The death march is a simple back strengthening and pre-hab exercise used to strengthen the lower back in particular in a flexed position.
With a pair of dumbbells at arms’ length, take a short step forward and keep the front leg straight or only very slightly bent, and bend at the hips and back to lower the dumbbells to the floor at either side of the front foot. After tapping the dumbbells on the floor, stand again and step with the other foot to repeat.
Introduce this exercise with very light weights and conservative volume until you know how you tolerate it!
The death march introduces back flexion and extension along with hip flexion and extension, which is a rarely trained motion but useful for back health and resilience.
Sets of 10-20 steps per leg are common for 3-4 sets. The death march should be done at the end of a training session when the back will no longer need to stabilize the spine under any load.
Different implements can be used such as kettlebells or a sandbag. The motion can be slowed down considerably as well.