Aerobic and Anaerobic- What You Need to Know

Aerobic and anaerobic are two words that many in the endurance coaching world including myself bound around on a daily basis, yet for the aspiring triathlete these can cause confusion at first.

The terms refer to how the body generates energy, imagine a six year old at sports day, belting across the school field towards the finishing line. When they finish their run they will likely be breathing heavily, exhausted from the 25M sprint they have just completed. When they move into secondary school and start running the 1500 on the track and cross country they soon realise something, if they want to run longer distances they have to slow down.

Once they run longer distances at a lower intensities they are not nearly as out of breath at the end of the effort. They may be exhausted and collapse in a heap with sore legs and no energy left, but their lungs will not burn in the same way as before, they will not be recovering from what is known as an oxygen debt.

The reason you experience an oxygen debt after short efforts is due to the body relying primarily on its anaerobic system heavily for short, hard efforts, this is where your body creates energy without oxygen. I won’t go into the science of how it works here, but what you need to know is that the anaerobic system can only function for around 2 minutes before the athlete accumulates a large oxygen debt and has to slow dramatically, this is our fight or flight reaction that allows us to escape from danger. Many predators in the animal kingdom rely on their anaerobic system heavily as they sprint after prey, if the gazelle manages to slip from the cheetahs grasp or zig zag enough to tire the cheetah, it can avoid becoming lunch as the cheetah has created an enormous oxygen debt it must recover from, akin to the six year old who has sprinted full pelt over a short distance and has nothing left at the end.

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A Cheetah relies on its strong muscles and high anaerobic prowess to hunt down its prey, but if it mistimes its sprint or the animal escapes, it is unlikely to make the kill (photo credit Federico Veronesi)

On the other side of the equation we have aerobic fitness, this is energy created using oxygen. This is much more efficient and is one of the leading reasons for our dominance as a species, where our prey relied predominantly on their anaerobic system to escape danger, we were able to keep them in sight and slowly run them into exhaustion as they were unable to hold the pace that we were over longer distances.

As triathletes we are focused almost entirely upon the aerobic system, as it is very rare that we will be putting the hammer down and become predominantly anaerobic when racing even a sprint distance triathlon as we will need time to recover from this effort. The exception to this is in draft legal triathlon where you may launch an attack off the front of the pack to try to bridge to the next group, which upon joining you will be able to sit in the wheels of for a minute or so while your body recovers from the oxygen debt.

This is the reason that so much triathlon training is done at an “all day” pace, to ensure we are building and strengthening our aerobic system and not our anaerobic system. The mistake that many athletes make is doing all of their training way too fast and making very little headway on the aerobic development side of things. You may be able to run a very quick 5K, but that doesn’t necessarily translate into a great marathon experience, I can vouch for that one personally!

This is where things get confusing, I am a fairly gifted anaerobic athlete, I can push myself harder and go deeper than many others over shorter periods, but tend to suffer over especially long efforts. Normally when I mention that I have a strong anaerobic system and that 5K is my best distance to an athlete a metaphorical finger is waved in my face. “Aha! But a 5K is over 2 minutes, so it’s not an anaerobic effort”. This is of course true, but what people don’t always realise is that your body is never generating energy on a 100% aerobic or anaerobic basis. If that were the case a 100M sprinter could run with his mouth gaffer taped shut and still hit the same time as his rivals.

Anaerobic energy is created in addition to the energy that is being generated aerobically, you are using anaerobically generated energy while reading this. It is only an incredibly tiny fraction of the energy being created (think several decimal places), but is it ticking over like a pilot light, ready to leap into action at a moment’s notice.

To illustrate this more clearly here is a graph created using WKO4 (more information here) that visualises the energy systems used by an athlete at different timeframes. The data is collated using the athlete’s best performances at the time periods listed on the X axis, with the maximum power than can sustain for that period on the Y axis. I use these graphs to help athletes gain a better understanding of their individual physiologies to help us understand where we need to focus our training effort.

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Today we want to focus on the green and the blue lines, the green line represents aerobic contribution, the blue line anaerobic. If we start to the left of the chart we can see that at 1 second there is very little contribution from the aerobic system as the body has not started increasing the rate at which it pumps oxygen to the muscles yet, but using glycosides the body can create energy within the muscles and get us moving immediately. As we look closer towards the 10 second mark the aerobic system is really starting to get up to speed now, additional oxygen has been absorbed from the lungs and is being pumped to the muscles to get them fired up.

For this athlete, it is at one minute 6 seconds that the crossover occurs, and the aerobic system takes over as the primary fuel source. The aerobic system has fuel, it can continue indefinitely for as long as it has fuel, the anaerobic system making a tiny contribution that can increase on hills or when accelerating hard.

Looking at the 20 minute data point, the anaerobic system is still contributing 10W of power, which is still a respectable amount, I’m sure if this athlete saw their FTP drop by 10W they would be mortified. Remember, this is looking at the athlete’s best 20 minute effort, not all 20 minute efforts use such a proportion of the anaerobic system.

