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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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92 comments on “Cardio Q&A”

    Lena says:

    Is Lagree a good form of resistance training for an endomorph?

      Sanja - Lean Legs Support says:

      Hi lovely,

      thanks for reaching out!

      Rachael hasn’t reviewed that workout yet so I am not able to comment. It seems to me it’s high-intensity so if you try it out, you need to observe your progress closely. However, If you are looking for a full-body workout program that focuses on building a lean & toned body overall and slimming down legs, then you might want to check out Rachael’s 3 Steps To Lean Legs program. :)

      I hope this helps, please let me know if you have any questions! xx


    Lena says:

    It’s getting to be really cold where I live, walking outside is not going to be an option in a few weeks. I don’t have a treadmill but I do have an elliptical, I am an endomorph. Would an elliptical work for getting my “walk” in if I leave it on zero resistance and zero incline?

      Sanja - Lean Legs Support says:

      Hi lovely,

      thanks for reaching out! <3

      I don’t think this machine will really cause bulkiness, but it won’t slim down your legs like running and walking will. The pushing down motion means you engage your quads more so it will build more muscle here. But it’s not the style of workout that will necessarily cause bulkiness. If you can’t walk or run for some reason, the elliptical is the next best thing. :)

      I hope this helps, please let me know if you have any questions! xx


    Kate says:

    Will hiking (uphill incline) 2 or 3 times a week cause legs to bulk up? This has been a regular work out for me because I live close to some hiking trails, but would like to slim down my legs following Rachel’s program. Thanks!

      Sara - Lean Legs Support says:

      Hi lovely <3,

      Hiking might bulk up your legs depending on your body type. <3

      If you're unsure of your body type, please do this quick quiz, it will only take a couple of minutes.

      Once you have your results, and if you have any other questions regarding this or any other matter, feel free to email us at info@rachaelattard.com


    Ally says:

    Hi, I have very weak hips so running is a problem for me. How long do you suggest I walk for instead? Thank you in advance. (:

      Ana - Lean Legs Support says:

      Hey lovely,

      You can feel free to power walk instead. :)
      It would be best if you’d double up on the time invested. If the run was supposed to be 20 minutes long make sure that you do a 40 minute power walk.


    Leonor says:

    Hey I’ve been trying to lose some muscle, specially in my legs since they are naturally very muscular but also a bit on my arms due to many years of competitive swimming. In order to do so I’ve been walking at least 10,000 steps everyday and cardio workouts like tae bo, but I would like to know if doing tae bo is a good way to reach my goal of losing muscle (more specifically in the legs).
    Could you advice me on that and maybe suggest better ways to do cardio in order to reach my goals?

      Sanja - Lean Legs Support says:

      Hi lovely,

      thanks for reaching out! <3

      Tae Bo isn't really a great way of losing muscle in the legs. But it is a great type of workout to tone up and shouldn't cause bulkiness. The best way to lose muscle is outlined in this blog post.

      I hope this helps! xx


    Marianne Vnuk says:

    Is the elliptical a good cardio exercise like power walking to slim down thighs?

      Sanja - Lean Legs Support says:

      Hi lovely,

      Thanks for reaching out!

      The elliptical is a good for when you can’t run or walk :) But Rachael encourages running and especially walking if you can!

      I hope this helps! xx


    Annick Trobak says:

    Hello, I am curious about the pace you suggest running. When you recommend running faster at like a 10-12 km/p pace, for how long is this? Because this is actually pretty fast. And I am wondering at what setting do you achieve this on a treadmill. I am asking because I have been training for 1/2 marathons for a couple of years but also lifting really heavy. I follow the run faster program of running 3 days a week. Sprints, tempo, and long run. I have been running at a fast pace but my life circumstances are changing things for me and I need to slow down. I am also wanting legs more like yours instead of my thicker legs. I am just wondering how fast I still need to run to get the benefits you talk about. I am also changing my lifting routine to look more like yours. I have you program, I am a mesomorph. I am also now counting my calories, which I was not doing when I first purchased your program, as I now understand that this is a major component. Thank you

      Diana - Lean Legs Support says:

      Hi lovely,
      We recommend running for about 20 minutes at this speed. If this is too fast for you, you can either decrease the speed or run in intervals (combine running and power walking) until you get more used to it. The important thing is to maintain your fat burning heart rate. Please refer to page 11-12 in the main ebook for some extra tips! :)
      If your legs are too muscular from running, I would avoid sprinting, doing cardio at incline and heavy weight lifting.
      Wishing you all the best! xx