Diabetes Exercise Physiology 200 – Fueling

Today’s notes on the material TeamWILD’s Marcey Robinson presented covers fueling for performance and recovery. This is a tricky thing for me. I want to use these guidelines, but I find that my evening workouts need significantly more carbs than Marcey recommends. I likely have too much insulin hanging around, either from an overly aggressive basal rate or (more likely) my lunch bolus. The guidelines work much better for my morning workouts, though. Hopefully, you’ll find something that works for you in these notes. Remember, for those of us with type-1 diabetes, our bodies responses to food and insulin is the same as for people without diabetes; we just have to manage the insulin ourselves. (That’s all!)

Bringing Energy with You to Your Workout:
Glycogen lasts about 90 minutes during exercise. It can take 24 hours to restore.

  • Half of the liver’s glycogen can be used overnight, making less available for an AM workout.
  • Lots of things impact glycogen use: Previous hypos, hyperglycemia, stress, intensity of exercise, training history, etc.
  • When you’re new to an exercise—or using new muscle groups—you tend to use more glycogen.
  • Higher initial BG causes a faster utilization of BG and glycogen.

Ideally, one would eat 3-4 hours before exercise, and take in 60-75g of carbs with a modest amount of fiber and fat.

    Pre-exercise snack:

  • If pre-exercise BG is ≤100 mg/dL (5.6 mmol/L), eat 15-30 grams of carb.
  • If 100-150 (5.6-8.3), eat 15 grams.

Fueling Exercise:
A Joslin study shows that BG doesn’t start to fall until about 40-60 minutes if insulinization is right.

As intensity goes up, the carb:fat ratio tips heavily toward carbs (glycogen).

You shouldn’t need to fuel with carbs if the activity is less than 60-90 minutes long, but it depends on available glycogen. [This also assumes no IOB and correct basal rates.] For exercise/events less than 90 minutes, focus on the pre-exercise meal/snack. Think fluids, not food. Use a sports drink or water. Also consider previous/recent hypo events or possible lower glycogen levels from a previous workout and compensate for those.

For exercise lasting longer than 90 minutes, everyone (with or without diabetes) needs carbs… or they’ll bonk! Need 30-60 grams/hour. (0.7 grams per kilogram of bodyweight. Remember: 1 kg = 2.2 lbs.) [This formula usually works perfectly for me!] Start within the first 30 minutes of exercise. Choose smaller, more frequent carbs. Pick foods low in fat, fiber, and fructose.

Favor 6-8% carb drinks. This yields about 35-50 grams of carb per bottle.

Drink 1 bottle of fluid per hour. With or without carbs, you need this much hydration.

Hammer products have slower absorption than some other brands. [This is definitely something I see.]

Fueling for Recovery:
Start fueling for recovery immediately after exercise (within 15-30 minutes). “Non-insulin-mediated glucose uptake” makes muscles more receptive to glycogen synthesis. Quickly restocking your muscles’ glycogen stores, is what you want to do. Start with 30-60 grams of carbs. Eat a regular, moderate carb meal within two hours.

You need to have adequate insulin for recovery, but you’ll be fore insulin sensitive. Insulin is necessary for glycogen synthesis (i.e., making and storing glycogen in your muscles).

Proper recovery fueling will help reduce delayed-onset hypoglycemia.

Protein aids in resynthesis of glycogen and for muscle repair/growth. It also helps with delayed hypoglycemia. Aim for 15-30 grams of protein during your recovery meal.

Don’t rely on fat for recovery fueling, but moderate amounts (particularly healthy unsaturated fats) can help with post-meal BGs.

Putting it all together: consider a recovery drink with protein, like chocolate milk, Protein Monster, Muscle Milk, etc.

Make sure to hydrate. It’s important for glycogen synthesis (and lots of other reasons).

  • Drink 1/2 your bodyweight in ounces daily. That’s your typical loss.
  • During exercise, drink to maintain hydration levels. (Weigh yourself before and after exercise. The difference is the extra amount you need to drink. Remember: 1 pound = 16 ounces.)
  • Drink 16 ounces (1 normal bike water bottle) of water within 2 hours of finishing exercise. Don’t chug; you’ll just pee it out, rather than storing it. Your body needs water to help with glycogen storage. (FYI: You store 4 grams of water with each gram of carb.)

Caffeine-containing beverages don’t count for hydration, because they’re diuretics.

