Physiology, biomechanics and bounded training models
What you must know
This independent foundation section studies the systems that move and support the body: the skeleton, joints, muscles, the cardiorespiratory system and how they respond to exercise. Learn major functions of the skeleton (support, protection, movement, blood cell production and mineral storage), the main bone groups (cranium, vertebrae, ribs, pelvis, femur, tibia, humerus, radius, ulna), and the joint types: hinge (elbow, knee), ball-and-socket (shoulder, hip), pivot (neck) and gliding (wrist bones).
For muscles, know the names and actions of the major pairs: biceps and triceps at the elbow, quadriceps and hamstrings at the knee, gastrocnemius at the ankle, deltoid at the shoulder, abdominals and gluteals at the trunk. Understand antagonistic pairs: the agonist produces the intended joint action while the antagonist can oppose or help control it; co-contraction can stabilize a joint. Distinguish concentric shortening, eccentric lengthening under active tension and isometric force production without an appreciable change in muscle length. Introductory isotonic models describe movement under approximately constant external load, not proof that actual muscle tension is constant, and between voluntary skeletal muscle and involuntary cardiac and smooth muscle.
For the cardiorespiratory system, be able to trace the path of blood and air, name the chambers and valves of the heart, and explain what happens during exercise: heart rate and stroke volume rise, so cardiac output rises; breathing rate and tidal volume rise, so minute ventilation rises; blood is redistributed to working muscles. Distinguish tidal volume from vital capacity and oxygen uptake from ventilation. Excess post-exercise oxygen consumption describes recovery oxygen uptake above rest; lactate is a metabolic intermediate and fuel, not the sole explanation for fatigue or delayed muscle soreness.
Traps to watch
Questions often swap origin and insertion, describe the left ventricle as receiving oxygenated blood from the lungs (it does, but via the left atrium), or confuse red and white blood cells. A common trick is asking which muscle relaxes during a movement - read carefully.
Worked example
During a biceps curl, the elbow is a hinge joint; the biceps produces elbow-flexion torque, while antagonist activity depends on the control demands. The biceps origin is on the scapula and its insertion is on the radius, so contraction pulls the forearm upward.
For a supplied measurement example, cardiac output equals heart rate multiplied by stroke volume. A heart rate of 120 beats per minute and stroke volume of 80 millilitres per beat give 9600 millilitres, or 9.6 litres, per minute. This is arithmetic with supplied measurements, not a recommended target. Trace oxygenated pulmonary venous blood through the left atrium and left ventricle to the systemic circulation, then distinguish that route from deoxygenated blood pumped through the pulmonary artery. Acute responses during a bout and chronic adaptations after repeated training are different observations.
Biomechanics and Skill Acquisition
Biomechanics applies mechanical principles to human movement. Use Newton's three laws and apply them to sport (inertia, force equals mass times acceleration, action-reaction). Understand force, mass, weight, momentum (mass times velocity), impulse (the time integral of net force, or average net force times duration, equal to change in momentum), and work, power and energy relationships. Know levers: first, second and third class, with the body mostly using third-class levers (effort between fulcrum and load) favouring speed and range over force. Understand torque (force times perpendicular distance from axis) and how changing the moment arm alters rotation. Study projectile motion: angle, velocity, release height and gravity determine trajectory; in an ideal no-air-resistance model at a fixed release speed, the range-maximizing angle is below 45 degrees when release height exceeds landing height. Understand centre of mass, base of support, stability and balance, plus angular momentum and conservation of angular momentum in spins and dives.
Traps
Confusing mass with weight; assuming a longer lever always improves performance: torque depends on the perpendicular force arm, and endpoint speed also depends on angular velocity; thinking 45 degrees is always optimal; ignoring air resistance; and muddling impulse (force over time) with force alone. Another trap is using the wrong lever class for a body segment.
Worked example
A gymnast tucks to spin faster. Reducing the radius of gyration reduces moment of inertia; when external torque is negligible, approximately conserved angular momentum means, angular velocity rises. Rule of thumb: smaller radius, faster spin; larger radius, slower spin. For catching a ball, a player 'gives' with the hands to extend impact time, reducing the force for the same change in momentum (impulse-momentum relationship).
Rule of thumb
When asked how to increase stability, lower the centre of mass, widen the base of support, and align the centre of mass over the base.
Calculate under stated assumptions
A supplied average net force of 200 newtons acting for 0.10 seconds gives an impulse of 20 newton-seconds. For a 2 kilogram object, that impulse changes velocity by 10 metres per second in the force direction. The values are hypothetical and do not describe an injury threshold. If a catch brings the same initial momentum to rest over a longer time, the required average net stopping force is smaller, but peak forces and the actual force-time curve still matter.
For a lever, draw the axis, effort and resistance before naming its class. Use perpendicular moment arms when computing torque, not merely the distance measured along a tilted limb. State whether gravity, friction, air resistance and external torque are being neglected. A mechanically convenient model explains a chosen feature without reproducing every force in a living body.
Exercise Physiology, Energy Systems and Training
This domain links acute responses and chronic adaptations to the three energy systems. Compare the ATP-PCr (phosphagen) system (rapid ATP resynthesis for brief intense work, without directly requiring oxygen in that reaction), glycolysis (rapid ATP production from carbohydrate, with lactate formation supporting continued flux under relevant conditions) and oxidative metabolism (oxygen-dependent ATP production using carbohydrate and fat, with its rate and contribution changing during exercise). Understand the interplay: all systems contribute at all times, with dominance shifting by intensity and duration. Know acute responses (heart rate, stroke volume, cardiac output, ventilation, blood pressure, temperature, sweating) and chronic adaptations (cardiac hypertrophy, increased stroke volume and capillary density, mitochondrial and enzyme changes, improved lactate tolerance).
Understand training principles: specificity, overload, progression, reversibility, individuality, variety, recovery and periodisation. Know FITT (frequency, intensity, time, type) and methods including continuous, interval, fartlek, resistance, plyometric and flexibility training, plus how each targets a system. Know VO2 max, lactate threshold, steady state, oxygen deficit and excess post-exercise oxygen consumption.
Traps
Claiming one system works alone; confusing lactate with lactic acid as the sole cause of fatigue; assuming fat is used only at low intensity (it is used across intensities, but proportionally less as intensity rises); and mixing acute responses with chronic adaptations. Another trap is applying overload without recovery.
Worked example
A 400 m sprint lasts about 50-60 seconds. Anaerobic glycolysis dominates, with ATP-PCr at the start and aerobic contribution rising late. Duration bands are teaching approximations, not switches that turn pathways on and off. The actual mixture depends on intensity, duration, training and how contribution is measured. Relate work and recovery to the actual aim and the individual. The same event can require technical, oxidative and high-rate ATP work; an assessment question does not establish a universal prescription.
Rule of thumb
Match the training method to the energy system and the sport's work-to-rest profile.
Separate a stimulus from its outcome
Specificity links the training demand to the desired adaptation. Overload changes a meaningful demand relative to the learner’s current capacity; progression manages how that demand changes over time. A larger workload is not automatically a better program if recovery or technique deteriorates. Reversibility describes loss of an adaptation when the relevant stimulus is reduced sufficiently, not an exact decline after a universal number of days.
Compare a plan with the sport’s actual demands, baseline and constraints. Record the supplied frequency, intensity, duration and type, then explain which variable changes. A hypothetical athlete completing four repetitions instead of three increases repetition volume by one third when the other factors are fixed. Do not invent energy-system percentages, recovery deadlines or a universal weekly 10 percent rule. Persistent unexplained symptoms require appropriate assessment rather than a paper-based diagnosis of overtraining.