Now I am new to the gym (well, returning after a 10 year break) and unsurprisingly have lost a lot of strength and endurance over the years. After about a month of weight lifting, I've noticed that my shoulders and biceps can only do a set of ~10 reps with full range of motion. Subsequent sets have about 4 reps of full ROM then the rest are half reps. (I do hold the weights at the max for a couple of seconds when I can't complete the rep; almost like doing isometric training.)
My trainer says that partial reps are okay in this stage. However, consensus is good. Assuming good form is maintained and full exertion, are partial reps good? The primary goals are muscle strength and maybe endurance since endurance seems to be lacking.