As we could often notice (cfr. many of our Comments to races), the gradient of a climb greatly influences the VAM performance of athletes: the higher the gradient in percentage, the higher the VAM values developed by the riders. 

But how much does the VAM increases for every grade in climbing, with the cyclist keeping a constant power output? 

Repeated measuring on a climb with a rider weighing 64 kg and pedaling at 300 watts gave the following results: 

5% gradient = 1180 VAM (m/h) 
6% = 1215 m/h 
7% = 1250 m/h 
8% = 1290 m/h 
9% = 1340 m/h 
10% = 1400 m/h 
11% = 1475 m/h 
12% = 1565 m/h 
13% = 1675 m/h 

As we can clearly see, VAM values exponentially rise up with every gradient increase.