Notes to help understand the physiology of training and make yours as effective as possible! Your target heart rate can guide you to how hard you should exercise so you can get the most aerobic benefit from your workout. 




Zone 1 Sessions

The purpose of training Z1 is to raise your aerobic threshold speed and build your aerobic base. This is the type of training required to train your slow twitch muscle fibres and teach the intermediary fibres lactate removal. The aerobic threshold determines how we perform in events that are 2 hours or more, and is the foundation that all other thresholds/zones are built upon. It is best trained by heart rate (HR) because most of us do our zone 1 work outside. Although we provide speeds/paces for Z1, as soon as the grade changes then speed/pace is no longer an accurate way of determining which zone you’re in.

Zone 2 Sessions

For the most part, Z2 is a junk miles zone. Spending significant amounts of time in Z2 teaches the intermediary muscle fibres to behave like fast twitch fibres causing a detraining effect (more lactate is produced). However, events of 60-120 min, such as a half marathon, are raced in Z2 so if your race requires Z2 then a small portion of training time should be spent in this zone as you get 6-8 build weeks from the race.

Zone 3 Sessions

The purpose of a Z3 session is to raise your lactate threshold speed. This threshold determines how we perform in events 20-60 min in length. In some cases it can act as a limit on our ability to raise the aerobic threshold. It is most effectively trained by doing a 30 min all-out run using variables other than HR to monitor the session (e.g. speed/ pace/ time / distance). HR is not an accurate measurement for this zone due to the natural HR drift, lag and variability during a session caused by body temperature or dehydration.

Zone 4 Sessions

Z4 is an event specific zone – you train it if it is relevant to your event (e.g. 5 K) - race pace training similar to Z2. Events that require repeated medium length, high intensity bursts (3-10 minutes) use this zone.

Zone 5 Sessions

The purpose of a Z5 session is to improve your max aerobic speed. Your max aerobic speed determines how we perform at events that are 2-5 minutes long and can potentially act as a limiting factor to the improvement of your aerobic and lactate thresholds. Improving your max aerobic speed is accomplished through longer traditional interval sessions between 1-3 minutes using time and distance as your markers followed by a 2-6 min recovery in Z1 or below to maximize recovery between intervals. Focus on quality, not quantity.

- Lewis Morrison

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