For a month, I was doing incline front raises as my main front deltoid isolation exercise with the pursuit of improving the 1RM of bench press as well as to find out if its reliable and if there’s a correlation. When I tested the 1RM of the partial bench press with 225 lbs, I was hoping to get more then a few reps that I got with 225 lbs, but still a little bit better. A session later, I decided to do reverse pyramid sets with the bench. Set #1: 215 x 4, Set #2: 195 x 5, Set #3: 175lbs x 14; not 6-7 reps; seriously. This isn’t the first time of having a higher 1RM max when doing higher reps compared to lower reps. I’ve now learned that even though there’s correlations with different exercises, it can be skewed with different rep schemes (3 reps compared to 19 reps) along with other variables like technique. I’m going to begin this post by sharing the exercise data.
Exercise Data
Dips
3/12/24 (high rep) 45lbs x 20 reps => 1RM: 185lbs @ 165lbs / total:350lbs
3/16/24 (low rep) 125lbs x 5 reps => 1RM: 160.6lbs @ 165lbs / total:325.8lbs
Ratio(high/low):1.0742
Dumbbell Press
7/31/24 (high rep) 65lbs x 9 reps; 83.3lbs 1RM
8/7/24 (low rep) 70lbs x 5 reps; 78.7lbs 1RM
Ratio(high/low): 1.0584
9/28/24 (high rep) 60lbs x 14 reps; 88.2 1RM (right side only)
10/1/24 (high rep) 60lbs x 16 reps; 92.3 1RM (right side only)
Incline Front Raises
8/23/24 (high rep) 22.5lbs x 23 reps; 39.6lbs 1RM
9/9/24 (low rep) 30lbs x 7 reps; 36.1 1RM
Ratio(high/low):1.0969
Bench Press (partials off of squat rack)
6/7/24 (high rep) 185lbs x 11 reps; 253.4lbs 1RM
9/1/24 (low rep) 215 x 4 reps; 233lbs 1RM
9/1/24 (high rep) 175lbs x 14 reps; 257.4 1RM (this is the 3rd set mentioned in intro and not the usual first set)
Ratio(high/low):at least 1.103
Shoulder Press
9/7/24 (low reps) 135lbs x 7 reps; 162.7lbs 1RM
Observations
Most of the exercises have similar ratios between higher rep exercises and low rep (7 or lower in this case). Because they have similar ratios, this can help form a rough formula based on working correlations. There are two pieces of data that need to be worked on: estimated higher rep bench press and possible ratios and high rep alternative for shoulder press that’s has a few lifting sessions as the last heavy shoulder press.
Possible Data Point #1
The bench press on the 3rd set was 175lbs for 14 reps as mentioned in the intro. A reasonable estimate would be 175lbs by 16 reps. If that’s so, then the 1RM would be 269.2 making the ratio 1.15 when paired with its low rep counterpart (215lbs x 4 reps; 9/1/24). 1.15 is still relatively close to 1.1.
Possible Data Point #2
There are two consecutive days of dumbbell shoulder press. I’ve decided to include both because the first day, I saved .5-1 rep in the tank since I had recently injured my left shoulder and didn’t want to risk injuring the right one while maintaining an active job where I need my shoulders; a soft gamble really. Second day, I felt more comfortable to give full effort and its still not injured thankfully. I didn’t exclude the first one because it wasn’t guaranteed that I would be able to complete 16 reps and the whole point was to have the days as close to each other as possible. I digress. The way I’m going to convert this lift to an estimated shoulder press is by referring to the strength standards website referring to both the dumbbell and shoulder press.
Some Math
Referring to 170lbs part of the table, I’m going to subtract 94 lbs (from the advanced section at 170lbs) by 69 lbs (intermediate section) equaling 25 to create the denominator which will be used in a moment. Then I will subtract the 1RM from 69 to create a percentage that will be used later on.
