Training Heart Rate Range (THRR)

Monitoring your heart rate allows you to maximize the effectiveness of your training. By knowing your Training Heart Rate Range (THRR), you can adjust your effort to work within those values, based on your goals for each workout.

Use the formulas on this page to determine your approximate THRR. For more accurate calculations, visit your physician and have a stress test done.

To determine your THRR you need to first determine the following values:

  • Maximum Heart Rate (MHR)
  • Resting Heart Rate (RHR)
  • Heart Rate Reserve (HRR)


The rule of thumb for MHR used to be 220 minus your age. However, recent studies have shown 205.8 – (0.685 × age) to be a more accurate guide.¹

¹ The Surprising History of the “HRmax=220-age” Equation, Robert A. Robergs and Roberto Landwehr, Journal of Exercise Physiology Volume 5 Number 2 May 2002.

You can also:

• Run or bike up a steep hill for about 2 minutes twice. Use your heart rate monitor or count your heart rate immediately after you stop each time for 10 seconds and multiply it by 6.

• Use the highest number you have recorded during Max VO2 Test, intensity workout, race or time trials.

To determine your RHR, take your pulse first thing in the morning, before engaging in any significant activity (ideally, before you get out of bed). For greater accuracy, do this for several days and average the results.

HRR = MHR minus RHR

Training Heart Rate Range

To determine your THRR, take percentages of your HRR and add them to your RHR. The percentage you take depends on whether you are doing aerobic or anaerobic threshold training:

  • For aerobic training, take 50–75% of your HRR and add it to your RHR
  • For anaerobic threshold training, take 80–85% or your HRR and add it to your RHR


A 50-year-old with an RHR of 62 results in the following values:

  • MHR: 205.8 – (0.685 x 50) = 172
  • HRR: 172 – 62 = 110
  • THRR for Aerobic Training: 115–143 beats per minute (bpm)
  • THRR for Anaerobic Threshold Training: 148–154 bpm



CXC Academy, how do you calculate the training hours per week in your training plans?

A great question! While training down to the exact second isn’t necessary for better results, it is good to know how the hours add up. The following components are all calculated into the total hours. The one thing that is worth noting is recovery time. Since many of our workouts require a recovery period dictated by heart rate, we include approximate recovery time into our total hours.

Here is what is included in the total hours:


Warm Up / Cool Down
Distance / Over Distance


Anaerobic Threshold Intervals


General Max VO2 Intervals


Specific Speed


General Strength
Specific Strength

New book: Too much exercise can hurt the body’s most important muscle

“Haywire Heart” provides research, case studies

by Mike Ivey

I still remember when I realized something was seriously wrong.

It was the day after my birthday five years ago and our regular Sunday morning group was rollerskiing on a country road near Cottage Grove.

Within the first 15 minutes I’d already fallen far behind and was short of breath. My buddies had to wait up for me and one of them joked I must have had one too many the night before.

“No. I’ve skied with a hangover before,” I said. “This is way different.”

On their advice, I cut the workout short and headed back to the parking lot. The next day I called my doctor who told me to come right in.

I explained to my MD that I’d been feeling gassed the past few weeks when I tried to do anything aerobic. Even going up stairs left me breathing hard—scary stuff for someone who thought they were in pretty good shape for an aging baby boomer.

So he listened to my heart. “You’re missing some beats,” he said. I was then hooked me up to an electrocardiogram machine which confirmed my heart was badly out of rhythm.

Unfortunately, it’s become a familiar story for many people as they continue to train hard into middle age. Spend much time around serious endurance athletes these days—the kind who do Ironman triathlons or take 100-mile bike rides—and you’re bound to hear stories about heart problems.

There is a growing body of medical evidence suggesting a lifetime of aerobic exercise can indeed cause heart arrhythmia, a serious condition where the four chambers of the heart are not beating in the proper sequence. I can personally name a dozen friends and competitors dealing with arrhythmias of one sort or another.

Given that we’ve been told for years that exercise is good for you, it seems counter intuitive to think it can actually mess with the proper functioning of your heart. If you’re looking to set a PR in a marathon or just keep up with your pals on the next bike ride, you need that heart working as efficiently as possible.

