In most areas of life, the word “extension” has positive connotations of freedom, looseness, success, expansion, improvement etc. When we “extend” something, we usually think that we are “opening it up” in an advantageous positive sense, for example “extending frontiers”, “extending our gains”, “extending our range of influence” etc. When we extend a muscle, we stretch it, and we normally think of this stretching as having a loosening, relaxing, invigorating action. Unfortunately, none of these positive descriptions can be used to describe the consequences of extensions on the cello! In fact, the word “extension” actually contains a perfect description of the problems that they cause us: EX(tra)TENSION !!
One of the most fundamental principles of good cello playing is “be as relaxed and loose as possible”. As a general rule, anything that produces excessive muscular tension, strain and rigidity, is bad for our playing. Tense and strained left-hand postures cause bad intonation, an ugly sound, stiff vibrato and a lack of fluidity (and accuracy) in articulation and shifting. They can make a good cellist sound suddenly very very …….. bad. Probably the most common source of excess tension for our left hand – especially for small-handed cellists – is our “extensions”.
The need for extended (strained) hand positions is much more frequent for cellists than for violinists and violists. Whereas the hand of violinists and violists comfortably covers a range of a perfect fourth between first and fourth fingers, we cellists (without the use of the thumb) have a comfortable range in the Neck and Intermediate Regions of only a minor third. Even a major third requires a contortion of the hand (extension) which, for cellists with small hands especially, complicates our playing enormously. Even doublebass players don’t use as many extended hand positions as cellists, because their instrument is tuned in fourths so they can just go across to the neighbouring string to find the new note rather than extending.
The hand is most stable, and the fingers are strongest, when the fingers are bunched up close together. When, on the contrary, we extend the fingers away from this stable centre, this requires new strength and flexibility in the hand that no other movements from ordinary life have prepared it for. The smaller cellist especially, will need to build this vital flexibility and strength both progressively and regularly, by diligent practice of specific material for extensions, in order to be able to play well but also to avoid injuries, most of which are caused by sudden unprepared forcing or prolonged cumulative strain. The smaller the hand in proportion to the cello size, the more training it will need to be able to do the normal cello extensions easily.
The most fundamental (and common) extension is the one-tone interval between the first and second finger. Next is the tone between the second and third fingers, which is only really used in the Intermediate Region and in Thumb Position. “Double extensions” concern the perfect fourth interval between the first and highest finger. “Other extensions” refers to the tone interval between third and fourth fingers and the consequent minor third between second and fourth finger.
The subject of extensions on the cello is so large and so important that it has been broken up into several different sub-topics (click on the highlighted links).