Male fertility in cystic fibrosis.

Infertility rates among males with cystic fibrosis (CF) approximate 97%. No information is currently available within Ireland determining an understanding of fertility issues and the best methods of information provision to this specialized group. This study aimed to determine understanding and preferred approaches to information provision on fertility issues to Irish CF males. A Descriptive Study utilizing prospective coded questionnaires was mailed to a male CF cohort (n=50). Sections included demographics, fertility knowledge & investigation. Response rate was 16/50 (32%). All were aware that CF affected their fertility. More than two-thirds (n=11) were able to provide explanations whilst only one-third (n=5) provided the correct explanation. Significant numbers stated thoughts of marriage and a future family. Half have discussed fertility with a healthcare professional (HCP). Mean age of discussion was 21.9 years. One third preferred an earlier discussion. The commonest first source for information was written material which was also the preferred source. Three-quarters requested further information preferring again, written material. Significant gaps in sex education of Irish CF males exist. Discussion should be initiated by HCPs and centre-directed written material devised to address deficiencies.

Measurement of body composition changes with weight loss in postmenopausal women: comparison of methods.

BACKGROUND: The accurate measurement of body composition changes is important when evaluating the efficacy of medical nutrition therapy and weight management programs, yet is not well documented in older women. OBJECTIVE: We compared methods of estimating energy-restriction-induced body composition changes in postmenopausal women. DESIGN: 27 women (59 +/- 8 y; BMI 29.0 +/- 2.9 kg/m2; mean +/- SD) completed a 9-wk energy restriction period (5233 kJ/d, (1250 kcal/d)). Changes in % body fat (delta%BF), fat mass (deltaFM), and fatfree mass (deltaFFM) were measured by hydrostatic weighing (HW), air-displacement plethysmography (ADP), dual-energy x-ray absorptiometry (DXA), and deuterium oxide dilution (D2O). The Baumgartner et al. (Am J Clin Nutr 53:1345-1353, 1991) four-compartment (4C) model with body volume from HW was the criterion method. The 4C model with body volume from ADP was also compared. Regression equations were developed based on 4CHW (dependent variable) utilizing results of change (POST-PRE) for each method. RESULTS: The women lost 6.8 +/- 3.2 kg; 9% of baseline weight. Based on 4CHW, the body composition changes were -2.4 +/- 4.5 delta%BF, -4.7 +/- 3.3 kg deltaFM, and -2.6 +/- 4.4 kg deltaFFM. No differences were detected by ANOVA for delta%BF, deltaFM, and deltaFFM among 4CHW, HW, ADP, DXA, D2O, and 4CADP. Bland-Altman limits of agreement showed differences between methods that ranged from 14.5 to -14.1 delta%BF, 7.8 to -8.1 kg deltaFM, and 7.5 to -8.4 kg deltaFFM for individuals. A bias was shown with 4CADP overestimating delta%BF (1.4 %) and FM (0.6 kg) and underestimating deltaFFM (-1.2 kg) compared to 4CHW. The regression model was acceptable for %BF (4CADP, 2CHW, and 2CD2O); FM and FFM (4CADP, 3CDXA, 2CHW, and 2CD2O), but not for other estimates of %BF, FM, FFM. CONCLUSIONS: These body composition assessment methods may be used interchangeably to quantify changes in % body fat, fat mass, and fat-free mass with weight loss in groups of postmenopausal women. 4CADP overestimates delta%BF and underestimates deltaFFM. When utilizing one of these comparison methods (4CADP, 3CDXA, 2CHW, 2CD2O) to quantify changes in fat mass and fat-free mass for an individual postmenopausal woman, regression equations may be used to relate the data to 4CHW.

Exercise during late-follicular menstrual phase: influence on immune parameters.

