Author(s): DHOTE, S., GROSPRÊTRE, S., ROSELLI, G., GIMENEZ, P., Institution: UNIVERSITÉ MARIE ET LOUIS PASTEUR, Country: FRANCE, Abstract-ID: 1272

INTRODUCTION:
Random practice, often associated with contextual interference, is known to transiently impair performance during acquisition while enhancing long-term learning [1]. However, its acute effects on neuromuscular fatigue, motor control, and subjective experience remain poorly documented, particularly when compared with intermediate practice structures such as serial organization. This study investigated the immediate effects of constant, serial, and random practice of an isometric force reproduction task on force accuracy, neuromuscular fatigue, and perceptual responses.
METHODS:
Fifteen physically active men (Age: 24.1 ± 4.3 years) completed three experimental sessions in a randomized crossover design. Each session involved pre-tests, a 15-min practice phase, immediate post-tests, and post-tests after 30 min. Participants performed isometric knee extensions to match different force targets under constant (CON: steady force level), serial (SER: steadily increasing force level), or random (RAN: randomized force levels) practice. Force error during the precision task, maximal voluntary isometric contraction (MViC), surface EMG activity of knee extensors and flexors, Force/EMG ratio, and coactivation were assessed pre, post and post 30min. Subjective responses were evaluated using visual analog scales and the NASA-TLX questionnaire.
RESULTS:
During practice, force error was higher in RAN than in CON and SER but decreased over time only in RAN. Force accuracy improved from pre- to post-tests in all conditions, with no between-condition differences in retention tests. MViC decreased similarly across conditions (-5,2 ± 8,7%, p=0.002), indicating comparable neuromuscular fatigue. No significant changes were observed in Force/EMG ratio or muscle coactivation. Task enjoyment was significantly higher in RAN compared with CON and SER, while perceived workload did not differ.
CONCLUSION:
Contrary to some previous studies [2,3], random practice did not improve motor accuracy compared to serial or constant practice after a single session. However, it led to greater enjoyment without inducing additional neuromuscular fatigue. These findings suggest that random practice may enhance motivation or engagement during training, even when immediate motor control benefits are not evident. Future studies should further explore its long-term effects and optimize task difficulty for maximal learning outcomes.
REFERENCES:
[1] Shea, C. H., & Kohl, R. M. (1990). Specificity and Variability of Practice. Research Quarterly for Exercise and Sport, 61(2), 169–177.
[2] Thürer, B., Stockinger, C., Putze, F., Schultz, T., & Stein, T. (2017). Mechanisms within the Parietal Cortex Correlate with the Benefits of Random Practice in Motor Adaptation. Frontiers in Human Neuroscience, 11, 403.
[3] Herzog, M., Focke, A., Maurus, P., Thürer, B., & Stein, T. (2022). Random Practice Enhances Retention and Spatial Transfer in Force Field Adaptation. Frontiers in Human Neuroscience, 16, 816197.