The Science of Fatigue

Curriculum Alignment

This lesson is designed for Year 11 VCE Physical Education, specifically targeting Unit 3, Area of Study 2: How does the body produce energy?. It addresses key knowledge of energy system interplay, particularly the lactic acid system, and its application to sport performance and fatigue. The lesson's examples will focus on Australian football (AFL) and tennis (Australian Open and prominent athletes).

---

Lesson Overview

Duration: 75 minutes
Topic: The Lactic Acid System in Sports Performance
Class Size: 22 students

This interactive and practical lesson introduces the lactic acid system, exploring how it functions during high-intensity, short-duration activities and contributes to fatigue. Australian Football (AFL) and tennis examples will help contextualise learning in real-world scenarios.

---

Learning Objectives

By the end of the lesson, students will:

1. Understand the lactic acid system: its role in energy production during anaerobic activity.
2. Explain lactic acid accumulation: how it causes fatigue and affects performance.
3. Apply knowledge to AFL and tennis: by analysing match scenarios and real-world examples.
4. Evaluate recovery strategies: to minimise lactic acid build-up and improve performance.

---

Materials Required

• Whiteboard/markers
• AFL and tennis highlight clips (AFL: moments involving sprints; tennis: extended rally footage)
• Laminated athlete performance data cards (e.g., heart rate, intensity levels of both sports)
• Cones and stopwatches for a mini practical activity
• Student notebooks and pens
• Sample VCE short-answer questions for formative assessment

---

Lesson Structure

Introduction (10 minutes)

1. Hook: Real-World Examples

• Play two short video clips:
  a. AFL highlight: a defensive player sprinting back to intercept the ball (e.g., 15 seconds of high-intensity activity).
  b. A tennis rally involving sustained, fast-paced volleys (e.g., Australian Open footage of Nick Kyrgios or Ash Barty).
• Ask students:
  "How do you think the body obtains energy during these intense efforts?"
  "Why do athletes slow down and show fatigue after short sprints or rallies?"

2. Learning Intentions and Success Criteria

• Share today’s focus: "We’ll explore the lactic acid system, its functions, and how it impacts performance in sports like AFL and tennis."
• Display clear success criteria:
  "By the end of the lesson, you’ll be able to explain what causes fatigue during intense efforts and apply strategies to address it for performance improvement."

---

Body of Lesson

Part A: Theory - The Lactic Acid System (20 minutes)

1. Mini-Lecture (10 minutes)

   • Use the whiteboard to break down:
     • ATP-PC system vs. lactic acid system: when the lactic acid system takes over.
     • Glycolysis and lactic acid build-up in anaerobic conditions.
     • Impact of lactic acid on muscle fatigue and performance.

2. Real-World Connections (10 minutes)

   • AFL example: explain how short-distance sprints and fast transitions (e.g., chasing the ball) rely on the lactic acid system.
   • Tennis example: show a point from the Australian Open where a long rally leads to visibly slower responses (indicative of muscle fatigue).

---

Part B: Activity - Feel the Burn (25 minutes)

Purpose: Students engage in a physical activity to experience the lactic acid system in action.

1. Set-up:

   • Divide the 22 students into four small groups. Use the football field or gym area to set up two activity stations:
     a. Station 1: Shuttle Sprints – Students sprint 20m cones in quick succession for 30 seconds.
     b. Station 2: Rally Simulation – Two students rally with tennis racquets while maintaining high intensity (approximately 30 seconds).

2. Data Collection:

   • After each activity, each group records heart rate, perceived exertion, and muscular sensations (e.g., heaviness, "burning" from lactic acid).
   • Rotate groups through both stations until all students complete the activities.

3. Reflect and Discuss:

   • Ask: "What did it feel like? Why do you think your muscles felt heavier during high-intensity efforts?"
   • Introduce the concept of oxygen debt and the role of active recovery in clearing lactic acid.

---

Part C: Group Analysis - Connecting Concepts (15 minutes)

Scenario Analysis (10 minutes)

• Provide data cards simulating athlete performance metrics (e.g., average heart rate, time spent in anaerobic activity). Include one AFL player and one tennis player.
• In pairs, students answer questions:
  "Which athlete is likely to feel the effects of lactic acid more quickly, and why?"
  "What strategies can the athlete use to recover efficiently after intense bursts of activity?"
• Share findings as a class.

VCE Skills Application (5 minutes)

• Provide a sample VCE short-answer question:
  "During a tennis rally, describe the role of the lactic acid system in energy production and explain how it contributes to fatigue. Suggest recovery strategies to minimise its effects."
• Students write brief responses individually. Review answers as a group.

---

Conclusion (5 minutes)

• Recap key points: "The lactic acid system is vital for short bursts of high intensity but leads to fatigue due to lactic acid build-up."
• Highlight application: "Understanding this system can help optimise performance and recovery in sports like AFL and tennis."
• Exit Ticket:
  Students write down one new thing they learned, one question they still have, and one way they could apply today’s lesson to their own physical activities.

---

Extension Ideas

If additional time or homework is possible, assign students to research and present relevant recovery strategies utilised by famous Australian athletes (e.g., AFL stars like Dustin Martin or tennis players like Ash Barty).

---

Assessment

• Formative Assessment: Active participation and responses during group discussions and practical activities.
• Summative Assessment: Quality of answers to the VCE short-answer question.

---

Teacher Reflection

After the lesson, consider:

• Did students actively engage with the practical activities?
• Were they able to connect theoretical concepts to real-world scenarios effectively?
• Did their written responses show a clear understanding of the lactic acid system's role and implications?