AIM: The purpose of this study was to examine whether training status and plasma hormones (estradiol--E2, progesterone--P, luteinizing hormone--LH, and follicle-stimulating hormone--FSH) have an effect on selected immune indexes during or following an acute bout of exercise. METHODS: Seven female triathletes (TRI) and 7 recreationally active (REC) females were randomly assigned to rest (RE) and exercise (EX) trials during the late-follicular menstrual phase (LF). The EX was 1 hour of cycling at 63.1+/-6% VO2peak (TRI) and 61+/-5.1% VO2peak (REC) and RE was 1 hour of sitting. Blood was drawn for both trials at baseline (0H), 1 hour (1H), and at 3 hours (3H). RESULTS: Positive correlations were found between E2 and CD19+ cells for both groups as well as P and CD8+ cells for the REC group. E2 increased during EX and returned to baseline at 3HEX for both groups, however, LH remained elevated at 3HEX for REC. There were significant exercise time effects for CD3+, CD4+, CD8+, and CD3- CD16+ CD56+ cells. The NCMC and 1:1 were elevated at 1HEX for both groups and returned to baseline by 3HEX. During RE, CD3- CD16+ CD56+ cell numbers for both groups and NCMC for REC remained elevated at 3HRE. CONCLUSIONS: E2 and P correlated with CD19+ and CD8+ cells, respectively. Although there were transient exercise-induced changes in immune indexes and E2 and LH, with LH remaining elevated at 3HEX for REC, both training groups elicited similar responses for plasma hormones, lymphocyte subpopulations, and NCMC.

The effects of chondroitin sulfate supplementation on indices of muscle damage induced by eccentric arm exercise.

AIM: Delayed onset of muscle soreness (DOMS) often results from unaccustomed exercise or exercise that involves heavy eccentric loading of skeletal muscle. Chondroitin sulfate (CS) has been reported to possess anti-inflammatory and analgesic properties and has been used widely in the treatment of osteoarthritis. Based on these findings, the investigators sought to determine whether CS supplementation might reduce DOMS symptoms associated with eccentric arm exercise. METHODS: Sixteen non-resistance-trained males participated in a double-blind protocol. Subjects consumed 3,600 mg x day-1 of encapsulated CS or placebo for 14 days preceding the exercise protocol and during 48 hours of follow-up measurements. Subjects performed a maximum of 50 eccentric contractions of the elbow flexors against a resistance that was 120% of the concentric one-repetition maximum. RESULTS: Significant time effects were present for soreness, relaxed elbow extension (joint angle), and creatine kinase; all measures were significantly altered 48 hours after the exercise session. No effects were present for complement system fragment C3a and prostaglandin E2. No significant treatment or interaction effects were detected for any of the variables. CONCLUSIONS: CS supplementation was not found to be effective in the prevention of DOMS, nor did it influence biochemical indices of inflammation and muscle damage following heavy eccentric loading of the arm flexors.

Threshold pressure training, breathing pattern, and exercise performance in chronic airflow obstruction.

The effects of six weeks of threshold pressure inspiratory muscle training (IMT) on inspiratory muscle performance, breathing pattern and exercise performance were studied in eight patients with severe airflow obstruction. The results indicated that IMT improved inspiratory muscle performance but did not affect exercise performance or breathing pattern during maximal exercise.

Improvements in exercise performance: effects of carbohydrate feedings and diet.

