Lie on your back on the floor (legs may be raised), hold the weights in front of your chest with your arms bent and press the dumbbells against each other (elbows close to your body pointing forwards), grasp the dumbbells with a neutral grip so that your palms are facing the respective side, push the weights upwards to bring your almost fully extended arms into the holding position, then lower/bend your arms back to the starting position.
Attention:
Do not fully extend your arms in the holding position and do not place the weights completely on your chest when lowering. Press the dumbbells firmly against each other during the entire exercise and keep your back in contact with the floor.
Lighten:
Less weight.
Harden:
More weight.
Variant I:
Hold the weights shoulder-width apart instead of pressing the dumbbells against each other.
Variant II:
Replace the dumbbells with a weight disc and pinch the disc between your palms (disc facing horizontally towards the floor) or hold the weight disc with both hands at the edge (disc facing horizontally towards the floor) for less strain on the chest muscles.