Professional Baseball Strength & Conditioning


Pitch Clock, Aerobic Capacity and Recovery

By Daniel Donohue, RSCC

Major League Baseball’s initiative to speed up the pace of play has altered the physiological requirements for Minor League players. Specifically, the addition of the pitch clock requires pitchers to deliver high intent, max- or near-max effort throws with a prescribed amount of rest. This, in turn, increases the need for higher aerobic capacity to enhance the ability to recover in a short window of time.

For some pitchers, the implementation of the pitch clock might create potential problems such as increasing workload, fatigue, and stress, which in turn, could have a negative effect on performance and potentially increase the risk of injury. With this increased demand placed on pitchers’ energy systems, the need arises for athletes to be able to recover quickly enough to continuously deliver max- or near-max effort pitches. If a pitcher is unable to fully recover between pitches, a negative snowball effect can occur. Incomplete recovery can build from pitch-to-pitch, which increases the workload, and elevates the heart rate to levels that make it hard to return to manageable levels.

With the constraints that the pitch clock brings, recovery becomes extremely important between pitches, innings and outings. If fatigue accumulates to unmanageable levels during an outing, it can increase the risk of potentially negative effects after multiple outings, series, or the entire season.

Pitching is an anaerobic activity fueled primarily by the ATP-PC system. Recovery between pitches relies on the aerobic or oxygen transport system to provide oxygen to the working muscles between pitches and between innings. The ATP-PC system provides a limited amount of energy very quickly to fuel the physical act of pitching. The oxygen system provides more energy, but at a much slower rate. Limiting time between pitches, especially in high-pitch innings and after multiple innings can limit the ability of the slower cardiorespiratory system to deliver adequate oxygen to fuel recovery in the working muscles which, in turn, can cause the body to call on the lactic acid system to provide energy and increase fatigue.  Elevated levels of fatigue associated with incomplete recovery and the accumulation of lactic acid can potentially decreased command, and increase the risk of fatigue-related stress.

If coaches can improve a pitcher’s abilities to quickly return his heart rates to lower levels between pitches, innings and outings, it should improve his ability to maximize the use of the ATP-PC system and limit the possible accumulation of fatigue-producing lactic acid. This, in turn, will give pitchers more consistent high-energy output, reduce fatigue and optimize the efficiency of energy system usage.

The pitch clock has changed the environmental constraints of the game to the point that pitchers have a greater need for aerobic fitness, proper breathing mechanics, and proper training to enhance the capacity and utilization of all energy systems. As Strength and Conditioning Coaches, it is our job to adapt programming to meet the new demands of pitching.

The following graphs provide examples of how heart rate is affected by the ability to recover after bouts of intense energy expenditure. In the following images, players performed Airdyne Bike sprints for 15 seconds, rested 45 seconds, and performed 7 repetitions.

Figure A:  Example of adequate recovery to a consistent baseline after repeated bouts of intense energy expenditure.  Note the sharp peaks and valleys of heart rate that suggest the ability to recover quickly.

Figure B:  Example of how the inability to recover to a consistent baseline can lead to increase demand on the aerobic energy system.

The peaks and valleys in the heart rate start off well, but they become shallower with the onset of fatigue. We can see this onset by analyzing how the heart rate is not able to return to a lower rate and rises to an increased level with each rep. This is the effect of stacking of workload and the insufficient recovery.

Figure C:  Example of having minimal ability to recover keeps the heart rate higher, placing an increased demand on the energy systems and tissues.

We can see in this example how this individual was unable to have their resting rates separate from his working rates. The peaks and valleys are extremely shallow, and the baseline continues to rise throughout the training session.

When it comes to training energy systems, it is hard to replicate game-like, max- or near-max intent pitches, with the pitch clock rest interval. The game itself is a vigorous training stimulus that we need to account for. Training to enhance aerobic capacity will enhance the ability to recover. Avoiding excessive fatigue may also help improve performance and minimize the risk of injury.

Pitch Clock Metrics:  

  • With no runners on base, the pitcher has 14 seconds between each pitch.
  • With runner or runners on base, the pitcher has 18 seconds after pitch is thrown to set and throw again.
  • Each new hitter resets the clock to 30 seconds.
  • During the change of inning there are 2 minutes and 15 seconds, however, the pitcher needs to have finished his warm-up pitches and be ready to go with 30 seconds left in the time slot, which brings the total amount of time of work to warm-up to 1 minute and 45 seconds.


  1. Bassett DR Jr, Howley ET. Limiting factors for maximum oxygen uptake and determinants of endurance performance. Med Sci Sports Exerc. 2000 Jan;32(1):70-84. doi: 10.1097/00005768-200001000-00012. PMID: 10647532.
  2. Noonan TJ, Garrett WE Jr. Muscle strain injury: diagnosis and treatment. J Am Acad Orthop Surg. 1999 Jul-Aug;7(4):262-9. doi: 10.5435/00124635-199907000-00006. PMID: 10434080.


Daniel Donohue, RSCC, is the Strength and Conditioning Coach for the Dayton Dragons, a Midwest League and High-A affiliate of the Cincinnati Reds.


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