This video shows you how to identify ventilatory thresholds VT1 and VT2 (approximately LT1 and LT2) without expensive lab equipment. You can then calculate your training zones using either a 3, 5 or 7 zone model.
The test involves progressively increasing the effort to the point where you notice an inflection in respiration. The first change is where the metabolism starts to rely on glycolisis which produces lactate. Some of the lactate is used as fuel by slow twitch muscle fibres but the rest is buffered with bicarbonate which produces CO2 as a by-product. This CO2 creates a respiratory response. The energy system is in equilibrium but the effort is harder than below VT1.
Increasing effort further and at some point lacate buffering is no longer sufficient and lactate begins to accumulate. Respiration is much heavier in an attempt to remove CO2. This point is VT2.
Note your heart rate at both inflection points. If you move over and under this point you should be able to notice your respiration changing and zoom in on the HR or power at which this occurs.
In a 5 zone model zone 1 and 2 are below VT1. Zone 3 and 4 are between VT1 and VT2 and Zone 5 above VT2. In a 7 zone model divide VT2+ into 3 zones.