1 3 Exp Brain Res DOI 10.1007/s00221-015-4281-1 RESEARCH ARTICLE More gain less pain: balance control learning shifts the activation patterns of leg and neck muscles and increases muscular parsimony Pierpaolo Iodice 1 · Stefano Cesinaro 2 · Gian Luca Romani 2 · Giovanni Pezzulo 1 Received: 20 October 2014 / Accepted: 6 April 2015 © Springer-Verlag Berlin Heidelberg 2015 deploy postural adjustments just-in-time and to transfer at least part of the control of posture from anticipatory to less- demanding feedback-based strategies. In turn, this strat- egy shift increases the cost-efficiency of muscular activity, which is a key signature of skilled performance. Keywords Anticipatory control · Feedback control · Skill learning · Expertise · Balance Introduction Maintaining stable upright posture in spite of various dis- turbances, such as those faced by skaters or surfers, is a hard task that requires the precise coordination of multiple muscles and the integration of various information streams from afferent visual, somatosensory, and vestibular systems within a unified “postural schema” (Bronstein 1986; Holmes and Spence 2004; Iodice et al. 2015; Massion 1992; Pezzulo et al. 2013). Developing such an expert skill requires the progressive adjustment of the patterns of motor commands regulating movement generation and an improved temporal and spatial synchronization of muscular contractions. This, in turn, requires coordinated learning processes across the central nervous system and the musculoskeletal system. The central nervous system (CNS) uses two main strate- gies to maintain and restore balance: feedforward control, which consists in executing anticipatory postural adjust- ments (APA) prior an expected body disturbance (Mas- sion 1992) and feedback control, which consists in execut- ing compensatory postural adjustments (CPA) initiated by sensory feedback signals after the disturbance (Alexandrov et al. 2005). Several studies have assessed the importance of these two control systems for skilled performance, but it is still incompletely known how they interact and how their Abstract Athletes such as skaters or surfers maintain their balance on very unstable platforms. Remarkably, the most skilled athletes seem to execute these feats almost effortlessly. However, the dynamics that lead to the acquisi- tion of a defined and efficient postural strategy are incom- pletely known. To understand the posture reorganization process due to learning and expertise, we trained twelve participants in a demanding balance/posture maintenance task for 4 months and measured their muscular activity before and after a (predictable) disturbance cued by an auditory signal. The balance training determined signifi- cant delays in the latency of participants’ muscular activity: from largely anticipatory muscular activity (prior to train- ing) to a mixed anticipatory–compensatory control strategy (after training). After training, the onset of activation was delayed for all muscles, and the sequence of activation sys- tematically reflected the muscle position in the body from top to bottom: neck/upper body muscles were recruited first and in an anticipatory fashion, whereas leg muscles were recruited after the disturbance onset, producing compensa- tory adjustments. The resulting control strategy includes a mixture of anticipatory and compensatory postural adjust- ments, with a systematic sequence of muscular activation reflecting the different demands of neck and leg muscles. Our results suggest that subjects learned the precise tim- ing of the disturbance onset and used this information to * Giovanni Pezzulo giovanni.pezzulo@istc.cnr.it 1 Institute of Cognitive Sciences and Technologies, National Research Council, Via S. Martino della Battaglia, 44 - 00185 Rome, Italy 2 Department of Neuroscience, Imaging and Clinical Sciences, Institute for Advanced Biomedical Technologies, G. D’Annunzio University, Chieti, Italy