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Lizards aren't actually able to efficiently breathe and run at the same time. The only time they can effectively breathe is when their bodies are straight. If a lizard were to take a step with its left foot, that would compress it's right lung. Once it starts running there wouldn't be enough time left to breathe.

There are however some papers that claim that lizards can't run for extended periods not due to lack of oxygen, but due to their hearts limiting them.

No matter which reason, lizards can't run for extended periods of time.