Final answer:
Training has been shown to improve exercise economy in both runners and cyclists by 8-15% over several years of training.
Step-by-step explanation:
Training has been shown to improve exercise economy in both runners and cyclists by as much as 8-15% over several years of training. This means that individuals who consistently train can become more efficient in their movements, using less energy to perform the same exercise. This improvement in exercise economy can lead to better endurance and performance.