Just posting this here after a DM discussion with Dr Alex. I want to preface this by saying that he knows where I'm coming from and I'm not trying to undermine his work. I've been using his mix (dubbed Alacrity Mix) for a few months now and haven't had an issue with it. I've adapted to the 100g CHO/hour and everything is ticking along. I've started seeing a dietician and she asked about my intra-training mix. When I told her, this was her response and after asking Dr Alex for his opinion and insight into her response, we decided it best to post it here so Alex could respond and hopefully enlighten the rest of us.
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The reason I queried this is because of the following;
Things to additionally note:
So, what does all of this mean? Basically, unless you are a freak of nature, you can't possibly be absorbing all of that CHO per hour, which means we can do some tweaking. However, I am very aware of athlete's comfort zones, and not wanting to mess around too much outside of what they feel comfortable changing.
Gatorade Powder - 560g weight, 324g Glucose, 180g Fructose, 4080mg Sodium, 1800mg Potassium
Table Sugar - 2000g weight, 1000g Glucose, 1000g Fructose
Totals - 2560g weight, 1324g Glucose, 1180g Fructose, 4080mg Sodium, 1800mg Potassium
20g serving - 10g Glucose, 9g Fructose, 32mg Sodium, 14mg Potassium
52/46% split between Glucose and Fructose
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Fire away Dr Alex!
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The reason I queried this is because of the following;
- Glucose (one of the forms of CHO you're taking on, approximately 52% of your current mix) maximally oxidises at 1g/min - which obviously then caps us out at 60g/hour. If this is 52% of our mix, this means we are roughly getting 52g/hour.
- To achieve higher CHO oxidation rates during exercise, we need to use multiple transportable forms of CHO. These limitations are based on intentional absorption of CHO. (Glucose needs the sodium-dependent transporter SGLT1 for absorption across the basolateral membrane of the intestinal lumen).
- This is achieved with the introduction of fructose (as it uses the GLUT5 transporter) which maximally oxidises at 0.6g/min (36g per hour). Fructose makes up the other 48% of our mix or 48g/hour.
- This puts us at a maximal oxidation possibility of 96g/hour, if 60g was coming from glucose/sucrose and 36g was coming from fructose.
Things to additionally note:
- The calculations I've done are based on the assumption that the "table sugar" i.e. sucrose is 50:50 glucose:fructose as accepted in the literature. I looked up the proportions of glucose:fructose in one container of gatorade and subbed those values in as well, see table at the end of the email.
- Intensity and time both play roles here too. At high intensity, any exercise <2.5 hours should only maximally need 60g/hour and can be kept to one type of CHO (i.e. glucose alone). Lower intensities require lower amounts of CHO. Once we get up past 2.5 hours (and if intensity is still high) that's when we drift up to 90g/hour.
So, what does all of this mean? Basically, unless you are a freak of nature, you can't possibly be absorbing all of that CHO per hour, which means we can do some tweaking. However, I am very aware of athlete's comfort zones, and not wanting to mess around too much outside of what they feel comfortable changing.
Gatorade Powder - 560g weight, 324g Glucose, 180g Fructose, 4080mg Sodium, 1800mg Potassium
Table Sugar - 2000g weight, 1000g Glucose, 1000g Fructose
Totals - 2560g weight, 1324g Glucose, 1180g Fructose, 4080mg Sodium, 1800mg Potassium
20g serving - 10g Glucose, 9g Fructose, 32mg Sodium, 14mg Potassium
52/46% split between Glucose and Fructose
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Fire away Dr Alex!