Effects of carbohydrate ingestion on gastric emptying and exercise performance

In an effort to determine the effects of 5 (CHO-5), 6 (CHO-6), and 7.5 (CHO-7.5) percent carbohydrate solutions on gastric emptying and performance, 8 trained male cyclists performed 4 trials of intermittent (7- x ;12-min bout) cycling at 70% VO2max. A final 12-min self-paced "performance" ride was performed on an isokinetic ergometer (Fitron) interfaced with a computer to provide total work output. A water placebo (WP) was used as a control. Each 12-min ride was followed by 3-min rest, during which a drink was consumed (8.5 ml.kg-1; mean total = 1,336 ml.2 h-1). Blood samples were taken at 0, 25, 55, 85, and 115 min for blood glucose analysis. Following the performance ride, gastric residue was obtained by intubation and aspiration. Of the original 1,336 ml ingested during each trial, the volumes emptied by the stomach for the four trials were 1,306 +/- 76, 1,262 +/- 82, 1,288 +/- 75, and 1,278 +/- 77 ml (+/- SE) for WP, CHO-5, CHO-6, and CHO-7.5, respectively. Only the volume in the CHO-5 trial was significantly different from WP. The performance data showed that in all of the CHO trials, significantly more work was produced compared to the WP trial (CHO-5 = 1.98 +/- 0.09 x 10(5) Nm vs WP = 1.83 +/- 0.11 x 10(5) Nm). There were no significant differences in performance between any of the CHO trials.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of radionuclide imaging to determine gastric emptying of carbohydrate solutions during exercise.

OBJECTIVE--To investigate the repeatability of continual assessment of the gastric emptying rates of carbohydrate solutions in exercising subjects using 99mtechnetium labelling. METHODS--Gastric emptying of a 5% glucose solution and an iso-osmotic maltodextrin solution was measured using 3 MBq of 99mtechnetium labelled diethylene triamine penta-acetic acid (DTPA) and continuous gamma camera imaging in five male subjects. The subjects performed four 1 h trials at 70% VO2 peak on a cycle ergometer. After 15 min, 200 ml of a radiolabelled solution of glucose or maltodextrin were ingested in a blind crossover protocol. The two solutions were each ingested on separate occasions (trial 1 and trial 2) to establish repeatability. RESULTS--Statistical analysis showed no differences between trial 1 and trial 2 for both solutions. There were no significant differences for the emptying rates between the two test solutions. CONCLUSIONS--Posterior imaging using a computer linked gamma camera following the ingestion of 99mtechnetium labelled DTPA mixed with carbohydrate solutions provides a repeatable method of assessing gastric emptying characteristics in exercising subjects. This technique showed no significant differences between the emptying rates of a single dose of iso-osmotic glucose or maltodextrin solution.     

Exercise and training effects on gastric emptying of carbohydrate beverages

Carbohydrate containing drinks are commonly consumed as an ergogenic aid during endurance sports activities. The efficacy of a given drink is limited by the rate of absorption, which is in turn limited by gastric emptying. A myriad of factors influence gastric emptying. The influence of several of these factors (training status, exercise intensity, and carbohydrate composition) was investigated by repeated experiments using a nasogastric tube and a modification of the technique of George. A group of well-trained bicyclists and a group of untrained subjects performed similar experiments. Three different carbohydrate containing drinks (15 g.100 ml-1 glucose (G), 15 g.100 ml-1 maltodextrin plus 3 g.100 ml-1 fructose (MD), 7 g.100 ml-1 sucrose (I] and artificially sweetened water were compared during rest and 50 and 70% Wmax bicycling. Experimental design was crossover. There was a trend for the carbohydrate drinks to empty initially more slowly under the influence of exercise. Differences in drink volume remaining in the stomach were significant (P less than 0.05), with I at 10 min (70%, mean = 48.9%; rest, mean = 30.5%) and at 20 min (70%, mean = 28.9%; rest, mean = 23.8%) and with MD at 10 min (70%, mean = 71.1%; rest, mean = 55.9%). A similar trend was also seen with 50% Wmax exercise; however, this trend was only significant with MD at 10 min (50%, mean = 72.1%; rest, mean = 55.9%). Drink composition was a much stronger inhibitor of gastric emptying. However, all drinks emptied exponentially with fast-phase initial emptying rates. No differences in gastric emptying or secretion were observed between trained and untrained subjects.     

