A Strong Bow Arm (with illustrative photos below)
A great deal of bowing force is sometimes required when playing the double bass. What's the key to a powerful bow arm? I think it's to keep the arm straight enough to deliver weight efficiently.
How bent should the bass bow arm be? Generally, I believe the German bow arm should be straighter than the French. It should be about as bent as when it hangs loose by your side. For a lot of players, that's straighter than what they are used to (or have been taught). A nominally straight arm provides the mechanical advantage necessary to deliver its own weight down into the string, accounting for most of the force applied. If more pressure is required, weight from the upper body should be added, but without changing the angle at the elbow or further pronating or torquing the arm (which causes tension in the shoulder). When the arm is too bent power never reaches the bow hand. The general long bow stroke should be led by the hand with the whole arm following, preserving the "pillar" of power of the arm. If one leads with the elbow or torso, there's likely a lack of extension in the arm and a corresponding undue tension in the shoulder when at the tip. The elbow should always point down to about the 5 o'clock position.
For French bow, from my limited experience with it (which amounts to about five years of practicing, but I'm pretty good with it), the arm will generally require a few degrees more bend at the elbow. This is because the arm is pronated - the more pronation, the more bend is required at the elbow if one is to avoid stressing the shoulder. There's still the same intent to relax the weight of the arm into the string (this is always best), but force beyond that might entail further pronating the arm slightly(again, not necessary with the German bow). When playing fast spiccato or sautillé, manipulating the bow properly is the issue rather than applying lots of power - less pronation is necessary. The elbow should point to around the 3 o'clock position, give or take a half hour, depending on the stroke or force applied.
For both bow arms, the greatest extension occurs at the tip on the G string. I have provided photos of this for those who are interested in how I look at that point. Extending is more natural with German because the arm is less pronated.
(I might have just provided "fuel for the fire" regarding the argument over which is better - French or German. I don't mean to, because I can't say convincingly one way or the other, as I am not a life-long French bow player. And I must also confess that I have been on many bass audition committees and have never been able to tell who's playing what from behind a screen...)
To give further example of why an overly bent arm is not strong, here are some sport-related activities where a straighter arm gets the job done…
1. A boxer: He doesn't throw a punch from 12 inches away - it's too close to have much power. Muhammad Ali would stand back and keep his opponent at bay with a persistent, powerful jab.
2. Football: The famous "straight arm" or "stiff arm" where the running back gets an extra ten yards because he pushes his opponents off balance. Really fun to watch!
3. Doing a pushup: Notice how easy it is to hold the start position (arms nearly straight), but if you stop halfway down (arms bent) you'll give out pretty quickly.
I can find a correlation in architecture, too: A classical column is constructed with stones stacked on top of each other. Your arm can be thought of as a pillar between your body and the bow, with your bones being the building blocks.
I should also be clear that I don't mean one should force the arm to be completely straight (like a true column) or hyper-extended. That's not natural. Again, a good rule is to maintain an elbow bend similar to when the arm hangs relaxed by your side. Your arm is o.k. with it, because it's that way practically every moment of your life.
It should be understood that when making adjustments to the bow arm angle (elbow), the bow grip might need to adapt to it. For instance, for French bow players a straighter arm might require a flatter bow grip, as the forearm will rotate back clockwise a few degrees. German bow players will be inclined to reduce bend in the wrist and adopt a grip which allows the bow to be held more straight in the hand (more like no. 11 from my Get a Grip Page).
Finally, the idea of a straighter arm might cause some players to rethink whether or not a small bass with narrow shoulders and short string length is suitable for them. One might discover that sitting up more and with a slightly longer reach is the most comfortable and powerful.
