Your guide to post-ride recovery nutrition – Part 3: Rehydration
When it comes to getting the most out of your cycling, few things are more important than recovery. It’s not enough to just smash yourself on the bike, day after day — you also need to give your body a chance to recover, and recover properly.
In this three-part series, dietitian Alan McCubbin takes a deep dive into the nutrition science behind recovery, giving you practical advice that you can apply to your own riding. In the first instalment we discussed the specifics of re-fuelling with carbohydrate; in the second we looked at repair (and adaptation) with protein.
In this third and final part we’ll look at the final of the three Rs, rehydration. We examine the context in which rehydration is or isn’t important, and speak to a researcher taking a more pragmatic view, with some surprising results.
Rehydrating to perform again
The purpose of focussed rehydration after a ride is mostly based on a need to restore body water (and with it blood volume) prior to the next ride. The amount of fluid required to do this will obviously depend on how much was lost during the initial ride, and this will vary enormously depending on factors like the intensity of the ride, weather conditions, body size, fitness, and how well acclimated you are to hot weather.
The recommendation often cited is that if you weigh yourself before and after exercise, and work out the amount of weight lost as sweat, you should aim to replace 125-150% of those losses within a few hours of finishing exercise. But this recommendation, which is probably quite appropriate for team sports and shorter duration efforts, assumes that a) the next exercise session occurs within a few hours, so rehydration needs to be rapid, and b) all of the body weight lost is from sweat, which is probably true of exercise less than three hours, but is not the case when exercising more than three hours.
So focussed drinking after a ride is probably important when the initial ride involved large sweat losses, the next ride needs to be of high quality, and occurs within only a few hours. Most of the time though these three factors don’t all coincide, and normal eating and drinking will suffice.
What to drink for rapid rehydration
There’s no shortage of focus on sodium as a nutrient which will enhance the absorption of fluid from the gut and increase the retention of that fluid in the blood (i.e. you don’t pee out as much of what you just drank). This is the basis of numerous sports and rehydration products on the market, which often include some carbohydrate as well, because glucose also assists in this process. More recently, researchers have even created a “beverage hydration index”, which rated beverages on the ability to absorb and retain fluid in the body.
But the use of this type of index is made on the assumption that the fluid is the only thing being consumed after exercise. This might be true in some situations, but a lot of the time we’re eating a meal or snack, or having a coffee after a ride, even with another one coming up soon. And remember, we don’t want to neglect the other two Rs of recovery if they’re relevant.
I spoke to Associate Professor Ben Desbrow at Griffith University on the Gold Coast about his take on the Beverage Hydration Index. “I understand why people did the Beverage Hydration Index. It’s good to be able to package things up and categorise them into certain boxes,” he said. “But its major limitation is the methodology. We don’t give a drink to someone and get them to sit around and not do anything else, not consume anything else. It’s not the way we live.”
To Desbrow, the Index simplifies the potentially complex response that we have to food and fluid combinations. As a result, his team has done some research looking at what happens when you combine post-exercise drinking with food.
“We started to combine the food because … there has only really been [two] other studies and they’re very prescriptive,” he said. “In addition, the foods chosen — jerky and a chilli beef and rice meal — weren’t the sorts of foods that people would often consume after exercise or have available to them.
“So we thought ‘Well if we’re going into the food and fluid space, let’s give people the option of not only consuming food, but different types of food and fluid in different amounts.’”
Desbrow’s team looked at how well different drinks rehydrated when combined with food that the athletes chose, in both males and females. It turned out that the choice of drink made no difference when combined with food, because the food contains a variety of nutrients (including sodium and carbohydrate), which compensated for any lack of these in the drink.
“We see good fluid retention from any beverage after two hours provided there’s access to food within the first hour,” Desbrow explained. “Any of the parameters we measured, which includes plasma osmolality [dilution of the components in your blood], markers in urine, and changes in body weight — they’re all the same. But when the drink contains calories (i.e. either sports drinks or milk-based beverages) you always end up consuming more calories than food and water.
