When J.Lo gives us a peek into her workout routine, we pay attention. The famously fit star (can you believe she's 48?) always looks incredible, whether she's slaying the red carpet or fighting corruption as police officer Harlee Santos in her show Shades of Blue.

Although genetics surely play a role in Lopez's insanely toned physique, it's no secret that she's seriously dedicated to her fitness—the A-lister often works out with Tracy Anderson and has even been spotted hitting the gym with The Rock. Yesterday, we got a glimpse into how Lopez gets her super-toned arms when she shared her upper-body workout with followers in a video on Instagram.

RELATED: 5 Booty-Boosting Exercises From J.Lo's Trainer

In the snaps (which she captioned "Gettin' it in!!"), Lopez proves she's a resistance band master by demonstrating a series of intense bicep curls. Celebrity trainer David Kirsch, who works with Lopez, tells Health that the move is called the bent over resistance row with curl. "I love to keep workouts with Jennifer high energy and high intensity, making sure the full-body workouts are fresh and always changing," he says.

If you often use free weights on arm day, resistance bands are a great way to change things up; by forcing you to literally resist your own body weight, these stretchy plastic bands will take any workout to the next level.

"I like using resistance bands because these workouts are something my clients can easily do with no time at the gym, and they are so transportable," Kirsch says. 

In addition to strengthening the upper body, Kirsch tells us that this move also helps tighten and tone the quads, glutes, and core. The tool J.Lo is using is mounted to a wall, but you can modify the move with a loose resistance band by stepping on it in the center and pulling the ends towards your chest.

This article originally appeared on Time.com. 

The upcoming total solar eclipse, which you can watch live on TIME.combeginning at 12 p.m. ET on Monday, will cross the U.S. in less than two hours, and Americans in some states will only witness seconds of it.

The once-in-a-lifetime event on Aug. 21 will engulf parts of 14 states in sudden darkness when it moves from the West Coast diagonally down toward the East Coast. The path of totality, which starts in Oregon and ends in South Carolina, is about 70 miles wide.

It’s the first total solar eclipse with a trajectory exclusive to America, as well as the first total eclipse of the sun that will be visible from the contiguous U.S. since 1979. Total solar eclipses can be seen when the moon passes directly between the sun and the Earth and the moon completely covers the entire face of the sun.

Watch Live as the 2017 Total Solar Eclipse Crosses the U.S.

Here’s what to know about the timeframe of the August total solar eclipse:

How long is the upcoming total solar eclipse?

The total solar eclipse, which has been dubbed “The Great American Eclipse,” will last for about an hour and a half overall, but each city that catches the eclipse will only see it for a matter of minutes or seconds. The moon's shadow travels at roughly 2,400 mph over the face of the Earth, according to Bill Kramer, a well-known expert in the eclipse chasing community.

Which cities are the first and last to see the eclipse in totality?

Skygazers in Lincoln Beach, Ore. will witness the rare event first. A partial eclipse begins there at 9:05 a.m. PST and totality starts at 10:16 a.m. The eclipse then makes its way through Idaho, Wyoming, Nebraska, Missouri, Illinois, Kentucky, Tennessee and Georgia, clipping several other states on the way. It ends near Charleston, S.C. at 2:48 p.m. EDT, just about an hour and a half after it began.

Which city will see the eclipse for the longest?

NASA says the longest duration of totality will be near Carbondale, Ill., where the sun will be completely covered for two minutes and 40 seconds. Some places, like Kansas City, Kans.— which is at the edge of totality — will only witness totality for about 20 seconds. The total solar eclipse will be visible in a hard-to-reach part of Montana for less than a minute. Here's where you can see what the eclipse will look like for you.

A video of what is quite possibly the most painful-looking leg cramp ever has gone viral. The 50-second clip, posted Monday by Angel Bermudez on Facebook, has racked up 16 million views and more than 177,000 shares.

"After the workout. Start to relax and then this happens. Painful yes it was," Bermudez wrote in the caption. The footage shows the muscles of his calf contracting and squirming, almost as if something were inside his leg, right under the skin.

Take a look, if you dare. (Warning: There's some NSFW language in the caption.)

RELATED: Here’s How You Can Use a Lacrosse Ball to Release Your Calves

"This is what a cramp looks like," you can hear Bermudez saying between grunts and groans, clearly in significant discomfort.

Plenty of commenters said they found the alien-like motion of Bermudez's cramp flat-out disturbing. But others had clearly been through similar pain, and were quick to offer advice: stand up and walk, stretch, eat a banana, drink more water.

Although we don't usually recommend following health advice from strangers on Facebook, in this instance, they're on to something. Those solutions might actually help.

Leg cramps are sudden and involuntary muscle contractions, and—even though they can hurt like heck—they're usually harmless. Leg cramps are thought to be caused by some kind of irritation or activation of nerves that tell the muscles to contract, and stay that way.

The irritation can be brought on by a range of things, from dehydration to a mineral deficiency, or even pregnancy. Ramping up your workout intensity too quickly, or over-training tired muscles can also lead to cramping. (For more on the possible triggers, check out "13 Causes of Leg Cramps—And How to Stop Them.")

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You can usually cure a cramp (especially one that comes up quickly after a workout) by hydrating with water, replacing electrolytes and minerals lost through sweat, and gentle stretching. But check with a doctor if you have frequent leg cramps that don't seem to be related to physical activity or your diet. Some underlying health conditions, like peripheral arterial disease and multiple sclerosis, can also cause leg cramps.