Here are extremely detailed slide-by-slide notes for Week 11 – Motor Control (MC11): Energetics as a Driver of Movement Changes, from your EXSS3062 lecture:

Slide 1: Title Slide

• Unit: EXSS3062 – Motor Control & Learning

• Topic: MC11 – Energetics as a Driver of Movement Changes

• Lecturer: Prof. Stephen Cobley

• Acknowledgement of Country and copyright statement included

Slide 2: Overview Diagram

• Shows interaction between:
  

  • Afferent sensory systems (e.g., proprioception, vestibular, exteroception)

  • Efferent motor system (neural commands from CNS to muscles)

  • Central processing: perception, cognition, decision-making, motor planning

• Emphasis on motor control through CNS efferent activity

Slide 3–4: Learning Outcomes

1. Recognise that skill development includes efficiency/economy

2. Define and differentiate between efficiency and economy

3. Understand how energetic changes relate to task adaptation (e.g., speed/pace)

4. Explain neural and energetic changes with skill learning

5. Compare skilled vs. unskilled performance from an energy perspective

Slide 5: Recommended Readings

• Sparrow & Newell (1998) – Key article on metabolic energy expenditure

• Poole & Ross (1983) – Study on energy cost in sheep shearing

• Lay et al. (2002) – Practice effects on energy expenditure & coordination

Slide 6–7: Skill Definition

• Definitions from Knapp (1964), Singer (1975), and Welford (1976)

• Emphasis on:
  

  • Learned ability to produce outcomes with maximum certainty

  • Achieved with minimum energy or time

  • Skill is not only learning, but involves efficiency and economy

Slide 8: Evolutionary Purpose of Energy Efficiency

• Energy conservation had survival advantages

• Efficient movement enables:
  

  • More work for same energy

  • Energy savings for other tasks

• Skill learning involves controlling/modifying energy cost

Slide 9: Efficiency Formula

• Efficiency = (Mechanical Work Done / Energy Used for Work) × 100

• Mechanical Work:
  

  • Force × Distance

  • Often calculated as Body Mass × Distance / Time = Power

• Input (Energy Used):
  

  • Muscle activation (via chemical energy)

  • Indirect calorimetry used (O2 consumption = energy expenditure)

Slide 10–11: Why Economy Is Used Instead

• Mechanical work is difficult to measure during submaximal, repetitive tasks

• Hence, economy = oxygen cost to complete a fixed task
  

  • More practical for cyclical or fixed-rate tasks (e.g., walking, cycling)

Slide 12–13: Efficiency vs Economy – Example in Horses

• Hoyt & Taylor (1981): Horses on treadmill at different gaits

• Each gait (walk, trot, gallop) has an optimal speed where energy cost is lowest

• Similar energy efficiency patterns exist in humans

Slide 14–15: Preferred Movement Speeds

• Horses (and humans) choose speeds that align with maximal efficiency

• Distribution of preferred speeds in bar graph confirms this

• Example extended to:
  

  • Bicycle ergometer

  • Step test

  • Hand pump ergometer

• Freely chosen pace ≈ peak efficiency pace

Slide 16: Constraints-Based Framework

• Influences on efficiency and energy use fall under 3 constraints:
  

  1. Organismic (Performer): body comp, strength, flexibility, skill history

  2. Task: nature of the movement (e.g., treadmill vs shearing)

  3. Environment: test conditions or real-world environment

• Coordinated movement emerges from interaction of these constraints

Slide 17–18: Skilled vs Unskilled – Sheep Shearers Example

• Senior vs Intermediate shearers:
  

  • Similar O2 consumption

  • Senior shearers were faster per sheep, thus more efficient

  • Result = lower energy cost per sheep

• Efficiency developed via skill and repetition over time

Slide 19: Soccer Kicking Example

• Asami et al. (1976): Skilled vs unskilled soccer players

• Findings:
  

  • Energy ↑ with ball speed

  • Skilled players used less energy at given velocity

  • Best accuracy at 80% of max speed for both groups

  • Skilled players had greater accuracy at higher speeds

  

Slide 20: Penalty Kick Example

• Chloe Kelly (2023 World Cup): 30.84 m/s penalty kick (faster than men’s EPL average)

• Factors in energy transfer:
  

  • Foot speed, hip/knee ROM

  • Stance, posture, coordination

• High-level coordination allows optimal force transfer, showing energetic efficiency

Slide 21: Skilled Movement Requires Coordination of Constraints

• Energy-efficient movement arises from:
  

  • Anatomical/biomechanical constraints

  • Environmental and task demands

• Reinforces the interaction of performer-task-environment

Slide 22: Lay et al. (2002) Study Overview

• Participants: 6 male rowing novices, trained over 40 days

• Constant work rate (100W), but efficiency and coordination improved

• Measured: EMG, force, stroke rate, O2 consumption, HR, RPE, economy

Slide 23: EMG Findings – Biceps Brachii

• From Day 1 to Day 10:
  

  • ↓ magnitude and duration of muscle activation

  • Shift to shorter, discrete bursts with rest intervals

  • Indicates refined neuromuscular control and improved coordination

  

Slide 24: EMG Findings – Vastus Lateralis

• Similar pattern to biceps brachii

• Greater cycle consistency

• ↓ bursts of activity = ↓ energy usage

Slide 25: Neural Signal – MVC Reduction

• Participants spent less time at high % of max voluntary contraction

• Indicates:
  

  • ↓ motor unit recruitment

  • ↑ reliance on low-threshold units (more economical)

  • Reduced energetic demand

Slide 26: Stroke Rate & Coordination

• Stroke rate became more stable

• Slower, consistent stroke pattern emerged

• Suggests improved motor planning and coordination

Slide 27: Energy Outcomes

• From Day 1 to 10:
  

  • ↓ O2 consumption

  • ↓ Heart rate

  • ↓ Perceived exertion (RPE)

• Economy of movement increased

• Training led to greater efficiency at same workload

Slide 28: Summary of Lay et al. (2002)

• Practice led to:
  

  • Refined neural coordination

  • ↓ Muscle activation = ↓ energy cost

  • Improved metabolic efficiency

  • Learning enhanced performance economy

Slide 29: Lecture Summary

1. Efficiency & Economy are fundamental to motor coordination

2. Preferred movement speeds often align with optimal energy use

3. Motor learning = restructuring recruitment and muscle coordination for efficiency

4. Skilled movement = ↓ global & local energy use, ↑ speed, stability, and accuracy

Slide 30: Lecture Conclusion

• Skill learning includes:
  

  • The ability to economically & efficiently control movement

  • Task success depends on this coordination

• Quote: “Ability to economically/efficiently coordinate & control movement to achieve the task goal” — Sparrow & Newell (1998)