IB SEHS unit 2

Phosphagen (ATP–CP) system

The energy system that provides immediate ATP using creatine phosphate; dominant for 0–10 seconds of maximal effort.

Glycolytic (anaerobic) system

Produces ATP from glucose without oxygen; dominant during high-intensity efforts lasting ~10–90 seconds and produces acidity (H+).

Oxidative (aerobic) system

Produces ATP using oxygen from carbohydrates and fats; dominant at rest and during long-duration submaximal exercise.

Energy continuum

All energy systems are always active, but their contribution depends on intensity and duration.

Why ATP–CP is used for explosive movements

It produces ATP the fastest and does not require oxygen.

Glycogen storage

Stored in the liver and skeletal muscles.

High muscle oxygen availability favors

Use of carbohydrates and fats.

Most ATP is produced by

The electron transport chain.

Creatine phosphate role

Rapidly resynthesizes ATP from ADP during short, intense exercise.

Stroke volume (SV)

Amount of blood pumped from the heart per beat.

Heart rate (HR)

Number of heartbeats per minute.

Cardiac output (Q)

Heart rate multiplied by stroke volume.

Why cardiac output increases at maximal exercise

Mainly due to increased heart rate.

Systolic blood pressure (SBP)

Pressure in the arteries during ventricular contraction.

Diastolic blood pressure (DBP)

Pressure in the arteries during ventricular relaxation.

Why SBP increases during exercise

Increased cardiac output.

Why DBP remains stable during aerobic exercise

Vasodilation in working muscles reduces peripheral resistance.

Why DBP increases during heavy resistance training

Increased peripheral resistance from muscle compression.

Blood flow during exercise

Increases to skeletal muscles and decreases to digestive organs.

Trained athlete oxygen delivery

Increased stroke volume.

Lower resting HR in trained athletes

Higher stroke volume and cardiac efficiency.

Cardiovascular drift

Increased heart rate and decreased stroke volume during prolonged exercise due to fluid loss and increased body temperature.

Ventilation

Movement of air into and out of the lungs.

Inhalation mechanics

Diaphragm contracts, thoracic volume increases, and pressure decreases.

Primary muscles of inspiration

Diaphragm and external intercostals.

Why ventilation increases during exercise

Increased carbon dioxide and decreased blood pH stimulate chemoreceptors.

Why ventilation increases when blood pH drops

To remove carbon dioxide and reduce acidity.

Expiratory reserve volume (ERV)

Air that can be forcibly exhaled after a normal exhalation.

Why ERV decreases during heavy exercise

Increased breathing frequency limits full exhalation.

Central nervous system (CNS)

Brain and spinal cord.

Peripheral nervous system (PNS)

Nerves outside the central nervous system.

Somatic nervous system

Controls voluntary skeletal muscle movement.

Autonomic nervous system (ANS)

Controls involuntary bodily functions.

Sympathetic nervous system

Fight-or-flight system that increases heart rate, stroke volume, and blood glucose.

Parasympathetic nervous system

Rest-and-digest system that decreases heart rate.

HR increase at exercise onset

Caused by decreased parasympathetic activity.

Proprioceptors

Receptors that detect body position and movement.

Baroreceptors

Receptors that detect changes in blood pressure.

Chemoreceptors

Receptors that detect changes in oxygen, carbon dioxide, and pH.

Hormones

Chemical messengers released into the bloodstream to regulate body processes.

Epinephrine and norepinephrine

Hormones that increase heart rate, blood pressure, and blood glucose.

Insulin

Hormone that lowers blood glucose by promoting uptake and storage.

Glucagon

Hormone that raises blood glucose by breaking down glycogen.

When blood glucose decreases

The body increases glycogenolysis.

When blood glucose increases after eating

The body releases insulin.

Antidiuretic hormone (ADH)

Hormone that increases water reabsorption in the kidneys.

Homeostasis

Maintenance of a stable internal environment.

Negative feedback

A mechanism where the response reverses the initial change.

Blood pH regulation

Controlled by respiration removing carbon dioxide.

Water and electrolyte balance

Essential for temperature regulation, blood volume, and muscle function.

Fluid loss occurs via

Sweat, respiration, and urine.

Dehydration effects

Decreased plasma volume, increased heart rate, reduced stroke volume, and decreased performance.

Hypernatremia

Excess sodium relative to water.

Hyponatremia

Low blood sodium caused by excessive water intake.

Hyponatremia risk increases with

Excess water consumption.

Sign of poor hydration

Decrease in body mass.

Electrolyte balance regulated by

Hypothalamus, pituitary gland, and kidneys.

VO2 max

Maximum rate of oxygen consumption during exercise.

High VO2 max indicates

Strong aerobic capacity.

VO2 max influenced by

Age, sex, body composition, fitness level, and lifestyle.

Highest VO2 max expected in

Marathon runners.

Why high VO2 max improves submaximal performance

Lower relative effort and delayed fatigue.

a-vO2 difference

Difference in oxygen content between arterial and venous blood.

Training increases a-vO2 difference

Improved oxygen extraction by muscles.

Internal attentional focus

Focus on body movements.

External attentional focus

Focus on the outcome or environment.

Broad attentional focus

Attention to multiple cues at once.

Narrow attentional focus

Attention to one specific cue.

Analyzing strategy during play

External-broad attentional focus.

Distraction

Attention directed away from task-relevant cues.

Controlled distraction

Deliberate shift of attention to manage stress.

Arousal

Level of physical and psychological activation.

Inverted-U theory

Performance increases with arousal up to an optimal point, then decreases.

Individual zone of optimal functioning (IZOF)

Personal arousal range for optimal performance.

Cognitive anxiety

Mental worry and negative thoughts.

Somatic anxiety

Physical symptoms such as sweating and increased heart rate.

Catastrophe theory

High cognitive and somatic anxiety cause a sudden drop in performance.

Limitation of self-report anxiety tests

Timing affects results.