In an effort to determine the effects of carbohydrate (CHO) feedings immediately before exercise in both the fasted and fed state, 10 well-trained male cyclists [maximum O2 consumption (VO2 max), 4.35 +/- 0.11 l/min)] performed 45 min of cycling at 77% VO2 max followed by a 15-min performance ride on an isokinetic cycle ergometer. After a 12-h fast, subjects ingested 45 g of liquid carbohydrate (LCHO), solid carbohydrate confectionery bar (SCHO), or placebo (P) 5 min before exercise. An additional trial was performed in which a high-CHO meal (200 g) taken 4 h before exercise was combined with a confectionery bar feeding (M + SCHO) immediately before the activity. At 10 min of exercise, serum glucose values were elevated by 18 and 24% during SCHO and LCHO, respectively, compared with P. At 0 and 45 min no significant differences were observed in muscle glycogen concentration or total use between the four trials. Total work produced during the final 15 min of exercise was significantly greater (P less than 0.05) during M + SCHO (194,735 +/- 9,448 N X m), compared with all other trials and significantly greater (P less than 0.05) during LCHO and SCHO (175,204 +/- 11,780 and 176,013 +/- 10,465 N X m, respectively) than trial P (159,143 +/- 11,407 N X m). These results suggest that, under conditions when CHO stores are less than optimal, exercise performance is enhanced with the ingestion of 45 g of CHO 5 min before 1 h of intense cycling.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate balance in competitive runners during successive days of intense training.

This study was designed to investigate the effect of intense training on muscle glycogen stores under conditions of controlled carbohydrate (CHO) intake. On two separate occasions, 10 highly trained distance runners increased their training load for 5 days (20 km/day, approximately 80% maximal O2 consumption) while eating a diet whose carbohydrate composition either equaled (EQ-CHO) or contained approximately 50% of the runner's estimated daily expenditure (LO-CHO). Total muscle glycogen levels were lower after the LO-CHO regimen. Photometric analysis of the glycogen content in individual fibers revealed that 27% type I and 17% type II fibers had optical densities less than 0.2 U after the LO-CHO regimen, whereas 7% type I and 0% type II were similarly depleted after the EQ-CHO diet. A linear relationship was observed between the histochemical and direct chemical analysis of muscle glycogen content. Treadmill O2 uptake measured at 185 and 238 m/min was higher during the LO-CHO than the EQ-CHO regimen. Ratings of perceived exertion were higher during the 238-m/min run for the LO-CHO regimen. After 3 days of rest, running economy and perception of effort returned to pretraining levels and muscle glycogen stores were approximately 85% of the pretraining values. Thus when CHO intake was only approximately 50% of the energy requirements there was a marked depletion of muscle glycogen stores, particularly in type I fibers, and a concomitant decrease in running economy and increased perception of fatigue.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of 4- and 8-h preexercise feedings on substrate use and performance.

Seven well-trained male cyclists were studied during 105 min of cycling (65% of maximal oxygen uptake) and a 15-min "performance ride" to compare the effects of 4- and 8-h preexercise carbohydrate (CHO) feedings on substrate use and performance. A high CHO meal was given 1) 4-h preexercise (M-4), 2) 8-h preexercise (M-8), 3) 4-h preexercise with CHO feedings during exercise (M-4CHO), and 4) 8-h preexercise with CHO feedings during exercise (M-8CHO). Blood samples were obtained at 0, 15, 60, 105, and 120 min and analyzed for lactate, glucose, insulin, and glycerol. Total work output during the performance ride was similar for the M-4 (217,893 +/- 13,348 N/m) and M-8 trials (216,542 +/- 13,905) and was somewhat higher for the M-4CHO (223,994 +/- 14,387) and M-8CHO (224,702 +/- 15,709) trials (P = 0.059, NS). Glucose was significantly elevated throughout exercise, and insulin levels were significantly elevated at 15 and 60 min during M-4CHO and M-8CHO compared with M-4 and M-8 trials. Glycerol levels were significantly lower during the CHO feeding trials compared with placebo and were not significantly different during exercise when the subject had fasted an additional 4 h. The results of this study suggest that when preexercise meals are ingested 4 or 8 h before submaximal cycling exercise, substrate use and performance are similar.

Effects of resistance training on selected indexes of immune function in elderly women.

