The law of specificity, or the SAID principle (Specific Adaptations to Imposed Demands) suggests that we will improve upon the skill we practice. This certainly applies to strength and conditioning training, albeit, with some gray areas in between.
The 225 bench press test is famous for being used at football combine as a measure of upper body strength. Though, this is a relative term based on how many reps are actually achieved by the individual. An athlete who can perform greater than 10 reps with 225 will actually be assessing endurance more than strength. An athlete who can achieve less than 10 reps, arguably, will probably derive a better indication of their maximal strength. From a general standpoint however, more reps will typically relate to higher strength levels and vice versa.
What about the usefulness of the 225 bench press test for tracking changes in 1RM bench press strength? Bryan Mann and his colleagues from the University of Missouri (and elsewhere), recently published a paper in Journal of Strength and Conditioning Research that endeavored to shine some light on this.
Before and after a 6 week strength training program, Division 1A football players were tested for both 1RM bench press and max reps at 225. The strength training program was designed to improve maximal strength with the main work sets ranging between 3-6 reps and DB work in the 6 rep range. 1-2 sets of assistance work (i.e., pulls ups, extensions, etc.) were also performed.
After 6 weeks, 1RM bench press increased on average by 4.2 ± 8.6 kg while reps performed in the 225 tests increased by 1 ± 3.2 reps. These differences were both statistically significant. Keep in mind that these are based on means, and some would have had much bigger gains, while others, much smaller. Most coaches know that there are typically responders and non-responders to training which can be attributed to a variety of factors, most notably, genetics. (though a topic for another day!)
The 225 test did not track changes very well in 1RM bench press strength. The author’s state:
Although the majority of players increased their 1RM, only 44% improved in both variables. Even in the players who increased in 1RM, the average change in NFL-225 repetitions was not greater than the smallest worthwhile difference (2 repetitions) previously established to indicate more than random variation in performance…
The results of this study reinforce the SAID principle. The 6 week training program was specifically designed to enhance maximal strength (which it did so effectively) while having no intention of improving endurance. The authors suggest that the 225 test may not be an appropriate test for tracking changes in maximal upper body strength after relatively short (i.e., 6 week) high intensity training programs. Coaches are probably better off using traditional 1, 3, or 5RM testing for max strength evaluation.
Mann, JB. et al. Efficacy of the NFL-225 Test for Tracking Changes in 1RM Bench Press Following Training in College Football Players. J Str Cond Res, Ahead of print.