Good news! You can benefit from BOTH high AND low reps with either light OR heavy weight.
It’s the EFFORT applied to either strategy that’s the most important factor.
Then, it’s mostly a matter of personal preference.
High reps with lower weights are painful, they burn and you run out of breath…
You may stop at 15 reps when you could actually do 20 reps which are the ones that really count.
Plus, you may feel overly exhausted after training with higher reps.
Heavier weights with lower reps are HARD and require a certain level of skill to perform safely.
There is a mental game to ‘lifting heavy’ as well, your mind may not think you can lift as much as your body actually can, so you miss out on the added load that will build your muscles.
So ‘pick your poison’ where weight lifting is concerned, just make sure you do it with maximal EFFORT whichever route you go.
Workouts don’t have to last hours, you can mix up the heavy/light combination to reap all the benefits that resistance training provides.
And I can help you too! Happy to chat what that looks like for you – there’s rarely a ‘one size fits all’ where health and wellness are concerned.
Here are studies to support this info:
https://pubmed.ncbi.nlm.nih.gov/35015560/
https://pubmed.ncbi.nlm.nih.gov/37414459/
https://pubmed.ncbi.nlm.nih.gov/37385345/
https://pubmed.ncbi.nlm.nih.gov/28834797/
https://pubmed.ncbi.nlm.nih.gov/25530577/