Nutrition Science and Practice

Nutrition during workouts, Part II

    Effective endurance performance is not just determined by how fast you can go; it is equally important how successful you are at delaying fatigue. Getting your hydration and nutrition right is a key component in endurance sports.  As discussed in the August blog even minimal dehydration can hinder an athlete’s performance caused by reduced blood volume and reduced amount of oxygenated blood pumped to working muscles. Common difficulties endurance athletes face is to consume adequate calories including key nutrients such as iron, protein, calcium. Timing of food intake around the exercise is another shared challenge. Read More... 

    For endurance athletes, consistency in training is the key to success. At the same time the goal is to minimize time lost to chronic fatigue, illness, and injury.  Returning to a performance ready state means to restore nutrient and fuel supplies, repair damaged muscle fibers, and ease mental stress. Fueling the body properly for performance and maximizing recovery are critical for athletes with a high volume of workouts week after week, for those who complete multiple daily workouts or training sessions of prolonged durations.  To protect your health and lean muscle mass, as well as maximizing performance, endurance athlete should: 

  1. Consume enough calories on a daily basis to cover the calories expended during exercise. Remember, as training volume and intensity varies throughout the year, you need to modify your food intake to match your calorie expenditure.

  2. Take in enough calories during workouts (120 minutes of exercise and above). As a general guideline you should aim for an intake of 30-70g of carbohydrate, or approximately 150-300 calories per hour. Relative to lean body mass, target 1g of carbohydrates per kg during each hour of exercise. This rate may need to increase in the later stages of sustained exercises as the body increasingly draws on blood glucose for fuel. As you might assume, exact needs vary tremendously among athletes - as well as for any individual on a given day – because of fitness levels, pre-exercise glycogen levels, sports the athlete is engaged in, intensity, and the environmental conditions. Therefore, it is necessary to train and experiment with different amounts of carbohydrate products to determine the appropriate fuel needs for an individual during exercise. As you have heard me saying in the past: “Review, revise, and repeat”.

A key conflict to overcome during exercise is the absorption of enough hydration and calories while under competition stress, especially when intensity and/or duration go up. We oftentimes hear that athletes have a hard time to absorb solid food and switch over to solely liquid calories. This does not need to be the solution though. The reasons behind this switch may be as follows:

  • You consume an overly concentrated calorie mix that does not digest efficiently. Simply too many calories in the gut at once.

  • Inadequate hydration that makes the absorption of nutrients in the small intestine overly difficult and inefficient.

  • Consuming products or nutrition sources along with a calorically dense sport replacement drink, which over-stresses the gut and the absorption process.

When these situations occur, our stomach cannot absorb the overflow, becomes bloated and you experience discomfort at best, and major GI issues as a worst case scenario. Here are some recommendations to overcome these situations:

  1. Micro-cycle. Instead of taking calories in every 30 to 60 minutes try to eat small portions every 5 to 10 minutes. With this approach, you’ll be taking in the same number of calories over the course of an hour except each bite contains a minimal number of calories. Forgetting to eat and drink early and consistently during a workout could end disastrous, no matter how well trained or prepared you are. As a general rule, try to replace approximately one quarter to one third the calories you burn each hour. Begin your nutrition & hydration in the first 15 to 20 minutes if you are planning to be out for three hours or longer.

  2. Don't just drink, hydrate! Implement a heavily diluted hydration beverage with a low level of carbohydrates (under 4%) and some sodium to get it to your stomach and lower intestines. Scratch Labs hydration is a good source, or mix half a bottle of Gatorade with half a bottle of water. Just be certain that you are also getting in enough electrolytes to ensure that the fluid you take in is getting where it needs to go.

  3. Reduce your calories by having a mix of protein/fat/carbohydrates (real food) early in the workout/race and adapting to more straight carbs as intensity or fatigue starts. While there are many sports bars and gels available you should experiment with real food. This can work just as well if not better than expensive, “engineered” nutrition. Try our salty goodness, a sandwich, boiled potato with salt, a banana or a ball of sushi rice mixed with basically anything to customize it to your taste preferences (e.g. chocolate, scrambled eggs…). These are just a few examples that provide you the calories needed without upsetting your stomach the way a lot of sugary gels or sports bars can. Experiment in training so you know exactly what you will utilize on race day.


The goals of drinking and eating during training and racing are to:

  • Maintain proper hydration status

  • Provide calories to fuel the performance level

  • Facilitate recovery from the training/racing session

Final advice: Go out and experiment with different options. Keep it simple and easy to follow and you’ll end up having more fun, because you’ll have good energy levels from start to finish.