FortyFive › Revision notes › IB Sports, Exercise & Health Science revision notes
IB Sports, Exercise & Health Science revision notes Group 4 · Sciences · SL / HL
A.1 is about how the body sends messages: fast electrical signals through nerves, and slower chemical signals through hormones. Both control how you move and respond to exercise.
Course topics A.1 · Communication · Nervous and endocrine systems, motor units, feedback · 2 subtopics A.2 · Hydration and nutrition · Water balance, macronutrients, energy for exercise · 2 subtopics A.3 · Response · Energy systems, cardiorespiratory response, training adaptations · 3 subtopics B.1 · Generating movement in the body · Joints, muscles, levers, types of contraction · 3 subtopics B.2 · Forces, motion and movement · Newton's laws in sport, momentum, projectiles · 3 subtopics B.3 · Injury · Types of injury, risk factors, prevention, rehabilitation · 2 subtopics C.1 · Individual differences · Personality, mindset, talent · 1 subtopics C.2 · Motor learning · Skill classification, stages of learning, feedback, practice · 3 subtopics C.3 · Motivation · Intrinsic and extrinsic motivation, goal setting · 1 subtopics C.4 · Stress and coping · Arousal, anxiety, coping strategies · 2 subtopics C.5 · Psychological skills · Imagery, self-talk, relaxation, routines · 1 subtopics Free lesson: A.1 · Communication Nervous system Fast, short-lived signals: brain, spinal cord and nerves Endocrine system Slower, longer-lasting signals: hormones carried in the blood Motor unit One motor neuron plus all the muscle fibres it controls Neuromuscular junction: an impulse reaches the end of the motor neuron and releases acetylcholine , which triggers the muscle fibre to contract.All-or-none law: when a motor unit fires, all its fibres contract fully. More force comes from recruiting more motor units.Small motor units (few fibres) give fine control, e.g. eyes and fingers. Large motor units give power, e.g. quadriceps.Negative feedback, blood glucose: glucose rises → pancreas releases insulin → cells take up glucose. Glucose falls → glucagon → liver releases glucose.Adrenaline prepares the body for exercise: raises heart rate and breathing rate, and makes glucose available.Worked example Explain how a sprinter produces more force at the end of a race than at a steady jog.
Each motor unit follows the all-or-none law, so a single unit can't contract “harder”. To increase force, the nervous system recruits more motor units. It also recruits larger, fast-twitch motor units. It increases the frequency of impulses, so fibres stay contracted for longer. Common mistakes Saying a muscle fibre can contract “a little”. Individual fibres follow all-or-none. Mixing up insulin and glucagon. Forgetting to name the neurotransmitter (acetylcholine). Using revision material from the old six-topic syllabus without checking it. Quick check What is a motor unit? A motor neuron and all the fibres it supplies . One motor neuron plus all the muscle fibres it controls.
Which neurotransmitter is released at the neuromuscular junction? Acetylcholine . Acetylcholine crosses the gap and triggers muscle contraction.
After a meal, blood glucose rises. The pancreas releases… insulin . Insulin helps cells take up glucose, lowering blood glucose (negative feedback).
Muscles that need very fine control have… small motor units . Few fibres per motor neuron allows precise, small movements.
FAQ What topics are in IB Sports, Exercise & Health Science? IB Sports, Exercise & Health Science (SL / HL) is organised into: A.1 · Communication; A.2 · Hydration and nutrition; A.3 · Response; B.1 · Generating movement in the body; B.2 · Forces, motion and movement; B.3 · Injury; C.1 · Individual differences; C.2 · Motor learning; C.3 · Motivation; C.4 · Stress and coping; C.5 · Psychological skills.
Are these IB Sports, Exercise & Health Science notes free? Yes. The topic pages, key terms and the first lesson are free. The full lessons, interactive diagrams and exam-style practice papers with mark schemes are in the FortyFive app, which you can start for free.
← All subjects
All notes, examples and questions are written by FortyFive. FortyFive is an independent resource, not affiliated with or endorsed by the International Baccalaureate Organization. “IB” and “International Baccalaureate” are trademarks of the International Baccalaureate Organization.