Women aged 67-84 yr were randomly assigned to either resistance exercise (RE, n = 15) or control group (C, n = 14). RE group completed 10 wk of resistance training, whereas C group maintained normal activity. Blood samples were obtained from the RE group (at the same time points as for resting C) at rest, immediately after resistance exercise, and 2 h after exercise before (week 0) and after (week 10) training. Mononuclear cell (CD3+, CD3+CD4+, CD3+CD8+, CD19+, and CD3-CD16+CD56+) number, lymphocyte proliferative (LP) response to mitogen, natural cell-mediated cytotoxicity (NCMC), and serum cortisol levels were determined. Strength increased significantly in RE subjects (%change 8-repetition maximum = 148%). No significant group, exercise time, or training effects were found for CD3+, CD3+CD4+, or CD3+CD8+ cells, but there was a significant exercise time effect for CD3-CD16+CD56+ cells. LP response was not different between groups, across exercise time, or after training. NCMC was increased immediately after exercise for RE subjects at week 0 and for RE and C groups at week 10. The week 0 and week 10 NCMC values were above baseline for both RE and C groups 2 h after exercise. In conclusion, acute resistance exercise did not result in postexercise suppression of NCMC or LP, and 10 wk of resistance training did not influence resting immune measures in women aged 67-84 yr.

Indomethacin does not influence natural cell-mediated cytotoxic response to endurance exercise.

Natural cell-mediated cytotoxicity (NCMC) has been shown to be attenuated during recovery from high-intensity or prolonged exercise. Two theories have been proposed to explain the transient suppression of NCMC: prostaglandin-induced inhibition of natural killer (NK) cell activity or a numerical redistribution of NK cells. This study was designed to examine the effects of oral indomethacin (a prostaglandin inhibitor) on NCMC before and after 1 h of high-intensity running (85% maximal oxygen uptake). A secondary purpose was to compare whole blood and isolated peripheral blood mononuclear cell assay procedures for assessing NCMC. Ten male distance runners completed two trials that were preceded by either 48 h of indomethacin (Indo; 150 mg/day) or no treatment (control). NK (CD3(-)/CD16(+)/CD56(+)) cell concentrations were significantly elevated postexercise but were not affected by Indo. NCMC was significantly suppressed at 1.5 h of recovery relative to preexercise only with the whole blood assay procedure. Indo was not found to influence NCMC, leukocyte, or lymphocyte subset concentrations. Mean cytotoxic response was significantly greater with the whole blood method.

Serum beta-endorphin levels during a graded exercise test to exhaustion.

Serum beta-endorphin levels during a graded exercise test to exhaustion. Med. Sci. Sports Exerc., Vol. 19, No. 2, pp. 78-82, 1987. Nine untrained college age males completed a graded exercise protocol to maximal capacity on a bicycle ergometer to determine if there was a relationship between intensity of exercise and serum beta-endorphin (beta-EP) levels. Subjects fasted for 12 h and abstained from physical activity at least 24 h prior to testing. Subjects completed the Multiple Affect Adjective Check List prior to and following exercise to ascertain if psychological state would be associated with beta-EP levels. The initial workload was 150 kilopond meters and was increased 150 kilopond meters every 3 min until VO2max or leg fatigue occurred. Expired gases were continuously analyzed, and a venous blood sample was drawn from an indwelling catheter during the final 30 s of each stage and 5-min post-exercise. beta-EP levels were determined from serum using a radioimmunoassay technique and corrected for cross-reactivity with beta-lipotropin using affinity chromatography. Resting beta-EP levels were 25.3 +/- 4.1 pg X ml-1 and did not demonstrate significant changes during any stage of exercise. A correlation analysis (r = 0.30) revealed no significant relationship between exercise intensity and beta-EP levels. Following exercise, beta-EP levels were significantly increased compared to resting values (38.8 +/- 4.8 pg X ml-1). In addition, psychological state was unaffected by exercise despite significant increases in recovery beta-EP levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of reduced training on muscular strength and endurance in competitive swimmers.

