Mini-Study Results: Max effort strength training improves sandbag strength endurance more than sandbag strength endurance training improves max effort strength


By Rob Shaul, Founder


Max effort strength training improves Sandbag Strength Endurance more than Sandbag Strength Endurance training improves Max Effort Strength.

We conducted a 4-week Mini-Study using remote lab rats to cross-test the effect of Max Effort barbell strength training to improve Sandbag Strength endurance, and the effect of Sandbag Strength Endurance to improve Max Effort Barbell Strength.

Two Lab Rat Groups (A and) Completed the Study in November-December, 2020.

Both Groups completed a Max Effort Strength (1RM Back Squat, 1RM Push Press) and a Sandbag Strength Endurance Assessment (Max Reps Sandbag Back Squats in 90 Seconds, Max Effort Sandbag Push Press in 90 Seconds @ 40-pounds for women, 60-pounds for men) at the beginning of the study – with a day rest between assessments.

After the assessments, the two groups completed different programming.

  • Group A (Max Effort Strength) completed a Max Effort strength progression based on their 1RM Back Squat and 1RM Push Press Results.
  • Group B (Sandbag Strength Endurance) completed a Sandbag Strength Endurance progression based on their Max Rep in 90 second Sandbag Back Squat and Push Press initial assessment results.

After 3 weeks, both groups reassessed 1RM Back Squat, 1RM Push Press, and Max Rep Sandbag Back Squat and Sandbag Push Press in 90 seconds. These results were compared to the initial assessment results.

Group A – the Max Effort Group – saw greater improvements in 1RM Back Squat and 1RM Push Press strength and Sandbag Back Squat Strength Endurance. Group B saw a greater improvement in Sandbag Push Press Strength Endurance.


MTI’s strength and conditioning research is focused on delivering actionable results to improve mission-direct program design.

The aim of this study was to do a macro-level test between two different ways to train strength – Max Effort Barbell and Sandbag Strength Endurance.

Conceptually, we’ve always understood that there was a difference between Max Effort Strength (the most you can lift for 1 repetition), and Strength Endurance (max reps at bodyweight or relatively lightly loaded). Anyone who’s tried to use heavy bench presses to improve push up max rep performance, or volume push ups to improve their 1RM bench press and experienced the fact that strength and strength endurance are not equally transferable.

However, we’ve never formally tested this limited transferability until now.

From an equipment perspective, COVID-19 has limited access for many to fully equipped gyms, and forced limited equipment training. Sandbags are a key piece of equipment for MTI limited equipment programming – and we were curious as to how sandbag training impacts max effort strength.


Results and Discussion

A total of 14 individuals completed the entire training cycle, 5 in Group A (Max Effort Strength) and 9 in Group B (Sandbag Strength Endurance).   Below are the individual lab rat results.

We began the study with approximately 10 lab rats in each group, and had greater study attrition in the Group A – the Max Effort Strength Group for whatever reason. 

Going in, we hypothesized that Group A would see significantly greater 1RM Back Squat and 1RM Push Press improvement, and Group B would see significantly greater Sandbag Back Squat and Sandbag Push Press strength endurance improvement. But … this isn’t what the results show.

Looking at the data above, both groups increased their Max Effort 1RM Back Squat and 1RM Push Press strength. Not surprisingly, Group A saw greater improvement, but every athlete in Group B also improved, which demonstrates that Sandbag Strength Endurance does help improve max effort strength.

The Group A Sandbag Strength Endurance improvements were the surprise in this study. Group A beat Group B in the Sandbag Back Squat strength endurance re-assessment, and nearly matched Group B in the the Sandbag Push Press strength endurance reassessment.

Within Group A, Stephen was the outlier in terms of Sandbag Strength Endurance Assessment. However, when we remove his results, Group A still matches Group B’s Sandbag Back Squat re-assessment improvement (14.6% to 14.5%), but significantly underperforms on the Sandbag Push Press reassessment (12.1% to 25.2%).

As well, for the purposes of this study, only one weight of sandbag was used – 40 pound for women, and 60 pound for men. Using a heavier sandbag could have made a significant difference in the study results.

Obviously, because of the few number of Group A lab rats who completed the study, these results aren’t definitive. But, the intent of MTI’s Mission-Direct research isn’t academic purity, but to test programming in hopes of validating current MTI programming theory or finding ways to improve it.

Based on this standard of “continuous improvement” there are two take aways from this study:

  • Max Effort Strength Training does surprisingly well at improving strength endurance.
  • Sandbag Strength Endurance Training, at a minimum, can maintain and even slightly improve Max Effort Strength

Next Steps?

This study used Sandbag Strength Endurance to test the cross-training abilities of strength endurance to improve max effort strength. It might be interesting to do another study using bodyweight only training. Although the 40 pound (women) and 60 pound (men) sandbags used in this study weren’t heavy, they are still load. We would hypothesize that sandbag strength endurance would do a better job at maintaining/improving max effort strength than bodyweight only training, but we need to test it to be sure.

And on the flipside, we were again surprised by the ability of max effort strength training to improve sandbag strength endurance. How would max effort strength training do improving bodyweight strength endurance?

For years I’ve advised tactical athletes facing an upcoming PFT which included a push up assessment to stop bench pressing and start doing push ups. Perhaps I should have advised them to cut back on bench pressing, but not stop it totally, and add in push ups? I won’t know until we test it!


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