After bike saddles, there's perhaps no area of triathlon where personal preference plays a greater role than nutrition. While almost all athletes exhibit strong preference, let's not forget that they are just that - preferences - and that Faris al Sultan won Kona stuffing on-course bottles of Gatorade into the back of his speedo on the bike. Most complexities in the nutritional realm are the result of poor pacing. The lower your effort and heart rate, the more blood that's available for your digestive tract and the more likely you are to do just fine on almost any calories. While there is some science arguing for multiple carbohydrate sources- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4008807/ - some protein - or at least BCAAs - in your drink (though the research here is admittedly much more mixed) - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7126259/ - most ultra-distance nutrition guidelines are pretty simple. Nutrition is much more often a pacing problem than a chemistry problem.

But while you can probably do equally well on a wide range of fuels, that doesn't change the fact that preference matters. You are more likely to drink things that you like the taste of (though by the end of an Ironman, it really is just about forcing yourself to do it because you need to). And there's definitely some individuality around what sits well in the gut, though in my experience if this is true for an Ironman, it means you are going too hard. For a half or an Olympic though, it definitely matters. Once you start talking about 90% of threshold or higher, it does seem that some of the personal preferences of fueling become more impactful.

Personally, I don't do well with pure water. I suffered massive cramping early on in my pro career, and it was only when I started taking a lot of sodium - at least 1000mg/hr and sometimes 1.5 - 2x that - that I started doing well. Gels, on the other hand, I just dislike. I'ved used gels in plenty of races, but I really do not like them. I don't like the consistency. I don't like the often overly strong flavor. And I don't think, at higher intensities, they digest well for me. So when First Endurance asked that I review their new Liquid Shot, I thought it best to seek out additional testers. I used Liquid Shot for most of my ultra distance races. But only as emergency calories. It was an easy way to get in a big hit of calories - a flask of Liquid Shot was 400 calories in the original formulation, and I knew it wouldn't upset my stomach. But I never really wanted to take it. EFS, on the other hand, I drank because I thought it was delicious. And still do, though my flavor preference has varied. And I'm a bit annoyed that the new Sour Watermelon flavor was not available when I was racing for a living.

While race day is certainly a time for pragmatism, during training, preferences really should reign supreme. And while there's no substitute for trying things for yourself, the collective wisdom of the Slowtwitch forums is not to be underestimated. I solicited testers on the forum for this article on a purely volunteer basis. Of the 13 testers, seven indicated the full/ultra distance races were their primary race distance, two indicated 70.3, and then one each said Olympic, century rides, ultra-distance gravel, and trail races up to six hours. With 11 men and 2 women, the demographics are a bit more skewed than I'd hoped for. However, while I put a great deal of stock in Dr. Stacy Sims' assertion that, "women are not small men." I would also say in own experience giving nutritional advice - I gave regular talk before numerous editions of Ironman Canada and elsewhere on race day fueling, I'd also say that it's more true that - from a fueling perspective for ultra-distance especially - we are essentially just humans of varying sizes.

Also note that I specifically solicited testers for First Endurance, so there's some obvious selection bias here. Folks who might have had a bad experience in the past are almost certainly less likely to have participated and folks who had a positive experience - or who were active First Endurance users - were almost certainly more likely to sign up. With all those caveats aside, I still think the collective opinion of 13 different athletes is more valuable than me sharing my opinion about a product line that's slightly changed - though very much in the same overall vein - as what I used for virtually the entirety of my professional career. Fans of First Endurance will find the core of the product line here largely unchanged with the notable exception of improved flavors. Mixability has also been improved, but as a long-time First Endurance user, it was the new flavors that really stood out to me. The sour watermelon, in particular, was unexpectedly delicious.

