Iron supports oxygen transport and aerobic energy production, calcium enables muscle contraction and maintains bone strength, while sodium and potassium regulate fluid balance, nerve impulses, and muscle function. Deficiency or excessive losses can therefore reduce health, exercise performance, and recovery.
Roles in health and performance
| Mineral | Physiological role | Effect on performance |
|---|---|---|
| Iron | Forms part of haemoglobin in red blood cells and myoglobin in muscle; supports aerobic energy production. | Adequate levels support oxygen delivery. Deficiency can cause anaemia, fatigue, breathlessness, and reduced endurance. |
| Calcium | Maintains bone. During contraction, calcium binds to troponin, moving tropomyosin and exposing binding sites on actin. | This supports force production; low intake may reduce bone density and increase stress-fracture risk. |
| Sodium | The main extracellular electrolyte; regulates fluid balance and helps generate nerve impulses and muscle action potentials. | Heavy sweat losses without replacement may reduce blood volume and impair endurance. |
| Potassium | The main intracellular electrolyte; maintains membrane potential and supports nerve impulses, muscle contraction, and heart function. | Abnormally low levels can cause weakness, fatigue, or irregular heart rhythms. |
Sodium and potassium concentration gradients across cell membranes permit action potentials. These signals stimulate muscle fibres, causing intracellular calcium release and initiating contraction. Together, the minerals link neural stimulation, muscular contraction, oxygen delivery, and aerobic energy production. This integration is essential during sustained and intense exercise.
A common misconception is that all exercise-associated muscle cramps result only from sodium or potassium deficiency. Electrolyte imbalance may contribute after heavy sweating, but neuromuscular fatigue and other factors can also be involved.
Exam technique
For IB SEHS subtopic A.2.2, connect each mineral to a physiological mechanism and a performance outcome. For example, iron forms haemoglobin, haemoglobin transports oxygen, and low iron availability can impair aerobic performance. Avoid listing food sources unless the command term requires them.
