The one rep max test is there to establish the heaviest weight you can perform 1 repetition of on a given exercise.
Obviously, this can get fairly dangerous as you will be getting near the point where the weight is too heavy for you. This will manifest in a failed rep attempt, or by you executing poor form in order to complete the weight.
We recommend that you USE A SPOTTER FOR ANY ONE REP MAX TEST.
We often use percentages of your one rep max to determine a block of training designed to increase your one rep max.
A one rep max isn't going to be absolutely flawless. If it looks easy, then its probably too light. That been said, the difficulty will likely show itself in a reduced speed of your typical lift. You will have to 'grind' the rep out and be patient. This does not mean that you should lose good, stable positions - it just isn't worth it.
It is more helpful for you to define your 1 rep max as the heaviest weight that you can lift well! If you bend your back and hike up a deadlift as your one rep max, you will have set yourself an unrealistic one rep max. This will affect your training and progress to increase it. Dial it back and get a difficult, but quality one rep max.
WARMING UP FOR A ONE REP MAX TEST
The aim is to get to set 6 whilst expending minimal energy. Attack each set so that it is as fast as possible and take approx 2-4 minutes rest between each set to fully recover. Feel free to add attempts after set 7 (with the same 2.5-5% increase) if you feel you can hit the lift successfully.
You can use this formula to get a rough idea of your one rep max:
1RM = Weight / [1.0278 - (0.0278 X Reps)
Simply perform a set correctly to failure to determine the variables and then you can use the chart below to figure out your warm up sets.