Gastric emptying: influence of prolonged exercise and carbohydrate concentration

Gastric emptying: influence of prolonged exercise and carbohydrate concentration, Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 269-274, 1989. The purpose of this study was to examine the effects of serial feedings of different concentrations of carbohydrate (CHO) on gastric emptying and to compare the rates of gastric emptying at rest and during prolonged exercise. Solutions of 0, 6, 12, and 18 g. 100 ml-1 (WP, CHO-6, CHO-12, and CHO-18, respectively) were tested. Ten trained male cyclists performed five trials involving 120 min of cycling. The first 105 min were at 70% of VO2max, and the final 15 min were an all-out self-paced performance ride. In one of the five trials, the subjects rode intermittently, completing seven 15-min rides at 70% of VO2max, with 3 min of rest between each ride. Every 15 min, approximately 150 ml (8.5 ml.kg-1.h-1) of one of the four test solutions were consumed. (In the intermittent trial, the CHO-12 solution was used.) Subjects were also tested during 120 min of seated rest using the above feeding schedule (6% solution). Gastric residue was determined by stomach aspiration following the performance ride. The volumes emptied during the CHO-12 and CHO-18 trials (1,049.8 and 889.2 ml) were significantly different from each other and were less than during the WP and CHO-6 trials (1,210.3 and 1,185.6 ml) (P less than 0.05). CHO delivery was significantly higher in the CHO-12 and CHO-18 trials (126 and 160 g) compared to the CHO-6 trial (71.1 g).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of intermittent high-intensity exercise on gastric emptying in man

PURPOSE: The effect on gastric emptying of brief intermittent high-intensity sprints and a moderate-intensity steady-state cycle exercise was studied. METHODS: Eight healthy male subjects were each studied at rest (R), during steady-state exercise at a constant power output corresponding to 66% of their VO(2max) (C66), during intermittent high-intensity exercise at a power output averaging 66% of their VO(2max) (I66), and during intermittent high-intensity exercise at a power output averaging 75% of their VO(2max) (I75). Gastric emptying was measured using the double-sampling gastric aspiration technique. Subjects ingested 600 mL of a 6% carbohydrate-electrolyte solution immediately before exercise or seated rest. Results: The volume of test solution in the stomach was less at all time points on trial I66 than on trial I75 (P = 0.023). The rate of gastric emptying, expressed as the median (range) time (minutes) taken to empty half the test meal volume (t(1/2)), was not different on trials R (20 (7--30)) and C66 (21 (7--49)), and was faster than on trial I75 (62 (27--100); P = 0.003 and P = 0.005, respectively). Median t(1/2) was faster on trial R than on trial I66 (30 (15--74) min; P = 0.019), but no difference was detected between C66 and I66 or between I66 and I75. However, over the initial 30 min period after ingestion, the median (range) volume of test drink delivered to the duodenum was faster (P < 0.01) on trials R (387 (296--541) mL) and C66 (389 (165--584) mL) than on trials I66 (331 (191--494) mL) or I75 (249 (79-335) mL). Conclusion: The data demonstrate that gastric emptying of liquids is slowed during brief intermittent high-intensity exercise compared with rest or steady-state moderate exercise.     

The influence of volume on gastric emptying and fluid balance during prolonged exercise

The purpose of this study was to determine the effect of ingesting approximately 800, 1200, or 1600 ml.h-1 of a carbohydrate (CHO) solution on gastric emptying (GE), ratings of stomach fullness (RF), plasma volume changes (PVC), electrolytes, fluid loss, and blood glucose (BG) during 2 h of cycling at 70% of VO2max. Eight male cyclists completed three rides during which they ingested either 11.5 (LV), 17.1 (MV), or 23 ml.kg-1.h-1 (HV) of a 7.5% CHO solution every 15 min. Blood samples were taken at 0, 60, 90, and 120 min and 15 min after the ride for the determination of PVC, sodium (Na+), potassium (K+), and BG. Body weight was recorded before and after the rides to determine dehydration. Rates of GE were determined via stomach aspiration after the rides. A significantly (P less than 0.05) greater volume of fluid was emptied in the HV trial (2268 +/- 70.8 ml) compared with the MV and LV trials (1860 +/- 72 and 1452 +/- 24 ml, respectively). The rate of GE in the MV trial was also significantly greater than in the LV trial. RF were significantly higher in the MV and HV trials compared with the LV trial throughout the rides. There were no significant differences in PVC (0.01 +/- 2.2%, 1.05 +/- 1.62%, and 0.97 +/- 1.28% for LV, MV, and HV, respectively), Na+, K+, or BG between the three trials. There was a significantly greater decrease in body weight in the LV (-0.77 +/- 0.14 kg) compared with the MV and HV trials (-0.38 +/- 0.13 and -0.14 +/- 0.14 kg).(ABSTRACT TRUNCATED AT 250 WORDS)     

