Chronic resistance training induces increases in muscle fibre cross-sectional 
area (CSA), otherwise known as hypertrophy. This is due to an increased volume 
percentage of myofibrillarproteins within a given fibre. The exact time-course 
for muscle fibre hypertrophy is not well-documented but appears to require at 
least 6-7 weeks of regular resistive training at reasonably high intensity 
before increases in fibre CSA are deemed significant. Proposed training-induced 
changes in neural drive are hypothesized to increase strength due to increased 
synchrony of motor unit firing, reducedant agonist muscle activity, and/or a 
reduction in any bilateral strength deficit. Nonetheless, increases in muscle 
protein synthesis were observed following an isolated bout of resistance 
exercise. In addition, muscle balance was positive, following resistance 
exercise when amino acids were infused/ingested. This showed that protein 
accretion occurred during the postexercise period. The implications of this 
hypothesis for training-induced increases in strength are discussed.