The energy 'created' (transformed) is still generated by the human by effectively burning carbohydrates/fats/etc. Might as well create a tiny alternator, spin i

The energy 'created' (transformed) is still generated by the human by effectively burning carbohydrates/fats/etc. Might as well create a tiny alternator, spin it by hand and be done with. Alternatively, attach magnets/coils to gym equipment and there you go. If you continue further, no need for springs and weights at all - make all gym equipment with NdFeB and copper instead - 'free' energy.