Sour Watermelon also turned out to be the overwhelming favorite among testers. 7 of 13 testers preferred it; 3 preferred Orange Splash; and 2 preferred the Lemon Lime. Samples of the Fruit Punch were not provided, and testers only received two samples - Sour Watermelon (the newest flavor) and another. First Endurance has generally had a relatively mild flavor profile, and the addition of Stevia along with other flavors is probably the biggest change here. These are much stronger flavors. Especially if you mix them at higher concentrations. One tester said they would like the Sour Watermelon, but diluted. That's probably not all that viable given that a basic serving is only 110 calories. But in typical fashion, for every review that said, "WAYYYYYYY too strong of a flavor I couldn't see myself consuming this during a race" there was another that said, "Sour Watermelon was the perfect blend - tart and light."

Feedback from the testers who noticed - and mentioned - the Stevia was fairly negative - "The flavor is fantastic, minus one element - the stevia. I know plenty of people like it but it gives a bad aftertaste and upsets my stomach (and my wife as well) - which sucks, because sour watermelon is the best tasting sports drink I’ve ever had, otherwise." But only two of the 13 testers even mentioned it. If you are sensitive to Stevia, this may not be the drink for you. But the sweetness is there to offset the lack of sweetness from the more complex carbohydrates that provide the vast majority of the calories.

Overall, the fickleness of taste came through. Five of 13 testers said the flavor was likely too strong, but then six seemed to indicate that the sweetness was spot on. If you're looking for consensus, sports drink flavors are not the place to find it. Overall, the strength of the flavors is both the biggest change from past First Endurance EFS of the past. For testing, all samples were of "regular" EFS and not EFS Pro. EFS Pro was introduced in 2015 specifically as an ultra-distance fuel. The biggest change - and one that I pushed very hard for - was a reduction in the amount of magnesium. I tend to mix my EFS very strong - about 400 calories per bottle - for Ironman racing, and regular EFS has a fair bit of magnesium - about 3x as much per serving as EFS-Pro. If you mix your drinks very strongly (like I do), that might be a reason to choose EFS-Pro for racing. For training, however, where I tend to get calories from a wider variety of sources, I preferred the stronger and sweeter flavor of EFS.

The first variation of EFS-Pro was very, very mild as it was designed to be palatable when it was warm (sitting in a water bottle) and you were way past the point of wanting sweetness (say 6hrs+ into a race). The problem was that this was a tough sell during tests like this one. It's hard to know what you'll like until you're actually in that situation. The Cucumber-Water flavor was a prime example of this. It was, admittedly, pretty awful in the first hour of a ride. But it was perfect at 5hrs+ in. But it just didn't sell because that first taste was not a great experience. The flavor profiles have, as of this latest iteration, been brought more in line so there's less of a discrepancy, though EFS-Pro is still notably less sweet - in large part because it does not contain the added Stevia. Overall, the distinction between EFS and EFS-Pro is still somewhat murky with it not being entirely clear which to choose. Generally speaking, I chose EFS for training and EFS-Pro for racing, and that's still the recommendation I'd make today, both for reasons of flavor and for the specific electrolyte profile of each version; EFS-Pros electrolyte composition was definitely influenced by my consumption requirements, and I still think it's one of the best contributions I made to the First Endurance line from a performance standpoint for ultra-distance athletes.

Performance of a drink is tough to measure, but no tester reported any GI distress or other issues during testing. Several testers made note of the relatively high electrolyte content, which is what has always been the real hallmark of EFS (Electrolyte Fuel System…). And that's what drew me to First Endurance in the first place, since I was tired of opening SaltStick caps and dumping them into whatever I was drinking. Even as an EFS user, I still used SaltStick caps during races, but I also was a relative outlier in terms of sodium needs. Most folks will likely find the electrolyte levels in EFS to be quite adequate. Even among the testers who noted their dislike for the strength of the flavor noted that EFS digested easily - "No complaints- past the strong flavor it sat well in my system." and "It seems like a good consistency and the calories seem to be calories that I can absorb without stomach issues however the flavoring is too strong." Turns out the science of performance is a fair bit easier than the science of taste preference.

