In high-intensity competitions — especially multi-event or multi-day formats — performance decline after the first event or Day 1 is rarely a fitness issue.
More often, it is the result of fuel debt: a negative balance of energy and fluids that accumulates faster than it can be replenished.
1. The issue is fuel, not fitness
From the first event, energy and fluid expenditure exceeds intake. This deficit may not be immediately noticeable, but it carries over into subsequent events or competition days.
2. Depletion of carbohydrate stores
Carbohydrates are the primary fuel for high-intensity performance.
During the first event (or Day 1), a large portion of muscle glycogen is consumed. Without adequate replenishment:
• depletion continues
• performance declines in later events
• perceived exertion increases
• legs feel heavy and transitions slow down
3. Hydration and sodium mismatch
Even mild dehydration, when combined with insufficient sodium intake, increases cardiovascular strain at the same workload.
Without a hydration strategy, the deficit carries into the next day.
Common outcomes include:
• unexplained elevated heart rate
• headaches
• cramps or muscle spasms
4. Poor between-event nutrition choices
Common mistakes:
• high fat and fiber intake → delayed digestion, gastrointestinal discomfort
• excessive protein → minimal immediate fuel contribution
• insufficient total intake due to stress → prolonged energy deficit
These choices compromise performance later in the competition.
5. Poor timing
Between events, refueling windows are short.
Missing them means starting the next effort already in deficit.
In multi-day competitions, Day 1 refueling directly determines Day 2 performance.
6. Fix #1 – Between-events protocol
0–15 minutes post-event:
• 30–60g carbohydrates
• 500–750ml fluids
• adequate sodium (especially with high sweat rates)
60–120 minutes before the next start (if time allows):
• easily digestible carbohydrate-based meal
• low fat and fiber
• small protein amount
Avoid large meals, high fat/fiber foods, and unplanned snacking.
7. Fix #2 – 3-day performance plan
• 3 days out: progressive carbohydrate loading with reduced fat and fiber
• After the final event each day: prioritize carbohydrates, fluids, and electrolytes
• Choose: easily digestible carbohydrates to maximize glycogen restoration and minimize GI risk
• Pre-workout meals/snacks: familiar and tested — no experimentation on race day
Sources:
1) https://pubmed.ncbi.nlm.nih.gov/39485653/
2)https://pubmed.ncbi.nlm.nih.gov/35809162/
3)https://pubmed.ncbi.nlm.nih.gov/40901614/
