Speed hills

Did a few hills last night with Tony's group. Instead of the usual 300m run we did some short sharp bursts. Two hills at right angles to each other. 80m up the first one, fast, 50m down the second slow. Then reverse it.

I ran well for the first few (about 5) really powering it up the hills and flowing well. But my back tightened a bit (probably due to the cold and the lack of warm up) so I eased off and stopped after 15 mins (of the planned 20). Not too concerned at the early stop as the quality and speed were good on the first few.