Fitness & Exercise

Busta Rhymes did much more than just throw a protein shake during that fight in a gym -- surveillance video now shows him totally losing it on an employee!

The incident went down in August at Steel Gym in NYC ... and the video, first posted by Page Six, shows Busta in some kind of verbal dispute with the employee who's sitting behind the front desk.

At some point the rapper gets tired of talking and throws a liquid at the man, then clears the counter top ... taking out everything in front of the guy ... including his computer monitor.

Now we know how 50 Cent keeps his body so swoll -- he drops a fortune to keep a trainer by his side nearly 24/7.

In fact, according to docs filed in his bankruptcy case obtained by TMZ ... the rapper pays more than $3k a month in workout expenses. A big chunk of that -- $2,800 to be exact, goes to his trainer, Jay Cardiello.

Jay has talked about working with 50 before, saying he pretty much eats, sleeps and breathes with 50 ... since they train together 3 times everyday.

And get this, despite the fact 50 hasn't had a #1 hit on Billboard's Hot 100 since 2003 ... he still makes $36k per month in royalties.

Britney Spears gave a bunch of dancing queens a huge surprise when she commandeered their class, and choreographed a new routine for them.

Fern Adair, the owner of a Vegas dance studio, says Britney's people contacted her a couple weeks ago, and said Brit wanted to reconnect with her dance roots. Just a few days later, Spears showed up to a class filled with kids aged 8 to 18.

We're told she spent an hour teaching them some steps to Pharrell's "Happy."

So, mission accomplished. Roots connected.

Some people spend hours at the gym ... Eva Longoria dances like a Pussycat Doll.

Eva flew to Mexico recently for a dance fitness retreat run by founder and choreographer Robin Antin. It's more of a sexy aerobics boot camp where they tried out the new PCDFIT weighted fitness gloves ... Antin tells us they were inspired by UFC fighter Ronda Rousey for an added kick-ass element.

Eva nails the intense routine, which clearly yields great results.

Kate Upton banged out a set of squats during a workout in West Hollywood with her personal trainer, who kept a watchful eye on ... her form.

Yes, he's actually getting paid to do this.

Rob Gronkowski wants to be the Tom Brady of gym equipment -- THE KING -- and now he's launched his own line of fitness products to take you to Jacked City.

The entire Gronk family is involved in Gronk Fitness ... selling everything from push sleds to battle ropes, squat racks and more.

Turns out, Gronk's dad used to own fitness retails stores and spent 25 years in the business -- and since his kids are bona fide muscle heads, they decided to put together their own gym equipment company.

We spoke with Rob's brother, Dan Gronkowski, who says the idea came about last year -- "We said if Rob wins the Super Bowl, we'll do it. And he did. So we did."

Dan says all the stuff is commercial grade quality -- "This isn't us slapping our names on some crappy product, this is quality stuff."

And the family is dead serious about growing the business -- "We want to be the place to go to for athletes and gyms."

Bob Harper thinks it's a stroke of genius on Weight Watchers' part to team up with Oprah, because she's a 10 on the relatability scale.

We got "The Biggest Loser" trainer leaving Brick CrossFit in West Hollywood Monday, after Weight Watchers' stock doubled on the heels of the announcement Oprah now owns 10% of the company's stock and will sit on its board.

Josh Gordon has been hittin' the weights ... hard ... killing himself to get ready for his NFL comeback in 2016 -- and judging by the footage of his workouts, dude looks ready to go.

The Cleveland Browns wide receiver was suspended for the 2015 season for violating the substance abuse rules -- but he's vowed to make a comeback and it looks like he's taking things seriously.

Gordon's agent Drew Rosenhaus previously told us the 24-year-old is keeping his nose clean and "doing all the things he has to do to get ready. We fully anticipate him being back for the 2016 season."

'Bachelorette' star Ben Z is more concerned about his rock hard bod than a follow-up run on "The Bachelor."

Ben surfaced this weekend in San Francisco where he competed in his first bodybuilding competition. He didn't win, but more importantly he didn't finish in last place ... ultimately coming in 8th out of 15.

Ben tells us he's 210 lbs now ... down 90 lbs from his days as a linebacker playing college football, which is when that "before" pic was taken. He claims he's leaned out naturally with diet and exercise -- sans steroids or testosterone boosters.

Many thought since he was last season's resident hardbodied badass ... he'd be a shoe-in for "The Bachelor." He tells us producers approached him but he didn't get back in time with his answer.

Spending too much time in the gym, Ben?

John Stamos should be using natural supplements instead of GHB for his fitness regimen ... so says one of the biggest lifters in the game.

Christina Milian has a great way to bounce back after a breakup -- hit the floor for a playful workout with your twerk guru. Works for us.

Milian and trainer Lexy Panterra decided to work their glutes ... although we suspect this session is more about Christina sending messages, such as: 1. Hey guys, I'm single, and 2. Hey, Lil Wayne ... hungry for cake?

Either way, this looks like a great way to shake off any lingering heartbreak ... while staying in shape, of course.

Giants fans looking for a boost, look no further than this video of Jason Pierre-Paul -- ON HIS GRIND, in the gym, and apparently ... ready to bounce back from his horrific hand injury.

Drake is taking this SWOLL patrol thing very seriously, especially in the arms department ... and it might have something to do with impressing his lady friend Serena Williams.

Champagne Papi hit the gym -- it was a curls-for-the-girls day ... and you gotta think all that upper body strength will come in handy on date night. Fact is, Serena's physique is world class -- so you'd expect Drizzy to step up his game too.

When Serena's the gain, you don't mind the pain.

No days off when you're a pro athlete ... even during a beach vacation in Mexico ... just ask Lindsey Vonn who workin' on her fitness while workin' on her tan.

Vonn and a bunch of her besties just got back from a girls trip to Cabo San Lucas -- but you can see in the pics, it wasn't just about margaritas and tequila shots ... Vonn was determined to keep her ass in shape.

Even with a busted ankle, Vonn knocked out some side bends and planks ... with her friends even giving her a spot.

Sylvester Stallone knows the secret to defeating Floyd Mayweather Jr. … but it doesn’t have anything to do with his next opponent, Andre Berto.

Almost no one is giving Berto a chance to win the fight -- so we asked Sly if he thinks he's even got a puncher's chance to upset Money. Check it out ... Sly says there's a chance, but not a puncher's one.

Stallone also throws a playful jab at "Southpaw" star Jake Gyllenhaal's on the topic of big screen boxers. We'll give you one guess which actor/fighter he IS backing.

Lamar Odom is taking at least one piece of advice from his ex-wife Khloe Kardashian -- he's taking steps to get fit by hitting the gym again on the reg.