The Aerobic Energy System

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Now days, when the word aerobics is mentioned, visions of leotard clad women in step class may come to mind. For others, it may bring to mind an image of a skinny marathon runner. The strength and power athlete may react to the word with fear, fear of losing strength gains and explosive power. The aerobic training system is an important component of conditioning, no matter who you are, or what sports you compete in. There are many methods to training the aerobic system. Let’s look at the different methods to choose from and the kind of adaptations that each workout facilitates. Let’s start with a detailed look at how the aerobic training system works.

Aerobic training has fallen out of favor over the last several years with the exception of endurance athletes. No matter what sport or physical activity you participate in, the aerobic system will play a part in energy production, especially as the length of a workout or competition increases. The definition of the word aerobic literally means requiring the presence of oxygen for life and pertaining to, or caused by the presence of oxygen. The aerobic system needs oxygen to create energy (ATP) and for long term energy production. It’s the only system that can break down fats as well as sugar for energy. With fats producing 9 calories per gram, it provides a little more than double the energy that sugars (4 calories per gram) provide. However, it cannot generate this energy as fast as the anaerobic energy system. It requires oxygen and has more chemical steps, which requires more time. The aerobic system can provide energy for hours while the anaerobic system is limited to minutes and seconds, and is much more fatiguing. There are a couple of reasons why we would want to train the aerobic system which includes strengthening the heart and lungs, improving oxygen utilization by the muscles, and increasing the availability of substrates and enzymes. There is a point we reach in activity where there is not enough oxygen available for the aerobic system and the anaerobic system kicks in with the majority of energy production.  This is known as the anaerobic or lactate threshold.

The anaerobic threshold is where the outer limit for aerobic energy production lies, and beyond this point, the body must rely on the anaerobic energy system. Fatigue sets in much more quickly when the anaerobic system is relied upon. The threshold can be increased with training, and a person can actually hit a higher heart rate before they reach it and/or produce more power at the current threshold.  Genetics also plays a part in determining a person’s threshold. A gas exchange test is the most accurate way of determining your threshold, but a person can also have a blood lactate test. If you don’t have access to a high tech laboratory, a modified Cooper’s test can be a simple and inexpensive way to estimate your threshold heart rate. This can be performed at the track, running as far as you can in 6 minutes. Make note of the distance, average heart rate, and average pace. While not perfect, it gives you a good determination of your heart rate and power (average running pace) at your anaerobic threshold. This data will also allow you to track your progress in the future.  One more thing, if you have a resting heart rate of 70 bpm or above, it’s a sign that you will benefit greatly from aerobic training.  The following are some workout options and the different adaptations they provide. They can be found in Ultimate MMA Conditioning by Joel Jamieson.

Cardiac Output Method: Helps increase the size of the left ventricle, which increases the stroke volume (the amount of blood the heart can pump with each contraction). It also increases the vascular network and slow twitch muscle fibers.  Examples: any long, slow distance training.

Threshold Training: Increases the maximum rate of oxygen utilization and the oxidative abilities of fast and slow twitch fibers. It can help raise your anaerobic threshold or increase your power at your threshold, thus delaying fatigue. Example: Steady state or tempo run.

Cardiac Power Intervals: Increases the force at which the heart contracts, increasing stroke volume. It also increases the maximum rate of oxygen delivery and cardiac tissue mitochondria. Mitochondria are considered the cells “power plant” because it generates most of the cells ATP. Example: any type of 1 to 2 minute speed intervals.

High Resistance Intervals (HRI): Increases the oxidative abilities (aerobic) of fast twitch fibers and power of the alactic (anaerobic) system. The alactic system can deliver energy quickly for maximum effort, but only lasts about 10 to 12 seconds. Reliance on the alactic system can lead to fatigue quickly. Example: Short sprint intervals.

High Intensity Continuous Training (HICT): Improves the oxidative abilities of fast twitch fibers and increases the number of mitochondria. Example: Uphill cycling or running.

Tempo Method: Produces slow twitch hypertrophy and increased mitochondria. Compound, multi-joint movements work best such as squats, overhead press, deadlifts,etc. Example: Functional strength training workout.

Aerobic Plyometrics: Improves oxidative abilities of fast twitch muscle fibers and increases reactive strength. Reactive strength is the combination of strength and speed, a rapid eccentric contraction immediately followed by a concentric contraction, producing a greater force output.  It makes use of the Stretch Shortening Cycle (SSC). Example: Explosive lower body movements like bounding and broad jumps. Explosive upper body movements like explosive push-ups and medicine ball rebounding.

Explosive Repeat Method: Improves the oxidative abilities of fast twitch fibers and the rate of aerobic recovery. Examples: Explosive lower body movements, such as squat jumps with weighted bar across the shoulders. Explosive upper body movements such as explosive push-ups and bench press.

If one energy system is trained, it is at the expense of another one. They can’t all be simultaneously trained to peak levels. Although, I came across an interesting concept in the book, Triphasic Training by Cal Dietz and Ben Peterson. They talk about a long lasting, delayed training effect known as the residual training effect. A table from Vladimir Issurin’s book, Block Periodization: Breakthrough in Sport Training, showed that the physiological adaptations for both aerobic endurance and maximal strength last close to 30 days after training. It appears that after focused training on the aerobic system and the subsequent cessation of training, training adaptations will decrease at about 2% per week, whether the athlete was highly trained or not.  This means time can be spent training other energy systems, but if you return to your aerobic training in approximately a month, little will be lost and you can start making progress again pretty quickly. With the use of block training, periods of time can be dedicated to focusing on training specific energy systems, instead of trying to develop many abilities at once.

With High Intensity Interval Training’s (HIIT) growth in popularity, aerobic training has been somewhat ignored by all except endurance athletes. As you have read, aerobic training provides very important adaptations for the body, whether it’s for health or athletics. My hope with this post was to shed light on the many different options of aerobic training, and the reasons for doing each specific one. You can decide for yourself, what type of adaptations you need most. I encourage you to check out Ultimate MMA Training by Joel Jamieson.  It’s an amazing conditoning resource for all athletes, not just MMA. While anaerobic training has great benefits and results, don’t forget about aerobic training. It doesn’t mean you have to dust off that leotard and headband and head out to step class.  Well, only if you really want to!

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