Files in this item



application/pdf9512509.pdf (7MB)Restricted to U of Illinois
(no description provided)PDF


Title:Meal timing and composition alter plasma amino acid and skeletal muscle protein metabolism after exercise
Author(s):Paul, Gregory Linden
Doctoral Committee Chair(s):Layman, Donald K.
Department / Program:Food Science and Human Nutrition
Discipline:Nutritional Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Biochemistry
Health Sciences, Nutrition
Health Sciences, Recreation
Abstract:The purpose of this research was to determine is feeding meals with various macronutrient profiles at different times relative to exercise affected plasma amino acid responses, fractional rates of skeletal muscle protein synthesis (Ks), or both.
In the first study, 12 subjects (6 males, 6 females) consumed isocaloric meals consisting of corn (C), oat (O), or wheat (W) cereals 90 minutes before cycling exercise.
Ingestion of O produced lower insulin levels and a lower rate of carbohydrate oxidation 85 min after meal ingestion compared C and W. During exercise, the drop in plasma glucose was inversely related to pre-exercise insulinemia, and free fatty acid responses and fat utilization were greater in the fasted trial compared to the fed trials. However, pre-exercise meal ingestion failed to influence performance times for the 6.4 km ride. After 60 min of recovery, the trp:LNAA ratio, perceived fatigue, and perceived hunger were significantly higher for F compared to all others.
From this study, we conclude that (a) pre-exercise meals influenced energy metabolism during the early phase of endurance exercise, (b) oat-based cereals minimized perturbations in plasma glucose and insulin levels, (c) pre-exercise meals affected trp:LNAA ratios before, during, and after exercise, and (d) pre-exercise feedings did not improve physical, cognitive, or psychomotor performance, but did minimize perceptions of fatigue and hunger during recovery.
A second series of investigations were designed to examine plasma amino acid changes and skeletal muscle protein synthesis rates after exercise, and determine if meal feeding before or after exercise altered recovery patterns. Untrained male Sprague-Dawley rats weighing approximately 225 gm were exercised on a motor-driven treadmill (26 $\rm m\cdot min\sp{-1}$ 1.5% grade) for 2 hr after 12, 5, or 1.5 hr of food deprivation. The fractional rate of skeletal muscle protein synthesis (Ks) was determined in the gastrocnemius muscle at 1, 4.5, and 8 hr following exercise using a 1-hr continuous infusion of $\sp3$H leucine via the jugular vein. A second group of 12-hr fasted animals were fed either a complete nutritional supplement or carbohydrate immediately after the exercise bout. Ks in the gastrocnemius of post-exercise fed animals was determined 1, 4.5, and 8 hr following exercise using a bolus injection (0.7 ml per 100 gm BW) of $\sp3$H isoleucine (200 mM containing 100 $\rm\mu Ci\cdot ml\sp{-1}$) via the jugular vein.
One hour after exercise, Ks was depressed 23-27% compared to non-exercised controls. After 4.5 hr of recovery, Ks had returned to control levels. The Ks recovery pattern was not influenced by pre-exercise fast length, although absolute Ks values were highest in 1.5-hr fasted animals. Only when animals ingested the complete nutritional supplement post-exercise were Ks values not depressed 1 hr after exercise. Plasma alanine concentration was inversely related to plasma leucine concentration and directly related to Ks while plasma leucine was inversely related to Ks. (Abstract shortened by UMI.)
Issue Date:1994
Rights Information:Copyright 1994 Paul, Gregory Linden
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9512509
OCLC Identifier:(UMI)AAI9512509

This item appears in the following Collection(s)

Item Statistics