Motor Skills and Games - Sensory Components

Motor Skills and Motor Games - Sensory Components of Motor Control

• The course is titled "Motor Skills and Motor Games - Sensory components of motor control"
• The professor is Juan Pablo Rey Lopez, with the email address [email protected], belonging to the Catholic University of Murcia (UCAM).
• The course has 4.5 ECTS credits and is scheduled for the first semester of 2024/25.

Introduction

• Understanding the anatomical and physiological basis of sensory systems (touch, proprioceptive, visual) is crucial in understanding movement control.
• Examples include reaching for a glass of water or catching a ball.

Sensory Components Involved in Human Sensory Physiology

• Three primary senses are involved:
  • Proprioception and motor control
  • Touch and motor control
  • Vision and motor control
• Other sensory inputs like auditory information are also important, especially in sports or balance.

Proprioception

• 1.1 Historical Background:
  • Aristotle believed there were only five senses (sight, hearing, smell, taste, touch).
  • Later thinkers recognized the sense of muscular exertion (position, body awareness)
  • German physiologists discussed "Muskelsinn"
• 1.2 Kinesthetic Sensors:
  • This deals with changes in limb position and movement.
  • Key tissues involved: skin, muscles, tendons, fascia, joint capsules, and ligaments
  • Muscle spindles are a key mechanoreceptor for proprioception.
• 1.3 Senses of Force:
• 1.4 Proprioception in the Elderly:
  • Age-related loss of muscle fibers and neurons (sarcopenia)
  • Reduced sensory endings in muscle spindles, especially the dynamic sensitivity of spindle primary endings.
• 1.5 Proprioceptive Training and Ankle Sprains:
  • Exercises challenging the joint's ability to detect and react to sensory input.
  • Examples: wobble board, throwing/catching/dribbling a ball while in single-leg stance, balance with eyes closed.

1.1 Proprioception - Historical Background

• Aristotle's view of limited senses.
• Sherrington's rejection of the idea of a solely central origin of muscle sense, emphasizing the importance of peripheral signals and sensory input from muscles to the brain to understand body position despite being relaxed.

Proprioception (further details)

• Proprioception is the sense of body position and movement in space, encompassing muscle force perception.
• Proprioceptors are any tissues with mechanical sensors exhibiting shape or tension change—these changes from passive or active motion are sensory input.
• These include afferents that sense skeletal muscles, tendons, joint ligaments, connective tissues around muscles, and skin.

Some Lines of Evidence of why Muscle Spindles are the Dominant Mechanoreceptor for Proprioception

• Joint replacement surgery: Position and movement sense remain even after all capsule and ligament removal.
• Muscle vibration: Vibration of tendon leads to illusion of movement and/or position change

Skin Affrerents

• Skin plays a large role in kinesthesia

• Their role in position perception is less important in joints nearer to the center of the body than in the extremities, and especially not in facial muscles which lack muscle spindles.

• Electrical stimulation of peripheral nerves (ulnar nerve) can trigger illusory movement sensations.

• Electrical stimulation of peripheral nerves/muscle spindles leads to illusory movement sensations.

Golgi Tendon Organs and Force/Heaviness

• Golgi tendon organs (GTOs) contribute to the sense of force and heaviness.
• Attached to muscle fibers in tendons.
• Activity in Ib afferents increases with muscle tension/force.

Senses of Force (1.3)

• Subjects can match target force both through direct and indirect control to reproduce a target force, matching it by means of visual, tactile, and proprioceptive feedback..

Interpretation of Force Overestimation During Self-Stimulation

• During self-generated force, there is a partial suppression of afferents, enabling us to focus.
• Force overestimation mainly occurs with low forces.

Force Overestimation Due to Fatigue

• Under normal conditions, force matching accuracy is high, approximately 5%.
• Fatigue leads to overestimating generated force.
• This error comes from efferent signals, with the unfatigued limb sending a higher force for similar activation.

Proprioception in Elderly

• Muscle fiber and neuron loss due to sarcopenia also affect intrafusal fibers and fusimotor neurons.
• Sensory endings in muscle spindles can be impacted, with a reduced sense of movement and dynamic sensitivity.

Proprioception and Ankle Sprains (1.5)

• Proprioceptive training consists of exercises enhancing a joint's ability to detect and respond to sensory input related to joint position..
• Examples include wobble board balancing, throwing/catching/dribbling a ball in single leg stance, or balancing with closed eyes.

Potential Benefits of Proprioceptive Training Reducing Ankle Sprains in Sporting Populations

• Analyzing RCT (Randomized Controlled Trials) results is key.
• Important factors for comparison are risk and rates, time-to-event analysis, and comparisons of means.

Relative Risk (Risk Ratio or Rate Ratio)

• Relative Risk (RR): A ratio of the likelihood of an outcome occurring in a group receiving a treatment or exposure to the likelihood of the same outcome in a control group (no treatment or exposure)
• RR = 1 indicate no association
• RR < 1 indicates a protective factor
• RR > 1 indicates a risk factor

Comparison of Two Risks: Relative Risk (RR)

• A table summarizing a calculation. It details how to calculate incidence in treated group and in the placebo group.

Survival Curve (Kaplan-Meier Curve)

• A visual representation of survival over time.
• Shows percentage of subjects still alive at different time points, and visually depicts deaths as downward steps.

Number Needed to Treat (NNT)

• The number of patients who need treatment to prevent one additional bad outcome.
• NNT = 1/ ARR (where ARR = Absolute Risk Reduction)

DPP trial: Primary Outcome – Diabetes

• Relative risk (RR) approximate values of the lifestyle, metformin, and placebo groups of 3 years, as well as cumulative incidence of diabetes based on the diagnosis criteria of the American Diabetes Association, are presented.
• Various figures are presented in graphs to highlight the differences and their statistical significance.

Other Notes from Summary

• The last several slides contain information relevant to how to analyze results from research studies and clinical trials.

• The last slides include questions for further student research, particularly about the effectiveness of proprioceptive training in preventing ankle sprains in sporting populations.