5.1 Explain how biomechanics can be used to develop efficient movements for sustained movement and improved performance

1. Biomechanics and movement efficiency

Biomechanics is the study of how and why the body moves. In sport and physical activity, it is used to analyse technique, identify inefficiencies and improve the way forces are applied, transferred and absorbed.

In this chapter, the focus is on application. The aim is not simply to name biomechanical ideas, but to explain how they can be used to make movement more efficient, easier to sustain and more effective for performance.

Efficient movement means achieving the required outcome with less wasted energy and less unnecessary joint loading. When movement is efficient, more of the force produced by the body contributes to the goal of the movement. When movement is inefficient, energy is lost through poor alignment, unnecessary motion, mistimed force production or poor force absorption. This increases fatigue and makes performance harder to sustain.

A clear way to understand the relationship is:

technique → force application and absorption → energy cost and fatigue → movement quality and performance

This cause-and-effect chain is central to the dot point. To explain biomechanics well, you need to show how a technique change alters movement efficiency and why that improves sustained movement and performance.

1.1 Efficient and inefficient movement

As fatigue increases, technique often becomes less efficient. Ground contact time may lengthen, braking forces may increase, posture may deteriorate, or force absorption may become poorer. This means the athlete must use more energy to produce the same result. Biomechanics helps identify these changes and guide technique adjustments so movement quality can be maintained for longer.

Example: A semi-professional netball centre can maintain quick accelerations and clean changes of direction in the first quarter, but by the last quarter begins to land more stiffly and allow the knee to collapse inwards when stopping. This shows how fatigue can reduce force absorption and alignment, making movement less efficient and harder to sustain.

2. How biomechanics improves sustained movement and performance

Biomechanics improves sustained movement and performance by showing how a movement can be made more economical, more effective and more repeatable.

2.1 Improving force application

Efficient movement depends on how well force is produced and directed. Force must be applied with the right magnitude, in the right direction, at the right time, and in the right sequence. If force is mistimed or directed poorly, energy is wasted and performance declines more quickly.

For instance, in running, force should contribute mainly to forward motion. If the foot lands too far in front of the body, braking force increases. This slows the athlete and raises the energy cost of each stride. A small change in technique, such as keeping foot contact closer under the hips, can reduce braking and improve running economy.

Example: A recreational 10 km runner training three mornings each week notices that the last 2 km always feel much harder than the opening stages, even when pace is unchanged. Video analysis shows the runner is overstriding as fatigue builds. This example shows that changing foot placement can improve force direction, reduce braking, and help the runner sustain pace more efficiently.

2.2 Improving force absorption

Sustained movement is not only about producing force. It is also about absorbing force efficiently. Repeated landings, stops, pivots and changes of direction place large stresses on the body. If those forces are absorbed poorly, fatigue rises more quickly and injury risk increases. Efficient force absorption spreads load across time, joints and tissues rather than allowing large peak forces to concentrate in one area.

This usually involves:

• appropriate joint flexion
• stable alignment
• strong eccentric control
• load sharing across the hip, knee and ankle

A stiff landing, for example, increases peak force and makes repeated jumping or decelerating more tiring. A softer, better-controlled landing reduces loading and helps performance be maintained.

Example: An elite basketball forward is still contesting rebounds late in the third quarter, but starts landing with less hip and knee flexion after repeated jumps. This increases peak force on landing and makes each jump more tiring. The example shows how improved force absorption can reduce fatigue and support repeated performance.

2.3 Improving movement economy

Movement economy refers to how much energy is required to perform a movement at a given speed or intensity. A more economical movement uses less energy to achieve the same output. This matters greatly in endurance events, repeated-sprint sports, invasion games, swimming and many workplace or everyday tasks.

Biomechanics improves movement economy by reducing:

• unnecessary vertical movement
• excessive side-to-side movement
• braking forces
• poor sequencing
• poor body position against resistance

The less wasted movement there is, the less energy the body has to spend correcting it.

Example: A competitive open-water swimmer lifts the head too high every time they sight the next buoy during a 2 km race. Each lift causes the hips to drop, which increases drag and raises energy cost. This example shows how a small biomechanical change in body position can improve movement economy and preserve energy for the final stages of the race.

2.4 Using biomechanical concepts to guide change

The following concepts are especially useful when explaining how biomechanics improves sustained movement and performance.

Example: An 800 m runner may increase gym strength over the pre-season, but if the added mass does not improve useful force output enough to offset the higher energy cost of carrying that mass, late-race speed may drop. This shows that muscle size and output must match the movement demands of the event.

Example: A javelin thrower may produce more effort at release, but if the angle of release is too low, the implement will not travel as effectively. This shows that projectile motion is not just about force, but about combining force with the correct release conditions.

