• Precision Fuel & Hydration Sweat Test Officer and running coach Joe Wenman ended his season on a high with a 6th place finish at the Portsmouth Coastal Waterside Ultra
• Pre-race, Joe refined his well-thought out Fueling & Hydration plan with the help of Sport Scientist Emily, increasing his confidence going into the race just before Christmas
• Having never completed a flat race before, Joe was interested in doing something different and thought this 50km with only 100m/328ft elevation was the perfect opportunity. Prior to this race, both his marathon and 50km PB were set on an 80km course with 2899m/9511ft elevation
• After finishing the race in a new 50km PB time of 4 hours and 4 minutes, Joe said “I was chuffed to keep up with the flat-landers to finish with a good result and a whole bunch of personal records”

Hydration

• Joe was able to weigh himself both before and immediately after the race to help us quantify his total volume of sweat losses (learn more)
• Joe finished the race with a -2.88% change in bodyweight. Although it has been widely debated how much dehydration individuals can tolerate before performance suffers, we know it can be highly individual. The 2% rule around dehydration is recognised to be a myth within Sports Science which originated from old scientific studies that purposely, and aggressively, dehydrated athletes ahead of exercise and saw performance, unsurprisingly, suffer as a result. It’s now more widely accepted that endurance athletes may finish 2-4% dehydrated without any obvious impediment to performance
• A contemporary theory is that well-trained athletes are more accustomed to these levels of dehydration (as a result of their high volume of training) and their performance is less affected
• From the data Joe collected, we were able to estimate his sweat rate. In total Joe drank ~1.7L/57oz and lost 2.3kg (5lbs) in bodyweight, which suggests his total sweat loss was ~4L/135oz and equates to an average sweat rate of ~1L/34oz per hour. It’s important to recognise in an event of this duration that this sweat rate is an estimate, and that not all bodyweight lost will have been from sweat losses (some may have been glycogen metabolism or respiratory losses)
• Joe drank an average of ~417ml/hr (14oz/hr), so we can see that he was replacing just under half of his estimated losses throughout the race. Taking into account the cooler conditions and the race duration, this is a decent level of replacement. That said, replacing a little more fluid (closer to ~500ml/hr) may have aided Joe’s performance
• Joe rated his hydration strategy as 7 out of 10, saying “it was perfect for the first half, but if the race had been longer I would have struggled”. This ties in with what we see in his numbers; his fluid intake was adequate for the distance but any longer and Joe may have struggled as his degree of dehydration became more substantial
• We can estimate Joe’s overall sweat sodium losses because we know from his Advanced Sweat Test that he loses 1,208mg of sodium per litre of sweat and he was losing ~1 litre of sweat per hour, so he was losing ~1,208mg of sodium per hour. In terms of Joe’s sodium intake, he consumed ~314mg/hr which meant the relative sodium concentration of his intake was ~754mg/L. It’s feasible that consuming a bit more sodium may have been beneficial, but we know that 100% replacement, especially in cooler conditions, isn’t necessary
• Joe said he chose to listen to his body and didn’t take on as many electrolyte capsules as he had planned because he didn’t feel he needed them towards the end of the race. He was happy with this strategy and didn’t experience any cramping during the run

Fueling

Conclusions

• Joe was “happy with the result” at the Portsmouth Coastal Waterside Ultra after meeting his goal to achieve both marathon and 50km personal bests! Therefore, he rated his race satisfaction as 8 out of 10
• He has many races lined up next year, including the Manchester Marathon, Endurance Life Pembrokeshire Ultra and Centurion South Downs Way 100 in June. For those events, Joe may benefit from trying to increase his hourly carb intake to see if that helps his performance, while he will want to increase his sodium intake in warmer race conditions