Does an endurance athlete’s hydration needs change as they age?

Sports scientist Andy Blow examines whether the hydration needs of endurance athletes change as they age, and whether these changes need factoring into their nutrition plan.

Triathlete drinking on the bike

The fact that we’re living much longer (combined with increases in free leisure time) has meant that more and more older adults are taking part in serious sporting events, from Ironmans to ultra marathons and long-distance cycling sportives like Audax events, and achieving things that would not have seemed possible even a few generations ago.

Advertisement MPU article

Like Rob Barel winning the men’s 60-64 age group at the 2017 Ironman World Championships in Kona in a staggering 9 hours and 46 minutes – a time that would have placed him in the top 10 of the race overall well into the mid 1980s!

How much dehydration can you tolerate during an Ironman?

How to fuel the Ironman

What are the different types of sports drinks and when should you use them?

Overall participation rates in the older age-groups in all manner of races and events are increasing year-on-year too.

 But do your hydration needs change as you age? Well, yes they do, whether you’re a long-distance triathlete or ultra-marathoner, and here’s why…

1)    You have less water on board to start with

Around 60-70% of your total body water is locked inside your cells in the intra-cellular compartment (and it’s known as ICF), with the remainder sloshing around outside them as extra-cellular fluid (ECF).

Because your muscle cells in contain a large amount of your ICF volume, the amount of muscle mass you have has a big influence on your total body water levels. Losing lean muscle tissue is an inevitable consequence of getting older (especially past the age of 50), so it follows that your total body water content declines as you age.

I’ve seen it reported that losing 4-6 litres of today body water between the ages of 20 and 80 is in the normal range, though there’s not a complete consensus in this area and my guess is that this may well vary considerably from individual to individual.

Although training (especially lifting weights) can help to reduce the loss of muscle mass with ageing to a certain degree, it’s basically impossible to halt it altogether. With this loss of muscle you also lose a significant chunk of your ‘reservoir’ of fluids as you age, meaning that dehydration can occur more rapidly when you’re sweating a lot than it can for younger athletes.

2) You tend to lose more water through urine

Another factor that impacts hydration levels in older people is that kidney function tends to deteriorate as you get older as well. Reduced kidney function means less concentrated urine can be produced and, as a result, more free water is lost when you pee.

This may be compounded in some by a reduction in levels of aldosterone, a hormone responsible for helping your body hold onto water more effectively. Less aldosterone = peeing more frequently = more total body water flushed down the pan each day.

3) Your sensation of thirst is diminished

A study published in 2001 clearly demonstrated that, whilst adults over 65 tended to drink sufficient fluids to maintain normal hydration status on a day to day basis, when their hydration levels were challenged by periods of sweating, their sensation of thirst – and therefore their tendency to rehydrate effectively – was compromised when compared with younger people.

The participants tended to correct this dehydration eventually, but possibly more slowly than would be compatible with optimal recovery from performance in high intensity sport.

These three factors suggest that older athletes need to be a bit more diligent with their hydration practices than youngsters as the margin for error is reduced and the risk of dehydration is somewhat increased.

What can older athletes do to avoid dehydration?

Well, for starters, just being aware that you probably need to drink a bit more is an obvious place to start. But, I’ve written about the perils of dramatically over-consuming fluids before.

In a nutshell, hyponatremia is a very real risk and this can really impact your performance and make you pretty ill, so that advice needs to be taken with a degree of moderation and common sense.

A more specific tactic is to aim to take in some additional sodium with your fluids when you’re sweating. Sodium helps you hold onto more water in your extra-cellular fluid and bloodstream and this reduces cardiovascular strain, helping you maintain your performance.

The concentrations of sodium in your body fluids are finely balanced by various processes, so it can be a sensible idea to add a bit of extra salt to your food – and/or some sodium supplements in your drinks – at times when you know your hydration levels might be challenged. Increasing your sodium intake also increases thirst, which should urge you to drink more too.

Finally, it’s very important for older athletes to start training or events properly hydrated and to ensure they rehydrate effectively after they’ve finished.

As an aside, it’s worth noting that the 1,000mg/l and 1,500mg/l electrolyte supplements we make at Precision Hydration are 2x and 3x stronger than typical sports drinks, so they’re often very popular with older athletes who’re struggling to stay properly hydrated with water or weak hydration supplements alone.

Advertisement MPU article

If you’re an older athlete who struggles with hydration issues like dehydration or cramp after longer period of sweating, it’s worth taking Precision Hydration’s free online Sweat Test to help you get started with personalising your hydration strategy. And, if you have any questions at all, just drop me an email.

Hydration: 5 mistakes triathletes make and how to avoid them

Electrolyte sports drinks: can you overdose?

What and when to eat before an Ironman

Does coffee dehydrate you?

Hyponatremia: What it is and how you can avoid it