“So the message is that we want you to drink to the context. If you’re an individual who’s exercising with a primary focus of [weight loss], and you don’t have to exercise in the next two or three hours, then just drink water. Because as soon as you start eating something you’re going to start retaining that fluid to a much greater extent than you would otherwise. And you don’t need to eat a lot, just a small amount.”
Desbrow explains that while sports drinks might be marketed as post-exercise beverages, they weren’t really designed for that use.
“You may feel like a better athlete doing it, but in essence look at what your dietary goals are, and what you’re trying to achieve from that particular event and what you’ve got in a subsequent event,” he said. “And if you don’t have anything in the next eight hours, then drinking water is a pretty good option”.
What about a post-ride beer?
Perhaps the work that Desbrow and his team are most well-known for is a series of studies looking at the effect of beer on rehydration, and their attempts to modify beer to improve its fluid retention.
“When you look at human behaviour it just became obvious that with volume consumption, beer is a beverage that people can drink in large volumes,” he explained. “There’s no other beverage that I’m aware of that routinely gets served in communal jugs.
“To optimise rehydration, palatability is important, so why not look at a beverage that people enjoy drinking in large volumes?”
Desbrow’s thinking was that if he and his team could manipulate beer in a way that enhances its fluid retention, then they should be able to capitalise on the social acceptance of the beverage.
“We’ve done studies where we’ve given sodium in beer to see if you get a [benefit to fluid retention] and you do seem to,” he said. “But palatability becomes an issue. The first one we only did a 25 mmol per litre [or 58mg sodium per 100mL of beer] that we thought that was a nice balance between palatability and physiological effectiveness, and it was effective. The second study we did we used two different sodium concentrations [25mmol/L again and 50mmol/L, or 115mg/100mL].
“Any beer with 50 mmol/L of sodium tastes fucking terrible, and you can quote me on that!”
These studies on beer came before the work on food combined with fluids, so I put it to Desbrow that the retention of fluid from beer would be greater when combined with food.
“Based on our alcohol work and rehydration, if you’ve got less than 3.5% alcohol in your beverage you’re not going to get a huge diuretic effect mediated by the alcohol,” he said. “And you are going to see an enhanced fluid retention from the beverage [taken with food]. So my advice is to stick in that mid- to low-alcohol range, have some food with it, and it’s probably a reasonable choice.
“For me that’s a nice message because you don’t always have to tell people not to do something — it’s a case of saying ‘if this is what you’d like to do we can use that, but this is what we need to do in terms of manipulating it”.
I also asked Desbrow about the effect of drinking champagne on the podium, and later that night with your teammates after a successful day’s racing:
“We’ve only done beer!” he said. “There’s a whole spectrum of other products to have a crack at. I don’t know the number of females who have come up to me and asked ‘When are you going to invent a rehydrating wine?’
“This is what I love about my job — it’s just good fun and I get paid to do it.”
As we’ve seen across all three articles in this series, the official recommendations on nutrition and hydration after a ride have come from a research background that looks at optimal, rapid recovery. Much of this work also comes (by way of necessity) from a background of isolating individual factors in the lab setting, which may or may not be relevant to athletes living in the real world.
These recommendations can still be important for many athletes, in many situations. But there are also a lot of times when rapid re-fuelling, repair and rehydration simply isn’t important. By thinking about the context of your cycling, you can pick and choose when these recommendations apply to you, and avoid either inadequate recovery or excessive recovery when it doesn’t matter.
About the author
Alan McCubbin is an Accredited Sports Dietitian, Accredited Practicing Dietitian and past president of Sports Dietitians Australia. He is currently studying his PhD in sports nutrition at Monash University. He is also the founder of Next Level Nutrition, an online sports nutrition consultancy through which he works with a range of athletes from recreational to Olympians.