Following 5 months of competitive training (approximately 9,000 yards.d-1, 6 d.wk-1), three groups of eight male swimmers performed 4 wk of either reduced training (3,000 yard.session-1) or inactivity. Two groups reduced their training to either 3 sessions.wk-1 (RT3) or 1 session.wk-1 (RT1), whereas the third group (IA) did no training. Measurement of muscular strength (biokinetic swim bench) showed no decrement in any group over the 4 wk. In contrast, swim power (tethered swim) was significantly decreased (P less than 0.05) in all groups, reaching a mean change of -13.6% by week 4. Blood lactate measured after a standard 200-yard (183 m) front crawl swim increased by 1.8, 3.5, and 5.5 mM over the 4 wk in groups RT3, RT1 and IA, respectively. In group RT1, stroke rate measured during the 200-yard swim significantly increased (P less than 0.05) from 0.54 +/- 0.03 to 0.59 +/- 0.03 strokes.-1 while stroke distance significantly decreased (P less than 0.05) from 2.50 +/- 0.08 to 2.29 +/- 0.13 m.stroke-1 during the 4-wk period. Both stroke rate and stroke distance were maintained in group RT3 over the 4 wk of reduced training. Group IA was not tested for stroke mechanics. Whereas maximal oxygen uptake decreases significantly (P less than 0.05) over the 4 wk in group RT1 (4.75 to 4.62 l.min-1), no change in maximal oxygen uptake was observed in group RT3. These results suggest that aerobic capacity is maintained over 4 wk of moderately reduced training (3 sessions.wk-1) in well-trained swimmers. Muscular strength was not diminished over 4 wk of reduced training or inactivity, but the ability to generate power during swimming was significantly reduced in all groups.

Mood disturbance following increased training in swimmers.

Twelve male swimmers were studied psychologically before, during, and after 10 d of increased training. Daily training distance was increased from 4,000 to 9,000 m.d-1, and intensity was maintained at 94% of VO2max. Three of the swimmers were unable to tolerate the increased training load, and they did the same distance at slower speeds. Swimmers completed the Profile of Mood States, a muscle soreness scale, and a 24-h history each morning prior to the first of two daily training sessions. Changes across days were evaluated statistically with a one-way repeated measures ANOVA. Significant (P less than 0.005) increases occurred in the ratings of exercise intensity, muscle soreness, depression, anger, fatigue, and global mood disturbance, along with a reduction in general sense of well-being. Swimmers were classified as "responders" or "non-responders" on the basis of distress patterns using separate physiological and psychological criteria, and these classifications were performed in a double-blind setting. Close agreement (89%) was achieved between the psychometric and physiological judgments, and the physiological results appear in related papers. It is concluded that significant psychometric changes occur with an intense 10-d training regimen, and these alterations resemble those observed in swimmers exposed to increased training across several months. These findings underscore the potential utility of monitoring mood states in the prevention of staleness.

Run training versus cross-training: effect of increased training on circulating leukocyte subsets.

The purpose of this study was to determine the effects of increased training via cross-training (run + cycle) and run training on circulating leukocyte subsets. Male runners (N = 11) participated in two randomly assigned increased training (IT) periods after 30 d of normal training (NT). Each IT began after a 14 d period of reduced training (80% of NT) followed by 10 d of IT (200% of NT). During IT, the subjects ran in the afternoon for 10 d (100% NT) and performed 8 additional training sessions in the morning (100% NT) on a treadmill (ITRT) or a bicycle ergometer (ITCT). Blood samples were obtained before (D0), on day 5(D5) and after 10 d (D11) of ITRT and ITCT. A significant increase in the CD4+/CD8+ ratio occurred at D5 compared with D0 and D11. The CD4+/CD8+ ratio was significantly lower during ITRT compared with ITCT at D11. The number of circulating CD3+, CD4+, and CD8+ cells were significantly reduced at D11 compared with D0. In conclusion, 10 d of IT resulted in a significant reduction in the number of circulating T cells independent of the training mode and a reduction in the CD4+/CD8+ ratio for ITRT but not for ITCT.

