What Is Muscle Soreness? Insights from Dr. Andy Galpin & Dr. Andrew Huberman
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What Is Muscle Soreness? Insights from Dr. Andy Galpin & Dr. Andrew Huberman

Ari Horesh

Understanding Muscle Soreness Beyond the Surface

ANDREW HUBERMAN: When discussing recovery, a common question arises about muscle soreness. Is it really just about the muscles, or are other tissues and cell types involved? This becomes especially intriguing with delayed onset muscle soreness (DOMS). Why does soreness peak 48 hours after a novel or intense exercise, and why does it decrease as we adapt to the activity?

ANDY GALPIN: Addressing these questions reveals that muscle soreness is not simply about muscle tears. Instead, it involves complex interactions between perception, physical response, and various physiological processes.

The Myth of Micro-Tears and Real Causes of Soreness

The traditional belief links DOMS to micro-tears in muscles. However, research shows that one can experience soreness without significant muscle damage. This indicates that muscle soreness is not a direct result of muscle tears but involves other factors, primarily an immune and inflammatory response.

The Role of Inflammatory and Immune Responses

The delayed onset of soreness can be traced back to the time-delayed nature of the body's immune response. After exercising, there's a sequence of reactions involving neutrophils and macrophages, leading to inflammation and fluid accumulation. This process peaks around 24 to 48 hours post-exercise, coinciding with the peak in muscle soreness.

Understanding Nociceptors and Pressure Sensors

Muscle soreness is not directly related to the muscle fibers but is likely influenced by nociceptors (pain receptors) and pressure sensors in the muscle. Swelling increases pressure on these sensors, triggering pain signals.

Neural Feedback Loops and Muscle Spindles

A significant part of DOMS might be a neural feedback loop rather than actual muscle damage. Muscle spindles, which are responsive to stretch and integral to proprioception, play a crucial role here. They detect stretch and initiate a contraction response to counterbalance it. The pressure from swelling could be stimulating these spindles, contributing to the sensation of soreness.

The Interplay of Pain, Touch, and Itch Sensations

Dr. Huberman adds that the interactions between neurons controlling touch, pain, and itch sensations are crucial in understanding soreness. For example, rubbing a sore area can activate touch sensors that inhibit pain signals, a phenomenon known as the gate theory of pain.

Practical Implications for Recovery and Exercise

This understanding suggests that light, low-level movement can be more effective for reducing soreness compared to stretching. Such movement helps in pumping out fluid accumulation and reducing pressure on pain receptors.

Exploring the Mitochondrial Connection

Dr. Galpin also touches upon the role of mitochondria and free radicals in this process. During exercise, the electron transport chain in mitochondria can release free radicals, leading to an inflammatory response. This might be the initial trigger for the immune response leading to soreness.


Muscle soreness, particularly DOMS, is a complex interplay of physiological processes. It involves more than just muscle damage, encompassing immune responses, inflammation, neural feedback loops, and the role of mitochondria. Understanding this can help in better managing recovery and exercise routines.

Key Takeaways:

  1. Muscle Soreness is Multifaceted: It's not just about muscle tears but involves a complex immune and inflammatory response.
  2. Neural Feedback Loops: Pressure on muscle spindles and nociceptors due to swelling contributes significantly to soreness.
  3. Practical Recovery Strategies: Light movement rather than stretching can be more effective in alleviating soreness.
  4. Mitochondrial Role: Free radicals from mitochondria may trigger the inflammatory response leading to soreness.
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