Dr Stacy Sims first developed sports hydration mixes in her kitchen to support her own training. Since then she’s
spent a decade working with athletes to improve their performance. She says strength and power in the gym can be
adversely affected by poor hydration.
Being thirsty should set your alarm bells ringing. It’s a sign you’ve lost 2% of your body water, which can mean 2.5% of your body weight, 11% of your aerobic power and 45% of your capacity for intense anaerobic exercise.
Having low levels of water in your blood results in low blood volume and poor circulation, which means your muscles fatigue sooner. Dehydration affects your central nervous system too, slowing neuromuscular signalling and reaction time, so your power plummets. And it impairs your ability to sweat, so your skin and core temperatures rise. Once they pass 39°C the contractile proteins of your muscles can be damaged, which reduces your strength.
There are two big mistakes people make with their hydration. The first is to drink lots of plain water. Many clients tell me they drink two liters a day but pee constantly and are still thirsty. That’s because plain water doesn’t hydrate efficiently. There’s no plain water in the body – it’s a solution of electrolytes, glucose and amino acids. If you drink large volumes, your body produces more dilute urine to get rid of the excess.
The second is to rely on typical sports drinks. These usually have the wrong osmolality – the balance of water and electrolytes – to promote fluid absorption. In fact, most promote fluid loss from the body.
The goal is to maintain blood volume for adequate muscle blood flow. Ensure you’re well hydrated before training by eating foods with a high water content and sip a functional hydration drink between sets to delay fatigue. Choose a drink that has 3-4g of carbohydrates per 100ml. It should include glucose and sucrose (two sugars are better than one for fluid absorption) but not fructose, which can upset your stomach. It’s also a good idea to add sodium and potassium because they provide support for high-intensity exercise.
But the simplest immediate fix is to add a dash of table salt – about one-sixteenth of 1tsp – to every 500ml of water to boost absorption. It’s better in your drink than on your chips.