My significant female other is a runner. I’m a cyclist. She likes riding but is afraid that if she does it anymore, that her thighs will get large which is something she doesn’t want.
Being a guy my body’s obviously different in how it reacts to training, but my thighs haven’t gotten really any bigger. So I can’t really confirm or deny her fears. What say you oh women of ST? Will the thighs get larger if cycling volume increases?
Not by much, my butt and thighs got bigger on the saddle. They were big (in my opinion) to begin with but are now more toned.
Depends what kind of riding she’s doing. Sprinting, yes. Endurance, not so much.
Case in point, a gal I raced with at the velodrome used to be more of a track-racer body type. In fact, the elite gals always have a contest to measure the quads. Bigger is better. She has signed with a pro road team and has been putting in the big miles on the road and less sprinting and she has totally changed the shape of her body…now she is lean and mean (and ripping it up in the big races.)
Unless she is also supplementing her riding with intense weight lifting workouts and slugging down creatine in massive protein shakes afterward… no.
It is incredibly difficult to gain substantial muscle when your natural levels of testosterone are low (majority of women) and your exercise is focused on aerobic endurance capacity.
That’s what I understand from a PT I worked with.
Personal experience- still no.
What’s wrong with big legs?
Not as long as you don’t eat too much
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What’s wrong with big legs?
+1
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+2
Agreed with what others have said. A lot of the elite females still have pretty small legs and they ride plenty. Look at our Olympians! Lean muscle but not much girth. I like lifting so mine aren’t quite so little 
Muscles hypertrophy (grow) in response to stress, so yes. Cycling tends to be anabolic (muscle-building), like swimming, while running tends to be catabolic. Just like swimmers develop shoulder muscles, cyclists develop larger quads…
I forget why bike/swim are anabolic and running is catabolic, but yes, her thighs will get larger if she rides a lot. By the way: a lot of women use the adductor machine at the gym thinking it will make their inner thighs look better, when all it does is build muscle in that area, so if they don’t lose any body fat, that looks bigger.
I’m sure you are right, strictly speaking. If you were able to do an experiment on two identical twins, who had never exercised before, and put one on an all-running regimen and the other on an all-cycling regimen, perhaps the cyclist’s legs would be bigger. Bigger by more than a trivial amount? Depends- depends on what the subject ate, what kind of riding they did, and on a large part, their genetics.
However, if one has a uni-sport background, like running, then switches over to an all cycling regimen, what happens? You’ve seen what happens when uni-sport pros become pro-triathletes, their body compositions change, but they have to work very, very, very hard for that outcome.
I would be completely surprised if you took a runner (like the OP’s girlfriend) and add in cycling recreationally (not seriously) that the body composition change would be at ALL measurable. Show me evidence (even anecdotal) otherwise and I’ll take your word for it.
I would be completely surprised if you took a runner (like the OP’s girlfriend) and add in cycling recreationally (not seriously) that the body composition change would be at ALL measurable. Show me evidence (even anecdotal) otherwise and I’ll take your word for it.
Agree.
Now put her on a heavy sprint program and then she should be concerned.
Yes, her thigh muscles will get larger. Any cycling involving strength (speed, hills) will build the thighs.
My legs look muscular like a man’s if I’m in shape.
My thighs get bigger/change shape, yes, but I wear the same size pants year-round. They don’t change that much.
It has been my experience that cross-training resulted in me being leaner- toned and stronger, but not larger. The only time I have seen women’s thigh muscles get bigger is when doing weight training and a protein-rich diet. aka crossfit and a paleo diet.
I am so baffled by this question. Is this 1955? I wish I could accidentally beef up my quads!
FWIW, I’m a longtime runner, 103 lbs. and have ramped up my cycling mileage and intensity drastically this year. Lazy about my diet (oh my god, I cannot take another protein shake sort of lazy), I have lost muscle, and now have to drastically boost my calorie/protein intake to rebuild.