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Cardio Q&A

By Rachael Attard, Updated Oct 5, 2020
cardio q&a

You guys probably know by now that I am an advocate of cardio, which is unlike most other trainers that focus mostly on heavy lifting (Nothing wrong with that! It’s just not for me).

I’m always asked a lot of questions about cardio, but more specifically, the best type of cardio to lean out your legs and avoid making them bigger and musclier. So thought I would answer all your questions here! If I haven’t answered your question, please feel free to ask below in a comment and I’ll add it to the blog post! xx


Not necessarily. Any walking is great and the more steps you can accumulate during the day, the better! But it is possible that you might burn a higher percentage of fat if you do your walking fasted (i.e. before breakfast).

Walking burns stored carbohydrates (stored in your muscles as glycogen) and fat. If you don’t have as much stored carbs, your body might burn more fat. Also, it will be more effective if you have eaten a low carb meal for dinner the night before.

cardio q&A

It can be beneficial to do your walking on an empty stomach, but it’s not necessary. Walking any time of the day is good!


These speeds should be used as a guide only. Speeds will also vary depending on your height (obviously taller people will be able to walk / run faster).

  • I would suggest aiming for a walking speed of 6-7km/hr or 3.7-4.3mph.
  • I would suggest aiming for a running speed of 10-12km/hr or 6.2-7.5mph.


I suggest zero. Walking and running is best done on a flat surface if you don’t want to bulk up your quads. Any uphill walking and running will use your quads more and can make your legs bulkier.

If you are on the treadmill, you can set your incline to 0.1% to replicate walking outside. But if you have trouble with shin splints (like me), I would keep it to 0%.


No, they will both have the same results. It’s just more of a personal preference.

Sometimes I prefer doing my cardio on a treadmill because I can track my speed and see if I’m improving (especially for running). But it just feels good running outside!

cardio Q&A

And I also don’t mind walking on the treadmill because I can watch a TV show on my phone as I walk ;) Another great benefit of having access to a treadmill is that you can do your cardio regardless of the weather conditions.


A lot of women tell me that run slowly for 45 minutes and are confused as to why this isn’t better than walking for 45 minutes, or running faster for 20 minutes. I’ll try to explain.

When you are jogging slowly, the action of your legs means that it is the same as running. Running does build muscle. The action of walking actually really helps to get rid of fat on your legs, not running or jogging. So slow jogging for 45 minutes means you will build muscle, without really getting rid of the excess fat that walking will. So you’re probably better off walking.

When you are running faster, your body is burning lots of calories and you’re pushing yourself so your fitness is increasing, which is great. But jogging slowly isn’t really that challenging, and you’ll burn less calories. It may even bulk up your legs because you are overdoing the running. You’re not getting the full benefits of running if you’re just slowly jogging.

I think it’s better and more effective to either run faster or just walk. That is my preference. Slow jogging is still better than nothing though so you can do it – it’s up to you. But I don’t think it’s as effective as the other two.

If you really want to slim down your legs, I have a 3 Steps to Lean Legs Program that will help you get lean and toned legs without the bulkiness :)


cardio q&A

Yes this is possible. Running does build muscle (but not as much as other forms of cardio or strength training). Usually only people who are shorter or are the endomorph body type (or both) have issues with building too much muscle with running. If running is a problem for you, I would avoid it.


I wrote another blog post on the best type of HIIT cardio to do to avoid bulking up your legs. As I mentioned, running builds muscle and HIIT running will build even more. If you’re interested in doing HIIT cardio, please have a read of this blog post!

Whether or not you do HIIT cardio depends on your body type and to a certain extent, your fitness level.

If you are short or an endomorph body type (or both), HIIT cardio may not be the best exercise for you. It will build some muscle and with a shorter frame, more muscle may not be your goal. It could make your legs look bigger. If you know that running makes your legs bigger, then I would avoid HIIT cardio.

I mention fitness level because HIIT cardio is hard, and you need to have a good base cardio fitness first to do this exercise effectively and get the benefits. Being able to run at a medium fast pace for at least 20 minutes would be a great start. After that, I think you would be fit enough to add in some HIIT cardio.

As I mentioned above, if you have any cardio related questions, please feel free to ask in the comments section or send me a message on Instagram and I’ll add them to the blog post :) xx

Picture of Rachael

Rachael is an Australian born certified personal trainer and nutritionist who holds a Bachelor degree in Science.

After struggling for years to find an exercise and diet program that is tailored to women striving for lean and toned body with no bulk she designed her Lean Legs Program. This program is tailored to each body type and focused on helping women get toned but feminine bodies, without getting bulky.

Her mission is to empower women and help them stay in shape in a healthy and balanced way.

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119 comments on “Cardio Q&A”

    Alankritaa Ghosh says:

    If i walk for about an hour 5 days a week, then in how many days can I see results. My BMI is 19.8
    Height 165 cm
    Weight 54 kgs

      Lean Legs Support says:

      Hi lovely! Everyone gets results at different rates so we can’t really determine when you’ll get to see progress. Power walking will definitely help burn thigh fat and slim down your legs but you also have to follow the right resistance workouts for your body type and adjust your diet for weight loss to get faster results. If you need more guidance, feel free to email us at info@rachaelattard.com ;)

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