Rick,

proc reg data=fitness plots=none;
model Oxygen = RunTime Age Weight RunPulse MaxPulse RestPulse / corrb;
quit;

I can get the following:
Variables Intercept RunTime Age Weight RunPulse MaxPulse RestPulse
Intercept 1.0000 0.1610 -0.7285 -0.2632 0.1889 -0.4919 -0.1806
RunTime 0.1610 1.0000 -0.3696 -0.2104 -0.1963 0.0881 -0.4297
Age -0.7285 -0.3696 1.0000 0.1875 -0.1006 0.2629 0.2259
Weight -0.2632 -0.2104 0.1875 1.0000 0.1474 -0.1842 0.1054
RunPulse 0.1889 -0.1963 -0.1006 0.1474 1.0000 -0.9140 -0.0966
MaxPulse -0.4919 0.0881 0.2629 -0.1842 -0.9140 1.0000 0.0380
RestPulse -0.1806 -0.4297 0.2259 0.1054 -0.0966 0.0380 1.0000

MaxPulse V.S. RunPulse = -0.9140
Age V.S. Intercept = -0.7285

The same result as yours .