A deeper discussion and understanding of the aerobic energy system

Aerobic fitness correlates with increased longevity

Aerobic fitness is positively correlated with increased longevity. While strength training is known to improve physical appears (for guys the sixpack), the studies suggest that the health benefits come from aerobic training. People think of aerobic training as get on the bike and run as hard as you can for 30-60 minutes or they think of it as interval training. From what I'm learning, higher intensity is not better and can only lead to overtraining in the long term. In other words the dose of aerobic stimulus is something to track in terms of overall volume where intensity going up means after a certain point the possibility of diminishing returns with regard to health.

The aerobic energy system is an exercise rate where you can move but you are not gasping for air. Air has to circulate well throughout your body for it to be aerobic. Anaerobic is when you pass the intensity threshold to where you feel out of breath and are operating without air. If you feel like you are holding your breath when you are pushing the aerobic training then it's anaerobic (beyond the anaerobic threshold). An activity which a person can do and feel at ease doing it (they feel like they can do it comfortably for hours) is the aerobic energy system.

This means going for a brisk walk counts as aerobics, it means going for a light jog, or bike ride, or similar. Volume is measured by intensity, duration, power and frequency. Power on an exercise bike is how much resistance you are using, while duration is how much total time you spend in a certain desired aerobic heart rate zone, while intensity is the heart rate zone you are in. If you go lower intensity you can train for longer and feel more comfortable doing so.

While I cannot give any advice I can only say from my own experience that if I'm out of shape I usually have to start at the lowest intensity possible. This could mean just walking. A week of walking turns into brisk walking the next week or so, and then into light jog and brisk walk (interval training) or into the fastest walk I can do while remaining at a heart rate of around 120-130 range (moderate intensity). Only when able to do a full week (around 7 workout sessions) in the 120-130 range for 60 minutes duration do I consider progressing to the 130-140 range which is considered vigorous intensity.

Aerobic fitness takes around 6 to 8 weeks to build up to a level of running a 5 minute mile. At the same time if you take 2 weeks off you will find you might be starting from scratch having to walk the miles rather than run or jog. In other words, gains are lost very quickly in aerobic fitness. This is why it might make more sense to build up muscular fitness for the first year and then after becoming muscular build up aerobic fitness. Aerobic fitness requires a lifetime of consistency or it's lost pretty much instantly while muscle gains (due to muscle memory) will stay for life.

Benefits of aerobic fitness include:

• Increased energy level.
• Sharper thinking.
• Decreased depression and mood enhancements.
• Reduced insulin resistance.
• Potential longevity benefits, reduced heart disease risk, increased HDL cholesterol, better circulation over time.

At the same time too much of a good thing is possible. Over training can and does occur if the intensity is too high. The symptoms include:

• Insomnia.
• Muscle pains and weird joint pains.
• Increased colds or viral infections out of no where.
• Anxiety, or feelings anxious.
• Heart rate irregularities such as supraventricular tachycardia or afib.
• Hormone irregularities such as changes in thyroid or and adrenal function.
• Rhabdomyolysis represented by high levels of creatine kinase.

And of course the symptoms can get worse from here. The end result of over training is hospitalization or in some cases heart failure as some marathon runners (very very small percentage) end up dying from the stress it puts on their heart. In other words it is possible to overdose on cardio.

The correct dose of cardio is the minimum dose to trigger the positive adaptations you are trying to trigger. This means why go any harder or more intense than necessary to reach the adaptive state? Marathon running is simply unnecessary. An hour a day on the treadmill is all that is actually necessary and even then it is only necessary to go at the moderate intensity pace. High intensity interval training is valuable but this is the kind of training most likely to lead to the over trained state. If you do it for more than 30 minutes a week you will risk over training. Once in an over medically measurable trained state it can take months or years to get out of it. Medically measurable meaning it's not just subjective (insomnia, fatigue, joint pain, etc, but it's also seen in blood tests (high CK, hormone irregularities, cortisol very high or unusually low, testosterone low, thyroid irregularities, etc).