Weighted Bat Warm-Up
Also known as: bat donut, on-deck donut, batting donut, weighted bat on deck, heavy bat warm-up, swinging a weighted bat, weighted warm-up bat, overload and underload bats
Swinging a donut-weighted or heavy bat on deck makes your game bat feel lighter, but studies have not found that it makes your swing faster. In lab tests, a heavy warm-up left the next swings with a normal bat no faster, and sometimes slower, even though players felt quicker. A few hard swings with your game bat, or a lighter bat, prepare you at least as well.
The donut ring is a baseball tradition, and the feeling it gives is real: after swinging extra weight, the game bat feels light. Measured bat speed tells a different story. In a 2002 study, players' first swing after a weighted-ring warm-up was 3.3% slower. At the same time, they said the bat felt lighter and their swing faster. Speed was back to normal by the second swing.
Later studies point the same way. In 2009, 19 players warmed up with a light (9.6 oz), normal (31.5 oz) or heavy (55.2 oz) bat. The light and normal warm-ups led to faster normal-bat swings than the heavy one. In 2020, 32 players swung faster after warming up with a plastic or normal bat than after a 57-ounce bat. A 2011 study of 22 Division I players found no difference in bat speed across ten warm-up devices. A 2021 review found repeated evidence that heavy bats hurt the swings that follow, including timing errors and a gap between how fast a swing felt and how fast it was.
Young hitters have extra reason to keep it simple. A 2025 study that included 12- to 16-year-olds found no bat-speed change from weighted or lighter warm-up bats. But it did find changes in swing angles. The authors advised that teens with less training experience avoid weighted or lighter bats for warm-up swings.
Training with heavy and light bats over several weeks is a separate question. One 8-week study of 17 varsity players found that a special training bat whose swing weight changes during the swing raised swing speed more than training with a normal bat. Research on younger players is thin, so build bat speed through strength work and hard, well-coached swings.
Tips by skill level
On deck, take three to five hard, game-speed swings with the bat you will hit with. Time them to the pitcher's delivery so your first swing at the plate is not your first real one.
If you like a heavy bat in your routine, use it early in the warm-up and finish with several swings of your game bat. Check with a bat sensor that your first swings are at full speed.
Example
A high school hitter has always swung a donut on deck. His coach checks his swings with a bat sensor and finds his first two game-bat swings after the donut are slower than after three hard swings with his own bat. He switches to his game bat on deck and feels just as ready.
Why it matters
The on-deck circle is the last chance to get ready for a pitch. A warm-up that feels good but slows the first swing works against the hitter.
Common mistakes
- Taking the last on-deck swings with a heavy donut, so the first game-bat swing comes at the plate
- Trusting the light feel after a heavy warm-up as proof the swing is faster
- Giving weighted warm-up bats to a young hitter whose swing is still forming
Frequently asked questions
Does swinging a weighted bat on deck help?
Not for bat speed. Studies have found heavy warm-ups leave the next swings no faster, and sometimes slower, even though the game bat feels lighter. Finish your warm-up with your game bat.
Do weighted bats increase bat speed?
Not as an on-deck warm-up. As multi-week training, one 8-week study of varsity players found a training bat whose swing weight changes during the swing improved swing speed more than a normal bat. There is little research on younger players.
What should I swing in the on-deck circle?
Your game bat. In lab studies, a few hard swings with a normal or lighter bat prepared hitters at least as well as a heavy bat.
Why does my bat feel lighter after using a donut?
It is a trick of perception. In one study, players said the bat felt lighter and faster after a weighted ring, while their first measured swing was 3.3% slower.
Sources
- Otsuji et al. (2002), After-effects of using a weighted bat on subsequent swing velocity and batters' perceptions, Percept Mot Skills
- Montoya et al. (2009), Effect of warm-up with different weighted bats on normal baseball bat velocity, J Strength Cond Res
- Miller et al. (2020), Evaluating the effects of underloaded and overloaded warm-ups on subsequent swing velocity, J Strength Cond Res
- Szymanski et al. (2011), Effect of various warm-up devices on bat velocity of intercollegiate baseball players, J Strength Cond Res
- Jermyn et al. (2021), The acute effects from the use of weighted implements on skill enhancement in sport: a systematic review, J Strength Cond Res
- Li et al. (2025), Impacts of dry swing intervention on bat speed and attack angle, Front Sports Act Living
- Liu et al. (2011), Effects of training with a dynamic moment of inertia bat on swing performance, J Strength Cond Res
Related terms
- Bat SpeedBat speed is how fast the barrel is moving at contact, in mph. It contributes to exit velocity alongside bat path and where on the barrel you make contact.
- Bat Speed by AgeBlast Motion, a bat-sensor maker, publishes practice-swing ranges of about 30–45 mph for 8- to 10-year-olds and 40–52 for 11- to 12-year-olds. For older players its ranges are about 46–62 mph at 13–14, 55–65 at 15–16 and 60–70 at 17–18. Treat them as rough guides from one sensor in tee and toss work. In MLB, Statcast's average swing was about 72 mph when bat tracking launched in 2024.
- Time to ContactTime to contact is the split-second a swing takes from trigger to ball. It sets how late a hitter can afford to start swinging against a given velocity.
- Bat Size by AgeEaston's age chart, a common starting point, suggests 24–26 inch bats for ages 5–7, 26–28 for 8–9, 28–29 for age 10 and 30–31 for 11–12. For older players it suggests 31–32 inches at 13–14, 32–33 at 15–16 and 34 at 17 and up. Then fine-tune by fit: pick a bat the player can swing fast and control, with the certification stamp your league requires.
Related guides & benchmarks
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