If you missed the introduction to Training Zones click here.
When we discussed Zone 1, it was all about performing your workout at an intensity where not enough stress is applied to your body to illicit any training adaptation. With Zone 2 we cross that threshold in order to start stressing our aerobic system. Simply stated your aerobic system uses the oxygen you breath in to create the energy your muscles need to perform the repetitive movements you need for endurance sports. The more efficient your body is at doing this, the better your performance will be in your sport. During longer races and events your aerobic system is the primary factor determining your performance. The shortest endurance races and events are still 15-60min in length, meaning your aerobic system is still a main contributor to your success. So clearly, this is an important training zone for endurance sports and that is why most of your training time is spent in this zone.
Improving aerobic fitness in this zone leads to building stronger heart muscle, increased number of mitochondria in cells, increased number of capillaries in muscles, and an improvement in stamina. These adaptations lead to increased efficiency in your aerobic system meaning you can perform your sport for longer and at a lower perceived effort meaning you will have more in the tank for harder efforts. Zone 2 is truly the foundation you build on top of for endurance sports.
It should also be mentioned that a lot of your training is performed in this zone because you can feasibly do so. For example, performing intervals in higher training zones every day is not possible or at least performing them with some level of quality and without injuring yourself is not possible. On the other end, training in Zone 1 could be done for eternity but you wouldn’t be working hard enough to reap real benefits from said training. Zone 2 doesn’t create so much stress that it will impede your training the next day, unless it is a particularly long run or ride, but still provides you a benefit.
The most straightforward way to perform a Zone 2 workout is simply to ride, run, or swim in Zone 2 for a whole workout aside from a brief warm-up and cool-down in Zone 1. These should be your longest workouts of each week and depending on your sport, ability, amount of training, and goal race/event these can be quite long workouts. They can be 5+hrs rides, 2+hr runs, and 1+hr swims as long as you are ready for that and your training goal requires it. They are low intensity and you should be able to carry on a conversation during these workouts, but can be fatiguing especially during your longer workouts in this Zone. The hard part in fact is again not going too hard. Where these are longer rides, you are likely to encounter hills, wind, etc. that will cause increases in your power, pace, or heart rate, but the key is to simply try and keep your effort in Zone 2 as much as possible throughout the ride. You can also find yourself going to easy during these workouts. Since you know Zone 2 should be easy, sometimes you can find yourself going to easy, so just make sure that you keep your effort above the bottom end of this zone’s intensity.
Just like Zone 1 workouts, Zone 2 workouts can seem a bit boring but now are much longer than Zone 1 workouts and hence boring for longer. So sometimes these workouts need to be spiced up. While most of your Zone 2 workouts should be only Zone 2 to maximize the adaptations listed above as well as save some energy for future workouts, from time to time you can insert other workouts or workout elements into a Zone 2 workout. One way would be to front load a long Zone 2 workout with a different workout early on. For example, perform some intervals in the first hour of a ride while still fresh, then ride in Zone 2 for the rest. Another way would be to insert a fast or race finish near the end of a Zone 2 workout. For example, run your long run at Zone 2 pace until the last 10-15min where you pick up the pace to your half marathon pace to simulate running that pace on tired legs as you would at the end of a half marathon. Don’t forget to cool down after. Lastly, you could intersperse small efforts throughout a longer Zone 2 workout. For example, every 15min during a 4 hour ride, you could stand up and sprint for ~8sec to a telephone poll or other marker. Just make sure that these additions don’t change your easy paced Zone 2 workout into something completely different. You should still have your longest rides/runs/swims for most weeks be pure Zone 2 for maximum stress to that energy system.
Zone 2 workouts are also often inserted into your training weeks on easier days between the hard days. You are still getting a training benefit with these workouts but are not getting yourself too fatigued to perform the harder workout the next day. When treated this way they are often not your longest workout of the week, but of more of a medium length. For multisport athletes, performing a Zone 2 workout after or later the same day as a harder workout in a different sport is also a good way to utilize them. Zone 2 workouts are essentially a utility workout that you can pencil in whenever you’re not sure what else to slot in.
Running ~87% of FTP
86-91% of FTHR 2-3 RPE
Cycling 56-75% of FTP 69-83% of FTHR 2-3 RPE
Swimming FTP + 6-10sec/100yds(m) 6-7 RPE
Duration: 30min-Several Hours
Continue reading about Zone 3 here.