Here are a few scenarios:

Scenario 1

First is my own. I am a competitive powerlifter, personal trainer and fitness model. My goals for cardio are

1. Maintain cardiovascular fitness/endurance

2. Maintain my body weight for my powerlifting weight class

3. Maintain lower body fat for aesthetics

4. Keeping the training low  impact on my joints (primarily knees and hips) because of heavy joint stress from powerlifting training.

I have found over the years that my body fat levels respond best to moderate intensity, semi-steady state cardio at longer periods of 30-60 minutes. Sometimes I will throw in a high intensity cardio session with interval training for 20-25 minutes. However, I do not do HIIT (High Intensity Interval Training) regularly because my muscles cannot handle it on a daily basis due to my sport recovery. HIIT also negatively impacts my power strength long term. Again, this is what I have found for MY body. Based on my cardio goals, I choose to walk on the treadmill or use the elliptical machine, training at 65-75% of my max heart rate. Sometimes I will do slow stair master sessions here and there, but not always due to knee stress. If I was not competing in powerlifting, I would likely be running outside because frankly, I love it. I love how running outside makes me feel inside and out. I used to run cross country and track in high school and since then was hooked. However, I need to focus on keeping my body healthy and balanced both for sport and health and running daily is too much for my joints right now.

Scenario 2

I have a client who is naturally lean. She trains for overall fitness, strength, and fun. While she does not need to do much cardio to maintain her body fat levels, I have her doing so for cardiovascular health and recovery. She enjoys high intensity the most, particularly sprints, because it simulates training from her prior volleyball days. For this client, a few 20 minute HIIT sessions per week is all she needs to maintain her aesthetic goals. However, I always have her do some slower, moderate cardio sessions for 30-45 minutes once a week or every 2 weeks– to change things up so that her body does not get accustomed to the same thing all the time, and to tax her cardiovascular system differently.

Scenario 3

Another client of mine is struggling to lose body fat. She also has a prior low back spinal injury as well as prior knee surgery for her medial meniscus. The only real cardio she can do is light swimming or the recumbent bike. She will not swim because she does not like what it does to her hair, nor does she have access to a pool. She definitely cannot handle intense spinning on the bike due to her knee, and because she needs to lose body fat, she needs longer sessions to stimulate more fat burn. Sometimes on a good knee day, she will be able to walk on the treadmill, but this does not happen often.
There is a constant debate between what cardio burns more fat– HIIT or steady state. HIIT burns more calories in a shorter amount of time, with a mixture of carbs and fat as the sources of energy, and raises the metabolism for a few hours after the session. The other burns more direct fat during the session but requires a longer session to do so.

The human body varies quite a bit from person to person which affects which cardio method is best for body composition.

Every body varies in the amount of slow vs fast twitch muscle fibers, which impacts the energy sources that body uses most optimally in training. Every body also has a different metabolic baseline, and some bodies need more fat burn to maintain a healthy body composition. Furthermore, a persons nutrition will also affect how well they handle high intensity vs low-moderate intensity training.

If there is one thing that frustrates me, it is when people speak in absolutes when it comes to the “right” training or nutrition. Everyone is different and I do not believe that any one way is best for any and every person or goal. I do not support articles that are titled “The Best Way to ___” or “The Secret to ___”.

It is important to distinguish between one of many variations and what is proven fact. 

Bottom line, some people respond better to HIIT training while others respond best to steady state cardio, and then some people do even better with a combination of the two. Some people do best at a fasted state in the morning, while others prefer the evenings. Furthermore, as our bodies grow and change, so does our response to training methods. Try varying your times, styles  and modalities every month or couple of months.

The key is taking your time and testing different cardio training methods and modalities to find what works best for you and your goals.

If you are an athlete, find what cardio training will best supplement not harm your performance. Everything you do should be to benefit you and your sport.

Every time you come across an article that completely supports one style of training over another, take the information and apply it to yourself before you make a final decision as to whether it is right for you. Try not to compare yourself to other people but rather, test out their methods and see how it affects you. Everyone will always have their bias, even if they try not to.

The best way to go about long term fitness and health is to invest your time in learning your body.