Effects of exercise and diet on muscle triglyceride

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Authors
Starling, Raymond D.
Advisor
Costill, David L.
Issue Date
1996
Keyword
Degree
Thesis (Ph. D.)
Department
Human Performance Laboratory
Other Identifiers
Abstract

The purpose of this investigation was to examine the effects of exercise and diet on muscle triglyceride. Seven endurance-trained men completed a 120min cycling bout at 65% of V O2max in an attempt to lower muscle glycogen and triglyceride. Each subject then ingested an isocaloric, high-carbohydrate (HI-CHO; 83% of kcal) or high-fat (HI-FAT; 68% of kcal) diet for the ensuing 24 h. A 1600 kJ cycling time trial was completed following this 24-h dietary period. Muscle glycogen concentration before (571±38 vs. 599±41 mmol•kg dw-1) and after (241±36 vs. 285±41 mmol•kg dw-1) the 120-min cycling bout was not different (P>0.05) between the HI-CHO and HI-FAT trials, respectively. Muscle triglyceride concentration before (33.0±2.3 vs. 37.0±2.1 mmol•kg dw-1) and after (30.9±2.4 vs. 32.8±1.6 mmol•kg dw-1) the 120-min cycling bout was also not different between the HI-CHO and HI-FAT trials, respectively. In addition, muscle triglyceride did not decrease significantly during the cycling bout for the HI-CHO (2.1±2.1 mmol•kg dw-1) or HI-FAT (4.2±1.8 mmol•kg dw-1) trial. Over the 24-h dietary period, a significantly greater amount of glycogen was resynthesized during the HI-CHO (308±41 mmol•kg dw-1) versus the HI-FAT trial (42±23 mmol•kg dw-1). Muscle triglyceride concentration increased 11.9±1.6 mmol•kg dw-1 (P<0.05) and decreased 3.4±1.8 mmol•kg dw-1 (P>0.05) during the 24-h dietary period for the HI-FAT and HI-CHO trials, respectively. Cycling performance time was significantly greater during the HI-FAT (139.3±7.1 min) compared to the HICHO (117.1±3.2) trial. The average V02 (3.40±0.12 vs. 2.96±0.17 L•min-1) and RER (0.89±0.01 vs. 0.82±0.01) during the time trial were higher for the HI-CHO than the HI-FAT trial, respectively. These data demonstrate that a small, insignificant amount of muscle triglyceride is utilized during prolonged, moderate-intensity cycling. Furthermore, 24 h of a high-fat diet increased muscle triglyceride concentration and reduced endurance performance.