睡眠剥夺对大鼠胃动力及胃黏膜损伤的影响

 目的探讨睡眠剥夺对大鼠胃动力及胃黏膜损伤的影响.方法采用小站台水环境法建立大鼠睡眠剥夺模型.用同位素99mTc灌胃测定大鼠胃液体排空率,观察胃黏膜损伤情况.结果睡眠剥夺条件下可导致胃排空障碍,在睡眠剥夺第3日大鼠胃排空率明显下降(73.9±4.1)%,在睡眠剥夺第5天和第7天大鼠胃排空率降低更明显,(70.6±4.9)%,(70.4±5.9)%.同时胃黏膜损伤也不断加重,在睡眠剥夺第3日,第5天和第7天大鼠胃黏膜损伤指数分别为(25.7±3.2),(28.9±3.8),(31.1±4.3).结论睡眠剥夺可导致胃排空障碍和胃黏膜损伤,而且二者与睡眠剥夺时间密切相关.     

Effects of dehydration on gastric emptying and gastrointestinal distress while running

Gastrointestinal distress is commonly reported by athletes after ingestion of a beverage. We speculate that ingestion may be occurring after dehydration has taken place. The high prevalence of GI disorders in marathon runners who have lost greater than or equal to 4% body weight supports this theory. To test this theory, the effects of dehydration, and dehydration in combination with endurance running, on gastric emptying (GE) and frequency of gastrointestinal (GI) complaints were tested in this experiment. A complete cross-over study was designed. Sixteen subjects ingested 8 ml.kg BW-1 of a 7% carbohydrate (296 mOsm.kg-1), solution after a euhydration or dehydration regime. Dehydration (4% BW loss) was produced by 60% maximal speed running at 30 degrees C or by intermittent sauna exposure at 100 degrees C. Euhydration experiments were conducted with a 2 h rest period with water administered at 20 and 40 min. Gastric drink volumes were measured every 10 min for 40 min. Emptying curves were compared using semi-log transformation of the percentage emptying data and simple linear regression. The slope of each line was used as a measure of average GE rate. Dehydration-exercise resulted in slower GE than in all other treatments (P less than 0.05). ANOVA revealed significant effects of dehydration (P less than 0.05) and exercise (P less than 0.05), these two effects being additive in delaying GE. GI complaints were reported by 37.5% of the subjects during dehydration-exercise experiments. No GI disturbance was reported in other tests.(ABSTRACT TRUNCATED AT 250 WORDS)     

急性缺氧对飞行员胃液排空功能的影响

为探讨急性缺氧对飞行人员胃液体排空功能的影响，在常压下吸入不同浓度氧（17％、16％、14％、12％、10．5％及9％）的低氧混合气体30min，采用B型超声波在实验前后分别测量了64名男性飞行员的胃液体排空功能。结果表明，吸入17％低氧混合气胃排空延迟，但经统计学处理无显著性差异（P＞0．05），吸入16％以下的低氧混合气后胃排空延迟，经统计学处理有显著性差异（P＜O．01），且随着缺氧程度加重，胃液体排空时间延长更加明显。提示当发生高空缺氧时，应考虑到缺氧对胃排空有抑制作用这一因素。     

The effects of consuming carbohydrate-electrolyte beverages on gastric emptying and fluid absorption during and following exercise

