9th
Sam Skinner's scorecard
Arc of Attrition
Friday 27th January, 2023
Within recommended ranges
Just outside recommended ranges
Significantly outside recommended ranges
87g
Carb per hour
343mg
Sodium per hour
313ml
Fluid per hour
1,098mg/L
Relative sodium concentration
20.83mg/kg
Caffeine per bodyweight
How Sam hit those numbers
How Sam's hydration and fueling went...
- After a strong 5th place finish at the 2022 Dragon’s Back race in North Wales, Sam was looking to secure another top-10 finish when taking on the gruelling 2023 Arc of Attrition in the South West of England
- Sam worked with the PF&H Sports Science team in the weeks building up to the race to refine his fuel and hydration strategy, with the aim of breaking the 24-hour mark for the 100-mile event
Hydration
- Sam drank ~450ml (14oz) of PH 1500 electrolytes with his breakfast on the morning of the Arc to ensure he was going into the race properly hydrated. Science shows that preloading with a strong sodium-based electrolyte drink ~90 minutes before endurance exercise can boost blood plasma volume, which will have helped Sam’s ability to regulate his temperature and reduced the strain on his cardiovascular system during the first half of the race
- Overall, Sam was able to drink an average of ~313ml (10oz) fluid per hour, with a relative sodium concentration of ~1,139 milligrams of sodium per litre (mg/32oz)
- We know from Sam’s Sweat Test that he loses 819mg of sodium per litre of sweat (mg/32oz), so his intake of ~1,139m/L was probably more than was required given the temperate conditions. Sam may have overdone his sodium intake slightly, which might well explain the “puffiness” he experienced
- This said, Sam was happy to share that he experienced absolutely no cramping, which has previously been an issue for him when he’s underdone his sodium intake during events like this
- Interestingly, when comparing his body weight pre- and post-race, Sam actually gained 3kg (~6.6lbs). This may partially have been due to a prolonged period of maintaining a relative sodium concentration which was too high for his individual losses and so resulted in some excess fluid retention
- Sam mentioned that he craved Coca Cola from around mile 21. Alternatively known as the ‘Red Ambulance’ in endurance circles, we often observe athletes turning to cola during the latter stages of races as it can provide fluid, carbohydrate and some caffeine all at once
- Interestingly, he also made sure to include some protein in his fluid intake, which isn’t something we’d say is necessary for performance during a ‘single effort event’ like this whereby he won’t be using it for energy, however it would almost certainly have had a benefit on muscle restoration, via protein synthesis in his post event recovery
- During extremely long events, especially when they take place throughout the night, it’s extremely common to see athletes exceed the general recommendations of 3-6mg/kg of caffeine. On this occasion, Sam far exceeded this, consuming 20mg/kg
- Sam has a high tolerance for caffeine and experienced no adverse effects during the race itself, although he reported excessive post race sweating. High caffeine intakes combined with muscle damage have been linked to this occurrence
- In future races, Sam is going to optimise the timing of his caffeine intake, especially overnight when he’ll be fighting his natural sleep cycle, to exploit the 4-5 hour ‘half-life’, and benefit from the increased perceived energy associated with it
Fueling
Quick Carb Calculator Recommendation
30g
carb 30 mins before
30-60g
carb per hour during
- Carbohydrate loading effectively in the days leading into an endurance event is incredibly important as it helps to ensure maximal stored energy in the liver and muscles come race day
- To achieve this, Sam ate between 8-12 grams of carbohydrate for each kilogram of his bodyweight for the two days prior to the Arc, and topped it off with a carb-rich bowl of porridge for breakfast on the morning of the event
- On the 90-minute bus ride to the start line, he ate a PF 30 Chew and drank 500ml (16oz) of energy drink so that he could top up his blood glucose for when the start gun was fired
- Sam had previously penned out a fueling strategy with the PF&H Sports Science team, which focused on sports energy products, but he felt incredibly strong cravings for a variety of unplanned “real foods” and fluids, especially Coca-Cola, once he was in the thick of racing
- Despite consuming everything from minestrone soup and jelly sweets, and being force fed rice pudding by his supportive crew (somewhat willingly), Sam was able to achieve an average carb intake of ~87g per hour
- This is right at the upper limit of the general recommendations for an event of this duration, with our Fuel & Hydration Planner suggesting an intake of ~75g/h. However, it’s extremely close to his pre-planned intake of ~90g/h
- This is testament to how well he can listen to his body, and how well his self described “granite gut” could tolerate these foods while averaging around seven minutes per kilometre (~11:15/mile) for over 22 hours!
- Going forward, Sam will be experimenting during training sessions to optimise the format of his carb intake by testing out a variety of different fueling products, rather than changing the already impressive volume of carb he’s able to consume
Conclusions
- Sam was mostly happy with how he executed his fuel and hydration strategy en route to a 9th place finish at the Arc of Attrition
- He rated his overall race satisfaction as a 7/10 and he’s focusing on a couple of aspects ahead of his next ‘A-race’
- Sam took on more sodium than he had in previous races and he reported that he was happy to avoid the cramping issues he experienced in previous ultras. He will look to reduce the relative sodium concentration of his intake, by either reducing his sodium consumption or increasing his fluid intake, to see if this helps avoid the post-race weight gain and “puffiness” he experienced
- Despite eating a wide range of foods and fueling products, Sam rated his GI comfort as a solid 8 (out of 10). He’s going to look at finding a bit more structure with the fueling products he uses going forwards
Key info
Sam Skinner
Male
72kg
Sweat sodium concentration
819mg/L
Sweat sodium classification
Moderate
* determined by a PH Advanced Sweat Test
Result
Position
9th
Overall Time
22:42:43
Bodyweight change
4.2%
Event information
Sport
Running
Discipline
Ultra
Event
Arc of Attrition
Location
Coverack, England
Date
27th January, 2023
Website
Total Distance
160.9km / 100.0mi
Race conditions
Weather Conditions
Mild
Precipitation
No Rain
Min Temp
2°C / 36°F
Max Temp
10°C / 50°F
Avg Temp
4°C / 39°F
Humidity
75%
Athlete feedback
Race Satisfaction
7/10
Hydration rating
6/10
Craving Coke from mile 21 was certainly not the plan!
Energy levels
7/10
I felt a lot worse overnight in the darkness
Toilet stops
Yes
I only had two wee stops along the way
GI comfort
8/10
I've got granite guts!
Cramping
No cramping
Sam's Thoughts
I think I could have finished closer to 21 hours, but I had a bit of a comfort blanket on and was a little ‘negative’ with my pace overnight
Sam's full stats
Carbohydrate (g) | Sodium (mg) | Fluid (ml) | Caffeine (mg) | Relative sodium concentration (mg/L) | |
---|---|---|---|---|---|
Overall | |||||
Total intake | 1,964 | 7,789 | 7,094 | 1,500 | 1,098 |
Per hour | 87 | 343 | 313 | 66 |
Data Confidence
1
2
3
4
5
There is an adequate level of accuracy in the data collected and the numbers reported. The athlete manages to recall what they ate and drank including most specifics (brands flavours quantities plausible estimations of volumes). However there are estimations made within the data which affect the overall confidence level in the data reported.