Overall, five of 13 testers indicated they would use EFS for racing and training, three said they would use it only for training, and one only for racing. Two testers said they would not use it for either. And then two testers were undecided and felt they needed to do more testing to see if it would work well for longer sessions more akin to a race.

In addition to the EFS drink mix, testers were also provided with samples of Liquid Shot, First Endurance's "gel." I say "gel" because unlike other products there are no binders or gelling agents of any kind - no guar gums, etc. Originally, Liquid Shot was viewed as a sub-product of EFS, but First Endurance has dropped the EFS prefix. But the idea that Liquid Shot is, basically, a concentrated sports drink remains. While I don't personally like gels, the absence of any binders meant that Liquid Shot always digested very easily for me. I never had any repeating, and - most critically - I never felt like I had a lump in my stomach after taking it, even without water. But the taste profile has always different. Originally, it was more savory flavors - Vanilla and Coffee. I don't know if it's the way it needs to be made - to get the consistency correct in the absence of binders, but the taste profile is just very strong. Always has been. The current Liquid Shot comes only in a single flavor - Wild Berry - but it's notably different than something like a Gu or ClifShot of the same "genre." It's much more akin to like a Raspberry Creamsicle. Liquid Shot has always had this sort of "creaminess" to it, which I think must just be a byproduct of the ingredients and also the manufacturing. The digestibility is fantastic. The flavor is more … contentious.

The ease of digestibility was by far the thing testers noted as well. No tester indicated any sort of GI issues and four of the 13 specifically called out how easily it digested. It really is a different product than a "gel," though that is of course what it's competing against. As one tester wrote - "Big fan of the consistency and the packaging. Nice and easy to get down, not sticky like gu. I really like that the packaging is almost flat. I do ultrarunning more than anything, and this picks well in pockets and vests. No stomach issues." In particular, the ability to take it without water has always been a hallmark feature, and one tester spoke directly to this - "I took the first gel without water 4 miles in to an 8 mile run. I felt like it gave me a little punch to finish well. My mouth was coated a bit but not too bad. Second gel I took with water about 5 miles into a 9 mile run. Again-felt like it gave me enough to finish well (no walking at all on either run)."

Flavor, on the hand, was split almost evenly. Seven of 13 testers liked the flavor - "Nice flavor. No need to chase with water. No after taste. Easy packaging to open." and "The mixed berry is the flavor sent to me-I really liked it...not overwhelming. I also liked that the texture was a little less gooey than some of the other gels on the market." But the other six were pretty dead set against it - "i got the berry flavor, and i hate to say it, but it was awful. long lingering after taste, i loved the old kona mocha flavor" and "WOW! A bit too strong in the raspberry, which I usually am a huge fan of. I am of the feeling that 3 hours in the flavor may be definitely over the top. I'd prefer it a bit more muted." I expect that First Endurance will probably need to introduce at least one more flavor - and perhaps even more - to appeal to a broader audience. But that's certainly a lot easier given that the biggest change overall is that Liquid Shot now comes as a single serving rather than the smallest serving being a 400cal flask.

Overall, in spite of issues with the flavoring, only three testers said they would not use the product again for racing or training. Three testers said they'd use it for racing and training, three said they'd use it only for training, and then one each for racing-only, maybe with more testing, and maybe with different packaging (the sample single serves were very long and skinny, more like a squeeze-pop, which has since been replaced by a more traditional "packet").

Ultimately, there's no accounting for taste. But thankfully, First Endurance makes every product available in single-serving packets. If you have a nutrition plan you're happy with, stick with it. If you're still searching, First Endurance has made a number of key improvements to their outstanding electrolyte and fueling system that might be what you're looking for. Thank you to them for providing samples. Lastly, I'd like to say thank you to the Slowtwitch forum users who volunteered their time and feedback for this article.