First of all, there is so-called “circular pedalling" which, strictly speaking, doesn’t really exist. What is meant by this is that in the pedalling cycle you not only push down at the front, but also lift your leg slightly at the back or, in the case of clipless pedals, even pull on the pedal. However, this is not easy and is only mastered by cycling professionals. But your pedalling efficiency also increases with every ride, because the interaction between your muscles and your brain as a control organ is constantly improving. An optimal riding position plays an important part in this.
During every revolution of the pedals, the various muscle groups of the leg have to make a coordinated contribution to propelling the bike forward. That doesn't just happen automatically, but requires precise coordination. For example, the knee extensors should only work in the front part of the pedalling cycle, in the back they must be relaxed so that they don't interfere with the work of the flexors in the knee. If it sounds complicated, that's because it is. And very, because scientists suspect that the secret of highly successful cyclists lies in the perfect interaction of the muscles. Unfortunately, you can only improve this ability to a limited extent.
Cycling without discomfort
Ergonomics in the case of bicycles aims above all to make cycling more pain-free. To achieve this, the interaction of the muscles must also be perfectly coordinated. If, for example, the arm or back muscles have to do too much support work for their individual fitness level, they react with pain. These are simple muscle fatigue pains that can take the fun out of cycling. That's why it's so important to find a riding position that suits your own physical requirements and causes little or, even better, no discomfort.