Aerobic Substitutions
Type any value in any field — everything else updates instantly. Covers all major erg types, calorie conversions, bodyweight alternatives, and coaching context.
Scale for
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Distance & Calorie Converter
Movement / Distance
meters
reps (50 ft ea.)
reps
Erg Distances
meters (same for both)
meters
Erg Calories
row / ski / bike erg
calories
calories
Time
–:–
ATP-PCr
Glycolytic
Aerobic
0–15s15s – 2 min2 min+
Non-standard distances? This converter interpolates between the reference points — enter any value (350m run, 15 Assault cals, 650m row) and get accurate equivalents. Ratios are linear between anchor points, matching how most coaches scale.
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Full Reference Table
| Run (m) | Shuttle | DU | Row/Ski (m) | Bike Erg (m) | C2 Erg Cal | Assault Cal | Echo Cal | Time |
|---|
C2 calorie note: Concept 2 ergs (Rower, SkiErg, BikeErg) all use the same calorie algorithm, calibrated for a 175 lb male. Lighter athletes will register fewer calories at the same effort level — this is a machine limitation, not a fitness gap. For the SkiErg specifically, most athletes are less efficient at skiing than rowing, so hitting the same calorie target requires more actual work. If you can’t hold a 2:00/500m ski pace, consider reducing ski calorie targets to about 80% of the row number.
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Calorie-to-Calorie Converter
WOD says 30 cal row but you only have an Echo Bike? Type 30 below and read across. The ratios: Assault ≈ 75% of C2 cals, Echo ≈ 60% of C2 cals.
baseline (1.00×)
≈ 0.75× C2
≈ 0.60× C2
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Double Under Substitutions
1×
1× (same count)
1.5× DU
1.5× DU
1.5× DU
Why 1.5× and not 2× or 3×? Doubling or tripling single unders drags out the workout and shifts the intended intensity. A 50% increase preserves the time domain. Jumping jacks use a similar arm + leg pattern, so the energy cost is roughly equal at 1:1.
| Double Unders | Jumping Jacks | Single Unders | Line Hops | Pogo Jumps |
|---|
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Bodyweight Alternatives (No Equipment)
If equipment, skill, or physical limitations prevent any listed movement, use the time column from the main chart and perform your chosen movement for that duration at moderate effort. Here are approximate rep rates at workout pace:
Burpees
~8–10 / min
High demand. Use for short bursts.
Tuck Jumps
~15–18 / min
Plyometric. Good DU substitute.
Walking Lunges
~20–24 / min
Steady aerobic + leg burn.
Air Squats
~25–30 / min
Lower intensity. Easy to sustain.
Jumping Jacks
~50–60 / min
Light. Good for longer durations.
High Knees
~60–80 / min
Run in place. Scales with effort.
How to use: Find the time equivalent for your prescribed distance (e.g. 400m run ≈ 2:00). Test how many reps of your chosen movement you can do in 1 minute at workout pace. Multiply by the number of minutes. Example: 400m run → 2 min → burpees at ~9/min → 18 burpees.
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Coaching Notes
Intent Over Equipment
Conditioning sessions target specific energy systems. The machine or movement you choose is flexible, but the time domain and effort level must be preserved.
Double unders aren’t just cardio — they train rhythm, coordination, and plyometric endurance. Swapping to an air bike hits the lungs but misses the skill element.
Shuttle runs build agility through rapid directional changes (1 rep = 50 ft / 15.24m — 25 ft out, 25 ft back). Replacing with straight-distance running changes the workout’s purpose.
If you can’t do double unders yet, don’t treat the workout as practice time. Choose an alternative that keeps you moving. Skill development belongs in focused, separate sessions.
Machine-Specific Considerations
Assault Bike vs Echo Bike: These machines calculate calories differently. The Assault Bike registers more calories per unit of effort than the Echo Bike. At the same perceived exertion, you’ll see roughly 25% fewer calories on an Echo Bike. Never use Assault Bike targets on an Echo — you’ll over-work significantly.
C2 Rower calorie algorithm assumes a 175 lb (79 kg) male. Lighter athletes register fewer calories at the same power output. This is a machine calibration issue — a 130 lb athlete working at the same wattage will see fewer calories than a 200 lb athlete.
SkiErg efficiency: Most athletes are less practiced on the SkiErg than the rower. Distance conversions remain the same, but calorie targets may need to be reduced ~20% for athletes unfamiliar with the ski pattern.
Bike Erg covers distance much faster than a rower — the standard ratio is 2:1 Bike Erg to Row distance. Calorie output uses the same C2 algorithm as the rower and ski erg.