Research Roundup: September 2020
Sep 30, 2020
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Current trends in the biokinetic analysis of the foot and ankle
Metsavaht L, Leporace G. Current trends for the biokinetic analysis of the foot and ankle. J Foot Ankle. 2020;14(2):191-6.
This literature review argues that clinically we need to observe functional - rather than conventional - biomechanics at the ankle and foot. Functional biomechanics observes that all segments in a joint can be simultaneously mobile. The authors suggest that "the reader should be able to understand how the 3-dimensional biokinetic analysis of the ankle and foot can contribute along with imaging examinations to the clinical setting, thus allowing the construction of a more complete proﬁle of the patient."
- The central nervous system works as the generator of complex movement patterns based on muscular synergies; the control of active joint stability is coordinated by the neuromuscular system and not by isolated muscle strength or range of motion.
- Functional ankle stability is mostly related to the capacity of triceps surae muscle to generate functional strength.
- The main structure that generates stability in gait is the foot; functioning as a stable base of support for movements of the proximal segments, the foot assists in the absorption of ground reaction forces and is a powerful lever arm for the ankle muscles during the propulsion phase of gait.
- The medial longitudinal arch (MLA) is essential for the proper functioning of the foot, working as a spring system, changing foot stiffness and allowing deformation for absorbing loads while transferring forces to the ground.
- The MLA works as a three-dimensional rather than two-dimensional structure.
- Resection of the plantar fascia can reduce foot stiffness by 25%; removal of the transverse arch can reduce foot stiffness by more than 50%.
- The functionality of the plantar fascia can be observed via the windlass mechanism, whereby hallux extension produces a tension in the plantar aponeurosis, creating a lever arm for propulsion.
- The role of eccentric control synergies is increased in running vs walking.
Gait Cycle; Biocinetica Laboratório do Movimento Ltda, Rio de Janeiro, Brazil.
Running Cycle; Biocinetica Laboratório do Movimento Ltda, Rio de Janeiro, Brazil.
Clinically: Pilates in Practice
- There's reason that we often start with footwork - but make it dynamic!
- For "toes on" footwork, ensure that the MTPJs are on the bar, encouraging a press into the forefoot to find hallux extension and wind up the plantar fascia to raise the heels.
- Encourage eccentric support and control of the feet and ankles through load; jump board on the Reformer, calf raises.
- Build foot posture and positioning into all hip/knee and lower limb work; feet in straps and leg springs too!
- Be sure to work on peroneal support around the ankle; foot waving, the foot corrector, and the toe gizmo can be integrated into standing work.
- Ensure hip and knee alignment and strength are addressed, rather than focusing solely on ankle stability.
- Change it up: wide stance, split stance, hip internal rotation, knee flexion, dorsiflexion; change foot and ankle position to reflect the functional task.
1. Cavalin, GA; Zeitoune, GG; Leporace, G; Nadal, J. Coordenação intersegmentar do quadril e do tornozelo em corredores recreacionais. In: 26o Congresso Brasileiro de Engenharia Biomédica, 2018, Búzios. Anais. Rio de Janeiro: SBEB; 2018
2. Venkadesan M, Yawar A, Eng CM, Dias MA, Singh DK, Tommasini SM, et al. Stiffness of the human foot and evolution of the transverse arch. Nature. 2020. 579(7797): 97-100
Analogies can speed up the motor learning process
Zacks O, Friedman J. Analogies can speed up the motor learning process. Sci Rep. 2020 Apr 24;10(1):6932. doi: 10.1038/s41598-020-63999-1. PMID: 32332826; PMCID: PMC7181737.
For motor learning tasks, analogies are usually given as a single biomechanical metaphor. This study demonstrates how analogies can influence motor kinematics and task outcome.
- The type of instruction given is important for motor learning.
- Different aspects of movement are affected differently by different instructional styles.
- "Analogies in the case of motor learning combine various task-relevant rules into a single biomechanical metaphor, usually given to the learner as a verbal instruction."
- Explicit instructions lead to smoother training for movement.
- Instructions given as a verbal analogy can support smoother movement training when movement tasks are slowed down.
- Analogies may help for motor skills that are otherwise hard to communicate or implement due to systemic limitations.
- Analogies increase cognitive efficacy due to a decrease in the verbal processing load.
Clinically: Teaching Pilates in Practice
- Find creative ways to communicate new tasks, especially when that task is broken down and slowed down.
- As per imagery, communication with your client is important to determine an analogy that is relevant.
- Experiment with analogies and explicit instructions, to find which allows your client to achieve the task more smoothly.
Neuroplasticity and motor learning in sport activity
Minino, Roberta, Patrizia Belfiore, Marianna Liparoti (2020): Neuroplasticity and motor learning in sport activity, Journal of Physical Education and Sport; DOI: 10.7752/jpes.2020.s4318.
This is a brief summary of neuronal plasticity and motor learning, particularly as it pertains to physical activity.
- Motor learning is defined as the ability to acquire new motor actions or new movement patterns.
- Cortical reorganization can be used for motor learning; the process follows a path consisting of two phases: unmasking and strengthening preexisting conditions, and creating new connections.
- In motor learning, the transition from coarse movement to a precise execution has three phases:
- Cognitive phase: Understanding the purpose of the action to be acquired and how to perform it.
- Associative phase: Structuring movements and finalizing the motor sequence.
- Automation phase: Automation of motor sequences, even during complex conditions.
- Physical activities are experience-dependent conditions that significantly contribute to cortical reorganization of the neural network and therefore also to neuronal plasticity.
- Neuronal circuits known as mirror neurons, which are activated when motor gesture is performed, can also be activated when a motor gesture is observed or imagined.
- (Therefore combining physical and mental training can help to acquire and improve a motor task.)
- Plasticity is a fundamental and persistent state of the neuronal system, allowing activation of various mechanisms for adaptive responses and environmental novelty.
- The main subcortical structures that play a role during motor learning are the cerebellum and striated nucleus; the cerebellum in first phase of acquisition, and the striatum in determining the correct type of.
- Anatomical changes usually take place during initial stages of practice, which results in an increase in grey matter.
- Increases in grey matter are generally accepted to be correlated with improved motor performance.
Clinically: Teaching Pilates in Practice
- Support client learning by identifying which phase of motor learning they are experiencing, and adapt appropriately.
- Incorporate imagery mental task practice with clients, to facilitate their learning of a motor skill; don't just rely on imagery, which can also be important for understanding and learning.
1. Jäncke, L. (2009b). The plastic human brain. Restorative Neurology and Neuroscience, 27(5), 521–538
2. May, A., & Gaser, C. (2006). Magnetic resonance-based morphometry: A window into structural plasticity of the brain. Current Opinion in Neurology, 19(4), 407–411. https://doi.org/10.1097/01.wco.0000236622.91495.21