Effects of feeding on muscle blood flow during prolonged exercise in miniature swine

Abstract

Eight exercise-trained miniature swine were studied during prolonged treadmill runs (100 min) under fasting and preexercise feeding conditions. Each animal ran at identical external work loads that corresponded to 65% of the heart rate reserve (210-220 beats/min) for the two exercise bouts. Cardiac outputs and stroke volumes were higher and heart rates lower for fed than for fasting runs (P less than 0.05). Preexercise feeding did not alter oxygen consumption, core temperature, mean arterial pressure, and arterial-mixed venous oxygen difference during prolonged exercise; however, mixed venous lactate concentration was lower at end exercise than during fasting conditions (1.2 vs. 2.6 mM, P less than 0.05). Microsphere measurements of regional blood flow revealed significantly higher total gastrointestinal flow (23%) for fed than for fasting conditions. Throughout the exercise bout, blood flow to the biceps femoris, semitendinosus, and tibialis anterior muscles was lower in fed than in fasted animals (P less than 0.05). Combined hindlimb muscle blood flow averaged 15 ml.min-1.100 g-1 (18%, P less than 0.05) lower under feeding than fasting run conditions. These findings provide further evidence that cardiovascular reflexes originate in the gut after feeding to increase cardiac output and redistribute a portion of the blood flow away from active muscle to the gastrointestinal tract during prolonged exercise.

Priority of blood flow to splanchnic organs in humans during pre‐ and post‐meal exercise

“…However, the maintenance of splanchnic flow during exercise in our study is at variance with results from investigations in animals such as rats and miniature swine (McKirnan et al 1991, Mush et al 1991) and also at variance with results reported in humans (Rowel1 et al. 1965, Rowell 1974,1984, Qamar & Read 1987.…”

“…1965, Rowell 1974,1984, Qamar & Read 1987. Marked exercise-induced reduction in splanchnic flow was a central observation in these previous studies, although McKirnan et al (1991) found evidence of some reflex redistribution of blood flow away from active muscles to the gastrointestinal tract during prolonged exercise in fed animals. However, no or only modest exercise-induced reductions in splanchnic flow were observed in dogs (Burns & Schenk 1969, Fronek & Fronek 1970, Sanders et al 1976 and baboons (Vatner 1978).…”

“…Workloads as percentages of ~o a m a x were calculated by comparing actual heart rates during exercise with expected maximum heart rate as determined by the subject's age. (Laughlin & Armstrong 1982, Mush et al 1991 and in miniature swine (Armstrong et al 1987, McKirnan et al 1991, whereas little or no such flow reduction has been reported in dogs (Fronek & Fronek 1970, Sanders et al 1976). In baboons, Vatner (1978) reported more moderate reductions in splanchnic flow on exercise, whereas very marked reductions were seen on excitement.…”

Androgen receptors and testosterone in men—Effects of protein ingestion, resistance exercise and fiber type

“…Even other explanations for the attenuation of the testosterone response to protein nutrition have to be taken into account. Pre-and post-exercise nutrition can re-distribute part of the blood flow away from active muscles to the gastrointestinal tract [46]. That might therefore even lower the muscle uptake of hormones during RE bout.…”

Effect of strength training session on plasma amino acid concentration following oral ingestion of leucine, BCAAs or glutamine in men

“…During eating, the blood Xow to the gastric area is increased, but when doing exercise the eVect is opposite (e.g. McKirnan et al 1991). …”