Supercharge your aerobic Capacity

Before starting specific race prep, it's common to hear athletes talking about building up their “base”, creating a fitness foundation upon which their training will build over the coming season. After a period of mileage building and basic training, how do you then level up? 

Read on to learn about the importance of having a strong aerobic engine and how to supercharge your aerobic capacity (and race performance!)

What is aerobic capacity and why does it matter?

Energy for all body functions is provided in two different ways – aerobically, meaning “with oxygen” and anaerobically, which does not use oxygen. You are ALWAYS using energy supplied both aerobically and anaerobically, but the proportion of each changes depending on duration and intensity of exercise. Aerobic energy supply is preferred during long exercises bouts because it is more efficient and and has an essentially limitless capacity (so long as you are well-fueled, but that’s for another article!). On the other hand, anaerobic energy supply can provide a quick burst of energy but is finite in supply.

The longer the race, the greater the proportion of energy supplied aerobically. In a full-out run lasting about 2 minutes, about half of your energy is supplied aerobically and half anaerobically. Yes- you read that right - in any race lasting more than two minutes, the majority of your energy is supplied AEROBICALLY! 

Let's Get Nerdy

During exercise, the oxygen you breathe in is transported from your lungs to working muscles through your bloodstream. In muscle, oxygen is used as a key ingredient for aerobic energy production. So, the more oxygen you are able to consume and use, the greater your rate of long-term energy production, allowing you to run/bike/swim/climb faster for longer. Training improves oxygen delivery and utilization in a host of different ways including:

● increasing capillaries - tiny pipes which transport oxygen to your muscles

● increasing mitochondria- the tiny cellular machines that metabolize energy

● increasing blood volume - oxygen is transported via the bloodstream attached to red  blood cells

Aerobic capacity can be assessed by measuring  VO2max – the maximal volume of oxygen consumed per minute during exercise, expressed in L O2/min or ml O2/kg/min.

 Genetics plays a role in the absolute upper limit of your VO2max, but reaching that limit requires substantial training. VO2max tests are often performed on elite athletes to accurately measure aerobic fitness and create very specialized training plans. This is done in a lab by analyzing carbon dioxide and oxygen inhaled and exhaled during an exercise test. VO2max can also be estimated based on HR testing or recent race results.

If this sounds complicated - don't stress! You don't need to know your actual VO2max value to improve your aerobic capacity. These workouts are highly effective when prescribed based on effort, pace, or heart rate. Typically, sessions involve longer intervals performed at a smooth but challenging pace - anywhere from 10km to marathon pace depending on the athlete and goals.

I'd describe the feeling of these workouts as a grind - the length and intensity provides both a mental and physical challenge. Aerobic power workouts are fatiguing and may be used more sparingly during peak race season when focus shifts towards sharpening and recovery. For that reason, "off season"/prep season is a great time to really focus on building your aerobic capacity.

Here are a few bread-and-butter aerobic power workouts:

Workout 1 - Tempo run: Tempo runs are a section of your run done at a substantially higher intensity then your usual “easy” pace. We define "tempo" as a pace that you could hold for about an hour maximally (ie if a bear was chasing you!)

A tempo workout could look like:

10-15 minute easy warm up

5x5 min tempo w/ 90 sec recovery

10-15 minute easy cool down

Workout 2 Fartlek: Fartlek is a Swedish word which means “speed play”. Fartlek runs involve picking up the pace for a section of time and then returning to easy run pace to recover before beginning another faster interval.  The pick up should be a hard effort but not so exhausting that you can’t run between segments.

There are lots of ways to structure a fartlek workout, one with an aerobic power intention could look something like this:

10-15 minute easy warm up

1min-2min-3min-4min-5min-4min-3min-2min-1min of hard running with 1 min of easy running in between everything for recovery. The short recovery is key here!

10-15 minute easy cool down

Workout 3 Progression Run: The name says it all! During this workout, increase your pace as the run progresses, transitioning from an easy to moderate to hard effort. A progression run could look like:

15 min Easy (i.e. 10 min/mile)

15 min Moderate (i.e. 9 min/mile)

15 min Hard (i.e. 8 min/mile)

Aerobic workouts take time, discipline, and mental toughness, but are well worth the effort when it comes to endurance performance.

By Jessica O’Connell MSc, CSEP-CEP, OLY. Coach at Fast Forward Run Coaching

For more coaching advice or to sign up for personalized online strength and run coaching, check out www.ffwdcoaching.com