I’m assuming that there is a diff in energy systems between 6 min on the rivet and around 4 minutes (although not much)…in the range of 4 gets a good athlete there for a 1500m at the track, 4000m pursuit, or 400m swim 
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I’m assuming that there is a diff in energy systems between 6 min on the rivet and around 4 minutes (although not much)…in the range of 4 gets a good athlete there for a 1500m at the track, 4000m pursuit, or 400m swim
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