Example: A competitive middle-distance runner changes from an older, heavily compressed training shoe to a newer shoe with more responsive foam and a stiffer forefoot design. This can improve energy return and reduce the energy cost of each stride, helping the runner maintain pace more efficiently over the later stages of a race. This example shows that equipment advances can improve sustained movement and performance by making force transfer more effective. However, the benefit still depends on technique, because inefficient running mechanics can still waste energy and increase loading despite improved footwear.

2.5 Measuring efficiency

Biomechanics is not based only on observation. It can also use measurement to assess whether a technique change has actually improved movement.

In practical settings, this may involve:

• video analysis
• observation of technique
• ground contact time
• left-right symmetry
• landing control
• speed of movement
• release angle or release height
• wearable technology or other performance data

This gives biomechanics practical value. It helps coaches, teachers and athletes identify what is inefficient, test changes, and judge whether performance has improved.

Example: A state-level hockey midfielder completes repeated sprint efforts at training while wearing a GPS unit. The coach notices that late in each effort block the player’s deceleration pattern becomes longer and less controlled. This example shows how monitoring data and movement observation can be used together to identify declining efficiency under fatigue.

3. Physical activity.

In physical activity, biomechanics is used to make movement more efficient, less tiring and easier to repeat over time. This is especially important in activities such as walking, running, cycling, swimming, group fitness and resistance training, where the same movement pattern is repeated many times. The goal is often to improve movement economy, reduce avoidable stress on the body and support long-term participation.

A common biomechanical issue in physical activity is wasted motion. If posture is poor, alignment is unstable, or force is directed inefficiently, the body must use extra energy to maintain the movement. Over time, this increases fatigue and can reduce performance or participation.

For instance, a recreational runner who overstrides may land with the foot too far in front of the body. This creates greater braking force and increases the impact cost of each stride. The runner may still be able to run, but the technique is less economical and becomes harder to sustain. A biomechanical adjustment, such as maintaining a steady cadence and landing closer to the hips, can reduce braking, lower cumulative loading and improve sustained pace.

Similarly, in cycling, inefficient posture can increase air resistance and place unnecessary strain on the lower back, neck or shoulders. In swimming, poor body position can increase drag, forcing the swimmer to use more energy to maintain speed. In both cases, biomechanics helps refine technique so the same activity can be sustained with less fatigue.

Biomechanics is also important in physical activity because it supports wellbeing and continued participation. When movement becomes more efficient, it is usually more comfortable, more manageable and less physically stressful. This can increase confidence and make it easier for people to remain active over time.

Example: A 45-year-old recreational cyclist joins weekend group rides of about 60 km. After 40 km, the rider develops neck tightness and begins sitting more upright, which increases frontal area and air resistance. This example shows how posture affects drag, energy cost and the ability to sustain movement over a longer duration.

Example: A new gym participant performs repeated bodyweight squats in a circuit class and lets the knees cave inward as they tire. This shows how poor alignment can reduce movement efficiency and increase unnecessary joint stress during repeated physical activity.

Example: A masters swimmer training for a 1.5 km ocean swim crosses the midline with each arm pull and lets the legs drift apart during the final laps of the set. This creates extra side-to-side movement and more drag. The example shows how reducing wasted motion improves movement economy.

4. Sport-specific movements.

In sport-specific movements, biomechanics is used to improve the efficiency, quality and repeatability of movement skills that directly affect performance. This includes actions such as running, kicking, throwing, striking, jumping, landing, tackling, turning, accelerating and decelerating.

In sport, performance is often determined not simply by whether a skill can be performed, but by whether it can be performed repeatedly, accurately and effectively under fatigue. This is where biomechanics is especially valuable.

A sport-specific movement becomes more efficient when:

• force is transferred smoothly from larger body segments to smaller ones
• unnecessary movement is removed
• alignment is maintained under pressure
• force is absorbed and redirected effectively
• technique remains consistent as fatigue increases

For instance, in a throwing or striking skill, efficient performance depends on correct sequencing. Force is usually generated from the ground, transferred through the legs and hips, then through the trunk and finally into the arm or implement. If this sequencing is poor, the athlete may rely too heavily on the smaller joints of the upper body. This can reduce power, increase fatigue and raise the risk of overuse injury.

A cricket fast bowler, for instance, may generate speed early in a spell through arm action alone, but this is difficult to sustain. If biomechanical analysis improves the transfer of force from the legs, hips and trunk into the arm, the bowler can produce greater speed more efficiently and with less strain. This improves both sustained performance and movement quality.

In jumping and landing sports, force absorption is equally important. A basketball player who lands stiffly after repeated rebounds experiences higher peak forces and greater fatigue. By improving hip, knee and ankle flexion and controlling landing alignment, the athlete can reduce loading and maintain repeated jumping performance.

