I remember to have read somewhere (and it seems to me reasonable) that you might damage your spinal disks by repetitive excessive stress with not enough recovery time (yes, correct form for the exercises, do not overtrain, reps within the strength / hypertrophy / endurance range, yak yak yak)
I wonder what is safer: more weight but less reps, or a lighter load that happens however more times. Of course, both cases must be somehow equivalent. Let's say that both cases lead to the same theoretical one-rep maximum calculation.
To put it in numbers, let's say you are dealing with Overhead Press. You might equally well do either:
- Up to 15 reps, close to failure, with 30 kg or
- Up to 5 reps, close to failure, with 44 kg.
For this example I have used Brzycki's one-rep max formula (for no special reason).
The question is, what of the two options is safer for your spinal disks?