Like an international spy, aerobic capacity goes under various aliases. You may have also heard it referred to as aerobic fitness or cardiovascular endurance. It’s all the same thing: the body’s capacity to use oxygen to power sustained physical activity. Think of it as how efficiently your body utilises oxygen during prolonged exercise such as, well, distance running.
Running on the treadmill vs. running outside VO2 max. The subtle difference is that VO2 max is a specific measurement – represented as a number – of the amount of oxygen you can effectively use while exercising. The higher the number, the better your VO2 max. Aerobic capacity, on the other hand, is the broader ability of your body to use oxygen to produce energy.
Why is aerobic capacity important to endurance runners?
It doesn’t require Sherlock Holmes levels of deduction to work out that the ability to use oxygen efficiently while exercising might come in handy when running.
‘Thinking in simple terms, aerobic just means “with oxygen”,’ says running coach Fiona English (@englishruns). ‘During aerobic efforts, we as runners are running on oxygen. The better your body can utilise the oxygen you’re sucking in while running, the higher the intensity you can endure at before lactate builds up and our muscles fatigue and exhaustion gets the better of us. It’s about helping your body learn to endure. With time, you’re working to build up so that a pace you used to find hard to sustain for five minutes, becomes a pace you can easily sustain for 20 minutes.’
Robbie Britton, a Team GB 24-hour runner and ultra distance coach, encourages runners to think of aerobic capacity is their engine size. ‘After that, it’s about how efficiently your body can deliver oxygen to your muscles and use it to create energy,’ he says. ‘The better your aerobic system, the more comfortable hard or moderate efforts feel – and the longer you can sustain them. Without it, your legs might be willing, but your lungs and heart will pull the plug first.’
Is aerobic capacity particularly useful for certain types of running?
Aerobic capacity is particularly key to runners looking to maintain speed endurance. If you find you’re running events that last less than a minute – 100m, 200m or potentially 400m – that are more focused on explosive strength, you’re using your anaerobic system (without oxygen) and there simply isn’t as much benefit to be gained from a big aerobic capacity in those events. But for the everyday recreational runner, likely interested in improving performance over 5k, 10k, half marathon or marathon, Best Garmin deals.
What are some of the mistakes to make when it comes to trying to improve aerobic capacity?
‘In order to increase your capacity, you’re going to have to practise pushing out of your comfort zones’ says English. ‘It’s about learning to run “comfortably uncomfortably”.’ Also, running the same sessions will stunt your ability to improve your aerobic capacity so try playing around with tempo pace blocks, fartlek and intervals.
Britton maintains, however, that easy running also have its benefits here. ‘It sounds almost too good to be true, but those conversational-paced miles are doing a huge amount of work under the hood, he says. ‘Running easily builds the capillaries around your muscle fibres, improves mitochondrial density (where aerobic energy is produced), and strengthens your heart. Long runs and consistent weekly mileage at low intensities lay the groundwork for every other pace. Think of them as your aerobic base — the wider it is, the higher you can build your fitness pyramid.’
What role can cross-training play in improving aerobic capacity?
Cross-training can help mitigate injury risk in two key ways. Firstly, by cross-training you can support a steady increase in the load we put in to our weeks. ‘Most coaches would advice against increasing by more than 10% a week in distance, elevation gain or intensity,’ says English. ‘You can get round this by adding in sessions in the pool or even doing something like a spin class.’
Secondly, cross-training can enable us as runners to tap into more HIIT training, high-intensity interval training. ‘HIIT training works on upregulating the anaerobic system and in turn can support aerobic endurance,’ says English. ‘Think of it as changing your perception of what hard and easy is. The easier you find your current hard, the better an endurance runner you’ll become.’
Britton agrees. ‘While not a perfect swap for running-specific adaptations –you won’t build quite the same specific conditioning or stride economy – cross-training can contribute to a stronger aerobic engine and keep you fresher for key run sessions. Just make sure you do sufficient work to get the conditioning you need for the event you are training for.’
What’s the best workout to improve aerobic capacity?
Everything you need to know about recovery runs Runner’s World US and 1968 Boston Marathon champ, is to run slightly faster (10 to 30 seconds per mile) than your 5k pace. If you’re a faster runner, you should be closer to the 10-second figure; if you’re a slower runner, you should be closer to the 30-second figure. For example, if you can race a 5K at 7:00 minutes per mile, you should run your max VO2 workouts at 6:40-6:50. You can run for distance (800 meters) or time (3 to 5 minutes). After each rep, jog for four to five minutes, and then do another. Beginners should aim for three to four reps, advanced runners for six to eight.
‘Don’t do these aerobic-capacity workouts more than once a week, and skip them on weeks when you have races,’ advises Burfoot. ‘These workouts cover less distance than tempo workouts, but they’re more taxing because the pace is considerably harder.’