Sport-specific biomechanics is also closely linked to projectile motion and fluid dynamics where relevant. In a kick, throw or shot, release angle, release height and release speed affect the result. In swimming, reducing drag and improving thrust help maintain speed with lower energy cost. In both cases, biomechanical refinement improves performance by making movement more efficient, not simply by increasing effort.

Example: A first-grade cricket fast bowler can maintain 128 km/h across the opening three overs, but drops sharply in pace by the sixth over because the action becomes more arm-dominant and less force is transferred from the legs and trunk. This example shows how better sequencing improves force transfer, reduces upper-body strain and supports sustained bowling performance.

Example: An elite 400 m hurdler begins clipping hurdles in the final 100 m because fatigue changes stride pattern and take-off distance. This shows how biomechanics affects timing, body position and the ability to maintain efficient technique under fatigue.

Example: An A-League winger repeatedly cuts inside off the left foot during the final 20 minutes of a match. When fatigued, the player takes a wider final plant step and the foot lands too far outside the body, creating less efficient deceleration and slower re-acceleration. This example shows how biomechanics influences change of direction efficiency in a sport-specific movement.

Example: A water polo player shooting late in the fourth quarter starts releasing the ball from a lower height because leg drive has decreased. This shows how reduced release height can affect projectile motion and decrease shot effectiveness even when effort remains high.

5. Functional movements.

Functional movements are movement patterns used in everyday life, work, exercise and rehabilitation. These include lifting, carrying, pushing, pulling, bending, reaching, squatting, stepping and changing level. Biomechanics helps make these movements more efficient so they can be repeated with less fatigue and less unnecessary strain.

In functional movement, efficiency often depends on:

• keeping the load close to the body
• maintaining stable posture and alignment
• using large muscle groups, especially the hips and legs
• avoiding excessive twisting or collapse under load

These factors affect torque, which is the turning effect of a force around a joint. If a load is held further away from the body, the moment arm becomes larger and the torque on the spine or joints increases. This makes the movement more demanding and more tiring.

For instance, a person repeatedly lifting boxes with a rounded back and the load held far from the body places greater stress on the lower back. This technique is less efficient because more effort is required to control the movement and the body is placed under greater strain. A more efficient technique involves bending through the hips and knees, keeping the load close, maintaining a neutral spine and using the legs to assist the lift. This spreads force across larger muscle groups and makes the movement easier to sustain.

Functional biomechanics is also important in the gym. Movements such as the squat, lunge, deadlift and push-up should be performed with efficient alignment and force control so the exercise achieves its purpose without unnecessary stress. This does not mean there is only one perfect technique for every person, but it does mean biomechanics can be used to identify safer and more efficient movement patterns for the individual and the task.

This is one reason functional movement remains an important example in the syllabus. It shows that biomechanics is not only for elite athletes. It also helps ordinary movement become more sustainable, more efficient and more effective in daily life.

Example: A warehouse worker unloading cartons for a two-hour shift twists while lifting each box from pallet height to chest height shelving. This creates repeated torque through the lower back and makes the task more fatiguing across the shift. The example shows how keeping the load close and turning the whole body can improve efficiency in a functional movement.

Example: A firefighter trainee carries a hose pack upstairs during a timed drill and begins leaning excessively forward as fatigue increases. This shifts force poorly through the trunk and hips and makes each step more costly. This shows how posture and load distribution affect sustained functional performance.

Example: A recreational gym member deadlifts for sets of eight repetitions and lets the bar drift away from the shins on repetitions six to eight. This increases the moment arm and the torque on the lower back. The example shows how a biomechanical adjustment in bar path can make a functional movement more efficient and safer to repeat.

6. Why biomechanics matters for sustained movement and improved performance

Biomechanics matters because performance is not improved by effort alone. Performance improves when effort is converted into effective movement. If technique wastes energy, misdirects force or absorbs force poorly, fatigue rises more quickly and movement quality declines. If technique is efficient, the individual can maintain speed, control, accuracy or power for longer.

This is why biomechanics is so important in this dot point. It explains how movement can be refined so that:

• energy cost is reduced
• fatigue is delayed
• movement quality is maintained
• performance is improved
• unnecessary joint and tissue stress is reduced

Biomechanics improves technique, improved technique changes force application or absorption, this reduces wasted energy and improves movement economy, which helps the individual sustain movement for longer and perform more effectively.

Example: A semi-professional rugby league fullback may still appear to be working hard in the final 10 minutes of a match, but if deceleration, landing and turning mechanics have become inefficient, each effort costs more energy and quality drops. This example shows the central idea of the chapter: biomechanics matters because efficient movement delays fatigue and helps performance stay effective for longer.