The New Fitness Rules

Think you know the drill on shaping up and slimming down? Think again. Find out how the latest science is rewriting the rule book on everything, including maximizing your fat burning and acing your running form, so you can finally reach your goal.

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Should You Eat Before a Workout?
Old school: Exercising on an empty stomach will burn more fat.
New rule: Have a 150-calorie jump-start meal an hour or two before your workout.
Ever force yourself through a workout, even though you were starving, simply because you thought you would tap into those fat stores faster? Next time, eat up. The latest research in the International Journal of Sports Nutritionand Exercise Metabolism found that exercisers who ate breakfast before treadmilling for 36 minutes had a significantly higher fat-burning rate for as long as 24 hours compared with those who ate post-workout, even though both groups consumed the same number of calories during the day. Plus, a recent report in the Strength and Conditioning Journal concluded that when you start off with a grumbly tummy, there's no fat-burn advantage: You won't be able to go as intensely or burn as many calories, and you'll also lose more muscle. Pre-workout, nosh on these easy eats from Nancy Clark, RD, the author of Nancy Clark's Sports Nutrition Guidebook: a banana and a half cup of plain low-fat yogurt, or a whole wheat English muffin with a half tablespoon of peanut butter.

The Best Running Sneakers
Old school: Get a sneaker that offers the most stability.
New rule: Less is more.
The shift toward minimalist footwear in the past few years has biomechanical experts rethinking what makes a good athletic shoe. "Like everyone else, I used to believe that the more motion control and cushioning a shoe had, the better," says Irene Davis, PhD, the director of the Spaulding National Running Center at the Harvard Medical School. But such training wheels, she says, can encourage runners to strike with their heel first before pushing off the forefoot -- a motion that creates a lot more impact on the joints, according to research conducted by Davis. In contrast, less built-up, minimalist sneakers and their "barefoot" counterparts, like Vibram FiveFingers, encourage a natural mid-to-forefoot strike, which creates a softer landing. A recent Penn State study suggested that minimalist footwear can help reduce injury rates among runners. Today you'll see minimalist styles by just about every sneaker brand. That said, you shouldn't become a convert to them overnight. A study from the University of Wisconsin-La Crosse found that among runners who switched to a barefootlike shoe design, those who continued to strike with their heels (as if they were in a traditionally cushioned running shoe) significantly increased the loading forces on their lower legs. So work on your forefoot strike before swapping in minimalist shoes.

Related: The Best Sneakers for Every Workout

When Should You Do Ab Exercises?
Old school: Save toning your abs for last.
New rule: Engage your core throughout your workout.
Cranking out crunches after a workout is so last millennium. "The core's biggest job is to provide a solid foundation for your extremities to work off of, so about 70 percent of your core training should be geared to strengthening the abdominals and lower back as stabilizers," says trainer Joe Dowdell, owner of Peak Performance gym in New York City. That means doing more exercises that require you to stiffen your core as you work against resistance -- such as doing planks or trying to keep your body from rotating as you pull a resistance band. "Exercises that strengthen the abdominal walls not only improve performance but also help reduce injuries," notes Stuart McGill, PhD, a professor of spine biomechanics at the University of Waterloo. To fill that remaining 30 percent of ab time, Dowdell recommends alternating in a few moves, like cable wood chops or medicine ball rotational throws, that work your core in a more integrated manner rather than just isolating its muscles with various crunches.

Do You Need a Workout Buddy?
Old school: Buddy up for the best results.
New rule: Sometimes it's better to go solo.
There's a long-held understanding that having an exercise partner will improve your fitness level because you're more likely to show up when there's someone waiting for you. But research from Santa Clara University found that, depending on your partner, you may actually exercise harder when you sweat it out alone. The key may be finding the right partner. While having a more fit pal can help push you, sticking with someone whose focus doesn't mesh with yours can ultimately compromise your workout, warns trainer Jonathan Ross, the author of Abs Revealed. "Your workout partner has to be similar enough in style for the situation to be a win-win," Ross says. "Chatty friends can be a distraction." Consider partnering with your BFF on easy workout days instead.

