohydrate-electrolyte solution (CES) were ingested ad libitum and in randomized cross-over design during the first 2 hrs of an observation period lasting 6 hrs. Measures: urine was sampled each hour for determination of color, osmolality and SEC. Net rehydration was calculated from fluid intake and fluid loss by sweat and urine. RESULTS: Fluid intake amounted 2.6 +/- 0.2 kg for CC, 2.2 +/- 0.2 kg for MW and 2.8 +/- 0.3 kg for CES representing 116%, 96% and 127% of fluid lost by sweat. Urine output showed a negative correlation with color, osmolality and SEC (p 0.05). CONCLUSIONS: Urine color, SEC and osmolality are poor indicators of hydration status measured from the balance between fluid intake and urine output up to 6 hrs postexercise. Publication Types: Clinical Trial Randomized Controlled Tria

The effect of different rehydration drinks on post-exercise electrolyte excretion in trained athletes.

Department of Human Biology, Maastricht University, The Netherlands. Eight well-trained cyclists were dehydrated (median [P25-P75 percentiles]) 3.21 [2.97-3.56]% of body mass by cycling in the heat (28 C). During the first 2 h of recovery, the subjects randomly ingested ad libitum either a caffeinated soft drink (CC), a low Na+ mineral water (MW), or an isotonic carbohydrate-electrolyte solution (CES). Fluid intake and urine loss amounted respectively to 2.77 [2.34-2.85] kg, 1.00 [0.82-1.20] kg for CC, 2.15 [1.86-2.79] kg, 0.96 [0.40-1.49] kg for MW, and 2.86 [2.15-3.58] kg, 1.10 [0.86- 1.50] kg for CES. Electrolyte retention was calculated from electrolyte intake with the drink and loss with the urine. Consumption of CC and MW which were low in electrolytes resulted in marked loss of Na+, K+, Cl-, Mg2+ and Ca2+. Consumption of CES resulted in Na+, Mg2+ and Ca2+ retention while K+ and Cl- loss were not influenced. The significantly lower Na+, Mg2+ and Ca2+ loss with CES compared to both CC and MW may be explained by its higher electrolyte content in CES, compared to CC and MW, which only had minor amounts of these electrolytes. Furthermore, it was shown that CC potentiated urinary Mg2+ and Ca2+ excretion. It is concluded that: 1) Post-exercise MW or CC ingestion results in a negative electrolyte balance, 2) Caffeine containing beverages potentiate Mg2+ and Ca2+ excretion; 3) Consumption of CES containing moderate amounts of Na+, Mg2+ and Ca2+ results in sufficient replacement to compensate for urinary losses. Publication Types: Clinical Trial Randomized Controlled Tria

Urine color, osmolality and specific electrical conductance are not accurate measures of hydration status during postexercise rehydration.

Department of Human Biology, Maastricht University, The Netherlands. BACKGROUND: The aim of the study was to determine whether urine color, osmolality and specific electrical conductance (SEC) provide an accurate index of hydration status and of fluid requirements during the recovery phase after an acute exercise-induced dehydration. METHODS: Experimental design: eight well-trained healthy males were dehydrated about 3% of body mass, 3 times, by cycling in the heat. To rehydrate after exercise, three types of drinks frequently consumed by athletes postexercise, i.e. a caffeinated soft drink (CC), a mineral water (MW), or a carbohydrate-electrolyte solution (CES) were ingested ad libitum and in randomized cross-over design during the first 2 hrs of an observation period lasting 6 hrs. Measures: urine was sampled each hour for determination of color, osmolality and SEC. Net rehydration was calculated from fluid intake and fluid loss by sweat and urine. RESULTS: Fluid intake amounted 2.6 +/- 0.2 kg for CC, 2.2 +/- 0.2 kg for MW and 2.8 +/- 0.3 kg for CES representing 116%, 96% and 127% of fluid lost by sweat. Urine output showed a negative correlation with color, osmolality and SEC (p 0.05). CONCLUSIONS: Urine color, SEC and osmolality are poor indicators of hydration status measured from the balance between fluid intake and urine output up to 6 hrs postexercise. Publication Types: Clinical Trial Randomized Controlled Tria

Effect of high and low rates of fluid intake on post-exercise rehydration

The effect of a high (H) and a low (L) rate of post-exercise fluid consumption on plasma volume and fluid balance restoration was investigated. Eight well-trained cyclists were dehydrated at 3% of body weight (BW) by cycling at 28 degrees C. During the recovery period, they ingested a carbohydrate-electrolyte solution in a volume equivalent to 120% of BW loss. Randomly, they ingested 60%, 40%, and 20% in the 1st, 2nd, and 3rd hours of the recovery period, respectively (H), or 24% x h(-1) during 5 hours (L). BW loss was similar for both trials and resulted in a total drink intake of 2.6 +/- 0.1 kg. Urine output in H exceeded significantly that of L in the 2nd and 3rd hours. This was reversed in the 5th and 6th hours. Plasma volume and fluid balance increased more rapidly in H compared to L. After 6 hours this difference disappeared. It is concluded that H results in a faster rate of plasma volume and fluid balance restoration compared to L, despite a temporary large urine output

Performance of the [13C]-acetate gastric emptying breath test during physical exercise

Maastricht University, the Netherlands. M. [email protected] BACKGROUND: The gastric emptying rate of liquids can be determined non-invasively using the [13C]-acetate breath test at rest. The aims of our study were to validate this test during physical exercise against the double-sampling method and to evaluate the time needed for intestinal absorption and the delay between absorption and appearance of 13CO2 in breath, both at rest and during exercise. DESIGN: Fifteen well-trained male subjects were investigated. Gastric emptying was determined simultaneously measuring the 13CO2 breath enrichment after intragastric administration of 0.5 L of carbohydrate solution with 150 mg of [13C]-acetate added and by the double-sampling technique (n = 9). In separate tests, 150 mg of [13C]-acetate was also applied intraduodenally and intravenously (n = 6), both at rest and during exercise. Time-to-peak (TTP) 13CO2 enrichment was determined using a curve fit and was considered as the parameter for gastric emptying. RESULTS: TTP enrichment derived from the breath test significantly correlated with the gastric emptying half-time obtained from the gastric aspirates. During exercise, median TTP enrichment values after intragastric, intraduodenal (i.d.) and intravenous (i.v.) administration of [13C]-acetate were 22.3, 10.3 and 5.4 min respectively. During exercise, i.d. and i.v. values were reached significantly earlier than at rest. CONCLUSION: The [13C]-acetate breath test can be used as a non-invasive method to determine relative gastric emptying rates of liquids during exercise, but the results are influenced by the rate of absorption and the time needed for subsequent oxidation of [13C]-acetate and exhalation of 13CO2