Read on to get Phil's tips on how to earn more with your dive.

Last week I introduced an equation as a way of looking at a dynamic swim:

Stroke Cadence * Stroke Speed/force*Stroke Amplitude = Drag Coefficient* Speed

Last week we looked at the 'spending' side of the equation (Drag and Speed). This week I'm going to look at the earning side of the equation; the efficiency of our propulsion through the water.

Research has found that for a given amount of work done (force x distance) a muscle will use more energy contracting at faster speeds vs slower. In simple terms this means that a short sharp stroke that provides the same propulsion as a long slow stroke will use more energy. So, providing streamline is not compromised in the process, a longer, slower stroke will be more efficient in terms of energy consumption than a fast short stroke.

Ever watched a video of William Trubridge doing CNF? Note how long his arm stroke is. Next time you are doing CNF/DNF reach right up/out for the catch and push smoothly all the way through, remove anything that might be 'thrashy' from your stroke. It works a little differently with Bifins, if you exaggerate the stroke size too far inefficiencies will develop. These inefficiencies become worse with poor technique - watch out for limited ankle flexibility resulting in negative blade angles and bent knees creating 'thigh drag'.

Phil 'NoFins'

Training Officer, Auckland Freediving Club