The weight lifting percentage charts are derived from strength testing a population by having them perform a single maximum repetition (1RM) of a given exercise. Once the values are obtained the group is tested in maximum endurance at a percentage of their obtained 1RM. A formula is gleaned that assigns a numerical value to each repetition.
Example :
A population of people found to have a max of 300 pounds on the bench press are further tested at 75% (225 Pounds) of their maximum . The average result is 10 repetitions for the test. The value of each rep is therefore 0.0333 or 7.5 pounds a rep.
0.0333 x 225 pounds = 7.5 pounds per rep.
7.5 pounds x 10= 75 pounds
225 pounds + 75 pounds = 300 pound max
Once a value is assigned to the repetition based upon the study, in this case 0.0333, a 'Weight Lifting Percentage Chart' is constructed for the general population.
To use the chart a weightlifter simply finds his or her maximum along the left side. The weight to workout with is taken from the chart based on the percentage and repetitions they are asked to utilize in their workout plan.
Sample of an athletes instructions from the Coach...
Today we are going to use 75% of our maximum for 10 reps, then 85% of our maximum for 6 reps and 90% for 4 on the bench press. The above chart tells you the weight you should be working out with based on your individual max to Get Strong.
The athlete with a 270 max chooses...
75% - 205 x 10
85% - 230 x 6
90% - 245 x 4
Exactly what these percentages really mean to the muscle tissue is a huge question. Weight Charts can be used as guides, yet to be accurate and take into account individual differences you need to make a chart for every exercise and every individual.
Try this to explore the reasoning of many charts...
Find your one repetition maximum in a multi-joint exercise such as a free weight barbell squat or bench press. Select a percentage such as 65%, 75% or 85% of that maximum and do as many repetitions as possible with that percentage and record your repetitions.
Now select a 'single-joint' exercise such as barbell curl and repeat the test. Whether trained or untrained you will find you achieve fewer repetitions at the same percentage of 1RM with a single-joint movement and more repetitions with a multi-joint movement. In other-words multi -joint and single-joint exercises have different values of a repetition. The amount of muscle mass involved in a multi-joint exercise and the neural system alter the outcome.
If this same test is done with a large group of athletes, say a team, you will get a similar result. You will also find a great deal of variability from athlete to athlete in the data.
Try this also......
Take all your athletes who's maximum is the same in a particular exercise. Let's say their maximum is 270 pounds on the bench press. Using 75% of their max in the above chart (205), test the maximum amount of repetitions they can do.
In general, most may achieve 10 reps as indicated on the chart, but you may find an athlete who can only do 6 reps or another who can do 15. Very normal stuff, as we all have different neurological efficiencies.
Charts are charts, they set a course. They give direction. Understand that they are not based on the scientific method and each athlete will be effected differently with the recommended weights and repetitions.
The best chart to hang in your weight room is the 'Effort Chart'. When you go to it, it says.... give a 100% effort to any weight you choose to..... Get Strong.
Pendulum 3 Way Row