The study found a negative coorelation. Coorelation is used to express associations between two variables. Negative coorelation coefficients mean that there is a general inverse relationship between the variables, i.e. as one increases the other decreases.

The coorelation coefficient, r, is the slope of the relationship found between the variables.

Here is a graphical depiction of coorelation.

R is always between -1 and +1, the closer the absolute value of r is to 1, the stronger the linear correlation between the two variables.

A negative r value means there is a negative correlation: as one variable increases, the other variable decreases.

In this case: r = -0.25, indicating a weak negative correlation. Meaning increased body fat is associated with lower lung capacity.

FA 2018 p.259