What is SPF or SPFF?
SPF = set, pause, finish
SPFF = set, pause, finish, freeze
from Mike Page:
Many pool instructors refer to the simple pendulum stroke as an “SPF” stroke, where the letters refer to SET, PAUSE, and FINISH positions. The drills you do in the Foundations courses are designed to help burn the SPF sequence into your muscle memory. These drills pay particular attention to the SET and FINISH positions.
THE SET POSITION
As in many sports, the set position is key. It is from here that the fuse is lit for the final stroke. The player’s body is held completely still in the set position for at least three seconds. During the Foundations courses, students should hold every set position for at least five seconds. Here are some characteristics of the set position:
• Forearm is vertical.
• Tip is close to the cueball.
• Eyes switch focus from cueball to target location, with at least two seconds on target location.
From the set position, the player draws the cue back slowly to the PAUSE position. It is not necessary to actually pause at the PAUSE position. Some top players do; others don’t. What is necessary is the cue be drawn back slowly (not jerked back) and the transition from backward to forward motion be slow and smooth. The cue is accelerated forward from the PAUSE position. When the forearm becomes vertical again, the tip will be at the ball. At the tip-ball impact on the forward stroke, the player is passing again through the SET position.
THE FINISH POSITION
Instructors in many sports, including pool, stress the importance of follow through. We disagree. Follow through focuses on what happens to the front of the cue, i.e., the tip. When a player decides in advance where he or she would like the tip of the cue to finish, there is no guarantee a pendulum stroke can comply. So a player attempting to get the tip to a particular location likely will call upon the shoulder joint. Pivoting about the shoulder joint drops the elbow and raises the tip.
We prefer instead to focus on FINISHING THE STROKE. The stroke is finished when the grip hand reaches its natural finish position—the natural end of the pendulum stroke. Depending upon the player’s body type and stance, this could be where the forearm hits the biceps, or it could be where the grip hand hits the side of the chest. So instead of focusing on follow through, we focus on finishing the stroke, on the grip hand going home.
A consequence of finishing the stroke is the tip of the cue will reach a particular finish location—for many people this is four or five inches beyond the cueball with the tip touching the cloth. So have no fear, others will think you are dutifully following through.
Unless doing so would disrupt the balls in play, freeze for at least two seconds in the finish position. Note that you’ve gone home.
The “set” position occurs at the CB, after your warmup cycle is finished. It’s the last conscious thought about, “Well? Are you ready or not?” With the tip at the CB, the “set” position is used to verify earlier decisions on angle, speed and spin. If it is a go, there are no more warmups, and the final backswing begins. The “pause” happens as we come to the end of the natural backward motion of the cue, so we can make a smooth transition to the forward swing. All strokes start from zero, and accelerate to whatever speed you’re hitting the shot with. The “finish” … The grip hand ends up in the armpit area, close to the chest; and the tip is on or close to the cloth, some distance past where the CB was sitting. The “freeze” is an opportunity for self-evaluation, that happens after the stroke is over, and you have remained motionless, except for your forearm. The freeze allows you to check components of your stroke, including the grip finish, tip finish, and speed control.
When do muscle transitions occur during the stroke?
if the real reason for a “pause” is to allow the “backswing” muscles to stop working before the “forward swing” muscles take over, then there is absolutely no need for a pause in MOTION, only a pause in acceleration.
When the “backswing” muscles relax, the stick is still moving backwards. There can be a finite period of relaxation before the “forward swing” muscles contract and apply force. AT THIS POINT, AND FOR A FINITE TIME AFTERWARD, THE STICK IS STILL MOVING BACKWARDS. It takes some finite time for the “forward swing” muscles to accelerate the stick to zero velocity. There will then be no finite time at zero velocity because the acceleration is continuous, so the stick progresses smoothly (semi-sinusoidally) from backward to forward velocity.
For this example, the “pause” was in acceleration, not velocity. This relaxation of backswing muscles and subsequent resumption of opposite force occurred entirely before the backwards motion ended.