When an online entertainer is as explosive as IShowSpeed, people start asking questions.
How does someone launch themselves 40 inches into the air, seemingly effortlessly?
Dr. Mike Israetel, a sport scientist and co-founder of Renaissance Periodization, recently broke down the athleticism of popular YouTuber IShowSpeed in a detailed analysis video, revealing the science behind vertical jumping, explosive power, and why some people are just built to fly.
And the answers might surprise anyone who’s ever wondered why their own vertical jump barely clears a phone book.
Jump to:
The Anatomy of a 40-Inch Vertical
IShowSpeed’s documented 40-inch vertical jump places him in elite athletic territory, comparable to NFL and NBA prospects.
According to Dr. Israetel, several key factors determine jumping ability, and most of them come down to genetics and anatomy rather than training alone.
Limb Length Matters More Than You Think
One of the primary determinants is femur length—the thigh bone that connects hip to knee.
The longer your thigh bones, your femurs are, the more time you have to put force into the ground until your butt and then your feet leave the ground.
Dr. Israetel explained that longer femurs create a longer acceleration phase. More time applying force means more impulse delivered to the ground, which translates directly into vertical height.
Someone with shorter femurs simply has less time to generate power before leaving the ground, regardless of strength or technique.
Fast-Twitch Muscle Fibers: The Secret Ingredient
Muscle fiber composition plays an equally critical role. Humans possess two main types of muscle fibers: slow-twitch (Type I) and fast-twitch (Type II).
Fast-twitch fibers contract rapidly and powerfully, making them essential for explosive movements like jumping and sprinting. Slow-twitch fibers excel at endurance but lack the same explosive capacity.
If your glutes and quads are more fast twitch, that means when your nervous system says go, they contract really rapidly.
Dr. Israetel noted that while muscle fiber type can be trained to a small degree, it’s overwhelmingly determined by genetics. Athletes with naturally higher fast-twitch fiber percentages will always have an advantage in explosive sports.
Tendon Stiffness: The Underrated Factor
Most people assume flexible tendons are always beneficial, but for explosive power, the opposite is true.
Stiffer tendons act like springs, efficiently transferring muscular force into movement. Flexible tendons absorb energy as heat, dissipating power that could otherwise propel you upward.
If your tendons are very stiff, your fast twitch muscles contract. It pulls right along everything. It pulls the rest of the bone up and you can generate a crapload of force.
This mechanical advantage allows athletes with naturally stiff tendons to convert muscle contractions into vertical displacement more effectively.
Training for Explosive Power: What Actually Works
While genetics provide the foundation, Dr. Israetel outlined practical training methods that can improve vertical jump within individual genetic limits.
Heavy Strength Training
Building maximum strength in compound movements forms the base of any jump training program.
- Squats for 3-5 reps at heavy loads develop absolute strength in quads and glutes
- Deep lunges target glutes specifically for horizontal power transfer
- Progressive overload ensures continuous strength adaptation
The stronger these primary movers become, the more force they can generate during the brief ground contact phase of a jump.
Plyometric Practice
Simply practicing jumping itself trains the nervous system to coordinate rapid, explosive muscle contractions.
Plyometric exercises like box jumps, depth jumps, and repeated vertical jumps teach the body to recruit fast-twitch fibers more efficiently and improve the rate of force development.
Technical Refinement
Proper jumping mechanics maximize power transfer from muscles to movement.
Key technical elements include arm swing timing, countermovement depth, and body positioning at takeoff. Working with a coach to optimize these factors can add several inches to vertical jump without any change in strength.
The Weight Loss Advantage
Perhaps the most accessible improvement method involves body composition.
The less you weigh, the higher you can jump. So, if your squats going up while you’re losing weight, your vertical jump is going to be A BIG, BIG DEAL.
Reducing body fat while maintaining or increasing strength dramatically improves the power-to-weight ratio, allowing the same muscular force to propel less mass upward.
Horizontal vs. Vertical Jumping: Not So Different
Dr. Israetel also addressed the relationship between vertical jumping and broad jumping (horizontal distance).
The biomechanics overlap substantially, with only minor differences in muscle recruitment and technique.
Muscle Recruitment Differences
Vertical jumping relies slightly more on quadriceps activation, while broad jumping emphasizes glute engagement for horizontal propulsion.
However, both movements require the same fundamental capacity: generating maximum lower body power in minimal time.
Technique Adjustments
The primary distinction lies in the angle of force application and landing mechanics.
Vertical jumps direct force straight down into the ground, while broad jumps angle force at approximately 45 degrees. Landing technique also becomes more critical in broad jumping, as athletes must stick a controlled landing rather than simply absorbing impact.
If you have the ability to jump high, your ability to jump far is a fucking rounding error away.
This means training for one jumping modality provides substantial carryover to the other, making specialized lower body power training efficient for multiple athletic applications.
The Danger of Loaded Jumping
In the analysis, IShowSpeed performed jumps while holding weights—a practice that caught Dr. Israetel’s attention for both positive and negative reasons.
While the added weight provides momentum that can assist with mid-air tucking, it significantly increases landing forces and injury risk.
Landing with way higher weight than your body weight from that kind of height is absolutely an increased chance of injury.
The impact forces during landing multiply when external loads are added, placing enormous stress on ankles, knees, and the lower back. These movements should only be attempted by experienced athletes with progressive preparation.
The Pull-Up Frequency Question
IShowSpeed also discussed his approach to pull-up training, claiming to perform 50 total reps daily by doing 10 pull-ups every time he uses the bathroom.
Dr. Israetel expressed skepticism about this high-frequency approach for most people.
I think a better way to go about it is to get that pull-up bar, but make yourself a plan with the RP hypertrophy app or any other thing that you choose to make yourself a plan with so that you can hit up pull-ups and other back work like maybe twice or three times a week.
Random, unplanned high-volume training can lead to overuse injuries, particularly in the elbows and shoulders. Structured programming with adequate recovery typically produces better long-term results for muscle growth and strength.
Genetic Limits and Athletic Reality
The central message throughout Dr. Israetel’s analysis emphasizes an often-uncomfortable truth: elite athletic performance depends heavily on genetic advantages.
Training can optimize individual potential, but it cannot overcome fundamental anatomical and physiological limitations.
Someone with short femurs, predominantly slow-twitch muscle fibers, and flexible tendons can train intelligently for years and still never approach the vertical jump of a genetically gifted athlete with minimal training.
This doesn’t mean training is pointless—far from it. Proper strength training, plyometrics, and technique work can add inches to anyone’s vertical jump and significantly improve athletic performance within their genetic framework.
But expecting to develop a 40-inch vertical through training alone, without the genetic foundation, sets unrealistic expectations that lead to frustration and potential injury from excessive training volume.
Practical Takeaways for Jump Training
For athletes looking to maximize their jumping ability, Dr. Israetel’s analysis provides a clear roadmap:
- Build maximum strength in squats and lunges with 3-6 rep ranges
- Practice explosive movements through plyometric training
- Optimize body composition by reducing body fat while maintaining muscle
- Refine technique with coaching or video analysis
- Train systematically rather than randomly to allow proper recovery
- Progress gradually when adding external loads to jumping exercises
Most importantly, understand and accept genetic limitations while working to maximize individual potential. Not everyone will achieve elite vertical jumps, but everyone can improve significantly from their starting point with intelligent training.
IShowSpeed’s athletic displays entertain millions, but they also serve as vivid demonstrations of what exceptional genetics combined with natural athleticism can produce—a reminder that while hard work matters enormously, biology provides the blueprint.
