By guest contributor, Jeff Rothschild
Jeff is a Registered Dietitian (RD) with a Master’s degree in Nutritional Science and a Board-Certified Specialist in Sports Dietetics (CSSD). Learn more about Jeff.
“I’ll just eat when I’m hungry and drink when I’m thirsty.”
This is the approach that many endurance athletes, at all levels, take with their fueling. While it may seem sensible at first, there are several reasons why this is a bad idea if you’re trying to ride/run/swim as fast as possible.
- 1. On a practical level, there should be an obvious disconnect between trying to fuel “naturally” while asking your body to do something that is quite unnatural like riding/running/swimming for 3 – 16+ hours as fast as possible.
- 2. When research studies compare eating and drinking “by feel” to eating and drinking according to the best scientific recommendations, we see significant differences in real-world endurance performance.
This is because there is a “sweet spot” of intake for optimal physical performance that is different than what people generally consume freely. This post will look at some of the relevant research studies on fueling plans for endurance athletes, so you can make your own decision on whether or not a fueling plan is important for you.
If you’re doing a long race, following a scientifically chosen nutrition strategy will help you finish faster.
This study took trained (but non-elite) cyclists and had them eat and drink freely or according to the best recommendations (1 liter of fluid/hr, with 500 mg sodium, 60 g glucose, 30 g fructose, and 5 mg/kg caffeine). They rode for 2.5 hours at 70% intensity, followed by a 40-mile time trial. As expected, the intake of fluid, carbohydrate, sodium, and caffeine was higher in those following the plan compared with the free eating scenario, which resulted in a 15% higher power output during the time trial and a finishing time that was 6.3% (eight minutes) faster.
Improved marathon performance by in-race nutritional strategy
This study used runners (also trained, but not elite level; marathon times around 3.5 hr) and again let them eat and drink freely or consume a scientifically chosen strategy during a marathon. Running recommendations are slightly different than cycling, and the athletes following this plan consumed 750 ml fluid/hr, with 60 g maltodextrin and glucose. Interestingly, the fluid intake was the same between groups, but the group following the plan consumed about 70% more carbohydrate during the race. This resulted in an improvement in finishing time of ~5%, which was about 11 minutes faster. Also noteworthy is that GI distress was not different between groups.
Prescribed Drinking Leads to Better Cycling Performance than Ad Libitum Drinking
A group of well-trained (but non-pro) cyclists performed two simulated races in the heat (~89 degrees F); once when they drank as much water as they wanted and once when they followed a preset drinking plan that matched their sweat rate.
The simulated race included three 5 km time trials separated by riding 5 km at 50% effort, which is a fairly good approximation of what a race might be like. During the first two 5 km time trials there were no differences in cycling speed, but during the third one the group following the drinking plan was able to ride on average 5.1% faster! In addition to performance, other physiological variables were measured and as expected the group following the drinking plan had a lower amount of heat stress (more precisely referred to as thermoregulatory strain), and were more effective at sweating. When drinking freely, the cyclists ended being dehydrated by 1.8% of their body weight, while the cyclists following the plan ended up with just a 0.5% reduction in body weight.
Effects of salt supplementation on performance during a half-ironman
We can also see average improvements of 26 minutes in Ironman 70.3 finishing times when athletes consumed additional salt compared with placebo.
Nutritional intake and GI problems in elite endurance athletes
This study was observational in nature, and looked at energy, nutrient, and fluid intakes during endurance competitions as well as associations with GI symptoms in elite athletes. Below is a graph of carbohydrate and finishing times during the Ironman European Championships. Total carbohydrate intake was correlated with faster finishing times, but also with increased nausea and flatulence. This further underscores the importance of carbohydrate in high-level endurance exercise, as well as the need for a smart nutrition plan so you don’t consume too much for your body to handle.
So how do you find that sweet spot of fueling?
PhysioPhyx BLAZE offers the perfect blend of carbohydrate and electrolytes to keep you hydrated and power your workouts. For a typical 24 oz cycling bottle, use 1.5 scoops per bottle in each of your bottles (no need to have one bottle of BLAZE and one water). That should be enough during workouts that are 1-2 hours. For rides longer than 2.5 hours, add in some additional calories from gels, chews, or food.