Summary
Joe DeFranco and Bret Contreras, PhD, discuss glute training, heavy sled training research, vertical jump training, and the tension between practical coaching experience and academic research. Contreras shares his top glute exercises and the story behind becoming known as "the glute guy." A major portion of the conversation covers the science-versus-experience debate around heavy sled sprinting. DeFranco was an early advocate for heavy sled drags to improve speed, but track and field researchers initially pushed back because heavy loads changed sprint kinematics. Contreras explains that early research only looked at acute kinematic changes, not longitudinal training outcomes, and that subsequent studies (including JB Morin's work on individualizing sprint training) vindicated the heavy sled approach. Both coaches emphasize that heavy sled training produced real speed improvements in athletes from high school through NFL caliber.
Key Points
- DeFranco was among the first coaches to advocate heavy sled drags for speed development, facing pushback from track and field researchers
- Early research only showed that heavy sled loads changed sprint mechanics (kinematics) — but never tested whether it actually improved speed over time
- Longitudinal training studies later confirmed that heavy sled training improves acceleration and sprint speed
- JB Morin's force-velocity profiling research now allows coaches to individualize sled loads based on each athlete's needs
- Heavy sled work improved 40-yard dash times even in advanced NFL-level athletes running 4.3-4.4 second times
- There's likely room for both heavy and light sled protocols within a periodized training plan
- Contreras credits DeFranco's early DVD work as influential — including hip thrust variations that predated the glute training movement
- Practical coaching experience with thousands of athletes can be ahead of the research by years
Key Moments
The science-vs-experience debate on heavy sled training
DeFranco and Contreras discuss how early research discredited heavy sled sprints by showing altered kinematics, but never ran longitudinal studies. DeFranco's thousands of hours of coaching experience told him it worked, and later research proved him right.
"I bring up the heavy sledge sprints and heavy sledge dragging all the time because that was just one of those things when the research was discrediting all the things I was saying. I would argue that to the depth because I had thousands of hours of."
Longitudinal research vindicates heavy sled training for speed
Contreras explains that the early research only looked at acute kinematic changes — not whether athletes actually got faster over weeks of training. Track coaches speculated it would hurt speed, but they never tested it.
"So the research wasn't, so the research back then was showing that it interferes with kinematics. Like, no shit. Of course, your mechanics are going to change. It's going to look nothing like regular sprinting. But they never had longitudinal research, meaning training studies, following guys over the course of, you know, whatever, a period of, say, 12 weeks, and saying, did it improve speed?"
Heavy sled work improved speed in NFL-caliber athletes
DeFranco pushes back on the idea that heavy sleds only help beginners, noting he had NFL players running 4.3-4.4 in the 40-yard dash who still got faster with heavy sled training.
"But I had guys in the NFL that were running 4-4 and 4-3s in the 40 that were getting faster. So they might not be world record holder 100-meter guys, but probably more advanced than 99% of the population that most in the audience were training. And it was working with them."
