Just read your feedback on heart rate - thanks for that.
So let's take an average resting heart rate (RHR) of 58 (midpoint between your 56-60)
Your age is 39 which means your age-predicted maximum (MHR) is 181bpm.
Using the Karvonen formula, can use this info to work out what your heart rate would be at different percentages of your maximum.
Eg. 75 per cent (steady run pace) = (MHR - RHR) x 75 per cent + RHR
75 per cent = (181-58)x75 per cent +RHR = 150bpm
85 per cent (tempo pace) = (181-58)x85 per cent + RHR = 162bpm
90 per cent (intervals pace*) = (181-58)x90 per cent + RHR = 168bpm
*On intervals, could be working as high as 99,100 per cent if v short with long recoveries.
So looking at your average HR across the 1000m intervals, you were working at between 85 and 90 per cent of your maximum. By the way - looking back at your results, you didn't take the full 90 second recoveries - you took 60 seconds instead. This would partly explain why your heart rate went up and up progressively...
Hopefully this formula will make sense to everyone. I'm terrible at maths so I am not sure how you use it 'in reverse' as in, plug in your heart rate to find out the percentage of max you were at. 