Home / / Cardio Q&A

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.

Leave a Reply

Your email address will not be published. Required fields are marked *


This site uses Akismet to reduce spam. Learn how your comment data is processed.

113 comments on “Cardio Q&A”

    alyssa says:

    Hey, pamela reif have home workouts and i oftne do the “dance” workout since its free. Do u think it is a good programme if i am 159cm, 54kg. Rlly want to lose weight especially on my thighs!! Ur programme sounds so amazing but i dont have the money for it :-(

      Lean Legs Support says:

      Hi lovely,

      Her dance workouts are a great form of cardio that could help you burn a lot of calories but if your main goal is to slim down your legs, you should combine the right type of resistance workouts and cardio for your body type and you should also adjust your diet for weight loss (eating at a calorie deficit). I have a very detailed blog post that will help you learn how to slim down your legs so please go give it a read. I think you’re going to find it very useful. :)

    Narayani says:

    Hi Rachael, thanks for maintaining such an amazing blog! I have a question regarding the power walking speed. I’m pretty short (5’1) so in an hour I’m able to cover 4.4km as opposed to the 6-7km/h speed mentioned. I don’t think I can walk long enough if I go any faster than this. Is this speed okay? Will it still help in slimming down my legs?

      Lean Legs Support says:

      Hi lovely,

      6-7km/hr is just a guide. Your speed will still depend on your height and the length of your legs so feel free to make some modifications. :)

      To burn more calories effectively, you can also try to aim for your fat-burning zone and adjust your heart rate accordingly. You can learn more about it in this blog post. :)

      I hope that helps.xx

    Caitlyn says:

    I was wondering if we could do walking workouts from YouTube to hit 10,000 steps a day?

      Lean Legs Support says:

      Hi lovely,

      If you’re referring to walking-in-place workouts, they are not really as effective as power walking outside or on a treadmill based on our customers. It can be a temporary substitute when you can’t walk/run outside but not as a permanent replacement. :) I hope that helps. xx

    Rocky says:

    Hi Rachael! Any thoughts on workouts using vertical climbers (eg. Maxi Climber)? Will that bulk up mesomorph body types? Thanks love!

    Nsovo Mgiba says:

    Hi, so if i have an endomorph body type and have noticed that I quickly bulk up, will it be fine to just Walk at 6.5 km/hr just fr starters? Or will I hv to walk at least near the max of 7km/hr to see results quickly?

      Len - Lean Legs Support says:

      Hi lovely,

      When power walking, the recommended speed is between 6-7km/hr so 6.5km/hr is okay. You should feel a little bit puffed but still be able to hold a conversation. :)

      I hope that helps. If you need more help or tips, feel free to email us at info@rachaelattard.com


    Valet says:

    So running fast for a short amount of time won’t cause bulk but you will put on some muscle? And can all body types run without bulk?

      Len - Lean Legs Support says:

      Hi lovely,

      Running is an amazing cardio workout because it burns a huge number of calories and helps you to slim down all over. But you also engage your quads a lot that’s why you can also build muscle while doing it. If you are the type who can bulk up easily, like endomorphs (especially the shorter ones), you could just substitute it with more power walks. For example a 20-min run should be replaced with a 40-min power walk. :)

      I hope that helps. If you have more questions, feel free to email us at info@rachaelattard.com


    Ansen says:

    Thank you for the great post, your explanation of running faster for shorter periods of time was very helpful. I was wondering if one can achieve the same results by splitting up walking over the course of the day into multiple, shorter periods (eg 4 times 15min). My job can make it difficult to find an hour during the day to walk within daylight hours.

      Len - Lean Legs Support says:

      Hi lovely,

      Don’t worry, cuz every step counts! :) What’s important is to walk around 10,000 steps each day so you can split your walks into shorter ones if it is easier for you to organize the rest of your day in that way.

      I am so happy to have you on board! Keep me updated on your progress. :)

      If you have any questions, feel free to email us at info@rachaelattard.com


    Kristina says:

    Thanks for the informative post!

    I’m a runner with an injured foot trying to stay in shape indoors on a stationary bike which I’ve been using for two months now, six days a week for an hour. I use the heart rate monitor on my garmin to vary the paces I use. I’m a mesomorph and want to avoid bulking up my legs.

    Should I stick to steadt state workouts in the lower hr zones or focus on higher intensity…the focus is slimmer legs.

    Thanks so much!

    Kristina from Italy

      Len - Lean Legs Support says:

      Hi lovely,

      If you’re still recovering from an injury, I suggest that you take a break from any type of workouts just to be on the safe side. Please wait until your doctor gives you a go signal before exercising again. I know you’re excited to achieve your goals but your safety should be our priority. :)