SumGood Foods Inc. · Scientific reviewer: Dr. Bohdan L. Luhovyy, PhD, Mount Saint Vincent University · Last reviewed: · 13 min read
By the time you feel thirsty after a hard workout, your performance has already dropped. That's not a slogan. It's the consensus position of the American College of Sports Medicine, which has held since 2007 that dehydration of just 2% body mass measurably impairs endurance performance. So why is most post-workout hydration advice still some version of "drink water and you'll be fine"?
The honest answer: water alone isn't enough, the timing matters more than people think, and almost no one talks about post-exercise nausea even though up to 90% of endurance athletes experience GI distress. This pillar walks through the established science from ACSM, NATA, and the IOC, and shares findings from a 2024 clinical study at Mount Saint Vincent University that tested a Canadian fruit-based freezie format in 60 healthy adults.
Why does hydration matter so much after exercise?
Dehydration of just 2% body mass impairs endurance performance, and at 2.5% body weight loss, high-intensity exercise capacity drops by up to 45% (ACSM Position Stand, Sawka et al.; Human Kinetics, 2022). Those aren't small effects. They're the difference between finishing strong and limping through the last interval.
What's actually happening inside your body? When you sweat, plasma volume drops. Your heart has to beat faster to move the same oxygen, a phenomenon sports scientists call cardiac drift. Thermoregulation gets harder because there's less fluid available to move heat to the skin. Recovery slows, soreness intensifies, and your next training session starts from a worse baseline.
The International Olympic Committee's medical and scientific consensus has long recommended athletes limit dehydration to less than 2% body mass during exercise (IOC consensus on sports nutrition, 2010). That's a hard target on a hot day or during a long ride, which is why what you do after the session matters as much as what you do during it.
For recreational athletes, the runner, the cyclist, the hot-yoga regular, the weekend hockey player, the practical question isn't "should I hydrate after exercise?" It's "with what, how much, and how soon?" The next sections answer all three.
For the timing-and-volume answer specifically, see how much fluid you should replace below, or detailed timing guide for hydration before, during, and after exercise.
How much fluid should you replace after a workout?
The National Athletic Trainers' Association (NATA) recommends replacing 125-150% of the body mass you lost during exercise within 2-6 hours after finishing, not just matching the volume you sweated out (NATA Position Statement, McDermott et al., 2017). The "150% rule" exists because some of what you drink will be lost to ongoing urine production, especially if you're rehydrating with a low-electrolyte fluid.
Translating this into practice is simple: weigh yourself naked before and after a hard session. Each kilogram lost equals roughly 1 litre of fluid you'll need to replace, plus another 25-50% on top of that. So if you finish a 90-minute ride 1.5 kg lighter, you're aiming for about 1.9-2.25 L of fluid intake over the next several hours.
Don't have a scale handy? Two practical proxies: urine colour and frequency. Pale-straw urine within a few hours of finishing exercise suggests you're on track. Dark urine eight hours later suggests you're not. Reference values for hydration biomarkers like urine specific gravity were updated as recently as 2025 (PMC, 2025). The urine-color check still holds up.
Is water alone enough?
No. Plain water without electrolytes induces diuresis and lowers plasma osmolality, leaving you under-rehydrated even when you've matched the fluid you lost (Nutrients, 2025). The body senses falling sodium concentration, your kidneys flush the excess, and the cycle repeats. You feel like you're hydrating. You're partly peeing it out.
This is why the Beverage Hydration Index research has consistently shown that drinks containing electrolytes, especially sodium, retain more fluid than water alone over the recovery window. The optimal sodium concentration for post-exercise rehydration sits in the 40-100 mmol/L range; below 20-30 mmol/L, results get inconsistent (Maughan & Leiper, BHI research, 2021).
