Positive skill transfer in balance and speed control from balance bike to pedal bike in adults: A multiphase intervention study.

BACKGROUND: Learning to cycle can be challenging for adults who did not acquire the necessary skills during childhood. Balance bikes have been used to teach children how to cycle, but it was unclear whether this approach could also be effective for adults. PURPOSE: To address this, a multi-phase intervention study was conducted to investigate whether healthy adults could be taught to cycle independently through the use of a balance bike. METHODS: In Phase 1, a case-control observational study was conducted in which 13 cyclists and 8 non-cyclists completed balance bike tests. Based on the findings, an 8-session intervention pre- and post-test study was conducted in Phase 2, using an 8 × 20-minute balance bike training programme to improve cycling postural stability and control. Another 11 non-cyclists completed the novel programme. The time taken to complete the balance bike tests was compared before and after the program, while their cycling confidence was recorded in each session. To assess the effectiveness of the programme, participants were invited to cycle on a pedal bike to evaluate their ability to cycle independently. RESULTS: The results in Phase 1 showed that cyclists performed better on the balance bike than non-cyclists, with Bayes factor analyses providing evidence of this difference, BF01 = 0.228 in the 15 m sprint test and BF01 = 0.138 in the two-turn curved sprint test. The novel training programme in Phase 2 demonstrated remarkable effectiveness in improving their balance bike riding performance, as evidenced by the Bayes factor for completion times in the repeated measures being BF01 < 0.001. All participants were able to cycle independently with confidence after the programme. CONCLUSIONS: This study sheds light on the idea that it's never too late for adults to learn how to ride a bike. It provides evidence that healthy adults can learn to ride independently with the help of a balance bike, a tool that's commonly used for teaching children. The study identifies five key principles for effective balance bike training in adults, including focusing on riding speed, gliding to turn, building cycling confidence, engaging high motor skills, and using a dual-task approach. Our evidence-based training programme offers a safe, enjoyable, and effective way for adults to develop the skills and confidence they need to ride, even if they've never ridden before.

Motor patterns of patients with spinal muscular atrophy suggestive of sensory and corticospinal contributions to the development of locomotor muscle synergies.

Complex locomotor patterns are generated by combination of muscle synergies. How genetic processes, early sensorimotor experiences, and the developmental dynamics of neuronal circuits contribute to the expression of muscle synergies remains elusive. We shed light on the factors that influence development of muscle synergies by studying subjects with spinal muscular atrophy (SMA, types II/IIIa), a disorder associated with degeneration and deafferentation of motoneurons and possibly motor cortical and cerebellar abnormalities, from which the afflicted would have atypical sensorimotor histories around typical walking onset. Muscle synergies of children with SMA were identified from electromyographic signals recorded during active-assisted leg motions or walking, and compared with those of age-matched controls. We found that the earlier the SMA onset age, the more different the SMA synergies were from the normative. These alterations could not just be explained by the different degrees of uneven motoneuronal losses across muscles. The SMA-specific synergies had activations in muscles from multiple limb compartments, a finding reminiscent of the neonatal synergies of typically developing infants. Overall, while the synergies shared between SMA and control subjects may reflect components of a core modular infrastructure determined early in life, the SMA-specific synergies may be developmentally immature synergies that arise from inadequate activity-dependent interneuronal sculpting due to abnormal sensorimotor experience and other factors. Other mechanisms including SMA-induced intraspinal changes and altered cortical-spinal interactions may also contribute to synergy changes. Our interpretation highlights the roles of the sensory and descending systems to the typical and abnormal development of locomotor modules.NEW & NOTEWORTHY This is likely the first report of locomotor muscle synergies of children with spinal muscular atrophy (SMA), a subject group with atypical developmental sensorimotor experience. We found that the earlier the SMA onset age, the more the subjects' synergies deviated from those of age-matched controls. This result suggests contributions of the sensory/corticospinal activities to the typical expression of locomotor modules, and how their disruptions during a critical period of development may lead to abnormal motor modules.

