A Pyramid Scheme

Building fitness and performance is like building a pyramid. The most important work is done in the beginning, the supportive structures that will allow construction and improvements towards reaching a peak. With this pyramid, the stronger the supportive structure, the stronger the performances once you reach the top or your peak.

Without the underlying structures, or base, the pyramid will not support itself. Imagine the heart rate zones of training in a pyramid structure, with Zone 1 as the base and Zone 5 at the top. Often athletes abandon training in lower heart rate zones out of frustration or boredom and move on to the higher zones. Athletes train in Zones 3 – 4 because it “feels good”, it allows us to go fast and get our competitive nature out. Or, they believe that training harder will yield faster, stronger results. Consequently, this thinking comes at the cost of performance, health, and fitness. Skipping out on training at lower heart rate zones is a sure way to watch your pyramid deconstruct into consistent injury, burn out, or never reaching your athletic peak.

Training with heart rate is one way to work towards building a solid pyramid. While perceived exertion and training by feel are useful, at times they will leave you training too hard when it’s time to go easy or going to easy when it’s time to go hard. However, knowing your heart rate is like having a window in your body. You can better understand how your body is responding to the workouts and improving over time. As such, training with heart rate is a systematic method of improving cardiovascular fitness. The body changes in respond to stress and demands. By training at sufficiently intense levels, you can appropriately stress your cardiovascular system. At rest, the body adapts to strengthen the cardiovascular system. Over time, your heart actually becomes more efficient at delivering oxygen and fuel required by muscles to maintain a higher level of performance.

Knowing your heart rate zones will allow us to better estimate and understand where to train to bring about the most cardiovascular improvements. Listed below you’ll find a description of the different heart rate zones.

Zone 1: Recovery

Zone 1 is the lowest level of training where you can still increase fitness. This zone is used for active recovery, beginners and to improve overall health. Fat is the primary source of fuel in this zone. This zone includes recovery runs, bikes, or swims. For example, flushing out the legs with a light spin after a harder run.

Zone 2: Extensive Endurance

Training in this zone develops and improves endurance and aerobic capacity. Aerobic endurance is built and production of lactic acid is low enough to allow for extensive, comfortable training. Training in this zone improves the ability of the heart to pump blood and the ability of the muscles to utilize oxygen. Training in this zone teaches the body to become more efficient at fueling muscles as they work and metabolize fat as a primary source of fuel. Slow twitch muscle fibers also become stronger and more capable of using oxygen to produce energy. In turn this allows muscles to conserve glycogen. This zone is the most commonly used in multisport training. Ironman distance training and racing takes place predominantly in this zone.

Zone 3: Intensive Endurance

Training in this zone is the most effective for improving overall cardiovascular fitness. Zone 3 training improves your body’s ability to transport oxygen to the muscle cells and carbon dioxide away from the muscle cells. Training here also improves overall muscle strength. With the increased intensity in this zone, lactic acid production also increases. As a result, fast twitch muscle fibers are recruited to support slow twitch work. Often, athletes make the mistake of doing all training in this zone. While this zone is still aerobic and training here ‘feels good’ it comes at the cost of not being easy enough to promote endurance or recovery and not being hard enough to really count towards improving performance. In other words, it becomes a dead zone. Training in this zone is often used early in the season and exchanged later for harder intensities.

Zone 4 – 5a: Threshold

Training in this zone feels hard, muscles fatigue easily and breathing is heavy. In this zone, the amount of fat used as the main source of energy is greatly decreased while stored glycogen is used instead. A by-product of burning glycogen is lactic acid. Lactate threshold is the point at which your body cannot remove lactic acid as quickly as it is produced. Training at threshold increases your anaerobic or lactate threshold which, in turn, improves performance. Through proper training, it is possible to increase your ability to tolerate lactic acid for longer periods of time and increase your anaerobic threshold. Aside from Zone 2 training, training in this zone is the most important training zone for multisport athletes. (note: Zone 4 indicates training below your LT, Zone 5a indicates efforts above your LT).

Zone 5b: Anaerobic Endurance

Training in this zone is possible only for short periods of time. Fast twitch muscle fibers are recruited for work in this zone increasing their growth and development. The body also learns to tolerate and remove lactic acid in this zone. Lactic acid develops quickly and muscles are placed into oxygen debt. High volumes of training in this zone may lead to overtraining and injury. As such, training here is used sparingly and carefully, followed by extended recovery to allow the body to rest and adapt.

Factors Influencing Heart Rate

Heart rate changes over time. It is important to test your heart rate zones throughout the year to be sure they are the most accurate for your current situation and fitness level. Other factors that may influence heart rate:

*Genetics (for example, two 30 year-olds will not necessarily have similar HR zones)
*Improvement in fitness may decrease heart rate at a given intensity
*Altitude may increase heart rate by 10 to 20%
*Age influences HR zones
*Dehydration may increase heart rate by up to 7.5%
*Humidity and heat may increase heart rate by 10 beats per minute

It’s important to remember that like any construction, building strength and fitness takes time. Training in lower heart rates is not easy – at times it requires holding back or even walking. However, the changes (improvements) that take place in the lower zones prepare your body to handle the increased workloads ahead. Again, jumping to higher zones too quickly is the quickest way to find yourself injured, fatigued, or stale. Take the time to build the base of fitness with aerobic, endurance training to train smart, train safe and train towards your potential for your best season yet.