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Daily carbohydrate needs for cyclists

Targets are expressed per kilogram of body weight. Recorded work selects the point within a daily range; duration selects the range. The base target without training is 4.0 g/kg.

Work determines the target

Two hours of recovery riding and two hours of hard riding use different amounts of glycogen. The app first selects a range from duration:

Without training3.0–5.0 g/kg
Up to 1 hour5.0–7.0 g/kg
1.0–3 hours6.0–10.0 g/kg
Over 3.0 hours8.0–12.0 g/kg

Recorded work divided by riding time gives average power. Dividing by FTP gives the intensity of the day's work:

average power = kJ ÷ hours ÷ 3.6 · daily intensity = average power ÷ FTP

Below 0.56 of FTP the target is at the bottom of the range; from 0.91 it is at the top. Between these boundaries it changes smoothly.

Example: 70 kg, FTP 250 W, 2 hours and 1440 kJ. Daily intensity is 0.8. The daily range is 6.0–10.0 g/kg, giving 8.7 g/kg and 612 g of carbohydrate. An easier ride of the same duration would use the bottom of that range, 6.0 g/kg, almost a third less.

The intensity boundaries are the lower edges of Coggan Z2 and Z4 already used in the app.

SourcesBurke, Hawley, Wong & Jeukendrup (2011), “Carbohydrates for training and competition”, J Sports Sci 29:S17–S27, gives the daily ranges. Impey et al. (2018), “Fuel for the Work Required”, Sports Medicine 48:1031–1048, supports fuelling for the work undertaken. Selecting a point by daily intensity is our implementation choice within those ranges; the boundaries use Coggan & Allen zones.

Without a power meter

Without recorded work the app uses duration and a selected point within each range:

Without training4.0 g/kg
Up to 1 hour5.5 g/kg
1.0–2 hours7.0 g/kg
2.0–3 hours8.5 g/kg
Over 3.0 hours10.0 g/kg

This estimate cannot distinguish easy from hard riding of equal duration. Recorded power enables the work-based calculation automatically.

SourceBurke et al. (2011). These duration-based points are our choices within the published ranges.

Before a race

Training volume falls during a taper, but glycogen needs at the start do not. During the last 2 days the daily target becomes 10.0 g/kg for a race longer than 90 minutes, and 8.0 g/kg for shorter races, including exactly that boundary.

The app takes the larger of the loading target and the day's training target.

SourceThomas, Erdman & Burke (2016), Nutrition and Athletic Performance, Table 2: events longer than 90 minutes use 10–12 g/kg per day for 36–48 hours. General preparation for shorter events uses 7–12 g/kg per day. Our choices are 10.0 g/kg at the bottom of the loading range, 8.0 g/kg within the general range and 2 days at the upper end of the loading window.

SourceGatorade Sports Science Institute, “Dietary carbohydrate and the endurance athlete: contemporary perspectives”, also describes this loading window and warns that starting earlier adds water and body mass without additional glycogen.

How the staff uses this

Recorded Garmin or Strava rides determine the daily target. Before a ride is recorded, the staff's assigned session can provide an estimate labelled as planned. A recorded ride takes priority over the plan.
For weight loss, carbohydrate may be reduced but stays above the light-day floor of 3.0 g/kg.
The app shows grams and grams per kilogram together for comparison with these rules.

The displayed rate is rounded to one decimal place; the calculation selects its range before rounding. A displayed 6.0.0 g/kg can represent 6.0.04, near the bottom of the range, or exactly the boundary. Daily grams are calculated from the unrounded rate.

Daily work intensity is based on average power (kJ ÷ time ÷ FTP), whereas ride IF uses normalised power. They describe different quantities and cannot be compared directly.

Carbohydrate during a ride (Russian) contributes to the daily target rather than being added on top. Related pages: daily calories (Russian) — carbohydrate takes priority and fat receives the remainder; protein and fat (Russian); Why this matters.

Questions: michaelkrsk@gmail.com