Going back to the graph, it would look very different for a track sprinter compared to a time trialist (which this athlete is classified as). In a sprinter the anaerobic system would make a much greater contribution, it would continue for much longer before the intersection with the aerobic system as sprinters need to hold maximum power for as long as possible. Their aerobic system will be very weak comparatively and they would struggle to keep up on a gentle Sunday club run as a result.

So now we’ve gone through the science, let’s have a look at the takeaway points, and how a better understanding of the two energy systems can aid your training:

-There is no benefit to developing your anaerobic system for most triathletes. I know an extremely successful athlete who has raced at Kona, yet claims he can’t sprint for toffee (never seen him sprint so can’t confirm this). He doesn’t need to train or develop his anaerobic system, he’s happy to let it fall by the wayside almost entirely to focus entirely on his aerobic system. That’s not to say that he won’t start leaning on anaerobic pathways during some sessions (such as hill reps), but the goal of these sessions is to develop muscular force, not to increase anaerobic ability although this may come as a byproduct.

-You’re never completely aerobic or anaerobic, the body is always using both, even if in very small amounts. Your anaerobic threshold is where you start to produce energy primarily from the anaerobic pathway and should be avoided for the majority of your sessions

-Avoid using large amounts of anaerobic energy in your training. It feels good as it leaves you feeling more fatigued, and changes in your anaerobic system are faster to gain and easier to track than gains in your aerobic system (“I’m 5 seconds faster up that hill!”), but are of little use to the vast majority of triathletes when it comes to race day. I know I’ve certainly fallen foul of this one in the past.

-Many fitness tests require you to use large proportions of anaerobic energy, as triathletes we are not testing you for improvements in these areas, rather trying to assess your current weighting between aerobic/anaerobic energy sources. If an athlete puts out the same amount of watts over a set period as his previous best but the anaerobic contribution is lower then the previous test, this will result in an increase in FTP when uploaded to WKO4.

I hope this has given you a better understanding of the role that aerobic and anaerobic pathways play in endurance sport, leave any questions in the comments below and I’ll do my best to answer them.

Introduction to Running Injuries

 

Running injuries are, unfortunately, part and parcel of running, with 65% of runners experiencing some kind of injury every year. However permanent damage and elongated time off of running are avoidable, let’s start looking at different types of running injury.

Impact Injuries

These are injuries which are as a result of getting it wrong while running or in day to day life, they can be anything from tripping on a tree root, rolling your ankle off the edge of a kerb or breaking a bone. Sometimes you just drop the ball momentarily or run out of luck and this will result in enforced time off of running. Luckily these are generally easy to treat as the body will heal itself in time and allow you to gradually return to running. There can be complications along the way, especially with complex fractures around the ankle joint, so always follow the advice of a medical practitioner before you return to running. As a result, there’s not too much point me dwelling on them here, so let me move onto the more common kind of running injury.

Overuse injuries

The bane of many a runner, these occur when you run too far, too fast or with poor form. These injuries traditionally affect the tendons and ligaments in the lower body but only occur after prolonged abuse, so learning the warning signs of these injuries is vital to avoid prolonged time sidelined. Let’s look at the most common running injuries

Achilles Tendonitis

This is one of the most widespread running injuries, and can take a long time to recover from. This manifests itself as a pain in the back of the ankle, although can be felt anywhere from the base of the heel to higher up the calf. This is caused by the stretching or inflammation of the achilles tendon, normally as a result of being pulled by a tight calf muscle.

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Image credit Foot Pain Explained

Achilles tendonitis is an especially dangerous injury as it can easily lead to a rupturing of the achilles tendon, which can require a long rehabilitation period or even surgery. The rupture can occur with very little warning, and has even been known to be audible to those nearby! For this reason it is very important to monitor this injury carefully and if in doubt stop running.

If you nip this injury in the bud you shouldn’t have any problems, but leave it for a prolonged period and it can be very difficult to recover from as the achilles tendon is a long way from the heart, so it takes a long time for enough blood to reach the tendon to repair it. Foam rolling and sports massage to loosen the calf is the best treatment, combined with regular icing to encourage blood flow.

Piriformis Syndrom 

The piriformis is a little known muscle that sits deep within the glutes, and prevents the knee from rotating too much. If the piriformis becomes tight it has a tendency to squeeze the sciatic nerve and cause pain when running, which is intensified when sitting.

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Image credit Back Pain Advisor

Tightness in the muscle is often caused by weak hamstrings, glues or hip muscles, and can also be caused by excessive overpronation, causing the piriformis to work hard stabilising the knee, resulting in tightness.

Treatment involves stretches that target the glutes and foam rolling the area to release tight muscles. If you have a history of piriformis problems, you can use exercises to strengthen the glutes combined with foam rolling to ensure you stay pain free. It may also be worth getting an assessment of your kinetic chain by a coach or personal trainer to help assess whether you suffer with any weaknesses that can be addressed.

