Published on February 3rd, 2013  by George Conte
0The importance of One Rep Max in bodybuilding
I order to design an anaerobic exercise program we need to first know what our goal is.

If we want to design different intensity programs we need to know our current strength levels. We need to know how much our one repmax or 1RM is.
There are various formulas we can use to determine this:
Adams Formula  w / (1 – (0.02 * r)) 
Berger Formula  w / (1.0261 * (e ^ (0.0262 * r))) 
Brown Formula  (r * 0.0328 + 0.9849) * w 
Brzycki Formula  w / (1.0278 – (0.0278 * r)) 
Epley Formula  (0.033 * r * w) + w 
Lander Formula  w / (1.013 – (0.0267123 * r)) 
Lombardi Formula  w / (0.522 + (0.419 * e ^ (0.055 * r))) 
Mayhew Formula  w * (r ^ 0.1) 
O’Conor Formula  w * (1 + (0.025 * r)) 
Wathen Formula  w / (0.488 + (0.538 * e ^ (0.075 * r))) 
(w=weight and r=repetitions)
Let’s say that we want to build muscular strength. This means that we need a high intensity program with low amount of repetitions (15). So we choose the range of 5 repetitions. For example we want to start doing 5 reps of squat but we don’t know how much weight we need to use for our first training.
First thing we can do is calculate how much weight we can now do before failure. So let’s hypothetically say we can do 10 repetitions of 100kg squats/220 pounds (taken to failure).
That means our 1RM is about 133kg (100% intensity) and we can do 10 reps at 75% intensity.
intensity % 
kg 
100% 
133 
95% 
126 
90% 
120 
85% 
113 
80% 
106 
75% 
100 
70% 
93 
65% 
86 
60% 
80 
55% 
73 
50% 
67 
We want now to build strength so we want to do 5 reps max (taken to failure).
reps  %1RM 
1 
100% 
2 
95% 
3 
90% 
4 
88% 
5 
86% 
6 
83% 
7 
80% 
8 
78% 
9 
76% 
10 
75% 
11 
72% 
12 
70% 
According to the statistics above we need to go from 75% (of our 1RM) intensity to 86% intensity and do 5 reps. we choose to do about 113kg X 5 repetitions.
Note that it is also important to frequently change our exercise programs from strength to muscle mass and endurance in order for our body to not remain static and improve even further.
As you can tell by now 1RM can not only help us create, change and improve exercise programs, but also is the universal indicator of our overall condition and improvement in bodybuilding.