Few topics in baseball conditioning spark as much heated debate as long-distance running. Traditionalists insist that pitchers and position players need a solid aerobic base to endure nine-inning games and the relentless grind of a season. Modern performance coaches counter that distance running erodes power, slows athletes down, and has no rightful place in a sport defined by explosiveness.
Both camps point to “science” to back their claims. In truth, the science tells a far more balanced (and individualized) story. Neither extreme fully captures the physiological reality of baseball.
Baseball is fundamentally an intermittent power sport. The decisive actions: pitching, hitting, sprinting to bases, throwing from the outfield, are brief and maximal. A pitch lasts roughly one second, and a swing even less. These movements rely primarily on the phosphagen (ATP-PCr) energy system, which fuels short bursts of maximal muscular effort.
Research on pitching physiology supports this classification. Studies examining the metabolic demands of pitching show that the delivery of a pitch relies predominantly on anaerobic pathways, with minimal contribution from the aerobic system during the movement itself. Reviews of baseball conditioning by strength and conditioning researcher David J. Szymanski emphasize this point clearly: the primary energy demand of pitching is explosive and anaerobic, which means training should prioritize the development of power and rapid force production.
However, the picture is incomplete without considering recovery.
Between pitches, pitchers typically have fifteen to thirty seconds of rest. During this time, phosphocreatine stores must be replenished so the next pitch can be delivered at maximal intensity. The restoration of these energy stores depends partly on aerobic metabolism.
When averaged over time, the metabolic demand of pitching corresponds roughly to moderate aerobic intensity, despite the explosive nature of each pitch. Measurements from simulated games illustrate this intermittent pattern: short maximal efforts separated by repeated recovery intervals. The aerobic system therefore plays a supporting role—not in producing the explosive movement itself, but in helping the athlete restore the energy required to repeat that movement.
Baseball therefore requires explosive power supported by aerobic recovery across innings, games, and a long competitive season.
The traditional argument in favor of distance running—that it builds the endurance needed to sustain performance—contains some truth. Extremely poor aerobic fitness can limit an athlete’s ability to recover between repeated high-intensity efforts, particularly late in games or during dense competition schedules.
The drawback appears when large volumes of steady-state endurance training are layered onto strength and power work.
This interaction is known in the scientific literature as the concurrent training effect. When endurance training and resistance training are performed together, endurance work can sometimes blunt improvements in strength, muscle hypertrophy, and explosive power—qualities directly linked to throwing velocity and bat speed.
A widely cited meta-analysis by Wilson and colleagues in the Journal of Strength and Conditioning Research examined numerous training studies and found that endurance training performed alongside resistance training reduced gains in strength and power compared with resistance training alone. The interference effect was more pronounced when endurance work involved running rather than cycling, and when the volume and frequency of endurance training were high.
These findings contributed to a shift in many baseball strength programs. Across numerous collegiate and professional organizations, traditional distance running has gradually been replaced by sprint intervals, shuttle runs, repeated-effort conditioning, explosive medicine-ball circuits, and power-oriented conditioning drills.
These methods better reflect the intermittent and explosive nature of the sport.
Yet more recent research has added important nuance to the concurrent training discussion. Recent umbrella reviews synthesizing multiple meta-analyses on concurrent training suggest that interference between endurance and strength development is not inevitable. Instead, the outcome depends heavily on context—training volume, modality, sequencing of sessions, recovery time, and the athlete’s training status.
When endurance work is performed through high-intensity interval training (HIIT) or sprint interval training (SIT), negative interactions with strength and power development often disappear and may even become complementary. Several meta-analyses examining sprint interval training combined with resistance training have reported similar improvements in strength, jump performance, and sprint ability compared with resistance training alone, while simultaneously producing significant improvements in aerobic capacity.
The common claim that endurance training “turns athletes into slow-twitch runners” is also scientifically exaggerated. Muscle fiber-type distribution is largely determined by genetics. While training can shift some fast fibers from type IIx toward more oxidative type IIa characteristics, it rarely converts a fast-twitch dominant athlete into an endurance specialist.
Both extremes in the debate therefore rest on oversimplified interpretations of physiology.
A deeper problem lies within the structure of much of the research itself. Most studies report average results from groups of athletes with widely different biological profiles. Yet athletes vary substantially in muscle fiber composition, neuromuscular characteristics, training history, and recovery capacity. These individual factors strongly influence how an athlete responds to conditioning stimuli.
Because these variables are rarely measured in baseball-specific research, conclusions drawn from group averages may not apply equally to every player.
For example, athletes with highly explosive physiological profiles may see power development compromised by high volumes of steady-state running. Others with more mixed physiological profiles may tolerate moderate aerobic work without losing power and may even benefit from it in terms of recovery capacity over the course of a long season.
Pitching illustrates this complexity well. A starting pitcher may throw eighty to one hundred maximal-effort pitches during an outing, each separated by brief recovery periods. The sport therefore demands repeated bursts of explosive power supported by efficient recovery.
If conditioning focuses exclusively on endurance, explosive qualities may decline. If aerobic capacity is ignored entirely, recovery between repeated efforts may become the limiting factor.
Modern baseball conditioning programs increasingly address this balance by emphasizing repeated high-intensity efforts rather than prolonged steady-state exercise. Sprint intervals, shuttle runs, explosive circuits, and repeated-effort drills allow athletes to improve conditioning while maintaining the neuromuscular qualities necessary for power.
Such methods align far more closely with the intermittent physiological demands of baseball.
At the same time, current evidence suggests that small doses of aerobic conditioning—particularly when intelligently programmed and kept at moderate volumes—are unlikely to undermine power development in most athletes.
The real mistake is not distance running itself.
The mistake is assuming that a single conditioning method should apply to every athlete in a sport where physiological profiles vary dramatically from player to player.
The physiology of baseball cannot be reduced to a simple rule such as “never run long distance” or “build an aerobic base.” Baseball is an intermittent power sport supported by aerobic recovery. Effective conditioning programs must therefore develop explosive power while ensuring that athletes can recover quickly enough to repeat that power throughout a game and across an entire season.
The best approach is not ideological but physiological: evaluate the athlete, monitor performance indicators such as velocity, power output, and fatigue, and adjust conditioning strategies accordingly.
The real question is not whether baseball players should run long distances.
The real question is whether their conditioning reflects the true demands of the sport—and the unique physiology of the athlete performing it.