There are “Brussels sprouts” and no “muscle sprouts,” but there are jokes.
     
“What kind of vegetables workout in a gym? Muscle sprouts” was posted on X/Twitter by Dr. John Zielonka on Decembr 18, 2012. “What vegetable do you find at the gym? Muscle sprouts!” was posted on X/Twitter by uri5el on January 27, 2019. “🥦What kind of vegetables do you find in the gym? 💪 Muscle sprouts!! 😂” was posted on X/Twitter by Kobi Simmat on October 24, 2019.
 
“Did you hear about the weightlifting vegetable? He was a muscle sprout!” was posted on X/Twitter by Wall’s Pastry on September 21, 2015. “Did you hear about the weight lifting vegetable? He was a muscle sprout” was posted on Reddit—Jokes on January 13, 2020. “Did you hear about the weightlifting vegetable? She was a muscle sprout” was posted on X/Twitter by Liftingthe Dream on September 19, 2021.
 
“What’s a bodybuilder’s favorite vegetable? *flexes too hard, forces a cramp* MUSCLE SPROUTS!” was posted on X/Twitter by Raulin Platt on April 20, 2018. “What’s a body builders favorite vegetable? Muscle Sprouts” was posted on Reddit—Dadjokes on April 22, 2020. “What’s a body builders favorite vegetable? Muscle Sprouts. #LaughoftheDay” was posted on X/Twitter by Jimmy RevJim Olsen on July 27, 2021.
 
“What do you call weightlifting vegetables? Muscle sprouts” was posted on X/Twitter by Ultimate Dad Jokes ‘N So Much Pun on June 3, 2024. “What do you call weightlifting vegetables? Muscle sprouts” was posted on LaffGaff on June 5, 2024.
 
“What’s the strongest vegetable?”/“A muscle sprout” is a related riddle.
   
   
Wikipedia: Brussels sprout
The Brussels sprout is a member of the Gemmifera Group of cabbages (Brassica oleracea), grown for its edible buds.

The leafy green vegetables are typically 2.5–4 cm (0.98–1.6 in) in diameter and look like miniature cabbages. The Brussels sprout has long been popular in Brussels, Belgium, and may have originated and gained its name there.
   
X/Twitter
Dr. John Zielonka
@DrZonHealth
Tyler’s (one of my 7 year-old twin boys) joke:
What kind of vegetables workout in a gym?
Muscle sprouts.
4:53 PM · Dec 18, 2012
 
X/Twitter
Wall’s Pastry
@WallsPastry
Did you hear about the weightlifting vegetable? He was a muscle sprout!
6:00 AM · Sep 21, 2015
   
X/Twitter
NFU Mutual
@nfum
IT’S A CRACKER! Did you hear about the weightlifting vegetable? He was a muscle sprout! #christmascountdown
Quote
NFU Mutual
@nfum
Dec 1, 2015
WIN: Chocolate #sprouts from @quirkygiftsuk via @NotonTheHighSt #adventcalendar T&C’s: http://ow.ly/Vku1i
1:00 PM · Dec 1, 2015
       
X/Twitter
Bev
@bev_metallica
@megafancydress Did you hear about the weightlifting vegetable?  He was a muscle sprout.
7:31 AM · Dec 3, 2015
   
X/Twitter
DONNA LEWIS
@DonnaImwishing
@RustlersOnline Did you hear about the weightlifting vegetable?
  He was a muscle sprout.
1:29 PM · Feb 17, 2016
 
X/Twitter
Sofa Snake 〓〓
@Sofa_Snake
Did you hear about the weightlifting vegetable?...
He was a muscle sprout!
2:13 PM · Dec 23, 2017
     
X/Twitter
Raulin Platt
@RaulinPlatt
What’s a bodybuilder’s favorite vegetable?
*flexes too hard, forces a cramp*
MUSCLE SPROUTS!
My 24 year old girlfriend doesn’t think that joke is funny.. but my 8 year old cousin does. Know your audience, folks.
2:27 PM · Apr 20, 2018
 
X/Twitter
uri5el
@zebrasyndicate
What vegetable do you find at the gym?
Muscle sprouts!
11:46 PM · Jan 27, 2019
 
X/Twitter
Kobi Simmat
@KobiSimmat
🥦What kind of vegetables do you find in the gym? 💪
Muscle sprouts!! 😂
#business #leadership #dadjoke
5:45 PM · Oct 24, 2019
 
Reddit—Jokes
TheBreed_—January 13, 2020
Did you hear about the weight lifting vegetable?
He was a muscle sprout
 
Reddit—Dadjokes   
AustinSpartan—April 22, 2020
What’s a body builders favorite vegetable?
Muscle Sprouts
       
X/Twitter   
Martin
@martychristiano
I love sprouts, I really do. That said, I’ve a tough one for ya (no pun intended):
Q: Did you hear about the weightlifting vegetable?
A: He was a muscle sprout.
7:09 AM · Dec 16, 2020
   
X/Twitter
Jess Bost, CFP®
@lady__bost
Hey @ChefLaurenOwens did you hear about the weightlifting vegetable?
She was a muscle sprout 💪🏼🌱
😂💜
3:49 PM · May 7, 2021
 
X/Twitter
Jimmy RevJim Olsen
@mybuddyjimmy
What’s a body builders favorite vegetable? Muscle Sprouts. #LaughoftheDay
8:06 AM · Jul 27, 2021 from West Des Moines, IA
   
X/Twitter
Lifting the Dream
@liftingthedream
Did you hear about the weightlifting vegetable? She was a muscle sprout. #sundaysareforjokes #liftingjokes
1:02 PM · Sep 19, 2021
 
X/Twitter
Karen Johnson
@editgirl1
😂😂 I do jokes too!
What’s a bodybuilder’s favourite vegetable??
A muscle sprout!💚😜
1:42 PM · Oct 18, 2021  
 
X/Twitter 
Painful Puns
@PainfulPunz
Q. Which veggies are the strongest garden growers?
A. Muscle Sprouts!
Botanists have developed a garden vegetable that eliminates the need to brush your teeth. It’s called Bristle Sprouts.
#veggies #humor #boogers
12:39 PM · Jun 13, 2022
   
X/Twitter
St. Edward’s Softball
@SEUSoftball
Did you hear about the weightlifting vegetable? He was a muscle sprout 🤣 💪 #MAXimized
11:31 AM · Nov 16, 2022
 
Reddit—- Dadjokes
jgoden—March 18, 2023
What kind of vegetable does the vegetarian bodybuilder eat?
Muscle Sprouts
 
X/Twitter
Andrew Bluebells
@andrewbluebells
Q: Did you hear about the weightlifting vegetable?
A: He was a muscle sprout
7:50 PM · Apr 28, 2023
 
Reddit—DoctorMike
Txur-Itan—December 7, 2023
Did you hear about the weightlifting vegetable?
He was a muscle sprout.
 
X/Twitter
Ultimate Dad Jokes ‘N So Much Pun
@MediocreJoker85
What do you call weightlifting vegetables?
Muscle sprouts.
12:04 AM · Jun 3, 2024
 
X/Twitter
Medium Value Man 🫡🇺🇸👨🏾‍🍳📸
@SecondTwo_None
What do you call weightlifting vegetables?
Muscle sprouts.
12:48 AM · Jun 3, 2024
 
LaffGaff
Weightlifting Vegetables
June 5, 2024 by LaffGaff
What do you call weightlifting vegetables?
Muscle sprouts.