Gordo's approach to learning how to use the green zones is practical. His method involves endurance testing:
Using a 20-minute loop (in his case, 3.9 km) and repeating three times continuously.
Transitioning from Zone One (Easy) in the first lap, to…
Zone Two (Steady) in the second lap, and to…
Zone Three (Moderately-Hard) in the final lap.
He emphasizes the importance of starting at the lower end of the designated zone in relation to heart rate and subjective perception, taking into account the heart rate drift that will inevitably occur during every loop. If the drift is controlled within a measure of 5-10 beats, it is likely that you are still within the desired zone. The heart rate zone should align with your subjective perception; otherwise, you may need to recalibrate your heart rate zones to match your current level of fitness.
Gordo underlines the significance of establishing a strong aerobic base before progressing to higher-intensity training. The test he suggests not only serves as a measure of your aerobic base but also doubles as a highly effective training session.
One of the training sessions I often prescribe is 15 minutes of Z1, Z2, and Z3; repeat this twice, which transforms it into a robust 90-minute aerobic workout for running or biking. For cycling, it is one of my favourite aerobic indoor sessions. When you are on the second set, be prepared that your heart rate is a few beats higher than the first set due to the heat generated.
Starting too fast is a common mistake, and Gordo’s advice to get to know the feel of your race pace by practicing it should be a crucial part of your training. I often prescribe sessions which include reps…
at
just above, and
below race pace,
…to get a good feel for what pace you can maintain for the duration of the event. If you use heart rate to guide you in an event, remember the following principles.
Your heart rate will be elevated prior to the event and during the very early stages thanks to the increased adrenaline in your system due to nerves and anticipation. Adrenaline is produced when we are alert or stressed in some way, which increases our heart rate in anticipation of what is to come.
After the first 5 minutes, once you have settled into your pace, your heart rate will stabilise and become more indicative of the zone you are in.
Always use subjective perception of your zone as a primary guide, but heart rate, pace (running), and power (cycling) will also give useful feedback.
Be prepared for heart rate drift when fatigue sets in as it takes more effort to maintain a certain pace. Zone 2 will become Zone 3 at the same pace and Zone 3 will become Zone 4, also subjectively.
This brings me back to my earlier discussion on heart rate drift. Several readers have pointed out that, besides it being affected by fitness level, nutrition, hydration and the onset of sickness, heart rate response can also be influenced by heat, cold and altitude.
This is true.
In addition to the blood flowing to the working muscles, extra blood flow to the skin is required to enable heat dissipation when heat and humidity are high, resulting in a higher cardiac output through increased heart rate. Our heart rates rise above normal when environmental temperatures exceed 20 degrees and humidity above 70%. That is a generalisation as there are individual differences in heat tolerance. A more conservative approach is required when training and racing in extreme temperatures. The increased heart rate response is a warning that needs to be managed by pace adjustment, hydration, and cooling methods.
Under cool conditions, we expect the heart rate to be elevated as well, given the increase in metabolic rate to keep the body warm. There is also more restriction of blood flow to the skin, with narrowing of the arteries, which creates more resistance in the circulation, forcing the heart to work harder. While we expect our heart rate to be up when exercising in cooler temperatures, many of us experience the opposite and find it harder to achieve the desired heart rate before our body has warmed up properly. This might have something to do with some loss of contractile capacity of our working muscles when cold. Wearing plenty of clothing to protect the body from the cold minimises the effects of colder temperatures on heart rate.
The effects of altitude on heart rate response have been extensively discussed in my series on altitude training, published previously in Endurance Essentials.
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