How to re-assign two variables in a conditional UPDATE

Question

Consider a simple update as

SET @var1 = 20;
SET @var2 = 26;
UPDATE table1 SET
    col1=IF(@var1>50, @var1 := @var1-col4, @var1 := @var1+col5),
    col2=IF(@var2>50, @var2 := @var2-col6, @var2);

How we can change two variables in one condition. For example, consider that when @var1<50, we want to change not only @var1 := @var1+col5, but also re-assign @var2 := @var2 + 100. In fact, regardless of the condition 2, we want to increase @var2, if the first condition fails (the second part).

Is it possible to re-assign two user-variable in a IF STATEMENT or we need to add another IF STATEMENT?

This will be equivalent to

SET @var1 = 20;
SET @var2 = 26;
UPDATE table1 SET
    col1=IF(@var1>50, @var1 := @var1-col4, @var1 := @var1+col5),
    virtual_col=IF(@var1>50, NULL, @var2 := @var2+100),
    col2=IF(@var2>50, @var2 := @var2-col6, @var2);

Here we have created a useless column, not to collect the data, but to repeat the IF STATEMENT for the @var2. Obviously, it is not good from performance point of view, as we are running a useless UPDATE action.