40% of the body warmth disappear by means of the head. If water is cold use then two swimming caps.
Swimming is what concerns physical work a good warming-up for cycling. For this reason these switch needs not be trained very intensive.
Running and bicycle training take advantage of each other.
In a sport it is almost impossible to do two successive days intensive interval training. In the triathlon you can do this because of the use of other muscle fibres. For example running and cycling.
Tip for swimmers and triatletes: swimming clothing made of lycra takes no water on and sits as a second skin. Because this way the water capacitance is less you will swim more rapidly.
The maximum heartbeat at swimming (freestyle) is 10 up to 15 beats lower than at running. This comes through the smaller use of active muscle fabric.
On the contrary to runners (at the most 2 time per week) swimmers can do 3, 4 time per week interval training.