My partner in crime in my latest venture, Go Fit Gals, keeps up with all the latest gossip on Twitter. While we both are on Twitter (that was blatant advertising on my part, by the way, but not as blatant as this is: feel free to “Follow” us @gofitgals), I am not on it nearly as much as she is. So, she has a better handle on what people are talking about on social media.

The latest word on the wire is that squats, lunges and running will make your thighs bigger. Obviously it is predominately women that are worrying about particular malady. In the 18+ years of training I have never had a man worry about his inner thighs touching. And, I think it is also safe to say that there is a particular age demographic that is perpetrating this rumor. Because, once again, in the 18+ years of training I have never had a woman in her sixties worry about the size of her thighs due to the squats that I throw at them. Instead, the focus is more on having the strength to do said squat and then the ability to walk the next day.

While I, too, like my legs toned and thin (and I work freaking hard to get them that way), I also recognize two things. First, my genetics make up a lot of how I look and how I carry my fat, and second, you need a lot of extra resistance to really “bulk” up those thighs.

Can’t Mess With Science
It is proven science that in order to build bulk within a muscle you need to apply resistance that is higher than the load the body is used to carrying. This load will cause microscopic tears in the muscle tissue and then for the next 24-48h hours the tissue will repair itself. This time stronger and bigger.

Body weight squats, lunges and running are not considered loads that your body is not used to carrying. Your muscles carry your frame around all day, everyday, leaving no extra applied resistance that is new to it.

You may see some tone, because running does produce forces greater than our actual body weight, and performing sets of squats and lunges can be more fatiguing to the muscles than walking, but not the bulk that my partner’s Twitter friends are concerned about.

Genetics – Blame Your Ancestors
There are also three distinct body types that each of us possess: ectomorph, mesomorph and endomorph, and no diet, exercise, or lack of squat or lunge will change that.

An ectomorph is naturally lean, carries low-level of fat, tends to have smaller muscles and frame in general. They have a hard time putting on muscle, and they are the people who the I-Want-Thinner-Thighs camp worship and wish they were.

The mesomorphs are more inclined to build muscle faster. They are the ones with the ripped looking abs in the magazines and on the internet. They are the more athletic-looking of the three body types and the ones that I wish that the I-Want-Thinner-Thighs camp would crave they had.

Finally, the endoporph will generally be soft and round looking. They can put muscle and fat on very easily and once that fat is on they will have a hard time losing it. These are the ones that the I-Want-Thinner-Thighs camp hopes that they are not.

My body type is a mesomorph. When I exercise my DNA is hardwired to produce muscle. Since I know this I do all my lower body movements with a light load and a high rep count – to avoid bulk within the thigh area.

I am also an avid 10km runner and I run intervals, hills and long runs every week. My legs are toned, but they are not Gwyneth skinny and toned – and they never will be.

Once again it’s not because I do squats and lunges, it’s because my body is built differently than ol’ Gwyneth’s (she’s an ectomorph).

If I didn’t squat, lunge and run, though, my legs would probably still be thin, but they would also be wobbly and jiggly, especially when I walk (like the picture of poor Nicole below). Not something that I want to aspire too.

If your body type is more on the thin side, an ectomorph, then you will have no problem achieving a large gap between the thighs. But, again if this is your body type then you risk looking like Nicole as well. You can be thin, but still unfit. I recommend that you do squats, lunges and run the hills on a weekly basis. Since your body is also what we term a “hard gainer”, feel free to pick up heavier dumbbells while performing your lower body routine because your body is hard-wired NOT to put on muscle.

Mesomorphs have it tough. They need to work harder than the next gal to get her thighs looking good. For this camp I would recommend light loads and really high reps. They will never have a gap in-between their thighs (again blame genetics, not a squat or lunge), but if they don’t train their legs the fat and cellulite will make them look larger than they actually are. A classic example of a mesomorph is Jennifer Hudson, and I think her legs look amazing.

Me – and I must perform well over 500 squats & lunges a week. Are my thighs big?

Jennifer Hudson – a mesomorph with amazing looking legs.

Thin thighs – all wobbly in the wind due to low-level of muscle tone. Not very attractive.