A 2023 trial in Frontiers in Sports and Active Living compared three commercial oral rehydration solutions to plain water and found that adding sodium significantly improved fluid retention versus water alone (Frontiers, 2023). The mechanism is straightforward: sodium pulls water with it across the gut wall and helps keep it in circulation rather than the bladder.
None of this means water is bad. It means water is incomplete. After a moderate or hard session, you want fluid plus the minerals your sweat carried out. The next section explains what's actually leaving your body when you sweat, and why generic sports-drink labels often overshoot or undershoot it.
What's actually in your sweat, and what should you replace?
Whole-body sweat sodium concentration in athletes typically falls between 20-80 mmol/L, with means around 40-50 mmol/L; sweat potassium hovers in the 3-8 mmol/L range, averaging about 6 mmol/L in marathoners (Foo et al., 2025; mySportScience, 2023). Within those ranges, individuals vary enormously. One athlete's "salty sweater" is another's barely-perceptible loss.
Now compare those losses to what mainstream products deliver per serving. The numbers aren't all calibrated to the same physiology. They're calibrated to different audiences.
Here's the implication that's rarely spelled out: if you're a 65 kg recreational runner doing 45-minute sessions in mild Canadian weather, drinking a serving designed for an ultra-runner means you're loading sodium you didn't lose. For most people, most of the time, the sweet spot is moderate sodium combined with adequate potassium, which is the next overlooked variable.
Why does post-exercise nausea happen, and what helps?
Exercise-induced GI symptoms affect 30-90% of endurance athletes, and nausea/vomiting was cited as the single biggest reason for not finishing 161-km ultramarathons in one widely-cited systematic review (MDPI Physiologia, 2022; Costa et al., Aliment Pharmacol Ther, 2017). That's a huge prevalence. So why does almost no post-workout hydration content address it?
The physiology is well-described. During hard exercise, blood is pulled from the gut to working muscles. Gastric emptying slows. Whatever's still sitting in your stomach, including any sports drink you took on board mid-effort, can trigger nausea once you stop. High-osmolarity beverages (read: too-concentrated sugar or electrolyte mixes) make this worse, not better.
What the literature actually supports for post-exercise GI distress: cool, palatable, lower-osmolarity options that you can sip rather than chug. Plain water frequently fails this test on the palatability side. If your stomach is unhappy, plain water is often the last thing you want. Sugary high-osmolarity sports drinks frequently fail on the gut-comfort side. Frozen formats land between the two on both axes: cold, easy to take in small bites, low-volume per swallow.
This is the gap SumGood's 2024 clinical study at Mount Saint Vincent University was designed to test. The next section walks through what they found.
What a Canadian university found when 60 adults tested fruit-based freezies post-workout
In a 2024 study at Mount Saint Vincent University's Department of Applied Human Nutrition (Halifax, Nova Scotia), 60 healthy adults completed a 30-minute moderate-intensity ergometer cycling protocol. Immediately afterward, they consumed two SumGood fruit-based freezies. Compared to immediately post-exercise, participants reported a 43% reduction in thirst (P<0.0001), a 38% reduction in fatigue (P<0.0001), a 49% reduction in nausea (P=0.04), and sustained energy gains of 32% versus baseline (P<0.0001).
A few details worth flagging about how the study was designed. Participants arrived after an overnight fast, with water permitted up to one hour before the lab visit. They completed 30 minutes of moderate-intensity stationary cycling, with the exercise intensity individualized. Subjective ratings were measured on a 100 mm visual analogue scale (VAS), the standard methodology for thirst, nausea, fatigue, and energy, at baseline, post-exercise, after the first freezie, after the second freezie, and 30 minutes after a follow-up lunch.
Beyond the symptom outcomes, the freezies scored 7.0 out of 9 on a hedonic pleasantness scale, a rating the researchers noted was statistically equivalent to pizza, one of Canada's most-liked foods ([download the full Mount Saint Vincent University study (PDF)]). Why does that matter? Because palatability drives adherence. The most clinically effective rehydration product in the world doesn't help anyone if no one finishes the bottle.
