Key points: The spinal cord is an important contributor to motor learning It remains unclear whether short‐term spinal cord adaptations are general or task‐specific Immediately after task acquisition, neural adaptations were not specific to the trained task (i.e. were general) Twenty‐four hours after acquisition, neural adaptations appeared to be task‐specific The neural reorganization and generalization of spinal adaptations appears to be time‐dependent. Spinal cord plasticity is an important contributor of motor learning in humans, although its mechanisms are still poorly documented. In particular, it remains unclear whether short‐term spinal adaptations are general or task‐specific. As a marker of neural changes that are observable at spinal level, we measured the Hoffmann reflex (H‐reflex) amplitude in the soleus muscle of 18 young healthy human adults before, immediately after (acquisition), and 24 h after (retention) the learning of a skilled task (i.e. one‐legged stance on a tilt board). H‐reflexes were elicited 46 ± 30 ms before touching the tilt board. Additionally, and at the same time points, we measured the H‐reflex with the subject sitting at rest and when performing an unskilled and untrained task (i.e. one‐legged stance on the floor). After task acquisition, there was a decrease of the H‐reflex amplitude measured at rest but not during the skilled or the unskilled task. At retention, there was a decrease of the H‐reflex when measured during the skilled task but not during the unskilled task or at rest. Performance increase was not associated with changes in the H‐reflex amplitude. After the acquisition of a new skilled task, spinal changes appeared to be general (i.e. observable at rest). However, 24 h after, these changes were task‐specific (i.e. observable only during performance of the trained task). These results imply that skill training induces a time‐dependent reorganization of the modulation of spinal networks, which possibly reflects a time‐dependent optimization of the feedforward motor command.

Aims: Different modalities of strength training cause performance enhancements, which are specific for the trained task. However, the involved mechanisms are still largely unknown. It has been demonstrated that strength training could induce neuroplasticity, which might underlie the performance improvements during the first training sessions. Thus, we hypothesized to find task‐specific neuroplasticity after a short‐term strength training of two distinct strength tasks.Methods: Young healthy male subjects were exposed to 4 sessions of either maximal isometric explosive (EXPL group, N = 9) or slow sustained (SUS group, N = 10) knee extensions. Pre‐ and post‐training, we measured H‐reflexes and motor evoked potentials (MEPs) in the vastus lateralis (VL) at the onset of both strength tasks.Results: Pre‐ and post‐training, H‐reflexes remained unchanged in both groups. MEP areas were lower in the trained task in both groups and remained unchanged in the untrained task.Conclusion: This study demonstrated that short‐term strength training induces specific neuroplasticity for the trained task only. The fact that MEPs were lower but H‐reflex amplitudes remained unchanged at the onset of the trained tasks suggests that strength training elicited neuroplasticity at supraspinal level that most likely reflect an improved task‐specific corticospinal efficiency.

Slackline training is a challenging and motivating type of balance training, with potential usefulness for fall prevention and balance rehabilitation. However, short-term slackline training seems to elicit mostly task-specific performance improvements, reducing its potential for general fall prevention programs. It was tested whether a longer duration slackline training (three months, 2 sessions per week) would induce a transfer to untrained tasks. Balance performance was tested pre and post slackline training on the slackline used during the training, on a slackline with different slack, and in 5 different non-trained static and dynamic balance tasks (N training = 12, N control = 14). After the training, the training group increased their performance more than the control group in both of the slackline tasks, i.e. walking on the slackline (time × group interaction with p < 0.001 for both tasks). However, no differences between groups were found for the 5 non-trained balance tasks, only a main effect of time for four of them. The long-term slackline training elicited large task-specific performance improvements but no transfer to other non-trained balance tasks. The extensive slackline training that clearly enhanced slackline performance did not improve the capability to keep balance in other tasks and thus cannot be recommended as a general fall prevention program. The significant test-retest effect seen in most of the tested tasks emphasizes the need of a control group to adequately interpret changes in performance following balance training.