Pitchers run after pitching to increase blood flow throughout the body, which helps flush metabolic byproducts from their muscles and speeds the transition from a high-adrenaline state back to rest. It’s one of the most visible traditions in baseball, with starters jogging in the outfield after being pulled from a game or logging miles the day after a start. But the science behind this practice has shifted significantly in recent years, and what pitchers actually do on those runs is changing.
The Traditional Logic: Flushing the Arm
For decades, the standard explanation was simple: pitching fills the arm with lactic acid, and running increases circulation enough to clear it out. Coaches called these “flush runs,” and they typically involved a pitcher jogging several poles (the distance between foul poles in the outfield) at a conversational pace the day after a start. The idea was that this steady-state cardio would carry lactic acid away from the shoulder and elbow, reducing soreness and preparing the pitcher for his next outing.
There’s a kernel of truth buried in here. Light activity after intense exercise does promote blood flow, which carries metabolic waste products to the liver, heart, and working muscles where they can be processed. Active recovery accelerates the restoration of normal pH levels in the blood and helps convert some leftover lactate back into usable fuel through a recycling process in the liver. These mechanisms are well established in exercise physiology.
Why the Lactic Acid Theory Fell Apart
The problem is that pitching doesn’t actually produce significant lactic acid in the first place. A 1992 study by Potteiger and colleagues measured blood lactate levels in college pitchers before and after throwing a simulated seven-inning game and found no significant difference. This makes sense when you think about what pitching actually looks like: a brief, explosive effort lasting about one second, followed by 20 to 30 seconds of rest before the next pitch. It’s not a sustained effort like running 400 meters.
Beyond that, the entire premise that lactic acid causes fatigue has been dismantled. Researchers have bathed isolated muscle fibers in lactate concentrations equivalent to what you’d see after an all-out sprint and found little to no drop in the muscle’s ability to generate force. In one striking experiment, adding lactate to already-fatigued muscle actually reversed some of the fatigue, restoring force output back toward baseline. As Dr. Mark Burnley, an endurance physiology expert at Loughborough University, puts it: “Lactate is one of the good guys.” It appears to have a protective effect on muscle, not a damaging one.
So if pitching doesn’t produce meaningful lactate, and lactate isn’t the villain it was made out to be, the classic justification for post-pitching distance runs doesn’t hold up.
What Running Actually Does for Recovery
That doesn’t mean post-pitching movement is useless. It just works for different reasons than coaches traditionally thought.
During a game, a pitcher’s nervous system is running in full fight-or-flight mode: elevated heart rate, heightened blood pressure, rapid breathing, stress hormones circulating. After the game ends, the body needs to shift back toward its rest-and-repair state, where heart rate drops, blood flow redirects toward digestion and cellular repair, and the nervous system calms down. Light cardiovascular activity, paired with controlled breathing, helps accelerate that transition. A gentle jog or easy bike ride essentially tells the body the threat is over and it’s safe to start recovering.
Increased blood flow also delivers oxygen and nutrients to damaged tissue in the arm and legs. Pitching places enormous stress on connective tissue in the shoulder and elbow, and while running won’t heal a torn ligament, improved circulation supports the early stages of the inflammatory repair process that begins immediately after the game.
Distance Running vs. Sprints
The bigger debate isn’t whether pitchers should move after pitching, but what kind of running they should do between starts. Here, the evidence has turned sharply against the long, slow jog.
Pitching is an anaerobic activity. Each pitch is a maximum-effort explosion lasting about one second. The energy system that powers it is the same one used for sprinting, jumping, and throwing, not the system that fuels a five-mile jog. Training the aerobic system with distance running improves endurance, but endurance doesn’t appear to be a limiting factor in pitching performance. Studies have found that a high VO2 max (the gold standard measure of aerobic fitness) doesn’t correlate with being a better pitcher.
Worse, distance running may actually undermine what pitchers need most. One study comparing sprint training to aerobic dance training in baseball pitchers found that the sprint group saw significant improvements in both pitching velocity and anaerobic power. Another in-season study by Rhea and colleagues in 2008 compared sprint training to long, slow distance running and found that the sprint group increased lower body power while the distance group lost it. That’s a meaningful difference over the course of a 162-game season.
The mechanical argument is just as compelling. Jogging is a repetitive, low-amplitude motion that primarily works the front of the thigh without engaging the deep hip flexors or hip extensors that pitchers depend on for stride length and velocity. Over time, the monotony of distance running can actually reduce hip mobility. Pitchers need hips that are explosive and mobile, not stiff and endurance-adapted. As one prominent strength coach frames it: when was the last time you saw a marathoner throw 95 mph?
What Modern Pitchers Actually Do
Most progressive training programs have moved away from long jogs and toward a combination of light active recovery immediately after pitching and sprint-based conditioning between starts. A typical post-game routine might include 10 to 15 minutes of light jogging or stationary bike work, just enough to bring the heart rate up gently and promote circulation without adding fatigue. Some pitchers skip running entirely and use a bike or elliptical to get the same blood flow benefits without the repetitive impact on their legs.
On the days between starts, the emphasis shifts to short sprints, shuttle runs, and lower-body strength work. These activities train the explosive energy system that pitching actually uses, maintain leg power throughout the season, and build the hip mobility and extension that contribute to velocity. Sprint intervals of 10 to 30 seconds with full recovery between reps mirror the work-to-rest ratio of pitching far better than a 20-minute jog does.
That said, not every organization has fully abandoned distance running. Some pitchers genuinely feel better after a longer run, and there was at least one thesis study that found the distance running group didn’t lose velocity or pitching performance during the season, though they did trend toward reporting more soreness than the interval training group. The tradition runs deep, and individual preference still plays a role. But the overall direction is clear: the old model of logging miles in the outfield is giving way to shorter, more intense conditioning that better matches what a pitcher’s body actually needs.