1.6 Demonstrate and analyse how the systems of the body work together in a variety of movements

1. What work together means during movement

One helpful way to understand systems that work together is to follow the pathway from decision to action to regulation:

1. Intention and decision (brain): you decide to move, choose a movement pattern, and set a goal.
2. Motor signal (nerves): the brain and spinal cord send a motor signal through motor nerves to activate muscles.
3. Force production (muscle contraction): muscle contraction creates force. This can be concentric, eccentric, or isometric, depending on the task.
4. Movement at joints (bones as levers): bones act as levers, and synovial joints act as pivot points to create actions such as flexion and extension.
5. Energy supply (cardiorespiratory, endocrine, digestive): oxygen delivery and fuel availability are adjusted so supply matches demand.
6. Feedback and correction (nervous system): sensory feedback helps refine timing, balance, and technique.

This is not a one-way process. The body constantly adjusts using feedback so the internal environment stays as stable as possible while movement continues. This matters more as working muscles produce more carbon dioxide and other by-products.

2. How the seven body systems coordinate to produce movement

Each system has a clear role, but movement makes the most sense when you link the systems together.

2.1 Skeletal system

• Provides the rigid framework for posture, protection and movement.
• Bones meet at synovial joints, allowing controlled mobility.
• Bones act as levers and joints act as pivots so muscle force can create movement.
• Alignment matters. Poor alignment can increase tissue stress and raise injury risk.

2.2 Muscular system

• Acts as the main force generator for movement.
• Creates movement by contracting and pulling on bones via tendons.
• Uses different contraction types for different demands:
  • concentric and eccentric for locomotion, kicking, and lifting phases.
  • isometric for posture, bracing and joint stabilisation.
• Recruitment patterns influence performance, especially the balance between fatigue resistance and power.

2.3 Nervous system

• Coordinates movement by controlling timing, order and force of contractions.
• Uses feedback to adjust balance, posture and coordination.
• During exercise, the nervous system helps support effort by increasing alertness and helping drive changes such as higher heart rate and breathing rate.

2.4 Cardiovascular system

• Transports oxygen, fuels and hormones to tissues and removes carbon dioxide and other by-products.
• During exercise there is usually an increase in:
  • heart rate
  • stroke volume
  • cardiac output
• Blood is redirected towards active muscles so oxygen delivery matches demand.

2.5 Respiratory system

• Brings oxygen into the body and removes carbon dioxide.
• Breathing rate and depth increase during movement to maintain gas exchange.
• Works closely with the cardiovascular system as the cardiorespiratory system.

2.6 Endocrine system

• Releases hormones that help regulate energy availability and exercise responses.
• Key examples during movement include:
  • adrenaline: increases heart rate, redirects blood to muscles, supports rapid energy release.
  • cortisol: helps regulate metabolism during prolonged stress.
  • endorphins: can influence mood and perceived effort during sustained exercise.

2.7 Digestive system

• Breaks down food and supplies nutrients needed for energy production and recovery.
• Supports performance through factors such as:
  • glycogen storage (carbohydrate reserves in muscle and liver)
  • Fat availability as an endurance fuel
  • Protein and micronutrients for repair and adaptation

3. Demonstrating system integration across movement types

The same seven systems coordinate differently depending on intensity, duration, skill precision and load.

3.1 Endurance movement: Road cycling (long ride or time trial)

Road cycling over long distances is mainly aerobic and relies on sustained coordination between working muscles and continuous oxygen delivery.

What the body must do:

• Keep muscles contracting repeatedly for a long time, especially in the legs and hips.
• Keep oxygen delivery and carbon dioxide removal high enough for sustained aerobic ATP production.
• Maintain posture and movement efficiency as fatigue increases, particularly through the trunk and hips.

How the systems work together:

• muscular system: repeated contractions produce continuous pedal strokes, with stabilising muscles maintaining pelvic control.
• skeletal system: provides levers through the hip, knee and ankle joints; efficient alignment reduces joint strain over time.
• respiratory system: increases breathing to bring in oxygen and remove carbon dioxide.
• cardiovascular system: increases cardiac output and redirects blood towards working muscles to support aerobic energy production.
• nervous system: maintains pedalling rhythm and technique, adjusting force output using sensory feedback from muscles and joints.
• endocrine system: helps release fuel (especially as intensity changes on hills) and supports prolonged effort.
• digestive system: provides glycogen stores before the ride and supports carbohydrate and fluid absorption during longer sessions when relevant.

