Do you think it’s your gym that helps you grow stronger? You may need to rethink that assumption.
Recent research is reshaping how scientists understand strength, shifting the focus from muscles alone to the central role played by the brain and nervous system. While muscle size and structure remain important, evidence increasingly shows that the ability to grow stronger is deeply influenced by how effectively the brain learns to control, coordinate and activate muscles. Strength, in this view, is as much a neurological adaptation as it is a physical one.
One of the clearest findings from modern exercise science is that early gains in strength are driven largely by changes in the nervous system rather than by increases in muscle mass. People beginning resistance training often become significantly stronger within weeks, well before any visible muscle growth occurs. Researchers now attribute this to improvements in neural efficiency: the brain becomes better at recruiting muscle fibres, firing motor neurons more rapidly, and coordinating different muscles to work together more effectively. These adaptations allow the body to generate greater force without changing the size of the muscle itself.
The brain power
New experimental work has also shown that the brain does not merely respond to exercise but actively governs how the body adapts to it. Certain brain circuits involved in motivation, effort and movement regulation become more active with training and appear to be essential for improvements in strength and endurance. When these neural pathways are disrupted in experimental settings, physical training produces far weaker results, even when the muscles themselves are capable of growth. This suggests that the brain plays a gatekeeping role, determining how much adaptation the body is allowed to express.
The researchers who have been leading this shift in understanding come from a range of fields including neuroscience, exercise physiology and motor control. Many of them work at major research institutions, using both human studies and experimental animal models to investigate how neural circuits adapt with training. Their work emphasizes that changes in the brain’s ability to activate and coordinate movement are a fundamental part of how strength develops, and they have published a series of influential studies showing that neural adaptations often precede and enable muscular gains.
In studies revealing the brain’s central role in strength and endurance training, one of the leading research teams was based at the University of Pennsylvania, where neuroscientists including J. Nicholas Betley and colleagues showed in animal experiments that changes in specific brain circuits, particularly in the ventromedial hypothalamus, help drive endurance improvements by altering how the nervous system supports muscle and cardiovascular function.
Other prominent research in the field has come from exercise physiology and neuroscience groups such as those at The University of Queensland in Australia, where scientists like Timothy J. Carroll and collaborators have long investigated how the nervous system adapts to resistance training and contributes to strength gains. There are also broader neuroscience institutions, including the National Brain Research Centre in India and the Werner Reichardt Centre for Integrative Neuroscience at the University of Tübingen in Germany, where researchers study general neural mechanisms of motor learning, coordination and adaptation that underpin strength development.
What the studies show
Beyond motor control, resistance training has been shown to physically alter the brain. Regular strength exercise increases neuroplasticity, the brain’s ability to form and reorganise connections. Regions involved in movement planning, coordination and executive control show measurable changes with sustained training. Levels of brain-derived growth factors also rise, supporting both neural health and cognitive function. In effect, strength training trains the brain alongside the body, creating a feedback loop in which improved neural function further enhances physical performance.
The brain’s influence is especially important in determining maximal strength. The maximum force a person can produce is limited not only by muscle size but by how strongly and synchronously the brain can drive those muscles. Even well-developed muscles cannot express their full potential if neural signals are weak or poorly coordinated. This explains why skilled lifters and elite athletes often outperform others with similar muscle mass: superior neural control allows them to access more of their available strength.
As training progresses over the long term, muscle growth becomes a more dominant contributor to further strength gains, but neural factors never disappear. Fine-tuned coordination, timing and motor learning continue to distinguish higher levels of performance. Research has also shown that mental rehearsal and motor imagery can strengthen neural pathways linked to movement, leading to modest but measurable strength improvements even without physical contraction. This further underlines the role of the brain as an active driver of strength, not just a command centre issuing simple instructions.
Taken together, current research points to a more integrated understanding of strength. Muscles provide the raw capacity to generate force, but the brain determines how effectively that capacity is used. Early strength gains are largely neurological, later gains are increasingly muscular, and peak performance depends on the seamless interaction of both. This growing body of evidence challenges purely muscle-focused training philosophies and highlights the importance of skill, neural engagement and intelligent practice in becoming stronger.