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Training your Nervous System: A New Approach to Interval Training

July 6, 2015

Everyone knows how important exercise is for health. For those who suffer from fatigue and chronic illnesses (autoimmune disease, chronic fatigue syndrome, chronic Lyme disease, fibromyalgia, adrenal fatigue, etc.), however, just the thought of exercise evokes the fear of not being able to get out of bed the next day. Unfortunately, the more that we rest and avoid exercise, the less energy generating capacity is available in the body.

The powerhouse of the cell is called the mitochondria. Cells that require lots of energy may have as many as 2000 mitochondria (such as liver cells) and cells that do not require any energy (like the red blood cell) have none. The body does not waste energy creating mitochondria if we choose not to exercise. This will lead to a decreased capacity for energy creation and can cause problems with fatigue. When we do exercise, the body will naturally increase the production of mitochondria, allowing the body to produce increased amounts of energy to meet the body’s demand. This is why exercise is so important for improving energy levels.

The question then becomes what type of exercise is best? While there is no one right answer to this question, for those with energy based issues, many have high levels of stress. Stress may be physiologic, as in the case of disease, or it may be more emotionally based. Either way it will begin a cascade of biochemical reactions in the body including the release of adrenaline, cortisol and norepinephrine. This is important to understand because exercise itself is a stressor that can increase the release of these stress hormones. So while exercise is good, too much exercise is not healthy at all. Overtraining can cause a breakdown of the body that generates elevated stress and inflammation.

Left to figure out exercise on their own, most people suffering from fatigue and related illnesses will generally choose a low-to-moderate level intensity aerobic exercise program such as walking. Intensity is determined by the percentage of your maximum heart rate (220-age). Light exercise is considered 40% to 65% of your maximum heart rate, moderate is 65% to 75% of your maximum heart rate, and high intensity is anything above 75% of your maximum heart rate. While all exercise will have a positive effect on immune response, the effects of high intensity exercise are much greater. This also holds true for insulin receptor sensitivity, nitric oxide response, and improvements in neuroplasticity/brain function. Even more importantly, only high intensity exercise allows for the release of growth hormones which improve the body’s ability to heal, as well as the release of opioids that allow you to feel great while exercising. Exercise is also a great way to help improve depression and anxiety. It is important to note that oxidative stress and risk for overtraining syndrome do increase with high intensity exercise. So, a little hard exercise goes a long way.

The bigger question in my mind has always been “Why is exercise so stressful on the body if it is so good for us?” The answer lies within the nervous system. Activities are generally controlled either by our parasympathetic nervous system (our “rest and digest” or “feed and breed” system) or the sympathetic nervous system (“fight or flight”). When the parasympathetic nervous system is working, the body can concentrate on relaxation, sleep, digestion, urination, defecation, etc. The sympathetic nervous system, on the other hand, controls the stress response, exercise, sweating, gut motility, etc. Even more importantly, these two control systems affect heart rate, blood pressure, and breathing rate. Left to its own devices with no nervous system control at all, the heart would beat at around 80 to 100 beats per minute (vagal heart rate). However, since the heart is innervated by parasympathetic and sympathetic nerves, the heart rate is actually controlled by these nerves. When the parasympathetic nervous system is under control the heart rate will be lower. How low this will be is influenced by age, gender, health, and fitness level. Athletes often have very low resting heart rates, as a fit heart has very good vagal tone. The typical resting heart rate is between 70 to 80 beats per minute with an average resting heart rate of 70 beats per minute for a man and 75 beats per minute for a woman. When the sympathetic nervous system takes over control of the heart, the heart rate will increase to above 100 beats per minute. So the harder you exercise the more time your body spends under sympathetic control.

Interval Training Program

In order to maximize health using exercise you need to spend time doing high intensity exercise. At the same time it is also important to realize that many with chronic illness are already fighting a dominant sympathetic nervous system. The solution is an exercise program that is intense, but does not overly tax the nervous system. I have found in my practice that the best way to do this is to do short bursts of intense activity (at an appropriate level for that client) with sufficient rests between intervals to allow the nervous system to recover. While traditional forms of interval training may provide a minute or two of rest between intervals and allow for partial heart rate recovery, this may be inadequate for the nervous system to recover.

What I recommend is a 10 to 15 second activity burst (more on this later) followed by a recovery that may be no activity at all, or mild activity that returns the heart rate to just below or around 100 beats per minute. Pulse may be taken with a heart rate monitor, the monitors built into cardiovascular equipment (recumbent bike, treadmill, elliptical, etc.), or by simply manually taking your pulse either at the wrist (radial pulse) or neck (carotid pulse). Each work out should begin with a five to ten minute warm up at an easy pace. The length of the interval portion should be determined by the time that it takes to recover. My rule of thumb is that if it takes more than five minutes to recover between intervals, this is a sign you are overtraining. If recovery is five minutes or less the interval may be repeated. No more than 15 to 20 minutes of intervals are necessary. This should be followed by a five to ten minute cool down at an easy pace.