Influence of selected carbohydrate drinks on cycling performance and glycogen use.

Eight well-trained male cyclists were used to determine the influence of carbohydrate feedings on exercise performance and muscle glycogen use. Two days prior to each trial, the subjects performed a 60-min "depletion ride" at 70% VO2max, which was followed by the ingestion of a high carbohydrate diet (approximately 500 g X -1). During the experimental trials, the men performed 2 h of cycling exercise and consumed 150 ml of 1 of 4 solutions at 24-min intervals. The drinks were: H2O (artificially flavored and sweetened); maltodextrin (5 g X 100 ml-1) and fructose (5 g X 100 ml-1); maltodextrin (7.7 g X 100 ml-1) and high fructose corn syrup (2.3 g X 100 ml-1); maltodextrin (3 g X 100 ml-1 and glucose (2 g X 100 ml-1). The amount of work completed during the four trials was not significantly different. Initial glycogen levels were high, and glycogen values were not significantly different at the beginning of exercise or at 90 min (185.35 +/- 3.26 and 91.93 +/- 3.39, respectively). Blood glucose was greater at 60 min in trial maltodextrin and glucose (5.70 +/- 0.36 mmoles X l-1), maltodextrin and high fructose corn syrup (6.05 +/- 0.54), and maltodextrin and fructose (6.03 +/- 0.42) compared to H2O (4.97 +/- 0.35) (P less than 0.05). Blood glucose remained elevated at 90 min during the maltodextrin and fructose and maltodextrin and high fructose corn syrup trials and at 120 min in the maltodextrin and fructose trial. No differences were observed between trials in blood lactate, serum glycerol, respiratory exchange ratio, or the subjects' perception of effort.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of sodium bicarbonate on sprint performance: relationship to dosage.

The purpose of this investigation was to determine the minimum oral dosage of bicarbonate needed to significantly elevate blood bicarbonate and the influence of induced alkalosis on performance in high-intensity, short-duration exercise. Nine endurance-trained cyclists performed four 2-min sprints on separate occasions using an isokinetic cycle ergometer (Fitron, Cybex, Inc.). One hour before each test, the cyclists consumed either a placebo (A), a solution of 0.10 g NaHCO3.kg-1 body weight (B), a solution of 0.15 g NaHCO3.kg-1 body weight (C), or a solution of 0.20 g NaHCO3.kg-1 body weight (D) in random order. Arterialized venous blood was taken before (PRE) and after (POST) ingestion, and 1, 3, 5, 10, and 15 min following the 2-min bike sprint. The results showed a significant increase in POST blood bicarbonate, and the elevation was incrementally related to the dosage. There was, however, no significant improvement in performance. Total work (mean +/- SE) for each treatment (N.m per 2 min) were: A, 47,267 (+/- 2,472); B, 47,004 (+/- 3,094); C, 46,312 (+/- 2,964); and D, 47,190 (+/- 2,621). The results of this study show that incremental doses of NaHCO3 of 0.20 g.kg-1 and below produce incremental elevations in blood bicarbonate but do not produce improvements in performance for a sprint bout lasting 2 min.

Effects of repeated days of intensified training on muscle glycogen and swimming performance.

Twelve, highly trained male swimmers were studied before, during, and after 10 successive days of increased training in an attempt to determine the physical effects of training over-load. Their average training distance was increased from 4,266 to 8,970 m.d-1, while swimming intensity was maintained at 94% (SE +/- 2%) of their maximal oxygen uptake, resulting in an average caloric cost during training of 2,293 kcal.d-1 (+/- 74). As a result of the intensified training regimen, the swimmers experienced local muscular fatigue and difficulty in completing the training sessions. Nevertheless, their swimming power, sprinting (s.22.86 m-1), endurance (s.365.8 m-1) performance, aerobic capacity, and muscle (m. deltoid) citrate synthase were unchanged as a consequence of the 10-d training regimen. Four of the 12 swimmers were, however, unable to tolerate the heavier training demands, and were forced to swim at significantly slower (P less than 0.05) speeds during the training sessions. These men were found to have significantly reduced muscle glycogen values, which was the result of their abnormally low carbohydrate intake. The findings of this research suggest that some swimmers may experience chronic muscular fatigue as a result of their failure to ingest sufficient carbohydrate to match the energy demands of heavy training.

