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It is that time of year again when the weather is perfect, it’s a beautiful time to enjoy the trails, and the events and races are on!


When it comes to preparing specifically for an endurance event, or simply training in cardio activities such as running, biking, or swimming; you want to keep your training out of the infamous “black hole”. It is named the black hole because it sucks the energy out of you without giving you the benefits. ACE (The American Council on Exercise), refers to the black hole as Zone 2 in cardiorespiratory fitness or the middle zone. In Zone 2 you are not working hard enough to produce the increases you want, and your body is not able to fully recover from that workout. ACE recommends keeping your training in Zone 1 or Zone 3.

To differentiate between the Zones, ACE Fitness uses specific percentages of your Maximum Heart Rate; Heart Rate Reserve; and VO2 Max. Since most recreational runners, bikers, and swimmers aren’t keeping track of their workouts in this manner, ACE also describes them as:

ZONE 1 – you can talk comfortably; you are working at a 3-4 effort on a scale of 1-10; you would rate it as “moderate” to “somewhat hard”


ZONE 2 - you are not sure that you can talk comfortably; you are working at a 5-6 effort on a scale of 1-10; you would rate it as “hard”.

ZONE 3 – you definitely cannot talk comfortably; you are working at a 7-10 effort on a scale of 1-10; you would rate it as “very hard” to “extremely hard”.


If you are going to put in the effort of training for a run, bike, or swim (whether you do an event or not), it’s good to have a plan, to be efficient with that plan, to stay healthy, and to have fun!

Part of that plan includes alternating easy and hard days and for the most part staying out of that middle zone. You want to stay away from doing two hard days in a row whenever possible.

HARD: Hard sessions include intervals, speed work, or your long distance day. Doing very hard sessions well is not possible if you have over-trained and are burnt out.

  • INTERVALS - An interval is a short intense effort often followed by an equal or longer recovery time. An interval can be a specific distance, such as 200m or 800m; or it can be a specific time such as running 2 minutes hard, and 3 minutes easy.

  • SPEED - A “fartlek” workout is Swedish for “speed play”. This is when you have defined periods of fast running, alternating with periods of slower running. It tends to be less calculated and more spontaneous than intervals.

The basic premise with both intervals and speed is the same; you want to focus on making your hard and fast sections of your workout exactly that – hard and fast. You want to do the slower sections of this workout ridiculously slow so that you can recover.

  • LONG DISTANCE - Although you will want your long distance day to be in the easy Zone 1, an endurance day is considered a hard day. You are taxing your body in other ways due to the sheer distance and longevity of the workout. Make sure you don’t drain your body doing double duty by running your long distance in Zone 2.


Easy days, allow you to recover from the hard days. These days are necessary as they increase mitochondria and capillaries in your body so that you become more efficient. It helps to keep your cardio base and without them you can’t do your intense runs. Even seasoned athletes need easy days in order to maintain hard-earned aerobic fitness and to make continual cardio gains. Pace is the most important thing to keep an easy day easy. You can still do hills on an easy workout, as long as you keep the pace slower and your heart rate down.

Dennis Barker, coach of Team USA Minnesota says, “Recovery is a training effect, maybe the most important one. It’s during recovery that adaptations from the hard training take place. If a runner doesn’t recover, the body is not going to adapt, and you’ll either continue digging a hole for yourself or get injured.”


  • Do not attempt to work on intervals, speed work, or long runs without first building a cardio foundation. Depending on what fitness level you are coming from, it is not advisable to add in endurance or speed until you have a foundation of doing 4 days per week of cardio for at least 2 – 6 weeks.

  • After having built a foundation, the next thing you want to focus on is to start increasing your long run.

  • Slowly add some intensity by doing some intervals, starting in that zone 2. You have to train in zone 2 before you can progress to zone 3. Start with longer, less intense intervals and work towards building up speed and going toward shorter, more intense intervals.

  • Eventually you can transition your zone 2 intervals and speed workouts to zone 3 which is similar to HITT.


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