Anaerobic Capacity Calculator
Our sports physiology calculator computes anaerobic capacity instantly. Get accurate stats with historical comparisons and benchmarks.
Reviewed by Sher, Sports Science & Nutrition Specialist
Formula
Anaerobic Capacity = (Avg Power x Duration) / (Body Weight x 1000) kJ/kg
Anaerobic capacity is calculated as total mechanical work performed during an all-out test divided by body weight. Total work equals average power multiplied by test duration in seconds. Fatigue index is calculated as (Peak Power - Min Power) / Peak Power x 100. Relative peak power (W/kg) is used for performance classification.
Worked Examples
Example 1: Sprinter Wingate Test Results
Problem:A 78 kg male sprinter (age 24) produces 1,050 W peak power, 720 W average, and 380 W minimum during a 30-second Wingate test.
Solution:Relative peak power: 1050 / 78 = 13.46 W/kg\nRelative average: 720 / 78 = 9.23 W/kg\nFatigue index: (1050 - 380) / 1050 x 100 = 63.8%\nTotal work: 720 x 30 = 21,600 J\nWork per kg: 21600 / 78 = 276.9 J/kg\nAnaerobic capacity: 0.277 kJ/kg\nPower drop rate: (1050 - 380) / 30 = 22.3 W/s
Result:Peak: 13.46 W/kg (Elite) | Fatigue: 63.8% | Capacity: 0.277 kJ/kg
Example 2: Team Sport Athlete Assessment
Problem:A 82 kg soccer player (age 27) achieves 820 W peak, 590 W average, 420 W minimum over 30 seconds.
Solution:Relative peak power: 820 / 82 = 10.00 W/kg\nRelative average: 590 / 82 = 7.20 W/kg\nFatigue index: (820 - 420) / 820 x 100 = 48.8%\nTotal work: 590 x 30 = 17,700 J\nWork per kg: 17700 / 82 = 215.9 J/kg\nAnaerobic capacity: 0.216 kJ/kg\nPower drop rate: (820 - 420) / 30 = 13.3 W/s
Result:Peak: 10.00 W/kg (Good) | Fatigue: 48.8% | Good sustained power for team sport
Frequently Asked Questions
What is anaerobic capacity and why does it matter for athletes?
Anaerobic capacity is the total amount of work your body can perform using anaerobic energy systems, meaning without relying on oxygen for ATP production. It is typically measured as total work output in kilojoules per kilogram of body weight during an all-out test lasting 30 seconds, such as the Wingate Anaerobic Test. This metric matters because many sports require explosive bursts of power that exceed what the aerobic system can provide, including sprinting, jumping, tackling, and rapid acceleration. Athletes with high anaerobic capacity can sustain near-maximal efforts for longer before fatigue sets in. Training specifically targets the two anaerobic energy systems: the ATP-phosphocreatine system for efforts under 10 seconds and the glycolytic system for efforts lasting 10 to 120 seconds.
How is the Wingate Anaerobic Test performed and what does it measure?
The Wingate Anaerobic Test is the gold standard for measuring anaerobic power and capacity, typically performed on a cycle ergometer with a resistance set to 7.5 percent of the athlete's body weight. The athlete pedals at maximum effort for 30 seconds against this fixed resistance while power output is recorded every second or every 5 seconds. The test measures three primary variables: peak power (the highest power output achieved, usually in the first 5 seconds), average power (mean power across the full 30 seconds), and fatigue index (the percentage decline from peak to minimum power). Peak power reflects ATP-phosphocreatine system capacity, while average power and total work reflect overall anaerobic capacity including both alactic and lactic energy systems. The test is extremely demanding and produces significant lactate accumulation.
How does body weight affect anaerobic capacity measurements?
Body weight significantly influences the interpretation of anaerobic capacity because absolute power values favor larger athletes with more muscle mass. Expressing results relative to body weight in watts per kilogram normalizes the data and allows meaningful comparisons between athletes of different sizes. Elite male sprinters typically produce peak power of 10 to 13 watts per kilogram, while elite female sprinters produce 8 to 11 watts per kilogram. Average untrained males produce 7 to 9 watts per kilogram and untrained females produce 5 to 7 watts per kilogram. However, relative values can be misleading for sports where absolute power matters, such as football or rugby, where a 120-kilogram lineman producing 8 watts per kilogram generates 960 watts of absolute power compared to a 70-kilogram sprinter producing 12 watts per kilogram for only 840 watts absolute.
What is the difference between alactic and lactic anaerobic capacity?
The anaerobic energy system has two distinct components that contribute to performance at different time scales. The alactic or ATP-phosphocreatine system provides immediate energy for maximal efforts lasting up to 10 seconds by breaking down stored phosphocreatine to regenerate ATP. This system produces the highest power output but depletes very quickly. The lactic or glycolytic system breaks down glucose without oxygen, producing ATP more slowly than the alactic system but sustaining energy production for efforts lasting 10 to 120 seconds. The lactic system produces lactate and hydrogen ions as byproducts, which contribute to the burning sensation and fatigue during intense exercise. During a 30-second Wingate test, the alactic system dominates the first 5 to 8 seconds while the glycolytic system becomes the primary energy provider from 10 to 30 seconds. Training each system requires different protocols.
References
Reviewed by Sher, Sports Science & Nutrition Specialist · Editorial policy