A variety of beverages formulated to provide fluid, carbohydrates, and electrolytes during and following exercise are commercially available. Such 'sport drinks' commonly contain 4 to 8% carbohydrate (as glucose, fructose, sucrose or maltodextrins) and small amounts of electrolytes (most often sodium, potassium, and chloride). The efficacy of consuming such beverages has been questioned primarily because of concern that beverage carbohydrate content may inhibit gastric emptying rate and fluid absorption during exercise, thereby jeopardizing physiological homeostasis and impairing exercise performance. Gastric motor activity, and consequently gastric emptying rate, is governed by neural and humoral feedback provided by receptors found in the gastric musculature and proximal small intestine. Gastric emptying rate may be influenced by a variety of factors including, but not limited to, the caloric content, volume, osmolality, temperature, and pH of the ingested fluid, diurnal and interindividual variation, metabolic state (rest/exercise), and the ambient temperature. The caloric content of the ingested fluid appears to be the most important variable governing gastric emptying rate, providing a mean caloric efflux from the stomach of 2.0 to 2.5 kcal/min for ingested fluid volumes less than 400 ml. At rest, gastric emptying is inhibited by solutions containing calories in a manner independent of the nutrient source (i.e. carbohydrate, fat or protein). Consequently, plain water is known to empty from the stomachs of resting subjects at rates faster than solutions containing calories. Gastric emptying is increasingly inhibited as the caloric content of the ingested fluid increases. During moderate exercise (less than 75% VO2max), gastric emptying occurs at a rate similar to that during rest; more intense exercise appears to inhibit gastric emptying. When fluids are consumed at regular intervals throughout prolonged exercise (greater than 2 hours), postexercise aspiration of stomach contents reveals that solutions containing up to 10% carbohydrate empty at rates similar to plain water. There is ample physiological justification for the addition of glucose, fructose, sodium, potassium and chloride to fluid replacement beverages. Fluid absorption in the small intestine is stimulated by glucose and sodium (and to a lesser extent by fructose and other electrolytes). Glucose and sodium are absorbed via a common membrane carrier in the mucosal epithelium of the proximal small intestine. The potentiation of sodium uptake by glucose establishes an osmotic gradient for fluid absorption.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect of the Garren-Edwards gastric bubble on gastric emptying

The Garren-Edwards Gastric Bubble (GEGB) was introduced in 1984 as an alternative to surgery (jaw wiring, gastrointestinal bypass, vertical banded gastroplasty) for the treatment of morbid obesity in patients who had failed behavior modification therapy or dietary management for weight reduction. Its mechanism of action is unclear and previous reports have not demonstrated any significant consistent alteration in gastric emptying (GE) as measured by radionuclide techniques. Other proposed mechanisms include: placebo, hormonal, mechanical "satiety", behavioral modification, and neuronal. In order to determine the effect of the GEGB on GE, ten obese (mean % overweight = 89%) patients, 27-50 yr old (mean = 36 yr), had solid GE scans before and 5 wk after endoscopic placement of the bubble. GE scans were performed in six patients after removal (12 = wk residence time). The meal consisted of 300 microCi [99mTc]sulfur colloid in the form of a 300 kcal egg sandwich (egg white 248 g, white bread 40 g, butter 6 g; composition = CHO 40:PR 40: FAT 20) with 180 ml deionized water. Images were obtained in the anterior and posterior projections at 15-min intervals for 1 hr (four patients) or 2 hr (six patients) and the %GE (decay corrected geometric mean) was calculated. Unlike other studies involving the GEGB, adjunctive therapy in the form of dieting and behavior modification were not employed in this study. The effect of the GEGB alone in the treatment of obesity has not been previously evaluated. There was a significant (p less than 0.025) delay in gastric emptying at 1 hr (pre-bubble mean % gastric retention = 46%; bubble mean = 57%; n = 10). After removal, GE returned toward baseline (mean % gastric retention = 51%; n = 6) (p less than 0.05) (Student's t-test). The average weight loss was 5.5 lb (n = 10; p less than 0.025). One mechanism of action of the GEGB may be delayed gastric emptying resulting in early satiety and decreased food intake with resultant weight loss.     

