Neil Pratt: What are the pros and cons of level-pacing as opposed to rowing the first and last 500m segments faster than the middle two?Terry O'Neill: Level pacing is a simplification, what in fact is happening is you are going along at the highest sustainable pace. If you go off too hard then you have to cope with high lactate levels caused by oxygen debt. This will result in a slowing down in the latter stages of the race that will cost twice as much as early gains.The reason the first 500 metres is normally the fastest is because of the way the energy system kicks in. To start with you have instantly available energy in the muscles that will last for about 10 seconds. Replacing this fuel takes time and therefore work cannot continue at the same intensity but you can still blast off for the first 10 seconds and it is this that reduces the overall time of the first 500 metres.The last 500 metres is normally the second fastest because you empty your tanks on this one to finish exhausted.