It is not uncommon for a litre of sweat loss to contain well over 1000mg of sodium. This can mean that an athlete losing 2.5 litres of sweat per hour may easily lose  over 5000mg (5g) in just 2 hours. This easily exceeds the recommended daily sodium intake in just 2 hours of exercise and highlights the importance of sodium replacement in best practice hydration strategies.
As potassium is widely found in fresh fruits and vegetables and the relatively small amount lost in sweat during exercise, athletic performance is not always impacted in well-nourished individuals.
Potassium is vital for heart and skeletal function and can be depleted from activities that place stress on the body, be it athletic, lifestyle of sickness, so if this is the case potassium supplements may be required.
SOS has a small amount of potassium in its formula as potassium plays an important part in regulating sodium absorption.
Magnesium is important for muscle function process, an imbalance can effect performance both physically and athletically, this effect is exacerbated in hot and humid environments.