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Energy intake (EI) and energy expenditure (EE) are relatively easy to measure accurately over short periods in a laboratory setting, but less so during a multi-day competition. Our goal was to measure EI and EE as accurately as possible during a 6-day, 10-stage cycling race. We prepared all meals and supplements, assessed EI (weighed diet-records) and macrontrient intake, total EE (doubly labelled water), resting metabolic rate (respiratory gas exchange), exercise EE (power meters), and body mass. Body composition was measured several days before and after racing (dual x-ray absorptiometry). Body mass remained stable over the course of the race. The mean EI (27.3+/-3.8 MJ/day) nearly matched EE (27.4+/-2.0 MJ/day). The majority (62%) of EE was exercise EE. Macronutrient intake was within or exceeded the recommendations. Lean body mass increased and fat mass decreased in most of our participants. Our study indicates that EI can match high EE with adequate macronutrient intake during multi-day cycle racing and may be facilitated by appropriate foods being available at appropriate times. This optimization of nutritional provision supports positive changes in body composition.

This study examined the effects of participation in the Tour of Southland, a 6-day bicycle race, on serum markers of bone turnover in 5 elite male cyclists. During the race, energy intake matched expenditure. Osteocalcin was increased approximately 300% on days 1-5; and C-terminal telopeptide of type I collagen was elevated (43%) on day 3. Participation in a cycling stage race does not appear to have deleterious effects on bone turnover.

This study examined the relationship between gastrointestinal (GI) symptoms and dietary intake in triathletes. Fifty-five male triathletes (age 31 +/- 6 yrs) were surveyed regarding the most recently completed half Iron Man triathlon. Questions were asked regarding GI symptoms and dietary intake. Fifty-two percent complained of eructation and 48% of flatulence. Other symptoms were abdominal bloating, vomiting urge, vomiting, nausea, stomachache, intestinal cramps, and diarrhea. More symptoms occurred while running than at other times. All individuals who had eaten within 30 min of the start vomited while swimming. Fat and protein intake was greater in those who vomited or had the urge to vomit than in those without these symptoms. Of the former, 93% had consumed a hypertonic beverage. Forty percent of those who drank a hypertonic beverage and only 11% of those who drank an iso- or hypotonic beverage had severe complaints. Four of five individuals with stomachache had consumed a strongly hypertonic beverage. All subjects with intestinal cramps had eaten fiber-rich foods in the prerace meal; only 10% of those without cramps had done so.

The incidence of gastrointestinal (GI) distress reported among long distance runners and not in practitioners of other sports with more gliding movements, such as bicycling, leads one to speculate that there is a difference in concussions and vibration of the GI region and that this may possibly be associated with the disparity in GI disorders. The present experiment was conducted to quantify the difference in vibration (accelerations/decelerations) of the GI region during running as compared to bicycling. An actometer was used which included a piezoelectric sensor. The sensor was placed on the abdomen of six subjects during identical trials of bicycling and running. Movement in three planes was detected by the sensor and recorded. The accelerometer output (AO) is an integral of these measurements. AO was used in making comparisons of the two types of movement, expressed as counts per minute. Mean AO was more than doubled in running, 859.5 +/- 130.1 (SD), versus bicycling, 425.8 +/- 149.5 (SD) (p less than .0001). The common assumption that running results in more body vibrations than bicycling has been substantiated and quantified. Although the differences are large, it can only be speculated that these differences explain the high frequency of GI symptoms among runners.

The high prevalence of gastrointestinal complaints in long-distance runners makes the movements specific to this type of exercise suspected of causing a disruption of normal gastrointestinal function. Gastric emptying rate is one indicator thereof. In the present study trained volunteers performed similar repeated fluid ingestion tests while running and while bicycling for 80 min at 70% VO2max. Control tests at rest were also conducted. Two drinks containing carbohydrate were tested, one hypertonic, and one isotonic. Artificially sweetened water was used as a control. Gastric emptying rate of the isotonic drink, expressed as a percentage of the volume in the stomach at the beginning of each measurement period, did not differ between cycling and running during the first 40 min and was faster during cycling than during running between 40 and 80 min. With the hypertonic drink no differences between cycling and running were observed. In comparing gastric emptying rates after each sequential bolus, at rest, the isotonic drink was observed to maintain a high emptying rate, equal to that of water, whereas the hypertonic drink emptied more slowly after the first 20-min period. A similar pattern was observed during both running and cycling. The isotonic drink continued to empty quickly after the initial 20 min, whereas GE rate of the hypertonic drink decreased after the initial 20 min.

Sustained exhausting exercise is thought to depress appetite and food intake. The aim of the present investigation was to study the effect of intensive cycling exercise, with an energy expenditure comparable to values derived from the Tour de France, on food and fluid intake, energy balance, nitrogen balance, and nutrient oxidation. Thirteen highly trained cyclists consuming a normal carbohydrate (CHO)-rich diet (60 En%) were studied during a 7-day stay in a respiration chamber. Two preparation days were followed by a standardized resting day (3), after which the subjects completed two exhausting exercise days (4-5). On day 6 the standardized resting day was repeated. Food and fluid intake were measured by weighed procedure. Energy expenditure was calculated from continuous gas analysis. Energy and nitrogen losses were calculated from all measured excretes. The results showed that energy balance (EB) and nitrogen balance (NB) were positive on the first resting day and became negative on the exercise days. EB was positive again on the recovery day whereas NB remained negative. Nitrogen losses almost balanced N intakes (1.7 g.kg-1) indicating an increased protein requirement. CHO oxidation exceeded CHO intake indicating endogenous CHO depletion. Contribution of CHO to energy exchange decreased from 51.4% +/- 3.1% on day 4 to 40.6% +/- 3.4% on day 5; this decrease was compensated by an increased fat oxidation. The food consumption pattern during days 4 and 5 was not different from days 2 and 6. In-between meal consumption accounted for 30.5%-34.3% of total energy intake. Fluid consumption was adequate to compensate for the losses.(ABSTRACT TRUNCATED AT 250 WORDS)

Field studies during the Tour de France indicated that cyclists consume 30% of daily energy intake as liquid carbohydrate (CHO)-enriched nutrition with the goal of maintaining energy and CHO balance. The aim of the present investigation was to study the effect of such dietary manipulation during 2 days of long-lasting exhausting cycling on food and fluid intake, energy balance, nitrogen balance, and nutrient oxidation. Thirteen highly trained cyclists were divided into two subgroups receiving ad libitum either a primarily maltodextrin-based beverage (Mf) (20% w/v, 85% maltodextrin, 15% fructose) or a 50/50% composed fructose-maltodextrin (FM) beverage in addition to their normal diet. The study was performed during a 7-day stay in a respiration chamber (2 preparation days, 1 standardized resting day, 2 cycling days, 1.5 standardized recovery days), allowing for continuous gas analysis, weighed food and fluid intake procedure, and collection of excretes. The data of this study were compared with data from the same subjects receiving a normal CHO-rich diet (N) (60 En%) in a separate experiment. The results showed that the cyclists receiving Mf were able to maintain EB during sustained exercise days in contrast to when receiving N and to subjects receiving FM. With Mf treatment CHO intake increased, up to 80 En% (17.5 +/- 1.0 g.kg-1 BW) and carbohydrate balance remained positive. The subjects receiving FM had the largest CHO oxidation, calculated from R. Protein oxidation significantly increased in N and FM as a result of exercise but not in Mf. The latter subjects were in slightly negative nitrogen balance at a protein intake level of 1.4 g.kg-1 BW.(ABSTRACT TRUNCATED AT 250 WORDS)