Day #1
(88.2 – 69) / 25 = .768
Day #2
(92.3 – 69) / 25 = .932
Moving on to the shoulder press exercise table, I’m going to find the difference between the advanced and intermediate section of the 170lbs row of the exercise which is 44. Then I’m going to multiply the previously calculated percentage and times it by 44 and simply add 136 (intermediate mark) to it.
Day #1
44 * .768 = 33.792 => 33.792 + 136 = 169.792
Day #2
44 * .932 = 41.008 => 41.008 + 136 = 177.008
With those two converted numbers done, those numbers will be used as a range.
The ratio between “the range” and the 135lb shoulder press is: (1.0435 – 1.0879)
Ratios of exercises (high/low)
Shoulder Press (lower end): 1.0435
Dumbbell Shoulder Press: 1.0584
Dips: 1.0742
Shoulder Press (higher end): 1.0879
Incline Front Raises: 1.0969
Bench Press: 1.103 to possible 1.15
Findings based on the data
The first thing I noticed was that the ratios were very similar between both types of shoulder press. The incline front raises had the closest ratio to the bench press compared to the other exercises. This is probably due to having the most similar muscle length when moment arm (upper arm) is parallel to the ground. All in all the ratio is about 1.08 SD .04 with all exercises having a ratio close to it indicating low and high reps can have different 1RM estimations.
Formula Creation Phase
| High Rep | Low Rep |
| IFR – 39.6 Seated Dumbbell SP – 88.2 – 92.3 Bench Press – recorded: 257.4/guess:265 Bench = SDSP * (2.871 – 3.004) Bench = IFR * 6.69 SDSP = Bench * (.3328 – .348) SDSP = IFR * (2.22 – 2.33) IFR = Bench * .1494 IFR = SDSP * (.429 – .4489) | IFR – 36.1 Shoulder Press – 162.7 Bench Press – 233 Bench = SP * 1.432 Bench = IFR * 6.45 SP = Bench * .698 SP = IFR * 4.5 IFR = Bench * .155 (*) IFR = SP * .22 |
I’m going to handpick a few formulas to use based on how “numerically friendly” they are, how conservative the numbers are, and how similar the values are on each side of the table.
Formulas to use based on personal preference
Shoulder Press = 70% of Bench Press (this isn’t original and can be found on many websites)
Bench Press = 6.45 * Incline Front Raises
Shoulder Press = 4.5 * Incline Front Raises
Seated Dumbbell Shoulder Press = Incline Front Raises * 2.25
Bench Press = Seated Dumbbell Shoulder Press * 2.85 – 3 (elite – intermediate; estimate)
Incline Front Raises = Bench Press * .155
Closing Thoughts
- The formulas created are under the assumption that the front delts are the weak point of the bench press
- The difficulty of the exercise will be based on how short or long is the moment arm that is used in the exercise in which be adjusted if the limb can be bent or straightened to its varying degree.
- The formula conversions of the high and low rep sections are very similar to each other helping ensuring the validity of the formula.
- The correlation between the two exercises will depend on the rep ranges, current adaptations, similarity of exercises, experience in the exercise, and other variables.
- It is advised when estimating the goal 1RM of an exercise of an expected rep range is to use the exercise that you want to convert with the same or very similar reps to estimate current 1RM of the target exercise and plan accordingly.
- Ex: to get 300lb bench press, is the goal to max out, do 5 reps of it, 10 reps of 225, or 150 reps of 31 reps. Depending on the reps you’re planning on doing to claim the 300, that’s the reps you need to use on other exercises to help estimate the current predicted 1RM of the bench press.
References regarding ratios between bench press and shoulder press
https://startingstrength.com/article/the_press [claim: OHP is 66% of BP]
https://www.livestrong.com/article/446756-shoulder-press-to-bench-press-ratio [claim: OHP is 60-68% of BP]
https://strengthlevel.com/strength-standards/shoulder-press-vs-bench-press/lb [stats: OHP is 64-66% of BP]