Energy Systems

Let’s get back to the 10 to 15 second activity burst. The first question people usually ask me- particularly personal trainers – is “Why is this so short?” The answer is quite simpe, really. We have three distinct energy systems that help us to create energy at the cellular level. ATP (Adenosine Triphosphate) is our cellular energy that we produce and is required for activity, biochemical processes, etc. The first system we use whenever we require energy is our ATP-PCr system. This system relies on the fact that at rest most cells (particularly muscle cells) will create ATP. Since this is active energy our body will actually take one of the phosphates away from this compound and store it attached to creatinine to create phosphocreatine (PCr) and Adenosine Diphosphate (ADP). Then, when your body requires a quick burst of energy lasting (you guessed it!) 10 to 15 seconds your body takes the extra phosphate group and adds it back to ADP to regenerate ATP. This is an anaerobic system, meaning that it does not require oxygen to function. If the ATP-PCr system cannot provide sufficient ATP for your requirements, then your body will produce energy using glycolysis. This system is also anaerobic and can generate more ATP from glucose so that energy will last up to two minutes long. The product of this system is lactic acid, which causes a burning sensation in your legs while sprinting. The lactic acid accumulates if you try to use this system for too long, but it can also be used to begin the third and final energy system, the oxidative system (which requires oxygen). The oxidative system can fuel much longer lasting activities and is the primary energy system used for exercise lasting for five minutes or longer.

Now that you have a basic understanding of energy systems, the last piece of the puzzle to understand is where in the cell these systems occur. While the oxidative system will generate the most energy it occurs in the mitochondria. The mitochondria are often not working at optimal levels in those with fatigue and chronic health challenges. To try and exercise in a way that further taxes the mitochondria is likely to cause more energy problems. On the other hand, glycolysis takes place in the cytoplasm (thick gel that holds the organelles of the cell) and the ATP-PCr system takes place in the sarcoplasm which is similar to the cytoplasm found within a muscle cell. So it only makes sense to concentrate on anaerobic metabolism for those with mitochondrial dysfunction. By choosing to concentrate on using the ATP-PCr system we can hone in on using the energy system that is concentrated in the muscle cell and spares the mitochondria from exhaustive work. Yet, this system still allows us to generate adequate intensity to challenge the body and reap all of the benefits of exercise.

When Should I Exercise

When you exercise really depends on your own unique energy pattern, which is called your circadian rhythm. Since circadian rhythm is intimately tied to the stress hormone cortisol, it really influences how you feel throughout the day. For those who have low morning cortisol, they have difficulty waking up in the morning, require coffee or caffeine to function, have no appetite in the morning, and feel that their energy is lowest the first hour after waking up. For these individuals, a brief high intensity session within the first half hour of waking up is ideal. This session does not need to last more than ten minutes to be effective for restoring energy levels. It can be done using a bike, short sprints, push-ups, squats, jumping rope, or even running in place. Again, these exercises should be done in 10 to 15 second bursts and then allow the heart rate to recover to 100 or less. The high intensity bursts of exercise allow for increased levels of cortisol which can help to replenish depleted early morning energy levels. For those who have elevated cortisol levels (you can check cortisol levels using a 4-point salivary adrenal stress index test) or insulin resistance/type 2 diabetes, exercising before lunch may be more appropriate. This can help to improve insulin sensitivity and decreases the stress response for exercise.

Right-Sizing Exercise

The term “high intensity” can be pretty scary for someone who has not exercised in a long time. The first step to any exercise program, particularly if you do have a medical condition, is to check with your physician to make sure that exercise is appropriate for you. Once you have your doctor’s clearance, you can then decide what sort of exercise appeals most. For those who have been severely ill or who are deconditioned, brief bouts of walking, chair squats (squat to a chair, stand up, and repeat) or recumbent biking are all appropriate. For those who are a bit more fit, strength training (8 to 10 repetitions per set) or sprints (can be on a treadmill, exercise bike, elliptical or swimming) are a better bet. The actual type of exercise is far less important than the intensity level and having sufficient recovery between intervals. Generally I encourage people to choose whatever exercise appeals most. The more you like the activity, the more likely you are to do it consistently.

Jessica Pizano is the owner of Fit to You, LLC, which offers personalized training programs and nutrition/health counseling. Her concentrations include genetics and nutrigenomics, general health and fitness, weight loss, food allergies/sensitivities, autoimmune disease, post-rehabilitative work, training/nutrition for medical conditions, obesity intervention, pre- and post-natal exercise and nutrition, and Pilates. In addition to being a certified personal trainer and a corrective exercise specialist through the National Academy of Sports Medicine, she is also certified in mat Pilates through PHI Pilates and earned her Clinical Exercise Specialist and Longevity Wellness Specialist through the American Council on Exercise. She completed her training to practice Health Coaching at the Institute for Integrative Nutrition and is certified as a holistic health practitioner through the American Association of Drugless Practitioners. She earned a master’s degree in human nutrition that emphasizes functional medicine at the University of Bridgeport. Currently, Jessica practices personal training, nutrition counseling, and nutrigenomics in her studio in Avon. She may be contacted at (860) 321-7234 or online at www.fittoyouct.com.

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