Age-Related Modifications of Muscle Synergies and Their Temporal Activations for Overground Walking.

Healthy ageing modifies neuromuscular control of human overground walking. Previous studies found that ageing changes gait biomechanics, but whether there is concurrent ageing-related modulation of neuromuscular control remains unclear. We analyzed gait kinematics and electromyographic signals (EMGs; 14 lower-limb and trunk muscles) collected at three speeds during overground walking in 11 healthy young adults (mean age of 23.4 years) and 11 healthy elderlies (67.2 years). Neuromuscular control was characterized by extracting muscle synergies from EMGs and the synergies of both groups were k -means-clustered. The synergies of the two groups were grossly similar, but we observed numerous cluster- and muscle-specific differences between the age groups. At the population level, some hip-motion-related synergy clusters were more frequently identified in elderlies while others, more frequent in young adults. Such differences in synergy prevalence between the age groups are consistent with the finding that elderlies had a larger hip flexion range. For the synergies shared between both groups, the elderlies had higher inter-subject variability of the temporal activations than young adults. To further explore what synergy characteristics may be related to this inter-subject variability, we found that the inter-subject variance of temporal activations correlated negatively with the sparseness of the synergies in elderlies but not young adults during slow walking. Overall, our results suggest that as humans age, not only are the muscle synergies for walking fine-tuned in structure, but their temporal activation patterns are also more heterogeneous across individuals, possibly reflecting individual differences in prior sensorimotor experience or ageing-related changes in limb neuro-musculoskeletal properties.

An inverted ankle joint orientation at foot strike could incite ankle inversion sprain: Comparison between injury and non-injured cutting motions of a tennis player.

Ankle sprain is very common in sports. Research on its prevention is as important as on its treatment as recommended in the 2016 consensus statement of the International Ankle Consortium. Successful prevention depends on the understanding of its mechanism, which has been presented with quantities in some recent case reports. Inciting event was suggested to be an inverted ankle joint at foot strike, however, is still lacking evidence from comparison with non-injury trials. This study investigated the ankle joint orientation at foot strike in successful non-injury cases and compared them with a previously analysed ankle sprain injury case. Two injury-free cutting motions with similar movement approach to a previously analysed ankle sprain injury performed by the same athlete were collected from an online search and were trimmed from 0.05 s before until 0.30 s after the foot strike. The video sequences were then processed by video editing software and then analysed by a model-based image-matching motion analysis technique. Ankle joint orientation at foot strike and the profiles were presented in inversion, plantarflexion and rotation planes, for both the previously analysed injury case and the two non-injury cases. The ankle joint orientation at foot strike was 0-1 degree inverted and 10-21° dorsiflexed in the two non-injury cases, compared to 14° inverted and 16° plantarflexed in the previously analysed injury case. From the case comparison, it can be observed that an inverted ankle joint orientation at foot strike in an inciting event of ankle inversion sprain.

Plasticity of muscle synergies through fractionation and merging during development and training of human runners.

Complex motor commands for human locomotion are generated through the combination of motor modules representable as muscle synergies. Recent data have argued that muscle synergies are inborn or determined early in life, but development of the neuro-musculoskeletal system and acquisition of new skills may demand fine-tuning or reshaping of the early synergies. We seek to understand how locomotor synergies change during development and training by studying the synergies for running in preschoolers and diverse adults from sedentary subjects to elite marathoners, totaling 63 subjects assessed over 100 sessions. During development, synergies are fractionated into units with fewer muscles. As adults train to run, specific synergies coalesce to become merged synergies. Presences of specific synergy-merging patterns correlate with enhanced or reduced running efficiency. Fractionation and merging of muscle synergies may be a mechanism for modifying early motor modules (Nature) to accommodate the changing limb biomechanics and influences from sensorimotor training (Nurture).