In the first part of this series, we reviewed the Physical Activity Guidelines for Americans 2nd edition [1], herein after "the Guidelines," and how regular physical activity can influence outcomes against the ten most common chronic diseases. These sentiments were also echoed in the book Outlive: The Science and Art of Longevity by Peter Attia, MD with Bill Gifford. We then focused on 2 key takeaways from Outlive that strength enthusiasts should consider to augment their training so that they can continue to train and enjoy life well into their later decades. The 2 takeaways are to:
Incorporate (more) conditioning work
Incorporate (more) stability work
These can be generally applied to all people regardless of health or performance goals. However, if you are not already training for strength at least 2 days a week, then you would be well-advised to make that a priority in addition to the conditioning and stability work noted above.
Dr. Attia states in Chapter 11 of his book that peak cardio respiratory fitness, measured in terms of VO2 max, may be the single most powerful indicator for living a long and healthy life. He notes someone of below average VO2 max is at double the risk of all cause mortality compared to someone in the top 25%. Attia further adds that someone in the bottom 25% is 4 times more likely to die than someone in the top 25%.
This post will specifically be focused on conditioning for strength athletes with the overall goal of improving cardiorespiratory fitness and VO2 max for health, while Part 3 of this series will be focused on stability. We will begin by first defining key terms and concepts to establish a base level of knowledge. Then, we will explore nuances of intensity, modality, duration and improving VO2 max. Finally, we will review how these can all be applied to help you meet the Guidelines and achieve your conditioning goals, through application in my own training.
Disclaimers:
I am not a Doctor or Medical Professional. The information provided here is for educational purposes only and does not replace medical advice. Consult your Primary Care Physician or other healthcare professional as needed before implementing any recommendations into your life style.
Any views and opinions expressed are my own and are not affiliated with USA Powerlifting or the authors of this book.
DEFINITIONS
The following are some key terms and definitions that are required to further enhance your conditioning regimen.
Conditioning: This is basically short-hand for "Cardiorespiratory Conditioning" or "Aerobic Conditioning" and more commonly referred to as "Cardio." Cardio and aerobic exercise are essentially the same but refer to different pathways. Cardio is generally associated with processes of the heart, like pumping blood throughout your circulatory system, while aerobic refers to processes associated with oxygen intake. "Metabolic conditioning" could also be used although this term is usually associated with "MetCon's" which are a very specific training modality. For the sake of discussion, we will use cardio, aerobic activity, and conditioning interchangeably. As a quick refresher from the last post, the Guidelines make the following recommendations for Adults and Older Adults with regard to conditioning.
Adults
150 minutes to 300 minutes a week of moderate-intensity aerobic activity, or 75 to 150 minutes a week of vigorous aerobic activity.
Additional benefits are gained by engaging beyond 300 minutes a week of moderate-intensity aerobic activity.
Older Adults
Multicomponent physical activity that includes balance training as well as aerobic and muscle-strengthening activities.
If unable to do 150 minutes of moderate-intensity physical activity a week due to chronic conditions, do as much as their abilities allow.
Note, the Guidelines provide recommendations for optimal health outcomes. That is, if you are seeking improvements in sport performance, you will need to go beyond the Guidelines depending on the specific sport and goals. The Guidelines also have recommendations for preschoolers, as well as children and adolescents ages 6 to 17. However, I am assuming most children will not be running into this blog.
Cardiorespiratory Fitness (endurance): A health-related component of physical fitness that is the ability of the circulatory and respiratory systems to supply oxygen during sustained physical activity. Usually expressed as measured or estimated maximal oxygen uptake (VO2max).
Intensity: Intensity refers to how much work is being performed or the magnitude of the effort required to perform an activity. Intensity can be expressed either in absolute or relative terms. The absolute intensity of an activity is determined by the rate of work being performed and does not take into account the physiologic capacity of the individual. Relative intensity takes adjusts for a person’s exercise capacity.
