After running in a marathon race in july, joshua felt weak and his body weight was about 3% less than before the race. based on this information, joshua was probably suffering from

Dehydration

Explanation:

Dehydration is the condition of the body which involves the loss of body fluid compared to the amount of water the body gets. Water is an important constituent of the human body making up to about two-third of the body. The normal body metabolism is affected when the amount of water in the body drops below the required level of water necessary for optimal functioning of the body.

Athletes usually suffer from dehydration, most especially long distance runners, as they tend to lose a lot of body fluid through sweating while the body tries to regulate the body temperature during the race. When the body is dehydrated, the heart works harder to pump blood to various parts of the body leading to loss of strength of the muscles.

Common signs a dehydrated person shows include feeling tired and lightheaded, loss of body weight etc.