Your time is precious—especially when you’re trying to sandwich happy hour, exercise and dinner all into one night. So if fitting in that gym sesh a few times a week is important to you, spend those precious minutes on the mat or machine wisely. We talked to nutrition, weight loss and fitness expert Dr. Roger Adams to uncover the exercise moves that are totally eating up your time (and what you should be doing instead).

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1. Crunches

You might consider them the gold standard of ab exercises, but regular old floor crunches are a big waste of time. “The crunch (lying on the floor, knees bent, hands behind your head and slowly lifting your shoulders and head off the floor) may be easy on your lower back, but it doesn’t engage much abdominal muscle,” says Adams. Instead of crunching your time away and not seeing a stronger, flatter stomach, he suggests doing planks instead. “There are dozens of variations and all of them engage more muscle than your traditional crunch.”

2. Smith Machine Squats

To reap maximum benefit during an exercise, you need to be able to control and move your body through its range of motion—especially unilaterally (i.e., each side moves independent of the other). “The Smith Machine doesn't allow for your right and left sides to work independently and takes away the need to balance or make body adjustments during a squat,” says Adams. “This greatly reduces the amount of muscle used during a squat.” Instead of squats on a Smith Machine, he suggests performing free-weight squats or squats with dumbbells. “These will challenge your body’s position and allow you to use larger amounts of muscle to perform the movement.”

3. Dumbbell Side Bends

“I see this one on a daily basis in the gym,” says Adams. “Folks stand with dumbbells in their hands and bend endlessly side to side. If your goal is a thicker middle, then this is the exercise for you!” Um, nope. Doing side bends can thicken your obliques (aka those muscles between your ribs and hips on the side of your body) and make your waistline look larger. Additionally, this move puts stress on your lower back. Instead, Adams suggests using a single cable pulley to perform a high-pulley cable side bend. “This uses way more muscle than side bends, puts less strain on the low back, requires constant stabilization, especially from your core and legs and doesn’t thicken your waist.” Win, win, win.

4. Broomstick Twists

Holding a bar across your shoulders and twisting side-to-side to trim down your waist might seem like a good move, but since there’s no resistance, Adams says you’re basically just burning a few calories and wearing out your lower back. “Since the motion is initiated by your shoulders and chest, it’s difficult to engage the abdominals to work during this movement.” A better movement to trim down your waistline? A side plank with a hip drop. “This is a simple move requiring lots of spinal stabilization, arm initiation and a lot more muscle than endlessly twisting a broomstick,” he says.

5. Decline Bench Press With Barbell

Adams points out that since the bar hits your chest before your pecs reach a full stretch, you don’t recruit a lot of the lower pec muscle fibers while doing this move. You have heavy weights on the bar and a very short range of motion—so basically, a recipe for injury. “Instead of using a barbell, perform the same movement with dumbbells,” he suggests. “The dumbbells track to your sides as you press, so you don’t have to worry about a bar hitting your chest limiting your movement.” He also recommends changing the angles of your dumbbells as you move them. “This really helps you feel the lower pecs and recruits way more muscle.”

6. Leg Press

While this move does have its place in a good lifting routine, Adams says there are much better exercises. “Leg presses are simple to perform: Load up the machine with large plates, sit down and push your feet on the platform. While you can traditionally use a lot of weight, your body doesn’t have to use any stabilizing muscles and overall development is low,” he says. “Also, the large amount of weight usually necessary to really ‘feel’ this exercise leads to an increased risk of injury.” Instead of being that annoying person with all the plates, grunting and groaning through a movement that gives little return, Adams suggests grabbing a single dumbbell, as heavy as you can handle, and performing a goblet squat. “This recruits the glutes a lot more and requires your entire body to stabilize throughout the movement.”

7. Seated Hip Abductor

This move, along with the adductor machines, is pretty foolproof, which is why so many people wind up using it. But while it’s popular, it can easily be replaced by one single movement that will work your entire lower body. “Leg movements should be functional and use all of your lower body, not just isolating your inner or outer thighs,” Adams says. “Work your thighs and the rest of your lower body all at the same time with a weighted side lunge.” The extra weight held at your shoulders also will force your arms, shoulders and abs to work to keep the weight still. Bam, you’ve just transformed your kind-of-effective move into a full-body workout.

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