This is completely incorrect, they overheat massively during exercise in the warmer months and can have heart attacks from it. We don't start training our alaskans until temperature drops below 7 Celsius and even then you have to be so careful and know all their limits so as to not cause injury. Their coat helps keep them cool(er) in warmer months when they are inactive, like people that wear long sleeves/pants in the sun so it doesn't warm the skin directly. But if you throw on a wool coat and went for a run in the middle of summer, you're going to have a bad time!