Ventilatory threshold is a great tool for estimating training intensity in the field. The Talk Test was first used by Professor John Grayson of Oxford University in 1939. The talk test was used to advise English mountaineers to “climb no faster than you can talk”. In more recent times, it is referred to as “conversation pace”. Recent research has found a close correlation exists between the ability speak and training intensity.
Below Ventilatory Threshold 1 (<VT1)
Below VT1, the majority of energy production comes from fat and lactate is easily metabolized. The ability to speak comfortably and carry on a conversation is a good way to assess if you are below VT1/aerobic threshold in training and in the mountains. The ability to speak in full sentences, recite the alphabet or speak for 10 seconds is considered comfortable. As you approach the aerobic threshold/VT1, talking in complete sentences will become more challenging.
Ventilatory Threshold 1 (VT1)
Ventilatory Threshold 1 is the point at which ventilation starts to increase in a non-linear fashion. It is the point of transition where the body is using more carbohydrates than fat for energy production. It is also the point at which lactate is produced faster than it can be cleared by the body. At Ventilatory Threshold 1, continuous talking is no longer comfortable. Conversation will become limited to a few words at a time to short sentences. Training at VT1 is approximately the highest intensity that can be sustained for one to two hours of exercise in well trained athletes.
Ventilatory Threshold 2 (VT2)
VT2 is a close approximation to OBLA (onset of blood lactate accumulation). OBLA is the point that blood lactate accumulates faster than the body can metabolize it. Talking at VT2 will be limited to a few words. Training at VT2 is approximately the highest intensity that can be sustained for 30-60 minutes in well trained individuals.
Above Ventilatory Threshold 2 (>VT2)
Exercise above VT2 is very high intensity training. Above VT2, talking is almost impossible. Exercise above VT2 can be sustained for 30 seconds to a few minutes (in elite athletes) due to an accumulation of blood lactate. The higher the intensity you train at above VT2, the shorter the amount of time you can sustain that intensity.
Ventilatory thresholds are a powerful tool for endurance athletes to quickly assess training intensity in the field. Knowing if your pace is sustainable for seconds, minutes or hours is crucial to success on an all day or multi-day endurance effort in the mountains.