Answer:
Step-by-step explanation:
There are a wide range of variables that can effect a marathon runner such as
Physical Fitness State
Mental Health State
Endurance levels
Weather
Environment
Hidration levels
etc.
As seen by the list above there are countless variables that can affect a marathon runner, the two main ones being their Physical and Mental Health state. If a runner is not physically prepared for a race then their body can easily turn on them and they can suffer from muscle cramps, fatigue, fainting, etc. While at the same time, if the runner is not mentally prepared for a race they can quickly lose interest and the desire to win/finish which are crucial.