What Kind of Cardio Training Is Right For You?
Walk into most gyms and you typically see rows of cardio equipment occupied by people working out in the “fat burning zone”.
Is this useful?
What Kind of Cardio Training is Optimum?
Let’s take a look.
Cardiorespiratory training is a component of exercise that can be used to:
- Improve performance in work, life, and sports
- Improve health by reducing cardiovascular risk factors (e.g., unhealthy body composition, unbalanced blood lipid profile, high blood pressure and blood sugar/insulin sensitivity)
- Reduce stress, anxiety and depression
- Manage weight and body composition
Two Important Principles should be considered with Cardiorespiratory Training:
- Specificity: The body will adapt to the specific demand(s) that are placed upon it
- Overload: To continually adapt, the body must be placed under a stress that exceeds the body’s current capabilities.
*Some adaptations are antagonistic to each other, such as doing a lot or steady state cardio while trying to increase lean body mass.
Choosing the amount and type of Cardio Training should be based on your SPECIFIC Needs and Goals.
Measuring Heart Rate (HR)
HR is an important measurement that can be used to guide and monitor training. The simplest and most practical equation is Maximal Heart Rate (HRmax).
HRmax= The highest number of BPM (Beats Per minute) that a one can safely attain, often determined by 220 – Your Age.
Training Heart Rate (THR) can then be used to as a guide to intensity.
THR= A selected percentage of maximal heart rate (as determined above) used as a guide for exercise training.
Review of Energy Systems
In order to exercise you need energy. This energy is provided by adenosine triphosphate (ATP), which is produced by the body from food.
There are two primary pathways leading to the production of ATP:
- Aerobic (with oxygen)
- Anaerobic (without oxygen)
The Aerobic System (Low power/Long Duration)
This energy pathway is often termed the oxidative (oxygen) system. It involves several body systems: Respiratory, cardiovascular, muscular, and endocrine.
During aerobic exercise, glycogen (stored carbohydrates in the liver and muscles) and fats are broken down in the presence of O2 to provide energy.
During rest and light activity, the energy required for muscle contraction is almost entirely from this aerobic production of ATP.
ATP production occurs in the cell mitochondria (the cell’s powerhouse). The greater the number of mitochondria, the greater the aerobic energy production capabilities of the cell.
Increasing the number of mitochondria is one adaptation of aerobic exercise.
During prolonged exercise, more than 99 percent of the energy required is generated by aerobic reactions.
The aerobic energy pathway is capable of using stored body fat as a primary source of energy. The amount of fat or carbohydrate used depends on the intensity and duration of exercise.
The Anaerobic System is composed of:
- Glycolytic- Anaerobic Glycolysis (Moderate Power/Moderate Duration)
- ATP-CP (High Power/Short Duration)
Anaerobic capability is the ability of the body to produce energy by metabolizing carbohydrates in the absence of O2.
As exercise intensity increases, the cardiovascular system attempts to increase its delivery of O2 into the mitochondria of exercising muscles to produce enough ATP aerobically.
At some point, as the intensity increases, the cardiovascular system becomes unable to supply enough O2 to the exercising muscles, forcing them to switch to the anaerobic systems to produce ATP rapidly.
The intensity level at which adequate O2 becomes unavailable is referred to as the anaerobic threshold (AT). It has also been termed the lactic threshold.
The anaerobic system cannot be used for a prolonged period. The primary source of anaerobic ATP production is glucose, which is stored in the muscles and liver as glycogen. During muscle contraction, stored glucose is broken down into CO2, lactic acid, and water. This energy pathway is often referred to as the glycolysis (lactic acid) system. It is used in moderate- to high-intensity activities.
Creatine phosphate (CP) is a molecule that can be broken apart quickly to help produce ATP. This energy pathway is often referred to as the ATP-CP system. The ATP-CP system is used for high-intensity, short-duration activities.
There is an extremely limited supply of CP, from which about 10 seconds of energy can be produced.
