Hypertrophy

Hypertrophy is the increase in the cross-sectional size of muscle fibres in response to training. It is distinct from gaining strength (a largely neural adaptation) or gaining weight generally — it specifically means bigger muscle tissue.

It matters because muscle size underpins a lean, strong physique and supports metabolic health and healthy ageing. Training for it is driven mainly by mechanical tension, sufficient training volume applied through progressive overload, and adequate protein and energy to build new tissue.

In practice, hypertrophy training usually means moderate-to-higher rep sets (often ~6–15) taken close to failure, enough weekly sets per muscle, and gradual load or rep increases over time.