Welcome to Your Guide on Analysis of Movement!
Ever wondered exactly how a professional athlete manages to pull off a perfect slam dunk or a powerful strike in football? It’s not just "magic"—it’s a precise combination of joints, muscles, and contractions working in harmony.
In this section, we are going to learn how to become movement detectives. We will break down physical actions into their smallest parts to understand exactly what the body is doing. Don't worry if it seems like a lot of terms at first; once you see the patterns, it becomes much easier!
1. The "Who, What, and How" of Movement
When we analyse a movement for your OCR PE exam, we are always looking for four specific things:
1. Joint Type: What kind of joint is moving? (e.g., Hinge or Ball and Socket?)
2. Movement Produced: What is the specific action? (e.g., Flexion or Abduction?)
3. Agonist and Antagonist: Which muscles are the "main workers" and which are "relaxing"?
4. Type of Contraction: Is the muscle shortening, lengthening, or staying the same length?
Quick Review: The Main Joints
Before we dive in, remember the two main types of joints we focus on:
• Hinge Joints: Like a door hinge. They only move in one direction (Elbow, Knee, Ankle).
• Ball and Socket: Like a joystick on a game controller. They have a huge range of motion (Shoulder, Hip).
2. The Muscle "Partnership": Agonists and Antagonists
Muscles never work alone; they work in antagonistic pairs. Because muscles can only pull (they can't push), they need a partner to pull the bone back the other way.
The Agonist (The Prime Mover): This is the muscle that is "in charge" of the movement. It is the one contracting to create the action.
Example: In the "up" phase of a bicep curl, the Biceps Brachii is the agonist.
The Antagonist: This is the muscle that relaxes and lengthens to allow the movement to happen. It acts as a "brake" to protect the joint.
Example: In that same bicep curl, the Triceps Brachii is the antagonist.
The Fixator: This muscle acts like an anchor. It stays still to stabilize the origin of the agonist so it can pull effectively.
Example: The Trapezius often acts as a fixator during arm movements.
Memory Aid:
Think of Agonist as A for Action. Think of Antagonist as the "Anti-movement" muscle (it's the opposite one).
Key Takeaway: Movement happens because the agonist contracts and the antagonist relaxes. If they both pulled at the same time, you wouldn't move at all!
3. Types of Muscle Contraction
Not all contractions look the same. Sometimes the muscle moves the bone, and sometimes it just holds it still.
Isotonic Contractions (Movement occurs)
There are two types of isotonic contractions:
• Concentric: This is when the muscle shortens under tension. Think of this as the "working against gravity" phase.
Example: The upward phase of a pull-up.
• Eccentric: This is when the muscle lengthens under tension. This is usually the "controlling the weight" phase.
Example: Lowering yourself down slowly from a pull-up.
Isometric Contractions (No movement)
This is when the muscle is under tension but stays the same length. No movement happens at the joint.
Example: Holding a "plank" position or a "wall sit."
Did you know?
Eccentric contractions (lengthening) are actually responsible for most of the "muscle soreness" you feel the day after a workout!
4. Step-by-Step: How to Analyse a Movement
Let's look at a common sporting example: The Preparedness Phase of a Football Kick (Pulling the leg back).
Step 1: Identify the Joint
The Knee is moving.
Step 2: Identify the Movement
The leg is bending, so the movement is Flexion.
Step 3: Identify the Muscle Pair
The Hamstring group (Biceps femoris, semi-membranosus, semi-tendinosus) is the Agonist because it's pulling the heel toward the glutes.
The Quadriceps group (Rectus femoris, etc.) is the Antagonist because it's stretching out.
Step 4: Identify the Contraction
Since the hamstrings are shortening to pull the leg back, it is a Concentric Isotonic contraction.
5. Common Mistakes to Avoid
• Don't forget the Ankle! Students often miss the ankle. Remember Plantar Flexion (pointing toes down, like a ballerina) and Dorsi Flexion (pulling toes up toward the shin).
• The "Lowering" Trap: When you lower a weight (like the downward phase of a squat), the Agonist is still the same muscle as the upward phase, it's just contracting eccentrically.
Common Error: Thinking the hamstrings are the agonist when lowering into a squat. (Correct: It’s the Quadriceps lengthening to control the descent!)
6. Summary Table for Analysis
Use this simple formula in your head for any exam question:
Joint + Movement + Agonist + Contraction = Full Marks!
Quick Review Box:
• Agonist: Shortens/Contracts (The Worker).
• Antagonist: Lengthens/Relaxes (The Partner).
• Concentric: Muscle shortens.
• Eccentric: Muscle lengthens (controls movement).
• Isometric: Muscle stays the same length (stability).
Don't worry if this seems tricky at first! Try standing up and doing a slow-motion squat. Feel which muscles get tight on the way up and which ones feel under tension as you lower yourself down. Your own body is the best study tool you have!