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Beginner

Bullpen Session

Also known as: bullpen, side session

A bullpen session is a practice throwing session, typically off a mound, in which a pitcher works through their pitch mix at game-like intent without live hitters or the pressure of a real game situation.

Bullpens are the primary setting where pitchers develop and refine mechanics, work on command of individual pitches, and build up arm strength and pitch counts in a controlled environment. A typical bullpen might include a set number of pitches at each pitch type — fastballs to work on command, then breaking balls and offspeed pitches to develop feel — often called to specific locations by a coach or the pitcher themselves, sometimes simulating full at-bats against an imaginary hitter to add game-like decision-making.

How bullpens are structured and how frequently they happen should be planned as part of a pitcher's total throwing workload alongside game innings and pitch counts, not treated as a separate, unlimited activity — pitches thrown in a bullpen still count toward cumulative arm stress even though they don't appear in a game box score. Recording bullpen sessions on video is also one of the most common and useful ways pitchers and coaches track mechanical consistency over time, since live-game footage alone rarely offers a clean, repeatable angle for the same view every time.

A pitcher throws a 30-pitch bullpen twice a week during the season, working 15 fastballs for location followed by a mix of changeups and breaking balls, with a coach charting locations from behind the plate.

Why it matters

Bullpen sessions are where most mechanical development and pitch command actually get built, and tracking them on video over time is one of the clearest ways to see whether changes are actually sticking.

Common mistakes

  • Not counting bullpen pitches toward total weekly or seasonal throwing workload, underestimating cumulative arm stress as a result.
  • Throwing every bullpen at full maximum effort rather than varying intent — some sessions are best used for feel and command work at less than max effort.

Frequently asked questions

How often should a youth pitcher throw a bullpen session?

It depends on the pitcher's age, workload from games, and time of year, and should be planned alongside — not in addition to — overall throwing volume rather than scheduled without regard to total arm workload.

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