But studies are showing that long hours of training over decades can indeed change the physical makeup of the heart muscle, throwing off the complicated electrical system that keeps it working properly. Some reports even claim endurance athletes are five times more likely to develop an arrhythmia than the general population.

A new book titled “Haywire Heart” does an excellent job of walking the line between alarmism and reality. It’s co-written by Lennard Zinn, a former U.S. national cycling team member and American Birkebeiner skier; John Mandrola, a cardiac doctor and lifelong runner and cyclist; and Chris Case, managing editor of VeloNews, a sister publication to VeloPress, and author of the article “Cycling to Extremes” that brought the heart issue to national attention.

The Haywire Heart by Lennard Zinn, Dr. John Mandrola, and Chris Case

You don’t usually die from a heart arrhythmia but the condition can lead to strokes or even cardiac arrest in the most serious cases. Atrial fibrillation, or “AFib,” is perhaps the best known since there are lots of TV ads currently touting a blood-thinning drug used to offset the increased stroke risk from it.

Still, exercise-induced arrhythmia is a tricky issue for health officials given the nation’s growing obesity epidemic. The multi-billion-dollar fitness industry also doesn’t want to broadcast that a lifetime of working out could cause some serious heart problems.

Both Zinn and Mandrola have experienced heart rhythm problems that have caused them physical and emotional distress. Serious athletes are often the kind of people who like to drive themselves harder than they probably should. They learn to suffer and learn to love the suffering.



To that end, the book takes special aim at those who may not want to hear the news or think they aren’t hurting themselves with obsessive exercise. The authors aren’t worried about retired Tour de France pros but rather than the weekend warriors.

“It’s the middle-aged people who think they’re training to race the Tour who can’t seem to stop themselves from pushing so hard for so long,” they write.

The 309-page book from Boulder, Colorado-based Velo Press in is certainly the most exhaustive look yet at the issue. It includes chapters on heart function and physiology that even the authors admit might be more information than most readers need.

But where “Haywire Heart” really shines are in the case studies of citizen athletes who have seen their lives turned upside down because of heart arrhythmia. For many of us, things like biking, running or cross-country skiing aren’t just ways to stay in shape. They become a focus of our social lives and a defining part of who we are.

The book acknowledges there is no simple answer to avoiding exercise-induced arrhythmia or dealing with it once it develops. Reducing the volume and intensity of exercise is the best antidote, the authors suggest, along with staying hydrated, watching the alcohol and eating a healthy diet. I was also glad to read about new medical evidence saying caffeine is not a trigger for heart rhythm problems as once thought.

In my case, I was lucky to get relief from a cardiac ablation, an increasingly common procedure where the bad electric circuit in the heart is cauterized to deaden the offending nerve cells. Since then, I’ve returned to biking and skiing, albeit at a lower level of intensity. I’m a tourist more than a racer these days.

The bottom line—and the real takeaway from “Haywire Heart”—is that moderation is indeed the best policy. Reducing stress, taking care of those you love and keeping your goals in perspective is advice we all should follow no matter our chosen pursuit.

Put another way, if you’re sweating it you’re likely trying too hard.

Mike Ivey writes the Footloose blog for


Pacing for Interval Training

With CXC Academy training plans it is very important to stay within the prescribed training zone for each workout. These training zones each have a very specific role in your training. The length and frequency of these workouts fluctuates throughout the year depending on the emphasis of each training period, all leading to peak performance during your race season.

Let’s talk specifically about Levels 1, 3 and 4, some of the most frequently used speeds.

LEVEL 1 training is mainly used as a warm-up/cool-down speed or as an easy, recovery day speed. You should always keep your heart rate within your easy Level 1 zone. This is generally under 130 bpm. Individual heart rate zones can be determined through physiological testing.

LEVEL 3 training can also be referred to as anaerobic threshold training. These intervals are longer and should be conducted at a lower heart rate and speed than level four intervals. Think of these as your ski marathon pace; an effort that is sustainable over 2 hours. When skiing level three intervals, we look for a nice consistent heart rate with no spikes in effort or intensity.

