A high fat meal, a bout of aerobic exercise and arterial function.

I thought I would start off with an easy article, that also serves as a prime example of what I am trying to accomplish with this blog.

A recent publication by Padilla et al. (2006) has recently unveiled some new evidence on the protective nature of exercise on arterial dysfunction following a high fat meal.

Atherosclertoic plaque

BACKGROUND.

It is estimated that 16 million people suffer from coronary heart disease (CHD). The underlying mechanism for CHD is the development of atherosclerosis, the narrowing of the coronary arteries due to a build up of fatty plaques.

Fundamentally, atherosclerosis occurs due to impairment of endothelial cells. The endothelial cells line the blood vessels in the body and are now known to be a key regulator in the health of a blood vessel. Any dysfunction can trigger a cascade of events leading to the formation of atherosclerotic plaques and thus heart disease.

One of the major factors found to cause endothelial cell dysfunction is a high-fat meal (Cuevas et al 2000). Many previous studies have found that a single high-fat meal can cause endothelial dysfunction lasting up to 6 hours (Gaenzer et al. 2001; Plotnick et al. 1997; Vogel et al. 1997).

It is thought that the post-meal increases in blood triglycerides are responsible for increases in oxidative stress and this triggers the endothelial cell dysfunction.

OVERALL HYPOTHESIS.

Both acute and chronic exercise are known to promote and preserve endothelial function, so Padilla et al. (2006) set out to find if an acute bout of exercise performed 2h following consumption of a high fat meal could protect the endothelial cells from the stress of the high-fat meal.

DESIGN AND METHODS.

Groups:

1). Low fat meal only (LFM) (Frosted Flakes, skim milk, and orange juice)

2). High fat meal only (HFM) (McDonalds Egg McMuffin, Suasage McMuffin, Two Hashbrowns and water)*

3.) High fat meal + 1 bout of aerobic exercise 2h post feeding (HFM-Ex)**.

* the LFM and HFM were both 940-950kcals.

* *aerobic exercise was 45 min of treadmill walking at low intensity (60% of VO2 peak/~77% of your max heart rate)

Subjects:

Eight subjects (5 men, 3 women; age ~25) free of obesity, cardiovascular and metabolic disease. Subjects were of average fitness for this age range (VO2max = 52.9 ml/kg/min)

Main Measure:

Flow-mediated dilation (FMD), which has been long used to measure endothelial function. One fantastic feature of FMD is that it can detect dysfunction in the arteries long before there is detectable atherosclerotic plaque development.

FINDINGS.

The flow-mediated dilations were significantly higher following the low fat meal (7.18%) and high fat meal + exercise (8.72%), suggesting improved endothelial function over the high fat only group.

SIGNIFICANCE.

This study suggests two very intersting ideas….

1. The meal to meal decisions you make play a direct impact on endothelial function and thus cardiovascular disease risk. This may change the way some of you look at your meal to meal food choices. It has for me. The idea that a single high fat meal has the capacity to induce arterial dysfunction is not surprising, but I believe it is unrecognized.

2. Exercise can counteract the endothelial dysfunction (as measured by FMD) encountered by a single high fat meal. This is a interesting finding, in that it offers us a means by which to protect ourselves from atherosclerosis. This is highly applicable, because one can essentially abolish the coronary consequences of that pizza and cheesecake you ate for dinner, simply by taking a 45 minute walk. While this is not a replacement for a good diet, nor a license for us to eat what we like at will, it does offer the health conscious a means by which to enjoy a “cheat meal” once in a while. Most importantly you can enjoy a cheat meal without deleterious effects to your cardiovascular health.

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