Take a look at this picture from Pavel's book Power to the people:
http://www.dump.no/view/files/74ca489b2114/myofibriliar_vs_sarcoplasmic.jpgSarcoplasmic hypertrophy comes mostly from high rep training, this is the kind of growth were bodybuilders get much of the muscular size from.
Myofibriliar hypertrophy is achieved from training with very heavy weights.
Since you are pretty new to strength training, you will not remain tight for very long yet. But in time, I guess you will

A Quote taken from the book:
Strength = tension = tone. It is that simple. Provided you gain strength learning
to generate tension, rather than by building muscle, generally the stronger you are,
the harder you will be! Strength and tone training is the same thing.
Hope it helped.