Mini Study: 3 Weeks of Extended, Multi-Modal “Grind” Training Sessions Maintain Strength, Work Capacity, Increase Endurance

Former Marine, Charlie, and Vokl sponsored FreeSkier, Forrest, grind through part (1)’s step up assessment.

By Rob Shaul



Six remote MTI Lab Rats following a 3-week, 5-day/week training cycle exclusively of extended (20-40 minute), multi-modal “grinds” maintained max effort strength and sprint-based work capacity, while increasing endurance. Below are the average changes in the assessed performance metrics.

  • Back Squat 1RM: +3.56%
  • Bench Press 1RM: +1.04%
  • Max Rep Pull Ups: +4.04%
  • Max Rep Prone to Sprint in 3 Minutes: 5.49%
  • Max Rep Step Ups in 12 Minutes: +9.99%

Background & Mini-Study Design

Extended (30-45 minute) multi-modal, moderate-paced “grinds” are an important component of MTI programming. We know already they have a significant general fitness effect, and strong transfer to real-world activities like sawing, chopping and stacking firewood, shoveling snow, moving furniture, extended fire suppression, long firefighter, etc. But we’ve never measured their specific impacts to assessed strength, endurance and work capacity. This study sought to begin answering this question in general, and possibly serve as the stepping off point for further evolution of “grind” programming methodology.

Extended (30-40 minute), multi-modal “grinds” are a growing feature of MTI programming overall, and currently a significant component of MTI programming for older athletes (ages 40+). These efforts generally combine 1-2 moderate, or lightly-loaded chassis integrity or total-body exercises with an endurance mode exercise (short run, step ups, sled drag, etc.). They are duration-based, and athletes are instructed to complete them at a “moderate” pace which is defined as “comfortable, but not easy.”

Below is one of the “Grind” efforts from this mini study:


“Grind” = work steadily, not frantically through the exercises in this circuit for the prescribed time. Pace yourself so you there is no rest between exercises.

One important element of MTI’s “grind” programming is these efforts do not include any specific loaded squatting movements other than the occasional sandbag get ups. This is in keeping with MTI’s concern about the impact of high-rep, light-to-moderately loaded deep squatting exercises programmed into work capacity efforts to longterm joint (knee specifically) heath. We call these “garbage reps” and try avoid them.

This specific mini study deployed an pre-cycle and post-cycle, multi-modal fitness assessment:

  • 1RM (1 Repetition Maximum) Back Squat
  • 1RM Bench Press
  • Max Rep Strict Pull Ups (no time limit)
  • Max Rep 40-Foot Prone to Sprint in 3 Minutes (Work Capacity)
  • 12-Minute Step Ups (16-20″ bench) for Reps (Endurance

Between fitness assessments, the Lab Rats completed extended, (30-40 minute), multi-modal “grinds” 5 days/week, for 3 weeks.

Going into this mini study we hoped to learnthe fitness effects of extended, multi-modal grinds on endurance, strength, and work capacity.


Results & Discussion

See the chart below for results from this cycle:

Six remote lab rats completed the study. Average assessment results increased across the board slightly for each of the assessed measures. But given the 5% or less improvement for strength and work capacity and the low sample size (just 6 athletes), we can only infer that these grinds maintained max effort strength and work capacity.

However, the nearly 10% in the endurance assessment (12 minutes step ups for reps), we feel is significant enough to believe these long grinds overall improve endurance.

Currently, these extended multi-modal “grinds” are a significant part of MTI’s programming for older athletes (40+) and this mini-study reinforces the appropriateness of their deployment for older athletes who must balance the need to maintain strength and work capacity, while avoiding heavy, deep loaded squatting movements to preserve knee health.

Next Steps

This Mini-Study results are encouraging and offer a foundation for follow-up multi-modal “grind” design. Areas to be explored and tested include the impact of extending the duration past 40 minutes, more targeted total body exercises based on athlete’s individual strength (for example, power clean + push press at 60% 1RM), and different endurance modes (long sled pulls, long farmer’s carries, rowing, spinning, jump roping, etc.)

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