Step into any bustling commercial gym during rush hour, and the noise is unmistakable: a sharp, guttural grunt cutting through the steady drone of treadmills and the rhythmic clash of weight plates. It might punctuate a massive deadlift or an intense chest press, or even emerge during a routine pec deck session that hardly seems demanding enough for such a visceral outburst.
So, under what circumstances is grunting acceptable, and is it reasonable to feel irritated by others doing it around you? James Nestor, the New York Times bestselling author of Breath and a prominent figure in contemporary breathing science, argues that the issue transcends mere gym courtesy. It boils down to factors like pressure dynamics, bodily physiology, and precise control mechanisms.
“Grunting proves beneficial solely as an unintentional side effect of effective breathing techniques,” Nestor shared in an interview with Muscle & Fitness.
This key differentiation between incidental occurrence and deliberate action sharply separates optimal performance breathing from what Nestor terms performative breathing.
The Critical Function of Intra-Abdominal Pressure in Intense Lifting
Nestor places intra-abdominal pressure at the heart of this discussion. When engaging in heavy lifting, the body requires a rigidly stable and pressurized core region to safeguard the spine and facilitate the smooth, efficient transmission of force throughout the musculature.
The diaphragm, that dome-shaped muscle positioned just below the lungs, takes center stage in this process. As it contracts and lowers, the abdominal cavity expands, generating substantial pressure that encases the torso much like a sturdy, air-filled pillar. In simpler terms, this is commonly referred to as belly breathing or diaphragmatic breathing.
“As this built-up pressure is gradually expelled via the airway, it can produce an audible sound—something akin to a grunt,” Nestor elaborates. “The grunt itself isn’t the objective; it’s simply the consequence of that pressure being methodically released.”
Nestor points out that extensive sports science investigations into breath management during high-force activities have demonstrated that momentary airway occlusion or resistance—techniques reminiscent of the Valsalva maneuver or regulated forceful exhalations—can boost maximum force production by 2-10%, varying by the specific exercise. These gains appear in metrics like enhanced grip strength, sustained isometric contractions, and greater explosive power generation.
“The benefit doesn’t stem from the grunt’s volume or intensity,” he clarifies. “Rather, it’s the temporary closure of the airway at the glottis that elevates intra-torso pressure, enabling muscles to contract with greater force and superior efficiency.” However, he cautions that when the grunt turns exaggerated or showy, it often indicates a failure in the system.
“Once a grunt is produced on purpose, it typically signals that the diaphragm has disengaged,” Nestor observes. “At that point, breathing relocates to the upper body—engaging the neck, jaw, and facial muscles, which are ill-suited for stabilizing substantial loads.”
Can Intentional Grunting Boost Your Strength and Power Output?
A widespread misconception in fitness circles holds that louder exhalations or grunts equate to superior power exertion. Nestor dismisses this as physiologically unfounded.
“No scientific evidence supports the idea that amplifying grunt volume enhances endurance capabilities,” he asserts. Research on breathing patterns in resistance training emphasizes that proper synchronization and rhythm far outweigh mere noise levels in determining effectiveness.
That said, Nestor acknowledges the potential value of a “functional grunt”—a brief, deliberate, and controlled vocalization. Mechanically speaking, this arises from introducing resistance in the airway. By constricting the vocal cords on exhalation, resistance builds, which aids in preserving lung volume and core stability, akin to the pursed-lip breathing techniques employed in respiratory therapy programs. It’s like allowing air to seep gradually from a tire instead of blasting it out abruptly.
“The body prioritizes pressure regulation over auditory output,” Nestor emphasizes. “Sound is just a secondary result. When that sound originates from tension in the throat rather than disciplined diaphragmatic action, the pressure escapes too quickly, compromising overall stability.”
Understanding Breathlessness and Gasping Sensations in Workouts
Yet another common gym fallacy suggests that feeling out of breath or gasping indicates an oxygen shortage. Nestor corrects this notion.
“You rarely, if ever, deplete your oxygen reserves during exercise,” he explains. “The real culprit undermining performance is the accumulation of carbon dioxide.”
Elevated CO₂ concentrations activate chemoreceptors, prompting the brain to issue an urgent directive to breathe. This redirects the nervous system’s focus from athletic output to basic survival instincts. In essence, your brain overrides the lift to prioritize respiration. Elite athletes counteract this by training to endure higher CO₂ thresholds.
“The greater your tolerance for carbon dioxide buildup, the more efficiently oxygen reaches your working muscles, allowing sustained high-level performance over extended durations,” Nestor states. Many gym sounds—forced exhales, groans, and grunts—emerge when CO₂ tolerance peaks, triggering the brain’s safety mechanism.
Thus, grunting ought to facilitate the lift subtly, not draw attention to it. “Grunting on warm-up sets, every single repetition, or whenever an audience is nearby points to underlying physical or mental challenges,” Nestor warns. “Moreover, grunting to mask pain could indicate suboptimal load selection and flawed breathing patterns.”
Mastering Optimal Breathing Techniques for Heavy Lifting Sessions
Breathing strategies must adapt to your workout type, the weight being lifted, and the overall physiological stress involved. Nestor outlines tailored approaches as follows:
- Maximal lifts: Emphasize pressure generation and precise timing. Extreme loads demand peak internal pressure exactly when needed to secure spinal integrity. Achieve this via brief breath holds or synchronized, measured exhalations that mimic a controlled leak.
- Repetition-focused work, such as AMRAP sets: Aim to maximize reps within a fixed timeframe. Maintain steady, rhythmic breathing that sustains pressure without inducing chaos. Over-breathing or prolonged holds typically reduce achievable reps and total training volume.
- Endurance and conditioning drills: Focus on streamlined ventilation and CO₂ tolerance. Nasal breathing excels here, as it moderates pace, boosts efficiency, and triggers nitric oxide production for prolonged, intense efforts without early fatigue.
Nestor highlights research showing recreational exercisers using nasal breathing can sustain up to 85% of their VO2max during demanding sessions. “They match the peak performance and oxygen use of mouth breathers but with over 20% less air volume exchanged,” he notes. This efficiency translates to greater strength endurance. Still, context matters—in high-intensity Zone 4 or 5 efforts, brief shifts to mouth breathing can yield advantages.
Guidelines for Appropriate Grunting During Gym Workouts
Next time a distant grunt catches your ear mid-session, pause before judging. It might signify a masterful pressure release amid a grueling lift. Alternatively, it could betray lapses in breathing form, load handling, or neural control. Strive to embody the former. The distinction is pivotal for results.
“Your body disregards facial contortions or vocal pitch,” Nestor concludes. “Its sole concern is producing pressure effectively, stabilizing the nervous system, and bolstering every physiological process at play.”