Maximal oxygen uptake (VO2max): The body’s capacity to transport and use oxygen during a maximal exertion involving dynamic contraction of large muscle groups, such as during running or cycling. It is also known as maximal aerobic power and cardiorespiratory endurance capacity. Peak oxygen consumption (VO2peak) is the highest rate of oxygen consumption observed during an exhaustive exercise test.
Maximum Heart Rate (MHR): The highest number of beats per minute your heart can pump under maximum stress. Max heart rate can be determined in one of three ways: 1) Use of Formulas, 2) Laboratory Testing or 3) Field Testing. The easiest way to determine MHR is through the use of formulas which we will cover in this post. However, lab and field testing will provide the most accurate predictor of MHR for you as an individual. For the purposes of meeting the Guidelines and improving health outcomes, the use of formulas combined with relative intensity measurements are more than sufficient. Here are the two formulas you can use as a starting point:
MHR = 220 – Age
MHR = 208 – 0.7 x Age
The first formula is the most common one used for the prescription of aerobic exercise but was never established with a sample including a sufficient number of older adults. The second formula determined in a meta-analysis by Tanaka et al. found that the first formula under predicted maximum heart rate in older adults. This is illustrated in Table 1 below comparing the maximum heart rate calculated with each formula.
This particular study concluded formula 2 was the better predictor of maximum heart rate, and that MHR can be predicted by age alone independent of gender and activity status. It should be noted that the study was conducted on healthy adults, and this may not be an "accurate" predictor for unhealthy or untrained individuals. However, these formulas should get you in the ball park.
Other factors that can influence MHR include exercise modality, altitude, medication and underlying health conditions. These cannot be accurately accounted for in the formulaic approach. Also, it is possible for MHR to stay the same or increase as a person ages if the training is dosed appropriately.
Modality: The type of activity or exercise that is being performed. Biking, walking, rowing, and weight lifting are all examples of different exercise modalities.
Progression: The process of increasing the intensity, duration, frequency, or amount of activity or exercise as the body adapts to a given activity pattern.
INTENSITY
The intensity for conditioning activities can be further described in either absolute or relative terms, and multiple methods of relative intensity can be applied. Meeting the Guidelines can be accomplished through a combination of both moderate and vigorous intensity as outlined below.
Absolute - Metabolic Equivalent of a Task (METs)
According to the Guidelines, absolute intensity can be determined through the use of a metabolic equivalent task or MET. "A MET is the ratio of the rate of energy expended during an activity to the rate of energy expended at rest. For example, 1 MET is the rate of energy expenditure while at rest. A 4 MET activity expends 4 times the energy used by the body at rest. If a person does a 4 MET activity for 30 minutes, they have done 4 x 30 = 120 MET-minutes (or 2.0 MET-hours) of physical activity. A person could also achieve 120 MET-minutes by doing an 8 MET activity for 15 minutes." [1]
"A simple rule of thumb is that 1 minute of vigorous-intensity activity counts the same as 2 minutes of moderate-intensity activity. The lower limit of vigorous-intensity physical activity (6.0 METs) is twice the lower limit of moderate-intensity activity (3.0 METs). Therefore, 75 minutes of vigorous-intensity activity a week is roughly equivalent to 150 minutes of moderate-intensity activity a week. The recommendation that adults do 150 to 300 minutes of moderate-intensity physical activity or 75 to 150 minutes of vigorous-intensity physical activity are both equivalent to doing about 500-1,000 MET-minutes a week. Because the MET range for vigorous-intensity physical activity has no upper limit, highly fit people can exceed 1,000 MET-minutes in 75 minutes if they do activities requiring 13.4 METs or more (running at approximately a 7.5 minute-per-mile pace or faster). This amount of activity will provide additional health benefits." [1]
Confused? Here's a quick conversion chart showing the relationship of MET-minutes keeping absolute intensity constant at varying time intervals. Here it's easy to see that you would require half the time at a vigorous intensity to hit the minimum MET-minutes recommended by the Guidelines based on the lower limits of 3 and 6 METs.
