The effect of motor solution exploration on the transferability of an acquired motor skill.

Movement variability can either facilitate or impede motor learning, dependent on the context of the learning environment. Most previous studies have evaluated reward- or reinforcement-based learning paradigms with a clear task goal and/or extrinsic feedback. We assessed the effect of movement variability when learning the kettlebell swing in a learner-regulated context, where participants relied solely on intrinsic feedback. We aimed to determine if high variability when first practicing the kettlebell swing enabled exploration of motor solutions that could be utilized to perform the movement under unique task demands. Twelve young adults (9F/3M, 20.53 (1.25) years) practiced the kettlebell swing over a one-week period. An uncontrolled manifold analysis was used to partition solution variability from error variability. Participants were separated into high and low solution variability groups based on their initial performance. At the end of the week, participants were challenged to perform the kettlebell swing with a water-filled kettlebell. A single trial motor equivalent analysis estimated the error variability for each repetition. Results indicated that participants with high relative solution variability during their early practice were able to perform the water-filled kettlebell swing with less errors. Higher solution variability was beneficial to acquiring a transferable kettlebell swing, but only when error variability was low. These findings suggest that high error variability might reduce an individual's ability to perceptually distinguish solutions from errors. Extrinsic feedback should help separate solutions from errors in order to construct a transferable motor skill.