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Biomedical subjects

Robert Murray

Publications and source records attributed to Robert Murray.

6 recordsLinked to original sources
PubMed2006

Training the gut for competition.

The gut is an important athletic organ because it mediates water and nutrient uptake during exercise. But upper- and lower-gastrointestinal complaints, common to many athletes during exercise, can negatively impact performance, and in severe cases put health at risk. The gut is sensitive to water and nutrient intake during exercise and to hypovolemia, hyperthermia, hypoglycemia, hypoxia, and ischemia. Most gastrointestinal complaints during exercise are mild and of no risk to health, but hemorrhagic gastritis, hematochezia, and ischemic bowel can present medical challenges. Proper training and nutrition minimize the risk of gastrointestinal discomfort during exercise by assuring rapid gastric emptying and absorption of water and nutrients and by maintaining adequate perfusion of the splanchnic vasculature.

Adaptation, Physiological↗
PubMed2005

Sweat and sodium losses in NCAA football players: a precursor to heat cramps?

This observational study was designed to determine whether football players with a history of heat cramps have elevated fluid and sodium losses during training. During a "two-a-day" training camp, five Division I collegiate football players (20.2 +/- 1.6 y, 113 +/- 20 kg) with history of heat cramps (C) were matched (weight, age, race and position) with a cohort of teammates (19.6 +/- 0.6 y, 110 +/- 20 kg) who had never cramped (NC). Change in body weight (adjusted by fluid intake) determined gross sweat loss. Sweat samples (forearm patch) were analyzed for sodium and potassium concentrations. Ad libitum fluid intake was measured by recording pre- and post-practice bottle weights. Average sweat sodium loss for a 2.5-h practice was projected at 5.1 +/- 2.3 g (C) vs. 2.2 +/- 1.7 g (NC). When averaged across two practices within the day, fluid intake was similar between groups (C: 2.6 +/- 0.8 L vs. NC: 2.8 +/- 0.7 L), as was gross sweat loss (C: 4.0 +/- 1.1 L vs. NC: 3.5 +/- 1.6 L). There was wide variability in the fluid deficit incurred for both C and NC (1.3 +/- 0.9 vs. 0.7 +/- 1.2%) due to fluid intake. Sweat potassium was similar between groups, but sweat sodium was two times higher in C versus NC (54.6 +/- 16.2 vs. 25.3 +/- 10.0 mmol/L). These data indicate that sweat sodium losses were comparatively larger in cramp-prone football players than in NC. Although both groups consumed sodium-containing fluids (on-field) and food (off-field), both appeared to experience an acute sodium deficit at the end of practices based on sweat sodium losses. Large acute sodium and fluid losses (in sweat) may be characteristic of football players with a history of heat cramping.

Adult↗
PubMed2004

Palatability and voluntary intake of sports beverages, diluted orange juice, and water during exercise.

Palatability and voluntary intake of 4 beverages commonly available to athletes were compared in a laboratory exercise protocol designed to mimic aerobic training or competitive conditions in which limited time is available for drinking. Diluted orange juice (DOJ), homemade 6% carbohydrate-electrolyte sports beverage (HCE), commercially available 6% carbohydrate-electrolyte sports beverage (CCE), and water (W) were tested. Fifty adult triathletes and runners (34 males, 16 females) exercised for 75 min at 80-85% of age-predicted heart rate, during which time they were given brief access (60 s) to one of the beverages after 30 min and 60 min of exercise. Results indicated that for overall palatability, CCE > W, HCE, DOJ; W > DOJ, and for amount of beverage consumed, CCE > W, HCE, DOJ; HCE > W, DOJ. The palatability of these beverages varied substantially, as did their voluntary intakes during exercise.

Adult↗
PubMed2004

Gastrointestinal discomfort during intermittent high-intensity exercise: effect of carbohydrate-electrolyte beverage.

This study investigated whether different beverage carbohydrate concentration and osmolality would provoke gastrointestinal (GI) discomfort during intermittent, high-intensity exercise. Thirty-six adult and adolescent athletes were tested on separate days in a double-blind, randomized trial of 6 % and 8 % carbohydrate-electrolytes (CHO-E) beverages during four 12-min quarters (Q) of circuit training that included intermittent sprints, lateral hops, shuttle runs, and vertical jumps. GI discomfort and fatigue surveys were completed before the first Q and immediately after each Q. All ratings of GI discomfort were modest throughout the study. The cumulative index for GI discomfort, however, was greater for the 8 % CHO-E beverage than for the 6 % CHO-E beverage at Q3 and Q4 (P < 0.05). Averaging across all 4 quarters, the 8 % CHO-E treatment produced significantly higher mean ratings of stomach upset and side ache. In conclusion, higher CHO concentration and osmolality in an ingested beverage provokes stomach upset and side ache.

Adolescent↗