Example: In the final 10 km of a time trial, rising fatigue can reduce how smoothly you pedal. This is often linked to reduced nervous system precision and declining glycogen availability, which increases the demand on the cardiorespiratory system to maintain output.

3.2 High-force movement: Shot put

Shot put is brief and high intensity, and it places large loads through joints and connective tissues while requiring precise technique.

What the body must do:

• Produce very high force quickly, with precise coordination through the whole body.
• Stabilise the trunk and joints so force is transferred efficiently into the implement.
• Return towards normal balance after the effort.

How the systems work together:

• muscular system: generates explosive force, relying heavily on fast-twitch recruitment in the legs, hips, trunk and upper body.
• nervous system: coordinates timing and sequencing so force moves from legs and hips through the trunk to the arm at release.
• skeletal system: provides stable levers through ankles, knees, hips, spine, shoulder and elbow, allowing efficient force transfer.
• cardiovascular system and respiratory system: respond with short spikes in heart rate and changes in breathing patterns.
• Some athletes use a brief breath hold and brace (similar to a Valsalva manoeuvre) to support trunk stability during the drive phase.
• endocrine system: adrenaline supports readiness, alertness and maximal effort.
• digestive system: supports readiness and recovery by supporting fuel stores and protein intake for repair and adaptation.

Example: A throw that “leaks” force (for example, hips rotating too early) shows reduced nervous system coordination. This decreases how effectively the muscular system can use the skeletal system as a lever, lowering distance even if the athlete is strong.

3.3 Intermittent sport movement: Netball

Netball includes repeated shifts between low-to-moderate intensity movement and short high-intensity bursts, with frequent jumping, landing, stopping, and passing under pressure.

What the body must do:

• Switch between aerobic movement and anaerobic bursts.
• Maintain coordination and technical execution (passing, catching, shooting) across the game.
• Manage repeated landings, pivots, and changes of direction without excessive joint stress.

How the systems work together:

• cardiorespiratory system: supports repeated efforts and recovery between bursts, helping maintain work rate late in quarters.
• muscular system and skeletal system: manage accelerations, decelerations, jumps, landings and pivots, with joint stability critical at the ankle, knee and hip.
• nervous system: integrates vision, decision-making and motor control; fatigue can reduce landing control and passing accuracy.
• endocrine system: adrenaline can rise in high-pressure moments (for example, a final-second shot), affecting focus and arousal.
• digestive system: hydration and carbohydrate availability affect concentration, reaction time and repeated sprint ability.

Example: Late in a match, a player may land with poorer knee alignment because the nervous system is less precise under fatigue. This increases stress through the skeletal system and can raise injury risk, even if the movement speed is unchanged.

3.4 Precision movement: Golf putting

Golf putting shows that working together is not only about high intensity. Precision needs fine control, stability, and a consistent internal state.

What the body must do:

• Produce steady, controlled movement without shaking.
• Maintain consistent alignment and joint position throughout the stroke.
• Control breathing and arousal to protect fine motor control.

How the systems work together:

• muscular system: low-force, highly controlled contractions stabilise the shoulders, wrists and trunk during the stroke.
• skeletal system: stable alignment supports repeatable technique and consistent putter path.
• nervous system: integrates vision and proprioception, then sends refined motor signals for small adjustments in force and direction.
• cardiovascular system and respiratory system: controlled breathing supports steadiness and reduces unwanted body movement.
• endocrine system: too much adrenaline can increase tension and reduce fine control, affecting touch and accuracy.
• digestive system: supports concentration through hydration and stable blood glucose, particularly across a long round.

Example: A putt struck too firmly under pressure can reflect increased endocrine arousal (adrenaline) increasing muscle tension. This reduces nervous system fine control and changes the force produced by the muscular system, even though the technique looks similar.

4. How training improves integration

Training does not only improve one system. It improves how the systems of the body work together, which can increase capacity and efficiency.

NB: When training, recovery and nutrition match the training load, the long-term outcome is a body that coordinates systems more effectively for safer and more sustainable movement.

Aerobic training

Strength and power

Hormonal and nutrition