More gain less pain: balance control learning shifts the activation patterns of leg and neck muscles and increases muscular parsimony

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 acquisition of a defined and efficient postural strategy are incompletely 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 significant delays in the latency of participants' muscular activity: from largely anticipatory muscular activity (prior to training) 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 systematically 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 compensatory adjustments. The resulting control strategy includes a mixture of anticipatory and compensatory postural adjustments, with a systematic sequence of muscular activation reflecting the different demands of neck and leg muscles. Our results suggest that subjects learned the precise timing of the disturbance onset and used this information to 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 strategy shift increases the cost-efficiency of muscular activity, which is a key signature of skilled performance.

Functional Electrical Stimulation: A Possible Strategy to Improve Muscle Function in Central Core Disease?

“…Worth to notice also that already at T1 (5 months) FES induced improvement in the ST test. These results suggest that the subject's balance may depend on muscle mass and strength (Figures 3, 4), as previously suggested (48, 49). The comparison of results in eyes-open and eyes-closed conditions (a) indicates that muscle force (likely needed to maintain balance) has a relatively greater role in eyes-closed condition, (i.e., the condition without visual perceptual information) and (b) suggests that the strength of lower limbs is crucial for the transfer of balance control skills to all environmental situations (50).…”

The perceptual shaping of anticipatory actions

“…We note, however, that in humans and animals, anticipatory and compensatory strategies often act synergistically across different sets of muscle synergies, reflecting different demands (i.e. upper extremities respond with a higher degree of anticipation compared to lower ones) [53]. However, those findings do not discriminate between the sensory prediction and motor-anticipation hypotheses.…”

Learned self-regulation in top-level managers through neurobiofeedback training improves decision making under stress

“…Latency was defined as the instant lasting for at least 50 ms when its parameters amplitude was greater (temperature) or smaller (skin conductance) than the mean of its baseline value plus 2 standard deviations 74 .…”