The study was not designed to make therapeutic claims, and we don't make any here. SumGood is a food product, not a treatment for nausea, dehydration, or any medical condition. What the study does provide is the kind of measurable, peer-reviewable data that's almost impossible to find in this product category, and a clear demonstration that "fruit, sea salt, potassium, frozen" is a format worth taking seriously for post-exercise recovery.
How should recreational athletes apply this science?
For most recreational athletes, one-hour workouts in moderate conditions, no extreme sweat losses, the practical post-exercise protocol is straightforward: weigh yourself pre/post when you can, replace 125-150% of fluid lost within 2-6 hours, choose a beverage with sodium in the 40-100 mmol/L range, and prioritize palatability over precision (Maughan BHI; NATA, 2017).
What does that look like in real life? If you finished a hot-yoga class drenched, your body lost mostly fluid and sodium. You'd benefit from electrolytes alongside water. If you finished a 30-minute run on a cool morning, your losses are smaller and water with a lighter electrolyte source covers it. The gap between "I exercise" and "I'm an elite endurance athlete" is enormous, and the same product doesn't fit both ends well.
Don't get distracted by the precision question if it's blocking action. Hydration cues that don't require a scale, thirst (an imperfect but useful signal), urine colour over the next several hours, how you feel the next morning, are good enough for most weekend training. If you're racing or training competitively, sweat-rate testing through a sports dietitian or a sports medicine physician gives you the precise prescription.
And finally: don't ignore your gut. If a product reliably makes you nauseous in training, it'll do worse on race day. The "best" recovery drink is the one your body tolerates and you'll consistently use, not the one with the most impressive label.
For a full breakdown of the study above, see post-exercise hydration & recovery: what 60 adults taught us. For the deeper electrolyte chemistry, see why electrolyte ratios matter more than the brand on the bottle.
When should you consider something other than water or a sports drink?
Consider an alternative format like a fruit-based freezie when post-workout nausea, taste fatigue, or hot-weather GI distress make conventional sports drinks unappealing. Palatability is the single biggest driver of post-exercise rehydration adherence (NATA, 2017). The science of "what to drink" only matters if you can also answer "what will I actually finish?"
Heat stress is a clear case for a frozen format. After hot-yoga, mid-summer cycling, or a hard CrossFit session in a non-air-conditioned box, you've taken on a thermal load on top of the sweat loss. A cold, palatable option helps with both rehydration and the thermoregulatory recovery your body is also trying to do. There's a reason ice slurries have been studied as a precooling and recovery tool. Cold matters.
The same logic applies if you're someone who routinely gets nauseous after intense effort. The literature on exercise-induced GI distress is consistent: smaller volumes, cooler temperatures, lower osmolarity, palatable formats. A freezie made from pressed fruit and a clean electrolyte blend hits all four. So does a thoughtfully-mixed sports drink served cold. The format isn't sacred, the principles are.
If you want to try the format that the MSVU study tested, you can shop SumGood freezies here. If you're more interested in the science than the product right now, scroll down to the FAQ, or jump to [our research page with the full PDF of the MSVU study].
The bottom line
Post-exercise hydration is more nuanced than "drink water," and the gap between elite-athlete formulations and recreational-athlete needs is real. Match the product to the use case, replace 125-150% of fluid lost within 2-6 hours, take electrolytes seriously without overdosing on sodium, and pick something you'll actually finish.
- Replace 125-150% of fluid lost within 2-6 hours after hard exercise.
- Plain water alone is suboptimal. Sodium and potassium matter.
- Most recreational athletes need less sodium than mainstream sports-drink labels suggest.
- Post-exercise nausea is real, common, and rarely addressed in hydration content.
- Palatability drives adherence. The best drink is the one you'll actually finish.
Want the full MSVU study? [download the full PDF on our research page]. Ready to try the format that was tested? Shop SumGood freezies →