By Emmett Shaul, MTI Coach
BLUF
Across this 4 week Mini Study, we found that the Trap Bar Deadlift increases Back Squat 1RMs by an average of 11.1%, while failing to meaningfully move the Hinge Lift, which increased by only 3.6%. Our sled push interval progression drove an overall 12.0% improvement in the 3 minute Prone to Sprint assessment; however, this was heavily influenced by our novice Lab Rat (Aspen, +26.3%). When isolating our trained Lab Rats (Emmett and Michael), the average improvement was a more modest 7.1%. Results for the Military Press transfer to Bench Press remained muddled, mirroring anomalies found in earlier MTI research. Finally, applying a modified Big 24 strength progression to Chassis Integrity movements produced gains of 15% to 23%, supporting a shift toward a scalable, assessment-based Chassis Integrity training model that accounts for both raw strength and high-load strength endurance.
Background
To start 2026, we ran a 4 week Mini Study to test four practical programming questions. First, we looked at the Trap Bar Deadlift (TBDL). Biomechanically, the TBDL is a “Squat-Hinge Hybrid.” Research indicates it elicits greater quadriceps activation (vastus lateralis) than a straight bar deadlift while placing less stress on the lumbar erectors. We wanted to test if this “middle ground” nature effectively drives strength in the two lifts it mimics—the Back Squat and the Hinge Lift—or if a lack of specificity limits its transferability.
Second, we investigated the relationship between vertical and horizontal pushing. While the Bench Press is a common metric for upper body strength, we wanted to know the transferability of overhead pressing to the bench. We tested if training max effort Military Press transfers to a higher Bench Press 1RM. Third, we explored whether Sled Pushes serve as a viable work capacity tool or if the adaptation is too specific to the apparatus. Current literature often frames sled pushes as a tool for sprint mechanics or horizontal force production, but we wanted to determine if they function as a viable mode for general work capacity. Finally, we challenged our long standing Chassis Integrity (CI) model. Historically, MTI has used fixed weights for CI circuits, just recently transitioning to “Hard, but doable” loading. We tested the viability of a modified Big 24 progression on the Good Morning, Standing Russian Twist, and Weighted Sit Up to see if we could increase raw chassis strength by scaling the load to the individual.
Study Design
Participants: 3 Lab Rats (Emmett and Michael are trained; Aspen is a novice).
Assessments (Pre and Post):
- Work Capacity: 3-minute max reps Prone to Sprint
- Strength (1RM): Back Squat, Hinge Lift, Bench Press, Military Press, Trap Bar Deadlift
- CI Strength: 10RM Good Morning, 5RM Standing Russian Twist, 10RM Weighted Sit-Up
Training (4 weeks):
- Trap Bar Deadlift: 3 sessions per week, density progression.
- Military Press: 3 sessions per week, density progression.
- Sled Push: 2 sessions per week, 30:60 intervals (work:rest), progressed from 8 rounds to 11 rounds to 14 rounds. We used 25# on the sled to ensure efforts remained at a sprint/run pace rather than a stomp/walk.
- Chassis Integrity: 2 sessions per week, modified Big 24-style loading progression (-10#, -5#, and At Assessment Weight).
Results
Prone to Sprint (3 Minutes)
| Athlete | Initial | Post | Change | Percent Change |
| Emmett (Trained) | 29 | 31 | +2 | +6.9% |
| Michael (Trained) | 27 | 29 | +2 | +7.4% |
| Aspen (Novice) | 19 | 24 | +5 | +26.3% |
| Group Total | 75 | 84 | +9 | +12.0% |
Strength (1RM)
| Lift | Athlete | Initial | Post | Change | Percent Change |
| Back Squat | Emmett | 335 | 350 | +15 | +4.5% |
| Michael | 275 | 325 | +50 | +18.2% | |
| Aspen | 155 | 175 | +20 | +12.9% | |
| Hinge Lift | Emmett | 325 | 335 | +10 | +3.1% |
| Michael | 325 | 335 | +10 | +3.1% | |
| Aspen | 185 | 195 | +10 | +5.4% | |
| Trap Bar Deadlift | Emmett | 380 | 420 | +40 | +10.5% |
| Michael | 400 | 410 | +10 | +2.5% | |
| Aspen | 220 | 230 | +10 | +4.5% | |
| Military Press | Emmett | 115 | 125 | +10 | +8.7% |
| Michael | 145 | 145 | +0 | 0.0% | |
| Aspen | 65 | 72.5 | +7.5 | +11.5% | |
| Bench Press | Emmett | 275 | 280 | +5 | +1.8% |
| Michael | 230 | 235 | +5 | +2.2% | |
| Aspen | 105 | 115 | +10 | +9.5% |
Chassis Integrity Strength
| Exercise | Athlete | Initial | Post | Change | Percent Change |
| Good Morning (10RM) | Emmett | 135 | 175 | +40 | +29.6% |
| Michael | 135 | 145 | +10 | +7.4% | |
| Aspen | 85 | 105 | +20 | +23.5% | |
| Standing Russian Twist (5RM) | Emmett | 65 | 75 | +10 | +15.4% |
| Michael | 75 | 80 | +5 | +6.7% | |
| Aspen | 25 | 35 | +10 | +40.0% | |
| Weighted Sit-Up (10RM) | Emmett | 65 | 80 | +15 | +23.1% |
| Michael | 65 | 75 | +10 | +15.4% | |
| Aspen | 45 | 60 | +15 | +33.3% |
Discussion
Sled Pushes and Work Capacity Transfer
MTI defines Work Capacity as high intensity anaerobic power. Ideally, you want your lungs and muscles to give out at the same time. This cycle tested whether sled push intervals could serve as a work capacity driver for the 3 minute Prone to Sprint assessment. Our trained lab rats improved by 7.1%. To judge that value, we compared it to previous MTI work capacity results using the same Prone to Sprint marker.
