Hopefully, you have set yourself up with the proper pre workout/racing fueling guidelines, but now you want to extend that through your workout or race. In this section, I want to discuss the considerations, but put a practical take on what that means. I want to give you clear advice on how to build your intake up to match your needs, and finally, where to put your focus. 

First, let’s talk about the considerations about our fueling needs during hard sessions. When we talk about how many calories we are burning, it’s roughly 100 calories per mile. When running easy, that caloric expenditure is primarily a mix of fat and carbs (in simplistic terms). If you are well trained, it should be more fat than carbs. As you increase your pace, that mix balances out, then relies progressively more on carbs. By the time you get to 5k pace and faster, you are relying on carbs to provide the vast, if not all, energy needed to supply your running. Besides the pace you are running, the runner’s weight will also play a role. If you take two runners of equal VO2max, but one weighs 30 pounds less, then it is becomes clear that it would take the lighter runner fewer calories to move at the same pace. Another factor would be temperature/environmental conditions. During the summer, a lot of you find this out as it takes a lot more work to run the same paces. Terrein would also be another factor. Lastly, something I have always described as metabolic efficiency plays a role, too. This is simply what amount of carbs are being used to run a certain pace. When I used to do testing, I’d see people with terrible diets “burn hot” and were already burning 70-80% carbs per mile at not much more than a walk. BUT, I don’t write this to say we need to really look at each of these with a microscope, but rather just note that when I am throwing numbers out, recognize that they are general guidelines, and you should be experimenting early in your training to dial in. If you really want to get this dialed in, I would suggest obtaining what’s called an AMR (Activity Metabolic Rate) Test. This will be a test that measures what’s called an RER (Respiratory Exchange Ratio)- you are comparing oxygen intake to carbon dioxide exhaled and that gives you a ratio. This will, in turn, tell you what the fuel breakdown is at whatever pace you want to. You can get numbers like calories expended per hour (at that pace) and what percentage of those calories are carbs to fat. This would allow you to know with great certainty how much you should be taking in during a workout. 

Some general guidelines 

• Under 45 minutes: No carb supplementation needed. 
• 45-75 minutes: Up to 30 grams of carbs
• 60-120 minutes: 30-60 grams
• 2-3 hours+: 60-90 grams 

The above guidelines could be used for workouts/long runs, and races as general guidelines. The other wrench I would throw in there is for marathoners. For marathoners under 2:45, you definitely want to be at the top end of that 60-90 gram recommendation. Beyond that, you’ll want to incrementally increase to that upper ceiling of 120 grams per hour. I recognize that’s a small number of people reading this, but as much as everyday runners tend not to even come close in their races, the same can be said for many elites. Room for everyone to improve! 

From a workout standpoint, here is how I would like you to approach. 

Easy runs

As much as we are discussing pumping our bloodstream with glucose to ship off to muscles, what makes us even better is being really good at burning fat. Running easy on our easy days for 45-60 minutes a time without taking in carbohydrates is a really good way to get better at using fat as a fuel. 75-90 minutes after a buildup period is even better. 

Speed

Many of these will fall into that 45-75 minute category. Maybe even less, for some. I think 30 grams is a good amount to aim for. You can start the process of getting used to having something in you stomach and trying to run hard.

Approaching this, when I fuel for these, it usually looks like a gel right before the start of the workout, and then having a water bottle with a sports drink that I’d sip on during recovery jogs. The vast majority of my calories would come from the gel at the start, though. 

Strength/LT

Strength and lactate threshold workouts are the most interesting because the volume is long enough and the intensity high enough, even though it might not feel like it. These workouts can easily sneak into the 75-90 minute range (even longer?), but also be at a point where the ratio of carbs being used compared to fat is. The result- you can drain carb stores enough to affect the last portions of the workout and how much you need to replace afterwards. You can see the problem with this is if you lack that, you have a fast turnaround to the tempo run on Thursday. Then you set that workout up to be underfueled. The cascading effects of this over several weeks are often visible on runners. Anyway, don’t spiral! At the very minimum, 30 grams an hour, but for faster runners, say 90 minutes, and faster half marathoners, I’d love to see this number up to 60 grams. I say 60 grams, but it might not be 60 grams an hour. 

How it might look:

• 25 grams- gel or a sports drink before the start. Within 15 minutes of starting the workout.
• 25 grams halfway through + sports drink taken during a recovery jog. 
• This could potentially get me to 60-75 grams, but be under 60 grams per hour. 

This might be a battle for some of you, but if in heavy training, whether for a half or a marathon, many times you are doing 2-3 big workouts a week. It will have an impact on the current workout, but will also help your following workouts. I am looking at this over the course of weeks and months of a hard segment. Gaining consistency here will help you be able to feel better longer and maintain higher levels of performance much longer into training. 

Marathon Tempo

Now, the vast majority of the time you have these, you are training for a marathon. Given that, while your biggest runs will fall in that 60-120 minute range, we want to build our intake beyond that to get close to the rates we want to be taking in during our goal race. So, we may start out in that 30-60 grams per hour range, by the time we get to 9+ mile tempos, you want to be pushing to that 60+ grams per hour range. 

How it might look:

Start: Gel

4-8 oz of fluids every 10 minutes (10, 20, 30, 40, 50 minutes) 

Gel every 20 minutes (20, 40 minutes) 

If you figure an average of 18 grams of carbs in a sports drink, then you can get 45-90 grams from a sports drink, plus another 50 grams of gel puts you in the 90-gram range. I wouldn’t start here, but I just want to show you how possible it is. We’ll discuss progressing to that point in training. 