高强度运动及心理应激对大鼠胃排空及胃肠激素的影响

目的 探讨高强度运动及心理应激对大鼠胃排空及胃泌素(GAS)、胃动素(MOT)的影响.方法 40只Wistar大鼠随机均分为空白对照组,低、高强度运动组,心理应激组.高强度运动+心理应激组.测定大鼠在不同强度运动及心理应激后的胃排空率及GAS、MOT含量.结果 与空白对照组比较,低强度运动组大鼠的体重、胃排空率、GAS无明显变化(P>0.05),但MOT升高(P<0.05);高强度运动组及心理应激组大鼠的体重、胃排空率、GAS、MOT均明显下降(P<0.01或P<0.05);与高强度运动组比较,心理应激组及高强度运动+心理应激组大鼠胃排空率、GAS、MOT下降更明显(P<0.01或P<0.05);高强度运动+心理应激组与心理应激组比较无显著差异(P>0.05).结论 高强度运动可引起实验大鼠胃排空率、GAS、MOT水平下降,而心理应激对胃排空率、GAS、MOT的影响更大,共同作用比单一因素的影响更显著.     

Effects of ingesting carbohydrate beverages during exercise in the heat

Ingesting carbohydrate beverages during exercise in cool temperatures can improve endurance performance. However, because hyperosmotic solutions leave the stomach more slowly than water, carbohydrate beverages could be less effective in minimizing the dehydration and hyperthermia that accompany exercise in the heat. To determine the effect of osmotically different beverages on prolonged (2 h) treadmill exercise (65% VO2max) in the heat (T db = 35 degrees C), five male runners (age 24 to 41 yr) performed three separate runs drinking 200 ml every 20 min of either 10% glucose polymer (GP), 10% glucose (G), or saccharin-sweetened water (WH). A fourth run was performed in a cool (T db = 25 degrees C) room and included drinking saccharin-sweetened water (WC). Drink osmolalities (Osm) for runs GP, G, WH, and WC were 194, 586, 94, and 71 mmol . kg-1, respectively. No significant differences were observed between runs in the heat (GP, G, and WH) for heart rate, rectal and mean skin temperatures, sweat rate, percent change in plasma volume, and gastric residue volume. When compared to the WC run, both the GP and G runs yielded greater (P less than 0.05) declines in percent change in plasma volume, but only the G run had a greater (P less than 0.05) gastric residue volume. Neither plasma osmolality, total protein, nor [Na+] varied between runs. Plasma glucose, insulin, and respiratory exchange ratios were similar between the GP and G runs. However, the GP run yielded the lowest (P less than 0.05) plasma glycerol values. Although gastric residue volume (r = 0.68) and final percent change in plasma volume (r = 0.69) were significantly correlated with drink osmolality, thermoregulation was similar between runs in the heat despite the beverage consumed.     

放射性核素胃排空显像

放射性胃排空显像具有方法简便、无创伤、可重复、符合生理状况、可精确定位等优点,它对消化道疾病病因学探讨和胃肠道功能研究具有重要的临床价值,是测定胃排空的金标准。本文结合临床工作经验和文献复习,对放射性核素胃排空测定方法、标记试餐标准化、胃感兴趣区的确定及常见影响因素等新技术、新观点加以评述。     

卡巴胆碱对大鼠烫伤休克早期口服补液时胃排空和胃血流量的影响

目的 研究拟胆碱药卡巴胆碱对大鼠烫伤休克早期口服补液时胃排空和胃血流量的影响.方法 雄性Wistar大鼠78只,随机分为假烫组(n=6)、单纯烫伤组(单烫组,n=18)、卡巴胆碱组(CAL组,n=18)、葡萄糖-电解质液组(GES组,n＝18)和GES CAL组(GES/CAL组,n＝18).用沸水(100℃,15s)造成大鼠背部35% TBSA烫伤.单烫组不补液;GES和GES/CAL组于伤后0.5h开始按Parkland公式量的半量(即每1%TBSA烧伤补液2ml/kg)分2次、间隔2h口服GES液;CAL和GES/CAL组于伤后0.5h口服CAL(60μg/kg).烫伤后2、4、6h用激光多普勒血流仪测定胃血流量,酚红法测定胃排空率.结果 烫伤后胃排空率和胃血流量显著降低(P＜0.05);GES或CAL各组胃排空率和胃血流量均显著回升,明显高于单烫组(P＜0.05);GES/CAL组胃排空和胃血流量改善比GES、CAL组更为显著(P＜005).结论 CAL能显著改善大鼠烫伤休克早期胃排空和胃血流量,提高口服液体复苏的效果.