Study: low GI carbs better for recovery in endurance athletes

[Johnka]

From Berardi's Review of the 2004 ACSM Conference

Topic: Low Glycemic Carbs and Recovery
Authors: Emma Stevenson and colleagues from Loughborough University
Abstract # 0157

It’s no surprise that high GI carbs ingested before exercise may, because of the rise in insulin concentration that accompanies a high GI meal, suppress fat oxidation. This can cause an increased reliance on carbohydrate energy during exercise and deplete carbohydrate reserves more quickly.

In this study, researchers fed subjects low GI meals and high GI meals 24 hours after an exhausting exercise bout. The nine male subjects ran for 90 minutes and immediately after ingested either a low GI diet or high GI diet for 24 hours. After the 24 hour recovery period, they performed a run to exhaustion at 70% VO2max.

Subjects eating the low GI diet performed better (+11 seconds in the time to exhaustion trial) and burned more fat than subjects eating the high GI diet leading up to this second bout of exercise. In the end, it appears that a chronic low GI diet offers advantages in endurance athletes.

I might add the caveat that endurance athletes still need their high GI carbs during and immediately after training in order to resynthesize glycogen quickly before getting back to those low GI meals.

[wingsfan]

Originally posted by Johnka:
From Berardi's Review of the 2004 ACSM Conference

quote:

---

Topic: Low Glycemic Carbs and Recovery
Authors: Emma Stevenson and colleagues from Loughborough University
Abstract # 0157

It’s no surprise that high GI carbs ingested before exercise may, because of the rise in insulin concentration that accompanies a high GI meal, suppress fat oxidation. This can cause an increased reliance on carbohydrate energy during exercise and deplete carbohydrate reserves more quickly.

In this study, researchers fed subjects low GI meals and high GI meals 24 hours after an exhausting exercise bout. The nine male subjects ran for 90 minutes and immediately after ingested either a low GI diet or high GI diet for 24 hours. After the 24 hour recovery period, they performed a run to exhaustion at 70% VO2max.

Subjects eating the low GI diet performed better (+11 seconds in the time to exhaustion trial) and burned more fat than subjects eating the high GI diet leading up to this second bout of exercise. In the end, it appears that a chronic low GI diet offers advantages in endurance athletes.

I might add the caveat that endurance athletes still need their high GI carbs during and immediately after training in order to resynthesize glycogen quickly before getting back to those low GI meals.

[/quote]i'm confused. so was the initial exercise bout that they started with the same as the one that they used 24 hours later? which leads to the question that the low-GI performed 11 seconds better. better than what? their previous times or the times of those that were ingesting the high GI meal?

[Kaiser]

As a guy converting to an endurance athlete, this is interesting. I wonder why taking the high GI carbs post-endurance exercise wouldn't promote fat gain?

Through experimenting with my diet and bike riding this summer, I've come to the following conclusions (for me):
-I need high GI carbs while riding anything more than 90 minutes or performance suffers
-I need to ingest some protein during any ride longer than 120 minutes or recovery is slower and the next performance suffers
-high GI meals the night before (the dreaded pasta bowl) seem to lead to better performance the next day, especially on rides lasting longer than 3 hours. This is much more true than when ingesting a meal with a good amount of protein in it.
-If I fail to eat a healthy meal about 1-3 hours before a long ride, I come back ravenous and eat everything in sight (usually not all 'good' food either).
-I cannot seem to maintain performance on the bike AND lose fat in the midsection at the same time. The same high GI carbs that promote good performance on the bike also seem to deter my body from losing fat, even when the on-bike kcalories expended during a long ride top 3,500.

Comments on my suppositions, John?

[Kaiser]

Originally posted by wingsfan:
]i'm confused. so was the initial exercise bout that they started with the same as the one that they used 24 hours later? which leads to the question that the low-GI performed 11 seconds better. better than what? their previous times or the times of those that were ingesting the high GI meal?

No the first exercise protocol was a 90 minute run. The second was a VO2 max test....would only be 90 minutes long for someone like Lance Armstrong. [img]smile.gif[/img] (J/K) So they went 11 seconds longer in the second test before having to quit, or before hitting lactate thresshold (it ddoesn't specifically say).