Absolute intensities for an assortment of activities can be found in the Compendium of Physical Activities [2]. However, there are many limitations when using this data as noted in the compendium. For example, "The values in the Compendium do not estimate the energy cost of physical activity in individuals in ways that account for differences in body mass, adiposity, age, sex, efficiency of movement, geographic and environmental conditions in which the activities are performed. Thus, individual differences in energy expenditure for the same activity can be large and the true energy cost for an individual may or may not be close to the stated mean MET level as presented in the Compendium." [3]
Thus, individual differences in energy expenditure for the same activity can be large and the true energy cost for an individual may or may not be close to the stated mean MET level as presented in the Compendium."
Relative - Heart Rate Zones
The Guidelines and many exercise programs refer to heart rate zones for relative intensity which are a percentage of your MHR, heart rate reserve, or functional threshold power depending on the method you choose. In Outlive, Dr. Attia promotes the implementation of "Zone 2" from the 5 zone model due to it's health benefits. Depending on where you look, some models only have 3 zones while others have 7 zones. Even when comparing heart rates for 5-zone models, there is no consistent guideline. See Table 3 below comparing different percent of MHR for three different 5-zone models. There are probably more out there I have not found; most of the versions I have seen are based on Model A.
Regardless of the heart rate percentages, the definitions of the zones are fairly consistent across multiple sources, but we will reference the definitions below from Polar. [4]
Zone 1: 50-60% of Max Heart Rate (Very Light)
This is the very low intensity zone. Training at this intensity will boost your recovery and get you ready to train in the higher heart rate zones. To train at this intensity, pick a form of exercise that allows you to easily control your heart rate, such as walking or cycling.
Zone 2: 60-70% of Max Heart Rate (Light)
Exercising in heart rate zone 2 feels light and you should be able to go on for a long time at this intensity. This is the zone that improves your general endurance: your body will get better at oxidizing – burning – fat and your muscular fitness will increase along with your capillary density. Training in heart rate zone 2 is an essential part of every exercise program. Keep at it and you’ll reap the benefits later.
Zone 3: 70-80% of Max Heart Rate (Moderate)
Working out in heart rate zone 3 is especially effective for improving the efficiency of blood circulation in the heart and skeletal muscles. This is the zone in which that pesky lactic acid starts building up in your bloodstream. Training in this HR zone will make moderate efforts easier and improve your efficiency.
Zone 4: 80-90% of Max Heart Rate (Hard)
Heart rate zone 4 is where the going gets tough. You’ll be breathing hard and working aerobically. If you train at this intensity, you’ll improve your speed endurance. Your body will get better at using carbohydrates for energy and you’ll be able to withstand higher levels of lactic acid in your blood for longer.
Zone 5: 90-100% of Max Heart Rate (Maximum)
Heart rate zone 5 is your maximal effort. Your heart and your blood and respiratory system will be working at their maximal capacity. Lactic acid will build up in your blood and after a few minutes you won’t be able to continue at this intensity. If you’re just starting out or have only been training for some time, you probably won’t have to train at this intensity. If you’re a professional athlete, look into incorporating interval training into your training plan for peak performance.
Relative - Level of Effort or RPE
An alternative approach to the use of heart rate zones is the level of effort or rate of perceived exertion RPE. On a scale of 0 to 10, resting would be 0 or no effort and 10 would be the highest level of effort possible. According to the Guidelines, moderate-intensity activity would be a 5 or 6 out of 10, while vigorous-intensity activities have a minimum effort of 7 or 8.
If you are unsure how to gauge RPE, an easy rule of thumb that can be used is the "Talk Test." A person performing moderate-intensity activity can talk but not sing. You should be able to have a conversation with someone, but that person should be able to tell you are exercising. A person performing vigorous-intensity activity would not be able to say more than a few words without gasping for air or reducing intensity of the activity. Dr. Attia also references the talk test in his podcasts which aligns with the Guidelines. See Table 4 below for a full breakdown.
