This is a chart showing pushrod load traces. The 2,000 rpm load is what you would expect to see. By 5,000 rpm, the load over the nose is still the maximum. Peak opening load is roughly twice what it was at 2,000 rpm. The 7,000 and 9,000 rpm traces show how the loading of the pushrod has changed significantly. This is due to the dynamics of the system. The time the cam spends opening and closing the valve at 9,000 rpm is a fraction of what it was at 2,000 rpm, so the load required must increase.