1. The problem: You kick with your feet.
Bending your knees to kick with your feet makes your butt drop, creates drag, and slows you down, says Jeff Kline, a certified triathlon coach and personal trainer with PRS FIT. Plus, it robs your glutes of swimming's awesome booty-sculpting powers.
The fix: Kick from your hips, and focus on keeping your feet just slightly below the surface of the water, he says.
2. The problem: Your hands enter the water straight in front of your head.
Or, even worse, they cross over your body's opposite side. This causes each stroke to propel you up and to the side, he says. You start bobbing and squiggling through the water.
The fix: For correct swimming technique, your hands should enter the water at approximately 1 o'clock and 11 o'clock—your head being noon, he says.
3. The problem: You over-rotate your head.
Popping your face completely out of the water every breath throws off your body's rotation—your straight-forward swim becomes more of a wiggle, says Jenny Klovdahl, a master swim coach with Snohomish Aquatics Center in Washington.
The fix: Let your body naturally rotate with each stroke, she says. As your right arm extends into the water, you should rotate slightly onto that shoulder.
4. The problem: Your hands smack the water.
Flopping your hands against the water slows you down, Kline says. Plus, just like belly flops, it's not very comfortable.
The fix: Your hand should enter the water with your wrist relaxed and fingers angled downward, he says. Pretend you're slipping them into an envelope.
5. The problem: You keep your in-the-air elbow straight.
If you keep your arm straight so that you're swinging your arm around in a full circle, windmill-style, you can easily throw your shoulder into overdrive and your hand is just about guaranteed to smack the water upon entry, Kline says.
The fix: When your arm lifts out of the water for your next stroke, keep it relaxed so your elbow points up to the sky and you move forward with proper swimming technique, he says.
6. The problem: You pull with just your hand.
Your hands can only do so much to pull you forward during each stroke, Klovdahl says.
The fix: As you pull your hand through the water, your elbow should bend 90 degrees, allowing you to pull with your forearm as well, she says. If you continue the windmill motion by keeping your arm straight, you'll lose power.
7. The problem: You start your turns too close to the wall.
Besides making bumping your head a very real possibility, starting your flip turns too close to the wall scrunches your body up and slows you down, Kline says.
The fix: Try using your last stoke coming from the black T on the bottom of the pool to start your turn, he says. From there, you can tweak things as needed. If your pool doesn't come with those markings, aim to complete your last stroke about two feet from the wall, he says.
8. The problem: You extend your neck to look forward.
We get it, you want to see where you're going. But facing the pool wall creates extra drag and can strain your neck, Klovdahl says.
The fix: Your neck should be relaxed so that your face and eyes are looking at the bottom of the pool, she says. Don't worry: If you're looking for that T (see #7), you won't crash into the wall.
9. The problem: You take shallow breaths.
Breathing in the water takes some getting used to, but taking shallow breaths keeps your muscles tense—not to mention deprived of the oxygen they need to do their best, Kline says.
The fix: "Exhale all of the air in your lungs when your face rotates back into the water," he says. "The more you exhale, the more you can inhale."