Purpose: This study examined the effect of variable-intensity shuttle running on gastric emptying of a carbohydrate-free placebo (Plac) drink and of a 6.4% carbohydrate-electrolyte (CHO) sports drink.
Method: We compared the volume of test drink emptied during two 15-min periods of walking exercise (WE) with that during two 15-min periods of the Loughborough Intermittent Shuttle Test (LIST). Gastric emptying was measured on the four trials using a double-sampling aspiration technique in eight healthy males after ingestion of a 420 +/- 49 mL and a 168 +/- 20 mL bolus of the appropriate test drink at the start of the first and second exercise period, respectively.
Results: During the initial 15 min of exercise, the mean (+/-SD) volume of Plac (124 +/- 95 mL) and CHO (71 +/- 43 mL) drink emptied was similar between the two LIST trials, but the volume of Plac (227 +/- 85 mL) and CHO (159 +/- 63 mL) drinks emptied on the WE trials was greater than for the respective test drinks on the LIST trials. Similar volumes of test drinks were emptied on all trials (P = 0.20) during the second 15 min of exercise. Over the 30 min of each trial, the exercise intensity of the LIST reduced the volume of the Plac (211 +/- 108 mL) and CHO (208 +/- 83 mL) drink emptied compared with that on the WE trial for the Plac (396 +/- 74 mL) and CHO (293 +/- 73 mL) drink, respectively.
Conclusions: The exercise intensity of the LIST is sufficient to slow gastric emptying of carbohydrate and noncarbohydrate containing drinks compared with walking. Dilute carbohydrate-electrolyte drinks empty at about the same rate as carbohydrate-free beverages during variable-intensity running.