What is the ergonomically correct technique for manual lifting of heavy cargo boxes (e.g. 25 kg pallet cartons) to protect the lumbar spine (Lendenwirbelsäule)?

1. Stand with feet shoulder-width apart close to the load, bend the knees while keeping the back straight, lift using the strong leg muscles, keep the load close to the body, and avoid twisting the torso while lifting
2. Keep legs completely straight, bend forward from the waist, and lift using lower back muscles
3. Jerk the load upward quickly with rotated spine to utilize centrifugal momentum
4. Lift the load with arms fully outstretched at shoulder height