So you’re taking tennis lessons and you’re doing well, but your coach keeps criticizing the follow-through motion on your serve. Why does it matter, you think, since it doesn’t affect how hard I hit the ball? Well, researchers from the University of Cambridge and the University of Plymouth have discovered exactly why these supposedly unnecessary movements matter. A new study finds that follow-through activates specific motor memories and so helps you learn — and learn faster.

Follow-through movement, then, “does have an effect — one can almost consider it occurring backwards in time — on the task itself, through its effect on the motor memory formation,” Dr. David Franklin, Wellcome Trust RCD Fellow at University of Cambridge, told Medical Daily in an email. In fact, there may be, as Franklin and his co-authors wrote in their published paper, “a critical time period both before and after the current movement that determines motor memory activation and controls learning.”

Similar but Different

The strokes for tennis and racquetball, very similar sports, are slightly different, as topspin is great when hitting a tennis ball, but not so much for racquetball. While it should be possible to learn and perform both sports well, many people find it difficult because they tend to confuse the unique strokes necessary for each. This also is true when a violinist tries to play the viola, a similar though larger instrument. While the adjustment in bowing and technique is very slight, it is still difficult for a violinist to learn this other, separate instrument.

Such learning snags are at the heart of the current study. The researchers wondered, Are we learning a separate motor memory for the two similar musical instruments, or are we learning a single motor memory for both?

To find answers, the researchers designed an experiment where participants learned a “reaching task” using a robotic arm. Aiming for a target, participants made controlled movements complete with follow-through motions. Next, the researchers adapted the force-field to create a second similar task for the participants. The research team not only observed how the participants learned two very similar tasks, then, but they also were able to examine which factors influenced the participants’ memory.

The researchers discovered it was important to practice a unique and consistent follow-through motion for each skill when learning two separate but similar tasks. The reason? Inconsistent follow-through motions would activate both motor memories instead of just the one motor memory — as a result of follow-through, then, confusion could arise, blurring two separate but distinct skills.

While the research may not be applicable to everyday life, it is highly relevant to stroke patients.

“Re-learning movements after a stroke takes an incredibly long time — months if not years,” Franklin told Medical Daily in an email. “Partially this is because many parts of the brain that are involved in learning (or the pathways involved in learning) have been injured. However, in our current study we showed that even a difficult task — taking 15 hours of experimental time for an single extremely-simple reaching movement — can use the lead-in and follow-through movements to allow a skill to be learned.”

To “maximize the speed of learning,” Franklin believes, a stroke victim would need to maintain a consistent follow-through (and lead-in) when practicing their movements. More importantly, when a patient is learning multiple tasks, it might be necessary to provide separate follow-throughs for each. In this way, the injured brain of a stroke patient will be more able to learn separate tasks… and more likely to learn them quickly.

Source: Howard IS, Wolpert DW, Franklin DW. The value of follow-through derives from motor learning depending on future actions. Current Biology. 2015.