Low- to moderate-intensity exercise for 1 hour attenuates lipid levels and insulin resistance

1. This randomized controlled trial found that compared to no exercise, low-intensity exercise on a treadmill for 1 hour significantly reduced serum triglyceride levels following a fat-rich meal that was ingested 12 hours post-exercise.

2. Furthermore, when compared to no exercise, moderate-intensity exercise on a treadmill for 1 hour significantly reduced insulin resistance following a fatty-rich meal ingested 12 hours post-exercise.

Evidence Rating Level: 1 (Excellent)

Cardiovascular disease is the leading cause of death worldwide. One of the many factors influencing this complex disease is serum triglyceride clearance. Prolonged triglyceride blood levels have been linked to impaired endothelial function, atherosclerosis, and insulin resistance. High prolonged blood insulin levels cause increased hepatic production of very low-density lipoproteins, increasing plaque deposition in arteries. A single bout of exercise has been found to decrease both post-prandial serum triglyceride and insulin levels. However, the effectiveness of different exercise intensities on this relationship has not been elucidated. Therefore, this randomized control trial aimed to study the effect of different exercise intensities on post-prandial triglyceride levels and insulin resistance in healthy individuals.

Ten healthy males with blood triglyceride levels ≤ 1.69 mmol/L were recruited. First, the VO2 max for each participant was determined. Then, participants underwent three exercise trials by running on a treadmill at 40%, 60%, and 70% of their VO2 max for 1 hour. Each participant additionally had a trial of not exercising, which acted as the control group. Then, 12 hours following an exercise trial, a meal containing 100 grams of fat was ingested. Blood samples were collected before meal ingestion and then 2, 4, 6, 8, and 24 hours following meal ingestion. The primary outcome measures were triglyceride levels and insulin resistance measured based on the Homeostatic Model Assessment for Insulin Resistance (HOMA2-IR). Additionally, the total area under the curve of triglyceride (AUCTG) concentrations was monitored.

The results show that at 2, 4, and 6 hours post-prandially, all three exercise intensities provided lower triglyceride levels compared to the control, but they were not significantly different from one another. Insulin resistance values over an 8-hour period post-ingestion showed that only 60% and 70% VO2 max exercise intensities were significantly lower than the control. However, this study had quite a small and limited sample size of 10 normolipidemic young males. Additionally, low- and high-intensity exercise was completed for the same time period (1 hour), which may make results less applicable to what is capable of the general population. Nonetheless, this study was valuable in outlining the optimal exercise intensity needed to reap cardiovascular benefits related to triglyceride and insulin levels.

Click to read the study in Journal of Exercise Science & Fitness

Image: PD

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