Bat Speed Protocol
8-week overload/underload progression — up to 8% bat speed increase
The Science
Overload/underload (O/U) bat training is based on research by Dr. Coop DeRenne and has been refined by organizations like Driveline Baseball and Caliburn Hitting. The principle:
- Overload (heavy bat): Builds strength through the swing zone. Trains the muscles to produce more force.
- Underload (light bat): Trains the nervous system to fire faster. Increases neuromuscular recruitment speed.
- Contrast effect: Alternating between heavy and light creates a "potentiation" effect — the body recruits MORE motor units after the heavy work, then expresses that as SPEED with the light bat.
Research shows up to 8% bat speed increase when using ±20% of game bat weight over 8-12 weeks.
Bat Setup
Going beyond ±20% of game bat weight changes the swing mechanics too much and doesn't transfer to game performance. Stay in the range.
| Game Bat Weight | Overload (+20%) | Underload (-20%) |
|---|---|---|
| 25 oz | 30 oz | 20 oz |
| 26 oz | 31 oz | 21 oz |
| 27 oz | 32 oz | 22 oz |
| 28 oz | 34 oz | 22 oz |
How to Create Training Bats
- Overload: Use a bat donut/weight ring on game bat, or a separate heavier bat
- Underload: Use a fungo bat, whiffle bat, or shorter/lighter training bat
- Budget option: PVC pipe (underload) + donut on game bat (overload)
8-Week Progression
This protocol runs on Friday (Day 3) of the hitting program. Volume builds progressively from 26 to 69 swings per session.
Learn the feel. No ball contact. Focus on swing path with each bat.
| Bat | Week 1 | Week 2 | Focus |
|---|---|---|---|
| Overload | 2x3 dry | 2x4 dry | Feel the heaviness, maintain path |
| Regular | 1x5 dry | 1x6 dry | Transfer feel |
| Underload | 2x3 dry | 2x4 dry | Let it fly, max speed intent |
| Regular | 1x5 dry | 1x6 dry | Integrate speed |
Total: Week 1: 22 swings | Week 2: 28 swings
Add ball contact off tee. Regular bat reps increase.
| Bat | Week 3 | Week 4 | Focus |
|---|---|---|---|
| Overload | 2x3 off tee | 2x4 off tee | Drive through ball with heavy bat |
| Regular | 1x6 off tee | 1x8 off tee | Feel the speed carryover |
| Underload | 2x4 off tee | 2x5 off tee | Max bat speed through contact |
| Regular | 1x8 off tee | 1x8 off tee | Integrate into normal swing |
Total: Week 3: 28 swings | Week 4: 34 swings
Move to live toss with contrast bats. Volume continues climbing.
| Bat | Week 5 | Week 6 | Focus |
|---|---|---|---|
| Overload | 2x4 front toss | 3x4 front toss | Timing with heavy bat |
| Regular | 1x8 front toss | 1x8 front toss | Immediate transfer |
| Underload | 2x5 front toss | 3x5 front toss | Max speed with timing |
| Regular | 1x10 front toss | 1x10 front toss | Game-speed integration |
Total: Week 5: 36 swings | Week 6: 45 swings
Full protocol with machine BP. Add max-effort exit velo testing.
| Bat | Week 7 | Week 8 | Focus |
|---|---|---|---|
| Overload | 3x5 (tee + toss) | 3x5 (tee + toss) | Full strength through zone |
| Regular | 1x8 off machine | 1x10 off machine | Transfer to game speed |
| Underload | 3x5 (tee + toss) | 3x5 (tee + toss) | Peak bat speed |
| Regular | 1x10 off machine | 1x10 off machine | Game integration |
| Max effort test | 5 max swings | 5 max swings | Record bat speed + exit velo |
Total: Week 7: 53 swings | Week 8: 60 swings
Weekly Bat Speed Test
- Full warm-up (arm circles, torso twists, 10 easy dry swings)
- 5 progressive swings off tee (50%, 60%, 70%, 80%, 90% effort)
- 5 max-effort swings off tee (middle-middle setup)
- Record best bat speed AND best exit velo
- Rest 15-20 seconds between max swings
Tracking Sheet
| Week | Best Bat Speed | Best Exit Velo | Notes |
|---|---|---|---|
| Baseline | ___ mph | ___ mph | |
| Week 1 | ___ mph | ___ mph | |
| Week 2 | ___ mph | ___ mph | |
| Week 3 | ___ mph | ___ mph | |
| Week 4 | ___ mph | ___ mph | |
| Week 5 | ___ mph | ___ mph | |
| Week 6 | ___ mph | ___ mph | |
| Week 7 | ___ mph | ___ mph | |
| Week 8 | ___ mph | ___ mph |
Benchmarks for 13-14 Year Old
| Level | Bat Speed | Exit Velo (off tee) |
|---|---|---|
| Average | 50-55 mph | 50-55 mph |
| Good | 55-60 mph | 55-60 mph |
| Elite | 65+ mph | 65+ mph |
| D1 Threshold | 70+ mph | 70+ mph |
8-Week Volume Summary
| Week | Overload | Regular | Underload | Total | Modality |
|---|---|---|---|---|---|
| 1 | 6 | 10 | 6 | 22 | Dry swings |
| 2 | 8 | 12 | 8 | 28 | Dry swings |
| 3 | 6 | 14 | 8 | 28 | Tee |
| 4 | 8 | 16 | 10 | 34 | Tee |
| 5 | 8 | 18 | 10 | 36 | Front toss |
| 6 | 12 | 18 | 15 | 45 | Front toss |
| 7 | 15 | 18 | 15 | 53* | Toss + machine |
| 8 | 15 | 20 | 15 | 60* | Toss + machine |
*Plus 5 max-effort test swings
After the 8-Week Protocol
After completing the full 8-week build, transition to maintenance:
- Keep O/U work on Friday (Day 3) as part of regular routine
- Volume: Week 6-level (~45 swings of O/U per session)
- Continue weekly bat speed tests
- Run another 8-week build after 4-6 weeks of maintenance if you want another jump
- During Phase 1 (nerve recovery): use modified grip with all bats
- If overload bat causes nerve symptoms, reduce weight or skip overload
- Never sacrifice swing mechanics for speed — slow down if form breaks
- Full warm-up before every session (arm circles, torso twists, progressive swings)
- Stop if any pain, numbness, or tingling