Why does speed on the bike feel so predictable, but in running it can change at the same effort? ✅ On the bike, power output directly drives speed — the machine keeps things consistent. ✅ In running, efficiency (aka running economy) matters just as much as your engine. Two runners can use the same oxygen, but the one who moves more efficiently will be faster. And when fatigue sets in, your economy drops — so speed at the same effort goes down. That’s why improving both fitness and economy is key

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