Exercise Intensity and How it Impacts Fitness, Health, and Mental Wellbeing 

Let’s start by defining Exercise Intensity as anything other than stress that raises your heart rate into Zone 1 or higher for a sustained period of time. How do you know your Zones (for HR they are 1 through 5)? Do a search there are many websites and formulas available. Most will get you close. As you gain fitness and understanding of your specific sport / activity physical demands and impact on HR you can fine tune accordingly. 

There are many fine products out there to help you monitor your HR when exercising or around-the-clock with a sports watch like the Garmin Venu 3 I wear. Whatever approach you take having accurate data that is readily available will help guide you as you progress from ‘getting started’ with simple exercises like walking at a brisk pace to jogging, running, swimming, hiking, or cycling. 

Once you are equipped with a suitable heart rate monitor and have followed the instructions to establish your HR Zones (many now will automatically calculate based upon your age, sex at birth, weight, etc. They can even auto detect HRV (heart rate variability) to determine how much rest (sleep) and recovery (low HR activity) you need. 

Some will monitor Stress. The HR time in zone does show up in your intensity data while the stress score and HRV components will be reflected in your accelerated need for Recovery. As the medical professionals have been telling us for years – stress kills. It does nasty things to your heart, cardio-pulmonary system, hormones, etc. 

It may feel a lot harder on your body to exercise for even one minute in Zone 5 than five minutes of high stress. But the Z5 effort will make you physically, mentally, and emotionally stronger while the stress is taking years off your life. 

Note that this is mental / work / emotional stress I am talking about and not the Training Stress Score for Exercise as reported by your Garmin or other sport fitness device. 

Giant disclaimer: in case you did not notice, I am Not a Doctor. Do not begin any exercise program or heavy physical activities without consulting with a professional. And even then, listen to your body. Only you can determine your current state of physical health and fitness. It changes frequently so don’t assume that just because you went on a half-hour walk yesterday that you can run 5k (3.1 miles) today. 

Ok so let’s see how all of this ties together. I am making a few generalizations based upon 60+ years of personal sports experience. As they say about fuel economy, your experience may differ. And most likely will!

Using the Garmin sports watch or HRM models (conveniently tied via the Garmin Connect app) they have very nicely adopted a 150 intensity ‘score’ as your weekly target. The Score consists of 1 point if you will for every one minute of exercise with a HR in  through Z4 and 2 points for every full minute in Z5. Trust me, when you exercise at that level you’ll know why! This based on sports medicine and AMA recommendations for Minimum levels of activity. 

So now you are out engaging in your sports / physical activity. Your device is reporting and recording your HR. Hopefully you have it positioned for easy viewing so you can start to feel how your body responds to exercise and changes in pace / load / weight (weight lifting) / effort. You may not immediately recognize this but your heart is slow to adjust to increases or decreases in exercise intensity. So give it and your HRM a few to 30 seconds to reflect the impact of your changes in intensity. Now for most people it is a few to 10 seconds but once your cardiovascular system is in ‘race’ condition changes may take a long while be reflected. 

With 150 as your initial goal you may find this is more time than you have been doing in the past. No problem. Try adding 10% more time each week. Maybe squeeze in 10 to 20 minutes of exercise one or two nights a week. Or mornings / lunch walks. It all adds up to help improve your fitness. All things remaining constant in your diet you will find your weight will drop, SLOWLY. Don’t be fooled by lost water weight from exercise on hot days. 

Perhaps now is a good time to tell you that with most sports activities you will be surprised at how FEW calories are actually burned an hour. And this isn’t something that changes drastically with fitness. We just go faster but the calorie burn rate remains the same. As a point of reference when I am in serious Z3/Z4 training with Z5 intervals I hit 475 to 500 calories an hour. When playing fairly aggressive pickleball I only burn around 300 calories an hour for comparison.

So a 150 score means a whopping 1250 calories when cycling. Please don’t use exercise as an excuse to overeat. 

Back to mental wellbeing, all this time we are now spending exercising frees our minds from the bad stress in our lives. It gives us time to reflect, relax, make new goals, enjoy the sights and surroundings (outdoor sports), friends we may be with, and listen to our bodies so we can start making plans for future activities. See my previous post on what do you think about when riding. 

Congratulations! Hopefully within a few months you are easily achieving your 150 score. Perhaps your daily step goal as well. Bet your sleep score is also improving. With this level of new, improved fitness you may want to consider gradually pushing to new levels. Time, health, work/life balance, and even weather permitting.