Originally Posted by Oso Polar

To me this sounds as if your seat is low, and I mean way too low - like by a few inches. This will naturally cause pedaling by the heels as this allows for a better leg extension and so will feel more comfortable and generate more power (compared to pedaling with a more front position of the feet which will result in even more cramped legs). And, indeed, way too low of a seat does feel like doing squats, as you describe.Your quads will be loaded significantly more than other parts of the leg if your seat is too low (and if you'll pedal not with the heels they'll be loaded even more because this shorters the reach to the pedals). In fact, if your seat is positioned at the proper height you'll simply not be able to "power on hills" by pedaling with the heels at all because you'll not be able to generate any significant power at full leg extension, it should be barely possible to pedal at all with the heels.