Serious workout or dumb Instagram trend?

But while it might seem like a relatively new trend, underwater strength training has been a thing for some time now — whether it’s used just in a training session, or in a group class that combines the core principles of aqua training and HIIT.

Earlier this year, Speedo and Lifetime Fitness partnered to create the Speedo Fit: Water Fitness Class program, also known as WTRX Water Xtreme. Basically, WTRX Water Xtreme combines a boot camp format with principles of a traditional aqua class, so it’s high in intensity, but with low-impact water movements. Classes use traditional equipment like dumbbells and kettlebells, but also equipment specifically designed by Speedo, such as Push Plates ($45.67, buy them here), and Clutch Paddles ($27.60, buy them here).

While the novelty of aquatic strength training probably sounds cool in itself, we wanted to find out: does it actually provide a solid workout?

Trainer Alex Isaly says that while you can’t lift as heavy as you would be able to at the gym, you’re still getting in both concentric movements (i.e, when you're doing a bicep curl and you lift the weight), and eccentric movements (i.e., when you lower the weight), both of which are crucial for ultimate resistance training.

“An example of this would be the bicep/tricep curl with the clutch paddles. You are using both concentric and eccentric movements on the curl up and the push down to work your muscles the whole time, both while lengthening and shortening with continued resistance,” he says. Regardless of your range of motion, allowing the muscles to be fully engaged through the entire exercise is crucial to a full-body workout.

What’s more, underwater weight training can even give your core muscles an extra blast, says Dr. Naresh Rao, an osteopathic primary care physician and sports medicine specialist in New York City, and head physician at the USA Men’s Water Polo Team. “Training on the water can provide a multitude of variables to create more unstable surfaces. The wave motion creates unpredictable instability, taxing the core muscles even more,” he says.

It can also benefit those with joint problems or arthritis, he adds. “Performing these exercises in the water puts less stress on the joints because the body is more buoyant, thus allowing the participant to train at a much greater effort for a longer period of time,” Isaly explains. The same goes for those healing from an injury, or those who have weakened bones or muscles, because there’s less pressure on your joints when you're in the water.

Still, there are some drawbacks to underwater training. If you’re looking to build more muscle mass, as opposed to boosting endurance, you might want to stick to the gym for weight training and reserve aqua training for cardio or recovery, Isaly says.

Plus, if you have balance issues or vertigo, steer clear, says Dr. Rao, as you're at risk of mishandling the weights. “Like with any exercise, it should be rotated with other exercises to prevent it getting stale and to work other areas of fitness. Varying fitness routines can benefit your physical and mental health,” he adds.

Still interested in trying it? We asked Islay to recommend a few exercises for various muscle groups.

1) If you're using the Push Plate, try this: “Hold the handle grips on the side and assume a wall-sit position along the edge of the pool. Submerge the Push Plate underwater at chest level, and with strong, rapid, powerful moves, push and pull the water in and away from your body,” says Islay. This exercise engages the chest, back, triceps and biceps, he explains, so it’s a killer upper body move.

Don't have a Push Plate? You can also use dumbbells to do curls and presses.

2) Squat plyo jumps are a good underwater exercise if you're holding a dumbbell in each hand. “Submerge your head below water going into a deep squat position while keeping the arms straight at your sides and elbows rigid. At the bottom of the squat, jump out of the water as high as possible maintaining straight arms,” Islay says.

If squats aren’t your fave, you can also do lunges.

3) You can also work with a kettlebell to do swings, suggests Islay. “In a standing position in the pool, hold the kettlebell with both hands on the handle and arms extended to the ground. Begin by moving the kettlebell up and away from your body until it completely comes out of the water. Reverse the move back to starting position,” he says.

4) Training underwater is great for your core, says Islay. “Standing in the pool, hold the Push Plate with the inside handles. Extend the arms directly out in front of the body with the Push Plate completely submerged in the water. Then, rotate at the torso from side to side pushing and pulling the water with the Plate,” he says. You can also do this exercise with a kickboard.

5) If you have a ViPR, try a Clean and Press. While you're standing in the pool, press the ViPR into the water as close to the bottom of the pool floor as possible, submerging your head under water. Clean by lifting the ViPR using biceps to the shoulders, then press the VIPR overhead as your head exits the water.