Physiological responses to successive days of intense training in competitive swimmers.

To examine the physiological responses to successive days of intense training, 12 male collegiate swimmers doubled their training distance (4,266 +/- 264 to 8,970 +/- 161 m.d-1) while maintaining the intensity at approximately 95% VO2max for 10 d. Blood samples were obtained pre-exercise and immediately and 5 min after a sub-maximal (approximately 95% VO2max) front crawl swim (365.8 m) on days 0, 5, and 11. Swim performance was assessed from a maximal front crawl swim (365.8 m), two maximal front crawl sprints (22.9 m), and a semi-tethered swim power test. No significant changes were observed in performance. Pre-exercise serum cortisol (17.5 +/- 1.5, 19.5 +/- 1.6, and 20.6 +/- 1.2 micrograms.dl-1 for days 0, 5, and 11, respectively) and creatine kinase (56.2 +/- 7.7, 93.1 +/- 10.1, and 119.0 +/- 23.1 U.l-1 for days 0, 5, and 11, respectively) values were significantly elevated (P less than 0.05) on days 5 and 11 compared to day 0. Resting plasma catecholamine concentrations were higher but not significantly different (P greater than 0.05) at the end of the training period. Measurements of hemoglobin and hematocrit indicated a relative increase of 11.4 +/- 2.7% (P less than 0.05) in estimated plasma volume during the training period. Resting blood glucose values were unaffected by the training regimen while small but significant decreases in resting blood lactate values (1.01 +/- 0.06, 0.85 +/- 0.06, and 0.86 +/- 0.06 mmol.l-1 for days 0, 5, and 11, respectively) were observed on days 5 and 11. Resting heart rate and systolic blood pressure were not affected by the increased training load.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of exercise and carbohydrate composition on gastric emptying.

To examine the gastric emptying characteristics of selected test drinks varying in carbohydrate composition and concentration, twenty-five runners ingested 400 ml of a solution in one or more of a series of trials followed by either 15 min seated rest or 15 min running (50 to 70% VO2 max). The solutions tested at rest included water, 5.0% maltodextrin, 3.0% maltodextrin + 2% glucose (MG5.0), and 4.5% maltodextrin + 2.6% fructose (MF7.1). Solutions tested during running included water, MG5.0, MF7.1, 5.5% maltodextrin + 2% glucose, and 5.5% maltodextrin + 2% fructose. At rest and during running, water emptied significantly (P less than 0.5) faster than all other drinks. In the running trials, the volume of gastric residue of 5.5% maltodextrin + 2% fructose (221.7 +/- 11.0 ml) was significantly greater than water (103.4 +/- 19.0 ml), MG5.0 (153.3 +/- 16.8 ml), and MF7.1 (167.3 +/- 14.8), suggesting an inhibitory role of glucose on gastric emptying. Running resulted in a significantly lower volume of gastric residue of water, MG5.0, and MF7.1 (103.4 +/- 19.0, 153.3 +/- 16.8, and 167.3 +/- 14.8 ml, respectively) as compared to the corresponding drinks at rest (209.3 +/- 12.6, 287.7 +/- 16.0, and 271.0 +/- 17.8 ml, respectively). These results suggest a possible advantage for including maltodextrin and fructose as carbohydrate sources in athletic drinks. Furthermore, the rate of gastric emptying is enhanced while running, possibly due to increased mechanical movement of fluid within the stomach.

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)