At SFuels, we’ve been consistently advising athletes on a unique, and in our view, fundamental approach to endurance fueling since our start in 2018.
The Five benefits include -
1) Endurance triathlon, cycling and marathon performance (study links below)
2) Avoiding spike and crash energy waves during training-racing
3) Protecting limited glucose stores, higher fat-oxidation, lower lactate/H+ production (0)
4) Eliminating the major risk of Gut/GI distress by over-carb intake
5) Reduced inflammation/muscle soreness from lower-carb, and higher glutamine intake.
To achieve this -
SFuels formulated specific fuels (called substrates) to support the changing physiology from rest, to aerobic intensity, and high-intensity training/racing. If you want to learn more about SFuels Extended Substrate - watch the videos- What is Extended Substrate, Raising Aerobic Capacity, Minimizing Gut/GI distress. Further to this, SFuels then frontiered the practical application of timed substrate-fuel use during training and racing, relative to exercise intensity. Together, we call it, the RIGHT FUEL RIGHT TIME method.
Many aspects of our fuel-processing metabolism change as we shift from sitting on a couch, to physical activity. It’s commonly assumed, that how our body moves and uses glucose, fat and protein as fuel is a fixed process, nothing could be more from the truth. Here's what actually happens.
Fueling - AT REST
At rest, when we drink some juice, or any form of carbohydrate, (particularly simple sugars, like sucrose, glucose etc.) sugars are rapidly absorbed into the bloodstream, and then move through the liver. These sugars (glucose), then trigger our pancreas to produce and push insulin into the bloodstream. By design, insulin will interface with muscle cells and trigger them to open up glucose channels, allowing glucose to flow into the muscle cell. Conversely, that same insulin also informs cells NOT to breakdown, transport or oxidize fat for energy.
Now, what happens DURING EXERCISE is very different.
Fueling - DURING EXERCISE
Repeated muscle contractions release chemicals like Calcium, nitric oxide, and free-radicals into the blood. While still being researched, it’s thought that these chemicals are responsible for triggering the movement of cell-transporters (namely, Glut-4) inside the muscle cell, to the edge of the cell, and open up glucose channels, allowing glucose to flow into the cell – WITHOUT INSULIN. This process is thought take several minutes to an hour, depending upon the intensity of the muscle contractions. The intensity of muscle contractions, is a key determinate factor in the speed of movement of Glut-4 to the cell edge and the opening of glucose channels in the muscle cell.
At this point, you now have a physiology, whereby the muscle cell is optimized for simultaneous transport and use (oxidation) of glucose, fats (fatty acids) and specific amino-acids for fuel. The capacity of transporting and using carbohydrates and fat for fuel, can be highly trained. SFuels athletes have shown cases of 300% improvement in fat-oxidation rates. Recent research (1), has also shown that the body can rapidly use the amino-acid Glutamine as a fuel, during low-glucose states.
But here's the ISSUE -
For the past 30 years of sports-nutrition guidance, athletes have been recommended to consume carbohydrate drinks, gels and chews before, and at the start of workouts and races.
Any intake of carbohydrate during restful and low-intensity states, will raise insulin and trigger a reduction in fat-oxidation capacity, while also suppressing triggers (2) of Glutamine breakdown (for fuel use). This reduces the substrate options of an athlete, forcing higher dependence on carbohydrates (and thereby higher lactate) to fuel the activity. In this 2021 study (3) it was demonstrated how,
1) Pre-exercise carbohydrate intake blunts fat-oxidation capacity during the exercise event, and,2) Consuming protein, or fat prior to exercise had no effect on reducing fat-oxidation capacity or training performance.
3 KEYS: PRACTICAL APPLICATION FOR ATHLETES
1) Choose Protein/Fat as a pre-training, and pre-race fuel. In the 3-4 hour period before your workout or race, take some fat-protein as a snack (SFuels LIFE Bar), and cognitive support like coffee, tea, (or SFuels PRIMED) to feel satisfied and energized going into the workout, or race.
2) Take water or, SFuels ZONE 2 (Glutamine/Medium-chain triglyceride fuel. Zero carbohydrate, Zero Fructose) in the first 30-60 minutes of your workout or race. Continue SFuels ZONE 2 use in aerobic slow, zone 2 long duration workouts. Avoid all use of Fructose based drinks, gels, bars during Aerobic training, to avoid (7) the associated blunting of aerobic training adaptions.
3) For Higher-intensity training, and racing, after 30mins into the activity, being using a mixed substrate (carbohydrate, fat, protein) fuel like SFuels ZONE4 (zero Fructose), or ZONE5 Gel with 30-60Grams of carbohydrate per hour during the activity.
GET STARTED GUIDE, for the practical application of implementing the RIGHT FUEL at the RIGHT TIME for aerobic, and higher-intensity threshold training and racing.
This is highly relevant for athletes to perform at their best in both high-intensity training sessions, and during racing.
To make this super simple for you, take a read of our Training Guide Recipes - DOWNLOAD HERE
REFERENCES
(0) Plews D. Lactate for Endurance Training: What is it?. Endure IQ. Nov 2022.
(1) Jeng P. et al. Negative regulation of AMPK signaling by high glucose via E3 ubiquitin ligase MG53. Molecular Cell. Feb 2021.
(2) Li M. et al. AMPK targets PDZD8 to trigger carbon source shift from glucose to glutamine. Cell Research. Jun 2024
(3) Rothschild J. et al.Pre-Exercise Carbohydrate or Protein Ingestion Influences Substrate Oxidation but Not Performance or Hunger Compared with Cycling in the Fasted State. Nutrients. Apr 2021
(4) Frandsen J et al. Maximal Fat Oxidation is Related to Performance in an Ironman Triathlon. International Journal of Sports Medicine. Nov 2017.
(5) Nemkov T et al. Metabolic Signatures of Performance in Elite World Tour Professional Male Cyclists. Aug 2023.
(6) Spriet L. Regulation of substrate use during the marathon. Sports Medicine. Nov 2012.
(7) SFuels. Fructose Part 2: Blunting Aerobic Development (link). Jan 2023.