Long Runs

I typically define a long run as a run over 90 minutes. As you get into runs that are 10-12 miles and beyond, then you’ll be in the range of needing 60 grams per hour. Do you need to get up to 90 grams an hour? It would depend on the person. I know it’s not an exact answer, but the faster you are, the more you should be looking at attempting this over time. 

How it could look would mimic what I laid out for Marathon Tempo Runs. I’ll lay out how to start from zero and build into those kinds of numbers. We’ll also look at other areas to consider. 

Putting into practice

Our three primary goals with fueling and hydration are to one, replace at least 30-40% of the calories from carbs that we utilized during the event. Secondly, we want to maintain fluid loss to less than 3% of our body weight. If we can do that, then we have a much better chance of sustaining a high level of performance throughout, and we improve our ability to recover from the work. 

The problem in training is going to be how we manage both the caloric needs with minimize fluid loss. Or, more specifically, how are we going to practice and become proficient at doing this the way we plan on doing it in the race? 

The big issue is what you are actually going to take in during the race. Are you going to be able to use what you are taking in going to be what you are taking in during the race? It’s happened more than once that a person would train with what they loved using, but then didn’t want to carry anything, so they just used what the race offered, and it ended in disaster. So, if you use it in training, make sure it’s what you are using on race day, too. On the reverse, it might not be a bad idea to make sure you can tolerate what the race will offer, in case of an emergency. 

The secondary issue is ensuring that you will be able to get the volumes in you are looking for with a combination of how you will carry your own stuff and what the race will offer- even if it’s just their water. 

The easiest problem to solve is gels. I am a huge fan of using things like gel flasks where you can compact 5 gels into a single flask and it will fit just fine in a shorts pocket. Can carry 1-2 in your shorts and one in your hands. Rather than explain again, here’s a full post I did on gel flasks: https://lukehumphreyrunning.com/fueling-tip-gel-flasks/

The hardest issue to overcome is getting the fluids you need. Let’s use a 150-pound person. If they stay within the 3% of bodyweight lost, then they could lose 4.5 pounds before suffering significant performance loss. The problem with that is the average sweat loss per hour of running is anywhere from 34-50 oz of sweat. Or a little over 2 pounds up to about 3 pounds per hour. If a person runs 3:30, you are looking at roughly 7.5 pounds of bodyweight lost. We need to replace at a very conservative minimum- 3 pounds of fluid. That’s 48 oz. of fluid, at a minimum. Let’s be honest, that’s a very rough estimate, and those numbers can vary wildly. If you want to calculate sweat rate, take your beginning weight before a 60 minute run. Then weigh yourself after (naked), and that will show you the pounds. Then multiply by 16 ounces and that’s your number of ounces. Then add any ounces of fluid you drank during the run. That’s your sweat rate. 

The reality is, someone with a lower sweat rate and who is out there for less than 3.5 hours can probably get away with either just hitting the aid stations or taking a handheld and aid station combo. For others, you might have to get creative. 

Here are some things we’ve had athletes take flip belts and swap bottles out with friends along the course. I’ve had people swap handhelds out along the way. I’ve had them focus on their fluids in the first half and stay optimally hydrated and then hit aid stations over the last 10 miles, knowing that they’d slowly lose what they had built up over the first half. The point is, we can have the things with us in training, but they may not be there during the race. Have a plan for how you are going to make up for it in the race. 

So should we use things like vests and handhelds during training? 100%!!! I think you train optimally, so you know what it feels like. For instance, I like to train on an old rails to trails and there aren’t any water fountains along most of it. It would be brutal to do 16-20 miles with no access to fluids. Here’s where having these tools is needed. But I can also set it up where I can do loops and swap out bottles every few miles, too. I think as long as you have a plan to account for the differences and practice a little bit, you’ll be ok. My overall thought is, if you train optimally and get used to all the things you should be doing, but only get 80-90% of it right on race day, then you’ll still be well ahead of where most people are. Even ahead of where you were last time. 

Progressing Intake

I realize I have been throwing around some big numbers. They can be really scary. If you have never had a system, then we have to start small. 

Phase 1: 4 weeks

• Aim for 30 grams of carbs on workout days. 
• This can be a gel at the beginning of a workout. 
• Sips of water during

Phase 2: 4 weeks

• Move into 45-60 grams 
• Perform as a gel at the start and another halfway through
• ~4 oz of water between reps or every 20 minutes

Phase 3: 4-6 weeks

• We’ve tested the waters pretty well; let’s be a little more aggressive. 
• Follow the guidelines discussed for Speed and Strength workouts 
• Tempos and Long runs
  • Gel before
  • Gel every 30 minutes
  • Fluids every 20 minutes

Phase 4: last 4-6 weeks

• If you feel good, let’s push the envelope a little further. If not, and this is more than you’ve ever done, stay put and make this automatic over the last stretch. We can always take it up a level during the next cycle. 
• If you can, push the gel intake to 1 gel every 20-25 minutes on Tempos and Long Runs. 
• Push the fluid intake to 4-8 oz every 10-15 minutes. 

Note: You have some freedom here. If you think fluids are going to be a bigger problem for you, then put your focus on those. If you are running out of gas, make fueling your highest priority. Experiment here and see what works better for you. 

At this point, you can get to the start line well prepared and confident, and be better at fueling than you were before. This is an ongoing process, and it takes consistency, just like your regular training. Stick with it, experiment, and figure out the combo that works for you! 

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