Altering the Autonomic Nervous System for Improved Health

Just before posting this piece I was looking at an exercise physiology textbook published in 2007. It only had two pages devoted to the discussion of the autonomic nervous system and it didn’t discuss the effects of exercise on it. That’s because most of the research is relatively new.

According to Fundamentals of Human Anatomy and Physiology 6^th Ed. (Martini, 2004) the autonomic nervous system (ANS) “coordinates cardiovascular, respiratory, digestive, urinary, and reproductive functions … and it does so without instructions or interference from the conscious mind.” When discussing the ANS a lot of complex terms are used, so bear with me as I get the definitions out of the way. Altering ANS output for improved health is a rather simple process.

The ANS can be divided into the sympathetic and parasympathetic divisions. In order to feel great and remain healthy we need to strike a balance between the two systems. Increased output from the sympathetic nervous system “stimulates tissue metabolism and increases alertness” (Martini, 2004). Maximum output from this system is known as the fight or flight mechanism, which is experienced during extreme duress. Increased output from the parasympathetic nervous system “conserves energy and promotes sedentary activities” (Martini, 2004).

Parasympathetic Nervous System (PNS)

Activities that increase PNS output include low intensity/long duration exercise such as walking and running, yoga, static stretching, massage, diaphragmatic breathing, and sleep. These activities are excellent for lowering stress.

Sympathetic Nervous System (SNS)

Activities that increase SNS output include high intensity interval training (HIIT), sprinting on flat ground and uphill, plyometrics, and weight training with moderate to heavy weights*. These activities improve energy levels and metabolism. I was at a presentation by Dr. Mark Swain from Inside Out Chiropractic and he referred to research on posture and the autonomic nervous system. If you’ve been sitting in a slumped posture all day you may start to feel tired due to increased PNS output. The trick is to sit up tall for a few minutes until your energy levels return.

*Warning: Sprinting and some plyometrics are higher risk activities and should only be used for advanced athletes.  

Putting It All Together

If you have a lot of stressors in your life include more PNS activities. When I was working a lot of midnight shifts in addition to running my business and volunteer coaching I would be short on sleep and would often miss several weeks of running. This led to an increase in resting and training heart rates among other things. While you can say that this occurred due to being out of shape a single 30min run would return my heart rate to normal for the next day. Aerobic fitness doesn’t return that quickly. Yoga and static stretching are excellent activities to perform before you go to bed but maybe not before a workout.

If you’re lethargic all the time or your exercise regimen is limited to PNS dominant activities, then include more SNS activities. I’ve found that if I run for several weeks at high volume without performing weight training or hill sprints that my legs feel very heavy. When I choose to accelerate my body doesn’t respond. After a few hill sprints my legs feel immediately fresher. Most people will need at least 48 hours rest after hard high intensity activities. Hill sprints may be too aggressive for you, but most people can learn to safely perform squat and deadlift variations with moderate to heavy weight.

While stress increases SNS output it doesn’t necessarily mean that one needs to avoid these activities. Short weight training sessions can be used a couple times a week, but HIIT training should probably be avoided.

In order to maximize our health we need to avoid focusing on one or two aspects of fitness and neglecting the others.

Stay fit,

Jonathan Pratt

Pratt's Pro Fitness 

Key Principles of Running

A couple months ago I gave a presentation on running titled In Defense of Running named after Michael Pollan’s book In Defense of Food. Pollan discusses how indigenous tribes thrive on vastly different diets, because there is one common theme: they eat real food. In comparison I discussed how there were many successful programs, but despite their differences there was also a common theme: there was a lot of running involved! I thought I’d share some of the ideas from that presentation.

There’s a lot that we can learn from studying the science of running, but it’s not necessary to have a strong science background in order to develop an effective program. We have more than one hundred years of trial-and-error evidence by thousands of coaches and millions of runners that’s easily available to anyone. From these individuals we find that although methods vary there are several common principles:

Consistency is the key: Long term success in running is not determined by some amazing workout or training week but through months and years of good and even average workouts. The best workout you can do takes too long to recover from and can lead to injury. These should be done sparingly.

Individualized training is great, but so is training in a group: If we take many runners preparing for the same event they will all have different backgrounds and different needs even if they run the same time for that event. Thus, these runners should have some individualization to their training. Having said that, group training has tremendous benefits psychologically which transfers into physical improvements. The goal then is to individualize training within the group.

All the elements of a program are important: It’s not all about the long run or interval workout or high mileage.

You need to run … a lot: Yearly increases in running duration and frequency are necessary for continued improvements for both middle and long distance events. Training at lower intensities allows one to recover more quickly from race specific intensities both during and after interval training sessions.

Paula Radcliffe won World Jr XC on only 25-30mi/week, but it took 120-160mi/week to become one of the best ever.

Research by Seiler and Tonnessen (2009) reveals that elite runners spend about 80% of their training at below 75% maximum heart rate. While this has worked very well for elites Esteve-Lanao wanted to know if it was applicable to recreational runners. He found that these runners tended to run too fast on their easy days and were therefore unable to achieve the necessary intensity on their hard days. When Esteve-Lanao (2007) made another group strictly adhere to running below 75% MHR on easy days they outperformed a group following a higher intensity protocol over 10km. While some elites “hammer” their easy runs they’re still running moderately high volumes and rarely exceeding their marathon race pace.

Easy runs at less than 75% maximum heart rate allow one to develop the cardiovascular system and aerobic energy pathway, but at an intensity low enough that it spares carbohydrate stores for race specific work. These runs also develop fat burning capability for events over 60min. The use of a designated long run is optional for events shorter than 60min.

Don’t forget interval training: While general conditioning improves the capacity of your engine interval training improves your engine’s power. This gives you a higher work rate.

For race pace training I use race pace +/- one event. Using the 10km as an example I use 5km to half marathon pace. For speed work I run up to two events faster i.e. up to 3km pace for the 10km.

There are many examples of runners that reached a world class level without interval training. These runners will often feel that they got slower from regular interval training. For example, Ron Clarke significantly lowered the 10 000 m world record just by running high volume and running hard on some of those runs. However, Clarke could never win major championships, because his engine wasn’t powerful enough to change pace quickly. He needed interval training, but he needed to use it sparingly to avoid breakdown.

Include some form of training to develop the stride: This type of work improves performance by increasing stride length, increasing stride rate (through decreased ground contact time), and lowering energy consumption at any particular pace (i.e. it improves running economy). The methods used vary dramatically from program to program but may include any or all of the following: form drills, plyometrics, weight training, hill running, and sprinting.

Stay fit,

Jonathan Pratt

Pratt's Pro Fitness