[Q.]

Originally posted by Kaiser:
-high GI meals the night before (the dreaded pasta bowl) seem to lead to better performance the next day, especially on rides lasting longer than 3 hours. This is much more true than when ingesting a meal with a good amount of protein in it.

In days gone by, this was called "carbohydrate loading." I used to do this the night before basketball marathon sessions... sometimes with pasta, sometimes with beer!

[Johnka]

Originally posted by Kaiser:
As a guy converting to an endurance athlete, this is interesting. I wonder why taking the high GI carbs post-endurance exercise wouldn't promote fat gain?

Through experimenting with my diet and bike riding this summer, I've come to the following conclusions (for me):
-I need high GI carbs while riding anything more than 90 minutes or performance suffers
-I need to ingest some protein during any ride longer than 120 minutes or recovery is slower and the next performance suffers
-high GI meals the night before (the dreaded pasta bowl) seem to lead to better performance the next day, especially on rides lasting longer than 3 hours. This is much more true than when ingesting a meal with a good amount of protein in it.
-If I fail to eat a healthy meal about 1-3 hours before a long ride, I come back ravenous and eat everything in sight (usually not all 'good' food either).
-I cannot seem to maintain performance on the bike AND lose fat in the midsection at the same time. The same high GI carbs that promote good performance on the bike also seem to deter my body from losing fat, even when the on-bike kcalories expended during a long ride top 3,500.

Comments on my suppositions, John?

Man Kaiser, that must be a grueling ride to burn 3500 k/cals!

Maybe you can try to carb load on low GI carbs rather than pasta. Something like beans or lentils (GI in 20's), rather than pasta, which ranges between the 40's-60's.

Those high GI carbs during and post workouts are a double-edged sword. They slow fat burning, but they also blunt cortisol via insulin, which saves muscle. I guess it's a balancing act.

How's that for wishy-washy? My hunch is that high GI carbs (together with protein) during and immediately following your ride are helping, not harming you. Maybe it is the large meals and appetite in between that is feeding that stubborn adipose. Maybe instead of rewarding yourself with large meals, try to eat several smaller meals to prevent overeating?

[Q.]

For some reason, I thought I heard before the white bread had a GI rating of 100 and that's what everything else was based on. Obviously, that's kind of dumb but I was curious (again) what the ratings meant and how different foods compared.

CHECK OUT THIS WEBSITE.

By the way, how would a diabetic weight train?

[wingsfan]

[quote]Originally posted by Kaiser:

So they went 11 seconds longer in the second test before having to quit, or before hitting lactate thresshold (it ddoesn't specifically say).

but 11 seconds longer than what? guess i'm confused as to whether they are comparing it a previous vo2 max test that may have been done prior to the longer 90 minute run. just making sure we're comparing apples to apples here.

[JimBo123]

If someone were trying to optimize fat burn but minimize muscle loss what would be the best decision? high GI carbs during and after a workout??

Johnka:
Those high GI carbs during and post workouts are a double-edged sword. They slow fat burning, but they also blunt cortisol via insulin, which saves muscle. I guess it's a balancing act.

Also if high GI carbs during and after a workout are best choice to optimize fat burn and minimize muscle loss, in what form should those high GI carbs be taken along with protein?? a protein shake with a good amount of carbs?

[jreimann]

FWIW
100% Whole Wheat Pasta is a good low GI food to carb up with. I pretty much can't eat any high GI foods now due to blood sugar issues(hypoglycemia most likely) but I have had a big carb up meal the other weekend with Whole Wheat Pasta that didn't bother me.

[Johnka]

Jimbo, I think the amount of sugars depends on your insulin sensitivity, so it will be different for everyone. For myself, I've found that while cutting, a drink of 20 g whey and 30-40 g simple CHO's like malto and/or dextrose works best. Fat loss isn't compromised, muscles are spared, and recovery is maximized. While bulking, I'll have about 65 g sugars in my PWO shake.