Iliotibial Band (ITB) Syndrom 

One of the hardest injuries to shift if left untreated, it manifests itself as pain in the outside of the knee, or in the IT band itself. The IT band is a very large fascial band which runs from the hip down to the knee, and can be pulled tight by a variety of problems which can include tight hip flexors, overpronating or weak core muscles/glutes.

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Image credit Vive Health

For all cases of ITBS I recommend immediately seeing a physiotherapist to help locate the cause of the pain, as it can come from various sources. To prevent problems ensure you foam roll regularly to keep muscles loose and strengthen your core/glutes to give your body a stable platform to run on, reducing strain on other areas.

Plantar Fasciitis 

A phrase that fills many runners with dread, this is an especially troublesome running injury not because of excessive pain but the difficulty many face in returning to running after suffering with symptoms.

The planter fascia is a strip of connective tissue that runs along the bottom of your foot from your heel to your metatarsals (long bones that run along your toes). It has the rather unfortunate position of being at the bottom of the kinetic chain, so tightness in any muscles on the lower body could eventually work their way down the leg to pull on the plantar. The function of the planter is to stabilise the foot, which means that those with high arches, which will put the planter under more strain, are at more of a risk.

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Image credit First Aid 4 Sport

The pain will normally manifest itself as a pulling in the heel, although can be experienced along the bottom of the foot towards the arch in rare circumstances. To treat the injury a two pronged approach is recommended, both releasing the plantar itself using a golf or tennis ball, alongside stretching and releasing the calf to reduce any pulling on the planter from further up the kinetic chain. These exercises along with barefoot running can be used to prevent an athlete from developing plantar fasciitis.

If you suffer with symptoms it is important to treat them immediately to stop the injury becoming chronic, which can result in a long time away from running.

Runner’s Knee

Patello-femoral knee syndrome, also known as runner’s knee is a common running injury that causes pain around the knee joint, and is especially painful when ascending or descending stairs.

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Image Credit Body Heal

This is traditionally caused by weak or tight quadriceps which will pull the knee tight during exercise, but can also be caused by overactive or weak hamstrings, something a medical professional will have to evaluate.

The best prevention is loosening your quads with a sports massage and regular foam rolling combined with strengthening exercises such as plyometric jumps. It is worth mentioning that unlike other injuries, rest will not help you recover from runner’s knee.

Shin Splints

There are two types of shin splints, muscular and skeletal.

Most cases are skeletal and if left untreated can lead to fractures so it’s important to rest and slowly increase running volume. This is especially common in new runners who increase the load too quickly when their body is not used to the strains that running places on the body. It is also more common in larger athletes who put more strain through their body with every step. There is little that can be done to help strengthen the body to prevent against shin splints, but it may be worth reviewing whether you are getting enough vitamin D.

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Image credit physiopedia

If you run your finger along the inside of your tibia and feel the muscle is sore rather than the bone, it is possible the pain is muscular, which accounts for roughly 10% of cases. The best treatment is rest combined with foam rolling of the muscles in the area to loosen them and release pressure. The causes of muscular shin splints are similar to skeletal, running too far/fast too soon.

Hopefully this has given you an insight into the most common injuries, to summarise the warning signs you should look out for:
Pulling on the back of the heel- Achilles tendonitis
Pain on the bottom of your feel- Plantar fasciitis
Pain on the outside of your knee- ITB syndrome
Dull pain above/below the knee- Runner’s knee
Pain in the shin during or after running- Shin splints
Pain deep within your glutes- Piriformis syndrome

Each running injury should be treated in the same fashion

  1. Immediately stop running or drastically lower running volume. If you are experiencing pain when running, it is for body’s way of warning you that you are doing damage.
  2. Locate the cause of the injury, preferably by visiting a professional. They will not be able to cure the injury for you, rather prescribe you with a series of exercises to help recovery.
  3. Follow up on the exercises prescribed by the professional. If there is no improvement after several weeks it may be worth visiting your GP to ensure it is nothing more serious.
  4. Get your running gait analysed to check for any areas of weaknesses that may have caused the injury, or any effects the injury may have had on your gait.
  5. Slowly return to running and try not to adjust your gait to favour the afflicted area, as this will likely cause issues elsewhere. Continue with the stretching and strengthening exercises prescribed to you to reduce the risk of the injury relapsing.

If you have taken time off with injury and are looking to get back into training E-mail Simon@phazontriathlon.com or call on 07515666325 and we can discuss the best way for you to make a successful return to running.

Disclaimer: The information in this article is designed to educate athletes on the symptoms, causes and basic treatment of the most common running injuries and should not be considered to be medical advice. If symptoms last more than a week or you are in any doubt, visit a medical professional for advice on the causes of your injury and a rehabilitation program.