There are two types of cardio people: those who choose aerobic exercise (i.e. running, jogging) and those who choose anaerobic exercise (i.e. HIIT, intervals). Although both are technically cardio, doing just one type is not enough and a well-rounded program will include both types.

Generally, exercise done in short bursts up to two minutes in duration will utilize the anaerobic system primarily. This includes any short burst of activity that can only be maintained for about two minutes, usually referred to as intervals. Exercise for an extended period of time at a slow or moderate pace, will utilize the aerobic system primarily, and is often referred to as “steady-state cardio”.

Those who prefer aerobic exercise (aka runners and cyclists) tend to neglect interval training, while those who prefer interval training (aka metconners) tend to neglect doing steady-state cardio. If cardio is cardio, why should it matter if I prefer hard and fast or long and slow?

Whether you should focus on anaerobic or aerobic exercises is entirely dependent on what your goals are. Ideally, you’re doing a mix of both in a balanced program. Aerobic exercise will help build endurance and increase cardiovascular health overall, while interval training will enhance muscle strength, power, size and speed.   Aerobic exercise helps build a bigger window in which you can perform intervals, or a aerobic base.  Without an aerobic base, you won’t be able to do a lot of intervals.

While each type of exercise will build and produce different results and develop different skills, the two types of training can function together to make you faster, stronger, and healthier overall. Training exclusively by one type of exercise will limit the progress you can make, and actually increases your chance of injury. Incorporating anaerobic training into an exercise plan that is mostly aerobic will lead to increased speed, power output, economy, increase VO2 max and decrease the chance of injury.

The way to improve cardio performance is to train at and above your threshold. This means to improve aerobic capacity (read: become a better runner) you need to incorporate training intervals that mean you’re working near your current aerobic threshold. On the flip side, those who only train using intervals will not increase their steady state endurance. What this means is that the metconner who also does steady-state cardio training will be able to work harder for longer (read: get more done in each interval).

Both interval and aerobic exercise should be incorporated into a balanced exercise plan. This balance will allow the two systems to complement one another and will maximize results and increase overall health, while minimizing the chance of injury.

Kristen Hansen, BA, CSEP-CPT, PFT-NAIT, NASM-CES, FRCms