Females gaining (muscle) weight with training? (weight class sport)

Training Q&A [Moderated]
1

I hear the females-gaining-weight-while-strength-training is a common question, but I feel like I’m having a tough time with my particular situation, in terms of finding a good answer.

As a 30-something, previously-inactive female (who, until last year, was an avid jiu jitsu hobbyist competitor), will beginning strength training cause me to bulk so much I have to jump to the next weight class?..

I have no athletic background from childhood, but still was somewhat active. I got overweight and detrained during college. I graduated and slowly built myself up via yoga, Pilates, etc. However, I really fell in love with jiu jitsu a few years back and lost the weight and gained even more cardio. I trained regularly both in sport and later with an athletic trainer for cross training/conditioning.

Awhile back, a jiu jitsu coach told me to strength train for longevity in sport (avoid injury). I started out with bodyweight exercises, kettlebells, TRX, and lighter dumbbells… I perhaps had a fear of the more traditional moves and equipment… that is, until I found the BBM podcast during a flare of back pain. I’ve been a follower of the podcast since. A great sports PT also helped me overcome my fear of movement/pain.

I very recently expressed interest in more traditional strength training to the athletic trainer, after the gym reopened (for the 2nd time since last year). I am still without jiu jitsu but want to stay in shape for when I eventually return and I am already getting enough cardio to meet those 2018/2nd ed guidelines.

Question is - I was told by a former hobbyist power lifter that I will gain significant muscle/weight if I continue to lift heavy things. That I will outgrow my weight class. This conversation started after I was saying I was quite sore after the first time I benched a barbell for the first time (2nd time was not anywhere near as bad). And I was told to do bodyweight exercises multiple times a day instead.

The trainer maintains I would need to eat a bunch more and do more specific training to get big. I’m only doing this strength training twice a week at most right now.

I am finding all sorts of “interesting” info about muscle building, and know it’s all multi-factorial overall. I’ve read a number of the BBM articles too. I wouldn’t mind gaining muscle/strength and losing a bit of fat, but given my height (5’2”, athletic build, 128lbs), I can’t just go to the next weight class in jiu jitsu (my competition would have too much of a height advantage, plus my weight class tends to have more competitors = more matches). I am currently hoping to lose 4-5 lbs and maintain that weight so I can compete at the top of my weight class. I need both mobility and flexibility and would like to be strong, too. Is this possible?..

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You are likely to gain muscle mass from any type of challenging resistance training - whether it be he heavy or moderate weights, though you won’t gain any body weight unless you’re in a Calorie surplus.
This is all adjacent to my uncertainty of the need to stay in a particular weight class.

In any case, resistance training is one of the best things you can do to build muscle and strength. It tends to be more efficient when using external resistance and somewhat challenging weights, but you won’t increase your body weight without eating more food.

Mobility is a completely separate issue and is specific to the positions you expose yourself to daily. Gaining muscle, strength, or lifting weights will improve your mobility to do those things and, provided you’re still training Jits, you’ll maintain or improve that mobility as well.