What to eat and when to eat it: Hear from Registered Dietician and Altra Elite Athlete Corinna Coffin. 



Corinna Coffin at an obstacle course race.


If you’re reading this, chances are you like to run and/or be physically active. And if that’s the case, perhaps you have some sort of workout schedule or activity game plan during the week to help keep you on task. But what about nutrition? Do you put the same kind of effort and attention into the food and meals you eat each day as you do your workouts? This might seem like a strange concept, but if you think about it, our encounters with food are far more frequent throughout the day than the time we spend running or lifting weights. If we didn’t have a game plan for our workouts each day and had to come up with them on the spot, we likely wouldn’t accomplish as much as we otherwise could if it were it all planned out (we’ve all been there before). Similarly, with nutrition, our food choices are likely to be poorer when we wait until the last minute to decide what to eat rather than plan ahead. If we compound this cycle of deciding what to eat until the last minute, day after day, week after week, month after month, it is likely to presume our health will take a serious toll.  

Needless to say, planning out your day (to some extent) nutritionally is important. But what should you focus on specifically? And how do you implement it? If you have any interest in health and performance, there are a few critical nutrition components you should implement to help take you to the next level: 


Consider your fuel substrate

The intensity at which we are exercising dictates whether we are utilizing mostly fat or carbs as our primary substrate. Carbohydrates are the body’s preferred and most efficient fuel source, so at higher intensities, particularly when we are anaerobic (or “without oxygen”), carbs are a necessity. Fat, on the other hand, requires more oxygen and multiple steps to be converted to usable energy, making it the primary substrate for lower intensity exercise. With this understanding, it makes sense why carbohydrates are essential for performance. 


Nutrient timing: Pre-workout

Understanding your primary fuel substrate during exercise leads us to proper nutrient timing surrounding workouts. If we wish to perform at a high intensity in our training or competition, it is important to supply our body with sufficient carbohydrates beforehand. Our muscles and liver can store a finite amount of carbohydrates before they’re completely depleted. Since these stores are rarely at full capacity, it’s important to fuel with carbohydrates beforehand. The timing of your food intake prior to exercise will determine the quantity of carbohydrate, as well as, to some extent, the quality or type of carbohydrate (complex vs simple). ‘Complex’ carbs provide more sustained energy but take longer to digest and process, while ‘simple’ carbs provide more immediate energy, digesting and absorbing rapidly into the bloodstream. Most pre-workout meal options should include a variety of both simple and complex sources, while smaller snack options closer to workouts should consist of mostly simple sources. When it comes to amount, this is where it can be important to trial and error for yourself to determine what your body can comfortably tolerate prior to exercise. The larger the meal or snack, the more time needed for digestion. Keeping fat and fiber content low will aid in faster digestion.


Corinna Coffin in a gym, drinking a nutritional drink


Nutrient timing: Intra workout 

Strategies to maintain high carbohydrate availability during sustained or intermittent high-intensity exercise have consistently been shown to enhance performance. When glycogen stores become depleted, fatigue in the form of reduced work rate, impaired skill concentration and increased perception of effort takes is inevitable. Simply put, fueling with carbohydrates during longer bouts of exercise is essential for optimal performance. A common mistake individuals often make is fueling too late. Whether it be a race or long training session, intra-workout fueling recommendations start the very first hour. Even though food might be the last thing on your mind 30 minutes into a run, it’s essential to stay ahead on your calorie intake to prevent from bonking, particularly the longer the run/race. Most sports gels and other carbohydrate supplements targeted for mid-race fueling contain ~20-30 grams of carbohydrates per serving, which makes things easy for the racer. To space out carbohydrate doses and minimize GI upset, a good rule of thumb is to consume 20-30 grams of carbohydrate every ~30min. 


Nutrient timing: Post-workout 

Once we finish a workout, we have depleted our muscle glycogen stores to some capacity, depending on the intensity and duration of our workout. In order to minimize muscle soreness and maximize recovery, replenishing these stores through carbohydrate ingestion is key. If you exercise earlier in the day, chances are you will consume a sufficient amount of carbohydrates over the course of the day to replenish what was lost. However, consuming some carbohydrates shortly after a workout, particularly a simple, fast-digesting source (ie. a banana or pretzels), enables these key nutrients to get to our muscles at a faster rate. During physical activity (particularly intense and/or sustained activity), our muscles face resistance which leads to microscopic tears within the muscle tissue. While this is a normal phenomenon of exercise and part of muscular adaptation, the consumption of high-quality protein in addition to carbohydrates has been shown to attenuate damage and aid in the maintenance, repair and synthesis of skeletal muscle proteins. To maximize recovery and support the repair/remodeling process, aim to consume 15-25 g of protein with ~1 g/kg bodyweight of as soon as possible within finishing exercise, followed by a well-balanced meal within 1.5-2 hours. 



Carbohydrate Targets Time Prior to Race/Event Comments
1-4 g/kg BW 1-4 hrs Focus on foods/fluids that will not cause gut discomfort during the event


(Thomas et al., 2016)



Situation Carbohydrate Targets

During sustained high-intensity exercise (45-75 min)

Small amounts, including mouth rinse A range of sports drinks/products that can provide easily-consumed carbohydrates

During endurance exercise (1-2.5 hr)

30-60 g/hr A range of specialized sports products ranging in form from liquid to solid may be helpful

During ultra-endurance exercise (>2.5-3 hr)

Up to 90 g/hr The athlete should practice to find a refueling plan that suits his/her individual goals, including hydration needs and gut comfort


(Thomas et al., 2016)



Amount & Type Timing


0.25-0.3 g/kg BW  (~15-25 g high quality protein)

0 to 2 hrs following exercise


~1g/kg BW

During the first 2 hrs of recovery


(Thomas et al., 2016)


Corinna Coffin running with a group



About the Author: 

Born and raised in the Virginia countryside, Corinna grew up on a horse farm with her three older brothers. From an early age, she developed a love for the outdoors and sports, always in pursuit of her brothers. Corinna's love for sports and fitness continued to evolve into a passion for health and wellness, which led her to pursue dual degrees in nutrition & exercise and Spanish at Virginia Tech. 

Corinna placed second at the Spartan Race World Championship in 2014, second at the US OCR Championship in 2017, first in the Tough Mudder X Championship in 2017, among many other CrossFit and OCR accomplishments. 



Burke, L. M., Loon, L. J., & Hawley, J. A. (2017). Postexercise muscle glycogen resynthesis in humans. Journal of Applied Physiology,122(5), 1055-1067. 

Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance. Journal of the Academy of Nutrition & Dietetics,16, 501-528.