It’s usually better to have electrolytes as part of the beverage during exercise. But salt tablets may be too much. Unless you have a specific need, try not to exceed 200-300 mg of sodium per hour.

  • Nuun has ~360 mg
  • Gatorade = 220 mg
  • Skratch Lab mix = 300 mg

“Power Foods”:
When choosing gels, chews, and other “power foods,” think about price/100 calories.

Some power foods are over-processed. There’s no magic bullet, and it’s okay to eat “real foods.”

If the food is hard and dry or has lots of fiber, it can hinder digestion and cause GI issues.

For lower glycemic index options, consider Hammer products or other things with maltodextrin, xylitol, and Stevia. Also consider Fig Newtons/Newmans, Lara Bars, Kind Bars.

Rest Week Nutrition:
On rest weeks, the overall quantity of calories should go down, but the quality should go up (especially for snacks). Aim for lower carbs overall, but keep your diet balanced.

Use your extra rest week time for nutrition and cooking.

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5 Responses to Diabetes Exercise Physiology 200 – Fueling

  1. Scully says:

    although some of this I don’t necessarily agree with, I still find it fascinating and totally helpful.

  2. Nira says:

    Great info. I have been training for a 200k bike ride as a type 1 and you actually hit all the issues really well! thanks.

  3. mary! says:

    I’m glad I remembered this post! I’ve been trying to read up on what to eat during a ride and post-ride. After my ride last sunday, I was STARVING, and I think I ate too much protein too quickly – I ended up feeling super lethargic in the evening. I believe my problem was that I didn’t anticipate the ride would be as long/intense as it ended up being, so I didn’t bring any food with me, just water. And I’d only eaten a luna bar beforehand.

    I think I also messed up my ride nutrition during last night’s club ride (combined with my commute home, it was 30 miles, 1500 ft elevation). I ate a banana about 30 minutes beforehand (good), but I didn’t eat anything during the club part of the ride. Back at the parking lot, I ate a kind bar (one of the nut-based ones) before riding the rest of the way home (maybe 7-8 miles). When I got home, my stomach was feeling pretty icky, but I knew I needed something, so I drank what was left in our bottle of kefir – probably about 12 oz.

    I’ve felt pretty weird all day today – hungry but at the same time a bit sick to my stomach. I don’t think I had enough carbs during/after last night’s ride. The problem I see, though, is that I’m not getting home from these evening rides until about 8:30, and I go to bed at 10:00. Any eating I do needs to happen right after I get home – I don’t want to be eating any closer than that to my bedtime. Assuming I bring along stuff to eat during these rides, going forward, what do you suggest I consume right when I get home?

    Going on a 50-miler tomorrow, with 5000 ft elevation (weather pending) – I’ll be packing the whole kitchen, haha!

  4. Jeff Mather says:

    Mary, I’m glad this was useful for you. People never quite believe me that the nutritional best practices for people with and without diabetes are the same. It can be a challenge finding what works best for you; hopefully this gives you a jumping off point.

    I have a couple of suggestions of what to consider eating after your evening rides. The ideal snacks/meals have a roughly 2:1 or 3:1 mix of carbs and protein. If you like chocolate milk, that’s often a good choice. If you’re not a milk fan but still appreciate dairy, consider yoghurt. 6 oz of yoghurt or 8-12 oz of chocolate milk (kefir is also good if your tummy takes to it) is probably sufficient.

    BTW, I’ve had that hungry-but-kinda-sick feeling after biggish rides a couple of times. As best as I can tell (for me) it’s a sign of wonky hydration. On those occasions I’ve been dehydrated or needed some additional electrolytes. It might be completely different for you, of course.

  5. mary! says:

    Hey, thanks! I did some poking around online and read some good information, which aligns with what you’ve got here. Since I posted that comment, I haven’t had any issues with fueling, which I guess means that I’m doing a good job – I’ve just made sure to bring more than I think I’ll need and force myself to take quick breaks to eat 30-35 carbs every hour, even if I don’t feel like taking a break and/or eating something (still not so great at eating while riding). Good point about it possibly being due to hydration. It could just be a coincidence that it happened those two times and hasn’t happened since – maybe I wasn’t well-hydrated on those rides, and I just thought it was linked to food. Either way, I haven’t been feeling yucky or overly hungry post-ride (or next day) since.

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