There, the shortest blog post ever!
As with all things training and nutrition, how much and what kind, depends on your goal, it depends on your ability and it depends on how much time you have.
Goal: Fat loss
If your main objective with your current training and nutrition plan is to lose some body fat, then cardio is a useful tool for increasing the calories-out part of the fat loss equation. Fat loss is dependant on you creating a calorie deficit, forcing your body to use stored fuel (fat) for low level activities. Bear in mind that low level bit. As intensity increases, your body wants and needs carbs to keep up with the energy demands that higher intensity exercise requires. This is why you’ll never see a high level athlete on a keto diet, their energy systems just can’t keep up.
But if your only goal is fat loss, reducing your carb intake a little on non-weight training days makes more sense.
Anyways, getting back to cardio.
From a fat loss perspective, both high- and low-intensity cardio both result in the same amount of fat loss, when calories burned are matched. So whether you like to get out for a long, brisk walk or prefer to power through a short blast of conditioning, the choice is yours.
In a recent study, 60 minutes of moderate intensity steady state cardio was tested against 20 minutes of 9s of slow and 6 sec all out sprinting on the bike for 3 sessions over 12 weeks. The results were that fat loss and cardio fitness changes were virtually identical. The higher intensity option also showing improvements in insulin resistance, useful for those with metabolic issues.
Whatever option you choose should be based on how likely you are to stick with it.
If your goal is adding strength, cardio still has a bit of a role to play in your training. Your ability to recover between sets and between sessions is an important part of you making progress. After all, you can’t expect to lift heavy if you’re still struggling to breathe after your last set.
Long, slow steady state (10-20 minutes at around 60% max effort) will build an aerobic base to aid recovery. Adding some higher intensity (8-10 rounds of 10-20 second short bursts at around 90% max effort) conditioning work will aid in recovery between sets.
Keep most of your higher intensity work on separate training days where possible and keep it short.
Goal: Maximising muscle gain
See Strength ⬆️
Adding muscle size is about 3 things: enough training volume, enough calories and enough recovery.
Training volume is sets x reps x load. You need to be able to recover between sets to maintain the load and reps for the programmed volume. You’ll gain more muscle lift 4 sets of 10 at 100kg (4000kg moved), than you would if you only got 2 x10 at 100, then 8 at 100, followed by 8 at 95kg (3560kg or 11% less).
You also need a calorie surplus to fuel training and recover and repair from the training stresses accumulated in training.
Recovery between sessions comes from the above-mentioned caloric surplus and the ability for your body to efficiently use the nutrients and provide plenty of oxygen to the muscles.
Improving your cardio fitness not only improves your heart and lung capacity, but also increase the number of capillaries delivering oxygen and nutrients to the muscles. This makes recovery quicker by removal of waste products and more efficient delivery of nutrients.
The importance of maintaining a calorie surplus is key. You need energy to build muscle tissue so don’t overdo the cardio side of things. Again, short or long duration cardio both work equally well for improvements in CV fitness. So do whatever works for you. Just maintain the calorie intake!
Building a big aerobic base for endurance athletes is the foundation of endurance training. Long and slow for most of it, adding in higher intensity work to increase your lactate threshold, is what’s called for you guys and girls. There are no shortcuts to be had here. Good quality runs/ bikes/ swims are what’s needed. Put in the time get the results.
Strength training can hugely complement your endurance too. Making time to do a short, relatively heavy strength session twice a week will make you stronger and help you perform better as you have more force going into the ground on each stride or rotation of the pedals. Just make sure you can recover adequately so your endurance work doesn’t suffer.