The main drawback of the anaerobic system is that low levels of ATP are produced coupled with higher levels of lactic acid, a limiting factor in sustaining higher intensity exercise.
Respiratory Exchange Ratio (RER) and Training Zones
The fitness industry has used many catch phrases such as “fat-burning” zone and “cardio” zone.
These zones were derived from the Respiratory Exchange Ratio (RER), which is the amount of CO2 exhaled divided by the amount of O2 inhaled.
The lower the RER and exercise intensity, the greater the amount of fat burned. As intensity and the RER increase, more carbohydrates are used as fuel.
Zone Training- Practical Application
Zone One: RER of 0.80 to 0.90 (65 to 75 percent of HRmax): This is also known as the fat-burning zone, recovery zone or cardio base zone. This initial zone is part of a three-zone system that trains the body to maximize its potential. Individuals who stay in this zone without variation will initially improve their volume of O2 consumption, but will quickly plateau. When this occurs, weight loss is slowed or stopped. If Zone One is maintained, the only solution to end the plateau is to keep increasing the length of time exercising, which is not very time efficient.
Zone Two: RER of 1.0 (80 to 85 percent of HRmax): Zone Two is close to the Anaerobic Threshold (AT). In this zone, the body can no longer produce enough energy for the working muscles with just the aerobic energy system. Similarly to Zone one, staying in Zone Two all the time will lead to a plateau for most individuals, based on the Overload Principle.
Zone Three: RER of 1.1 (approximately 90 percent of HRmax). This is considered High Intensity. Zone three results in overload, as it requires achieving peak exertion. Getting into Zone Three is often done with High Intensity Interval Training (HIIT). Zone Three training will overload the Cardiorespiratory System resulting in enhanced aerobic and anaerobic adaptations as well as fat loss through EPOC (Excess Post Exercise Oxygen Consumption). Going to Zone three too often can result in overtraining, so should be limited to two- three times per week and not on consecutive days.
The Benefits of Stage Training is that it allows for positive physical changes to the cardiovascular system combined with the proper recovery.
It is important to note that the overload happens during the exercise, while the adaptations occur during recovery. Individuals who exercise hard without the proper recovery can experience symptoms of overtraining, such as recurrent infections, digestive disturbances, amenorrhea, low libido and mood changes.
For individuals who are more interested in strength, physique and weight management adaptations, cardio should be limited to three to four 20 minute sessions per week, preferably done as a combination High Intensity Interval Training and Low Intensity Steady State Cardio. These individuals should focus on resistance training.
High Intensity Interval Training (HIIT)
HIIT has been shown to be beneficial for:
- Conditioning (Both aerobic and anaerobic)*
- Weight management
- Reducing health risk factors
*Whereas aerobic exercise enhances aerobic capacity. Anaerobic exercise, e.g. HIIT, results in both anaerobic and aerobic adaptations.
- Cardio is not a one-size-fits-all. It should be personalized based on the goals of the individual
- Because cardiovascular adaptations are specific and in some cases antagonistic to other adaptations, time and intensity need to be very specific
- HRmax and THR (Training Heart Rate) are equations that can be used to guide exercise intensity and Stage Training Zones
- There are 3 Training zones:
Zone One (the recovery zone or base cardio zone)- 65-75% of HRMax
Zone Two (typically the high-intensity zone)- 80-85% of HRMax
Zone Three (a true high-intensity zone)- 90% of HRMax
- Stage training is a system that dictates the specific intervals to be used in each Zone over a given period of time
- HIIT has been shown to be beneficial for:
Reducing health risk factors
- Before beginning any exercise routine, it is imperative to get a comprehensive fitness assessment. The assessment will aid in monitoring possible contraindications to training and ensure an appropriate beginning point and progression sequence
NASM- Cardiorespiratory Training For Fitness
Clark, M. A., Lucett, S., & Corn, R. J. (2008). NASM essentials of personal fitness training. Lippincott Williams & Wilkins.