Relative - Functional Threshold Power (FTP)
Since I am primarily focused on strength performance, FTP is not something I personally use for myself or my athletes, however, I did want to mention this as a viable option for those who are more interested in endurance activity performance. Functional Threshold Power or FTP refers to the maximum effort you can maintain with mostly aerobic energy systems. For most trained athletes, this is similar to the maximum effort they can maintain for an hour. Going above this threshold effort will result in a “burn” in the muscles and, after a few minutes, require stopping or slowing in order for the body to clear the lactate acid. [5] If you are interested in learning more about FTP, especially how to determine and apply it, then I suggest you check out www.trainingpeaks.com.
MODALITY
The mode of conditioning you choose should be specific to your preferences, goals, and resources. Personally, I prefer a stationary bike where I can fine tune resistance to maintain desired tempo and RPE. If your goal is to improve conditioning through steady-state cardio, trying to bike or jog at a steady pace on busy city streets would be difficult. If the effort to travel to a trail or track with less obstacles is not worth the hassle, then you may want to consider indoor options like a stationary bike, treadmill, etc. Also, routes with multiple changes in elevation and or terrain can make it challenging to maintain a specific MET, RPE, or MHR.
The modality of conditioning will also influence your maximum heart rate. For example, people generally attain higher MHR's running when compared to cycling due to the amount of muscle mass used. Conversely, exercise modes like swimming and arm ergometers yield lower MHR's due to the smaller muscle mass of the upper body. This means that if you are going to opt for laboratory or field testing to determine your MHR, you should do so using the modality that is representative of what you will be trying to improve.
It should also be noted that strength training does not count against your conditioning goals. Even though your heart rate may be elevated during strength exercises, the exercise is not contributing to cardiorespiratory fitness unless you are new to training or returning to training after a very long time off.
DURATION
Previous studies recommended at least 10 minutes of continuous physical activity for it to count towards your weekly aerobic activity. However, newer research suggests that less than 10 minute bouts, and even more recently bouts of any length, actually contribute to your weekly activity. From an application perspective, similar to modality, we will want to choose a duration that is specific to your goals. For example, if your goal is to run a marathon, developing a training plan centered around 10 minute bouts would not carry over well to the goal of running a marathon.
IMPROVING VO2 MAX
All intensities of aerobic exercise support the development of your VO2 max. Dr. Attia recommends the 80/20 rule which anecdotally seems to align with the way many high performers train in different disciplines. This rule is something I typically consider for strength training. Generally, you want 80% of your training to be moderate intensity and 20% to be vigorous. While the moderate intensity work will not improve your VO2 max directly, it will yield other health benefits noted above and helps build your base to handle the vigorous intensities required to push up your VO2 max.
APPLICATION
Application of all of the above information is highly nuanced and will depend on a person's goals, preferences, level of fitness or training, etc. As mentioned above, I prefer to use both heart rate and RPE to build my cardiorespiratory capacity, and my modality of choice is the stationary bicycle. Below is how I apply conditioning to my own training, which can give you insights in how to augment your own.
Intensity
I am 39 years old as of the publishing of this post, so the MHR based on the two formulas provided above is approximately 181 beats per minute. Since I do not have a desire to conduct lab or field testing, I also use RPE via the "Talk Test" described above to ensure the level of effort is within the correct range in case the calculated maximum heart rate and associated heart rate zones are not accurate. As mentioned under definitions above, MHR can improve over time, so relying on heart rate zones alone would not take into account any improvements in fitness for your chosen modality.
Frequency & Duration
Currently, I train cardio 160 minutes per week as broken out below when I am more focused on maximal strength development.
Saturday: 60 minutes of moderate intensity steady-state cardio on stationary bike
Target Exertion: RPE 6
Target Heart Rate: 115 to 130 bpm
Sunday & Friday: 5 minutes of reverse treadmill at vigorous intensity after my strength training
Target Exertion: RPE 7 to 8
Target Heart Rate: 140 to 160 bpm
Monday & Wednesday: 45 minutes of moderate intensity steady-state cardio on stationary bike
Target Exertion: RPE 6
Target Heart Rate: 115 to 130 bpm
This breaks out to about 150 minutes of moderate intensity cardio and 10 minutes of vigorous intensity cardio. Does this follow the 80/20 rule? No, but I am also not currently interested in directly training V02 max through vigorous cardio. I am currently more interested in improving general endurance, capillary density, and blood circulation with minimal lactic buildup. As I get closer to a powerlifting competition, I will peel back to 90 minutes, 60 minutes, 30 minutes, and eventually none during the week leading up to competition. You can experiment with different cardio taper durations based on how you respond in training.
