Every coach agrees that strength training matters, but how quickly does performance actually decline when resistance work is removed? This new study helps answer that question with hard numbers.

Over an 8-week fall season, 12 NCAA Division I pitchers followed a structured pitching program — but due to COVID-related restrictions, they had no access to a weight room. Pitchers threw weekly bullpens off regulation mounds, increasing total effort throws from 30 to 50, with workload scaled across the 2-month span. Their velocity, mechanics, and elbow stress were tracked using radar and wearable IMUs.

What happened? Their arms didn’t break. Their mechanics didn’t fall apart. But their fastballs slowed dramatically.

What the Study Found

• Ball velocity dropped by 6.3 mph on average (from 84.3 to 78.0 mph) over the 8-week training period (p < 0.001).
  
  
• Arm slot angle, arm velocity, and elbow torque all remained statistically unchanged (p > 0.05).
  
  
• The pitching-only program featured progressive effort increases and live batters, but without lifting, velocity still declined.
  
  
• No significant joint stress adaptations occurred, suggesting mechanical outputs stayed stable while force generation declined.
  
  
• Velocity loss occurred despite adherence to the pitching program and use of mound work with game-intent sequencing.
  
  

Why This Matters

The takeaway here isn’t just that strength matters. It’s how fast it matters.

These athletes weren’t detrained in the traditional sense. They were throwing consistently, building volume, and even facing hitters. But removing the external stimulus of strength training, even for just two months, cut their fastball velocity by over 7 percent.

This illustrates the fragility of power output in the absence of load-based adaptation. Pitchers often assume that velocity is protected if they just keep throwing, but this data suggests otherwise. The force that drives high-output movement patterns doesn’t sustain itself without reinforcement, especially in athletes already adapted to high training levels.

What makes this even more concerning is the possibility that the athletes didn’t feel this decline happening. The study reported no significant changes in arm velocity or torque, meaning their throwing patterns may have remained the same, even as their ability to generate force declined.

And that creates risk. It’s one thing to reduce output intentionally. It’s another to throw the same way, at the same effort level, while unknowingly producing less force, or worse, compensating elsewhere to make up the difference.

How We Apply This at VeloU

At VeloU, this study reinforces what we observe every fall with returning athletes: even short-term training gaps matter. In-season or off-season, strength isn’t a luxury; it’s the support system for everything you’re trying to maintain on the mound.

We treat lifting and throwing as integrated parts of the same system. Not just because strength helps velocity, but because training continuity protects against the silent creep of regression. Most pitchers don’t lose velocity in one bad lift or one tough bullpen. They lose it over 6 weeks of inconsistent input.

This study doesn’t prove causality in every context, and the sample size is small. But it’s a timely reminder: pitchers don’t just need mound time, they need resistance to maintain the engine that makes velocity possible.

This article is part of Applied Baseball Science by Dr. Nicholas Serio, where we break down the biomechanics, performance science, and injury research shaping the modern game. Powered by VeloU (Velo University) — where research meets real-world baseball.

Reference

Gdovin, J. R., Hogan, B., & Williams, C. C. (2025). Limiting access to resistance training equipment during the off-season: The impact on collegiate pitching metrics. Journal of Strength and Conditioning Research, 39(3), 347–351.