During the first 4-6 weeks of resistance training the body will experience very fast strength gains. These gains will not be apparent in size, for the gains are almost entirely due to neurological adaptations of the body. In plain terms, the body becomes more efficient at lifting weights. It learns how to use less muscle to lift a given amount of weight. An example would be the bicep curl... Let us imagine the bicep as being one whole muscle. If we just begin training we may find that it takes all of our strength to curl a 25lb dumbbell; and as we curl this 25lb for one repetition our entire muscle is working. As we continue to train the bicep becomes stronger and the body begins to make changes which will eventually lead us to using only half of the muscle to lift the same 25lbs...leaving "extra" muscle to lift more weight! These neuromuscular adaptations can come in the form of enhanced neurotransmitter release, increased myofibrillar packing density, increased motor end plate size, quicker nerve conduction rates, and greater force production rates. These neuromuscular gains continue through your training regimen; however, as the training progresses past 6-8 weeks, hypertrophy begins to play a similar role in strength gains.