LEVEL 4 training consists of shorter, more intense intervals than level three training. This is your 5-15km race pace. You should ski all terrain just as you would in a race, powering over the tops of hills and transitioning smoothly and powerfully through different techniques.

Make sure that you stay true to each training zone while conducting a workout. It is easy to ski out of your training level to keep up with friends or get in a hard workout. Each level has a role and it is important to stick to the plan.

How to Shuffle Workouts to Fit Your Lifestyle

Scheduling Workouts Within Each Week

Try to shuffle the days within each week to fit your lifestyle and schedule, but avoid “loading” up missed workouts from other weeks to “make up for it.”

Be sure not to have two consecutive general strength or specific strength days during the week. For example, it is okay to follow a general strength day with specific strength the next day, but avoid having two general strength days in a row.

It is okay to have two consecutive interval days within the week on occasion, since that replicates some race weekends in the winter where you race both Saturday and Sunday. However, a majority of the summer training should allow for at least one day of recovery between hard Level 4 or 5 interval sessions.

If you have a workout that utilizes the upper-body heavily (such as double-poling or specific strength) try to focus the next workout on the lower-body (running, cycling) to ensure proper balance and recovery.

If you have the opportunity to train with other people, feel free to change your workout schedule around so that you can have partners to train with. Sometimes there is more value from what you can learn from other athletes than following a plan perfectly.

Scheduling Workouts and Training Twice-a-Day

When time conflicts arise, or during high-volume training weeks it can be most convenient to have two workouts in one day. It is important to follow proper protocol with multiple workouts in a single day.

It is better to schedule only one interval session per-day. Try to make the first workout of the day the interval session, and plan the second session to be a strength or distance workout.

Be sure to allow at least 3 hours between the end of the first session and the start of the second session.

Always allow at least 48-hours between each strength session

Always allow at least 48-hours between each interval session

It is a good idea to schedule the “off” day after very hard efforts, race days or race weekends with travel for recovery.

Adjusting Training Plan Hours

Let’s say you need to adjust your yearly training volume… For example, to modify the 250hrs/year training plan and make it 300hrs/year plan, you might consider adding more time to the distance and over distance workouts. Add 30 min to the distance workout and 45 min to the over distance workout.

Another example of adjusting to the 450 hrs/year training plan. Below is one of CXC Academy coach’s comments, just to give you an idea…

The easy answer is just to say there are 52 weeks in the year and we generally take 2 weeks in the spring almost completely off. Thus you have 50 weeks and need to add 50 hours to a 400 plan…. add 1 hour per week. Is it just that simple? Yes and no. Generally we operate under an 80-20 intensity cycle. This means that 80% of the training generally ends up being distance/technique/over distance/warm up/cool down while, 20% of the training is intensity (racing/intervals/sometimes strength/etc.) By this breakdown, you’d be adding approximately 12 minutes per week of intensity training and 48 min of volume training.

2018 NNF Trip to Tyrol, Austria and World Cups

The National Nordic Foundation (NNF) and Lumi Experiences are excited to announce the 2018 NNF Trip to Tyrol, Austria.

The NNF and Lumi Experiences are partnering to offer a trip to the 2018 cross-country and Nordic combined World Cup competitions in Seefeld, Austria. On this 11-day trip, designed by Olympian Garrott Kuzzy, we will ski in the Alps, cheer on our favorite athletes at the World Cup competitions and relax in three- and four-star hotels. Travelers will also have the opportunity to participate in the Dolomitenlauf Worldloppet!

Olympian and past US Ski Team athlete Garrott Kuzzy has over five years of experience developing skiing, biking, and hiking tours throughout Europe. He currently lives in Innsbruck, Austria and has developed this trip in his new backyard. As a former US Ski Team athlete, Kuzzy is partnering with the NNF to benefit developing US athletes. Proceeds from the trip go to funding NNF programming.

Scheduled for January 19 – 29, 2018 the trip is limited to 16 guests and priced at $3,900 per person (not including airfare) if reserved before March 31. For more information and to sign up, go to: