Electrolytes such as sodium are commonly included in popular sports drinks and there are salt tablets on the market to help endurance athletes rapidly increase sodium intake. Sodium is often said to benefit performance but there have not been many studies looking at it. Even the small number of studies done were not carried out in hot weather and they didn’t personalize sodium intake to match the individual needs of participants. With these limitations in mind, let’s take a look at what they say.
Sodium for runners and cyclists
A study from 2003 looked at 13 well-trained female runners. They were given 1 litre of water per hour with either 680 mg/l of sodium, 410 mg/l of sodium or no sodium during three separate 4-hour runs. The results showed no performance differences among the three scenarios. It is worth noting that some of the athletes developed hyponatraemia during the no-sodium trial run, a dangerous low-sodium state.
In 2013, a different study observed 5 male and 4 female well-trained cyclists during a 72-km road cycling time trial. Athletes were randomized to receive either 280 mg/h sodium or a corn flour placebo. They received as much water as they wanted. The results show that during this approximately 3-hour time trial, the sodium intake didn’t improve performance.
Another trial from 2015 studied 11 experienced runners and cyclists who were asked to do 2 hours of fixed-pace running or cycling followed by a time-to-exhaustion test with increasing intensity. They received either a high dose of 900 mg/h sodium or a placebo. The results show that the sodium intake didn’t impact physical performance.
These trials are showing that low, medium or even high doses of sodium do not influence performance as long as water is provided. The only issue is high water intake combined with no sodium intake, which results in hyponatraemia.
Sodium for triathletes
A 2006 study followed 114 triathletes during the Cape Town Ironman triathlon. This course included the standard 3,8-km swim, 180-km bike course, and 42,2-km run and took the competitors an average of 12 hours to complete. The athletes were given 284 mg/h of sodium, placebo or no supplementation. The study found that sodium supplementation was not associated with any difference in triathlon racing performance.
Another study from 2016 looked at 26 well-trained male triathletes. The athletes were competing in a half-ironman distance course that includes 1,9 km of swimming, 90 km of cycling, and 21,1 km of running. They were given either salt tablets with 504 mg/h of sodium or a placebo. The results show that the salt group completed the course 26 minutes faster on average.
“This positive effect on performance relates to an increase in the concentration of electrolytes in the blood, making them drink more fluids during the race (as salt stimulates thirst) and improve the water and electrolyte balances during the competition,” the researcher commented.
This was the only study showing a benefit. There is one possible problem. The reported benefit of 26 minutes, roughly an 8% improvement in the total time, is much higher than what would be expected from a nutritional intervention such as optimised hydration. This brings up concerns about whether other factors could have influenced this result.
Will sodium improve your cycling performance?
Based on the limited evidence available, it seems like sodium intake itself is unlikely to improve performance. If, however, you end up drinking more as a result of increased sodium intake, you would maintain a better hydration status, which would improve performance. Sodium intake during exercise can also help you prevent dangerous hyponatraemia. Overall, it’s a good idea to take in sodium during long endurance exercise, either in the form of food, supplements or sports drinks to avoid health issues. But don’t expect to go faster as a result.