As part of a study investigating symptoms mountain climbers experience at high altitudes, researchers looked at the skeletal muscle tissue of a random sample of climbers. Each trained for two weeks on a bicycle, either at a normal oxygen supply or under hypoxic conditions corresponding to an altitude of 13,000 ft. They also were assigned to train at either a high or low level of energy expenditure. The percent change in vascular endothelial growth factor mRNA was measured and all relevant assumptions were confirmed. Below is a table of their results:

Effect df. F p-value

O2 supply 1,60 16.05. <0.001

Energy

Expenditure 1,60 5.78. 0.009

O2 Supply*Energy. 1,60 1.14. 0.207

Ep.

1. What is the appropriate conclusion for each main effect and the interaction between oxygen supply and energy expenditure on growth factor mRNA