Forward Sled Pull Intervals yielded a 3.8% increase in a 3 minute Prone to Sprint Assessment, while a High-Rep Kettlebell Snatch Cycle yielded 10.2%. In our 2019 volume mini-study, the high volume group improved Prone to Sprint by 8.7% and the reduced volume group improved by 7.6%. In our 2020 follow-on study, high-volume 45-minute training sessions improved Prone to Sprint by 11.9%.
By keeping the sled load light (25 pounds) to maintain running pace, we confirmed sled pushing is a legitimate work capacity tool, but in this cycle it appears less efficient than other modes for driving Prone to Sprint performance.
Trap Bar Deadlift: Can One Lift Replace Two?
We went looking for peer reviewed training studies that directly tested whether trap bar deadlift training transfers to a full Back Squat 1RM and/or a straight-bar deadlift/hinge 1RM, and we could not find a clean match. Most of the published trap bar literature is acute biomechanical work comparing the lifts during 1RM testing rather than longitudinal transfer (example: A Biomechanical Comparison of the Back Squat and Hexagonal Barbell Deadlift). The closest intervention we found compared 8 weeks of trap bar deadlift training to barbell half squats and measured crossover strength, but the squat pattern tested was a half squat, not the full Back Squat we assess at MTI (Comparison of resistance training using barbell half squats and trap bar deadlifts). This gap is part of why we ran this Mini Study.
This cycle was framed around the Trap Bar as a potential “hybrid king” as described in our January Lab Rat Cycle Overview. Our results showed a strong 11.1% overall increase in the Back Squat, which is competitive with our MTI Strength Progression Comparison (Density vs. Super Squat) which showed an 8.8% Back Squat 1RM increase in 3.5 weeks. However, the Hinge Lift only moved 3.6%. The TBDL carries the squat effectively due to torso positioning, but it is not a direct hinge replacement. If you must pick one lift to save time, the Trap Bar is a valid squat substitute, but a dedicated hinge is still required for meaningful gains in that movement pattern.
Military Press and the Continued Pressing Anomaly
Michael’s Military Press stayed flat at 145 lbs, yet his Bench Press increased. This mirrors the “muddled” results from our King of Upper Body Lifts mini-study. Vertical pressing training in this cycle was focused on max effort strength, yet the transfer was inconsistent. The lack of a direct, linear relationship between a 1RM Military Press and a 1RM Bench Press suggests that vertical pushing volume may provide a foundational stability that benefits horizontal pressing even when vertical 1RM strength remains unchanged.
The Evolution of Chassis Integrity: Strength vs. Durability
This cycle highlighted a critical bottleneck in our long standing CI protocols. A modified Big 24 approach drove gains of 15% to 23%. However, Chassis Integrity is not just raw strength; it is strength endurance—the ability to hold posture and transfer force under fatigue during long efforts, as seen in the field. Even our 10RM and 5RM tests are only a partial look at that reality. We found that the Weighted Sit Up is a poor assessment because of how much the shoulders are taxed as well as difficulties in holding/balancing the weight. We are moving toward barbell and plate based loading primarily to solve the loading friction inherent in sandbags—which are limited by an 80# “weight ceiling” and difficult to adjust quickly during a training session—though sandbags still have a place in the broader CI assessment.
Next Steps
- Evolve Chassis Integrity to Assessment Based Programming We are looking at developing Chassis Integrity to be assessment based and progressed, rather than just circuits or grinds with fixed loading—though those remain useful for training chassis integrity strength endurance. This cycle showed that individualizing the load is effective, but there is a fine line between training chassis strength and chassis strength endurance. We plan to build a framework with two lanes: a Strength lane and a Strength Endurance lane to ensure the chassis doesn’t buckle when the athlete is under fatigue or during long efforts.
- Flexion Assessment Redesign The Weighted Sit up is no longer a viable flexion assessment as the implement becomes the limiting factor. We need a flexion assessment that measures flexion and scales cleanly. We have previously tested Sandbag Sit ups and Pull-up Bar Heel Taps. We must consider facility limitations, as rack mounted pull up bars in many gyms (including ours) lack the clearance for full range of motion heel taps.
- Investigate Military Press Transfer We will continue to investigate the Bench Press increase despite flat Military Press numbers to further understand the transfer mechanics between vertical and horizontal pressing patterns.
Questions, Comments, Feedback? Email emmett@mtntactical.com