When I am not focused on maximal strength, like during restoration or developmental blocks, I will do something like this to target VO2 max directly, but will still keep the majority of my work in the light to moderate intensity range.
Saturday: 60 minutes of moderate intensity steady-state cardio on stationary bike
Target Exertion: RPE 6
Target Heart Rate: 115 to 130 bpm
Sunday & Friday: 5 minutes of reverse treadmill at vigorous intensity after my strength training
Target Exertion: RPE 7 to 8
Target Heart Rate: 140 to 160 bpm
Monday: 45 minutes of moderate intensity steady-state cardio on stationary bike
Target Exertion: RPE 6
Target Heart Rate: 115 to 130 bpm
Wednesday: 16 to 24 minutes interval training on stationary bike
4 minutes "on" at RPE 8
4 minutes "off" at RPE 1
Target Heart Rate: As high as possible while being able to maintain consistent RPE 8 effort
This breaks out to about 105 minutes of moderate intensity training and 26 to 34 minutes of vigorous intensity training.
Progression
Using a stationary bike as my modality of choice, here are two methods I use to progress my fitness without having to VO2 max lab or field test on a periodic basis. My particular bike allows me to adjust magnetic resistance on a scale of 0 to 100; 0 being no resistance other than the friction between moving parts and 100 being unable to move the pedals. The methods described below are in the context of light/moderate intensity steady-state cardio, but the same principals can be used for vigorous intensities.
Method 1 - Progressing Resistance at Constant Pace
In this method, I will hold a steady pace or speed at a given resistance level while maintaining the target RPE and Target Heart Rate for as long as possible until I hit my target duration.
For example, if it is Saturday, I currently can maintain resistance level 18 for 60 minutes while staying at or below 130 bpm and RPE 6, at a pace of between 30 to 33 km per hour (I don't think that is my real speed but if I'm using the same machine it shouldn't matter). To progress, I would raise the resistance to level 20 and see how long I can maintain a similar speed at RPE 6 and at or below 130 bpm at 30 to 33 km/h. I may find I can only maintain this resistance and pace for 20 minutes before going above the target heart rate. I would then lower the resistance back down to 18 for the remainder of the session. Over time, I would incrementally progress at resistance level 20, with all other things constant, to 25 minutes, 30 minutes, 45 minutes, etc. until I can maintain for a full 60 minutes. Once I can maintain level 20 resistance for 60 minutes consistently without going above RPE 6 or 130 bpm, then I know measurable improvements in fitness have been attained and I can repeat the process at a higher resistance level.
Method 2 - Progressing Pace at Constant Resistance
In this method, it is very similar to Method 1 with regard to maintaining RPE 6 and keeping heart rate at or below 130 bpm for my Saturday workout. However, instead of increasing resistance, I will try to progress my pace to between 33 and 36 km/h at level 18 resistance until I am able to maintain for the full 60 minutes.
Other Methods
These are not the only methods available. For example, you could progress constant pace and resistance for longer bouts of time, say 65 minutes, 70 minutes, etc. at the target RPE and heart rate. However, since I do not desire sitting on a bike for more than an hour, I prefer progression methods that are restricted to a fixed duration.
REFERENCES
https://health.gov/sites/default/files/2019-09/Physical_Activity_Guidelines_2nd_edition.pdf
Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol. 2001 Jan;37(1):153-6. doi: 10.1016/s0735-1097(00)01054-8. PMID: 11153730.
https://sites.google.com/site/compendiumofphysicalactivities/home
https://www.trainingpeaks.com/learn/articles/thresholds-411/
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