How Many Rest Days Do You Need?
Old school: Wait 48 hours to recover after a strength workout.
New rule: If you've gone hard, you may need an extra day.
You've heard it plenty of times: Take at least a full day off between strength workouts to allow your muscles to rebuild and get stronger. But if you've taken a sculpting class that's left you shaking, press "Pause" a little longer. One study from Brazil determined that beginners who did four sets of 10 reps of biceps curls needed more than 72 hours of rest to recover. "If you start working those same muscles too soon, you could be compromising your results and even risking injury," explains exercise scientist Wayne Westcott, PhD, at Quincy College. That's because after your workout, your muscles have to work hard to rebuild those torn-down tissues, which is what will ultimately make you stronger and more sculpted. "Intensity is definitely more important than frequency," Westcott says. On those off-days, let cardio -- for instance, power walking, running, swimming, and cycling -- serve as an active recovery, so you can burn fat while allowing your muscles to rebuild.

How Active Should You Be?
Old school: Working out is king when it comes to staying trim.
New rule: Your whole day comes into play.
We're not going to argue against the benefits of regular exercise and watching what you eat, but more and more experts say that you need to consider what you're doing for the rest of the 16 waking hours a day when you're not at the gym. "We realize now that it's your total daily energy expenditure, not just how many calories you burn during exercise, that will ultimately make a difference in your bottom line," says Fabio Comana, an exercise physiologist for the National Academy of Sports Medicine. Research from the National Cancer Institute found that even among those who like to work up a sweat on a regular basis, the longer they sit around, the higher their risk for dying sooner. And remember: The more you move, the more you burn. Scientists at the Mayo Clinic found that among adults of a similar size, individuals' daily energy expenditure can differ by as many as 2,000 calories -- mostly because of bursts of activity, like going to the restroom on a different floor, talking a walk at lunchtime, or standing up while on the phone.

Related: Burn 500 Calories in 45 Minutes

Classic Exercises Get a Modern Makeover
Squat
Old school: Don't bend your knees past 90 degrees.
New rule: It's OK to go over.
If you've sampled the barre workout craze, you know that your booty brushes the floor during endless squat variations. Why is it suddenly cool to get way down? There has been a debate among experts, but the consensus seems to be that it is a natural human movement. "Research found that if you do a squat and force yourself to keep your knees behind your toes, as in a 90-degree bend, you increase the stress on your hips by more than 1,000 percent," explains Michele Olson, PhD, a FITNESS advisory board member. "But if you allow your knees to come forward, you have only a bit more stress on your knees -- just 20 percent or so -- and significantly less pressure on the hip joint."

How to Do a Push-Up
Old school: Do a modified, on-your-knees push-up if you can't manage the full one.
New rule: Modify the angle, not the pose.
Always stuck doing "girl" push-ups? You'll get better results if you take them off the floor, says McGill. "Doing a full push-up, even one that's on an angle that makes the movement easier, is a lot more effective than trying to power through a set on your knees." That's because the point of a push-up, McGill adds, is to work through a full range of motion with power and speed. "You just can't do that on your knees." As an alternative, place your hands on a low bench or countertop and focus on keeping your body straight. Gradually work your way toward an angle that's lower to the floor.

How to Do a Sit-Up
Old school: Don't bother with a full sit-up.
New rule: Full-range moves hit ab muscles that your crunches may be missing.
Trainers nixed full sit-ups for crunches long ago, thinking that once you get past a certain height, you're working your hip flexors more than your abs. But lately pros say to aim higher. In a Pilates move like the roll-up (lying faceup on the floor, peel your torso off slowly until you're sitting upright, then reach for your toes), "you're moving with control while rolling up through the spine as if it's a large wheel, so the axis point keeps changing," Olson explains. The key difference is that because your knees are kept straight and your spine is curving, the hip flexors don't help nearly as much, allowing a greater percentage of ab muscle fibers to be recruited.

How to Do a Lunge
Old school: Keep your front knee over your toes with each lunge.
New rule: Focus instead on staying tall.
You've probably also heard the same "Don't let your knee move past your toes" warning for lunges, but some experts say there's really no magic point at which your knee reaches perfect form. "The theory is that the more forward you go, the greater the sheer force on the knee, but there's often a trade-off, because you might be putting more stress on the hip and spine if you stop the movement short, especially if you have long legs," says trainer Brad Schoenfeld, the author of Sculpting Her Body Perfect. Instead, Schoenfeld says, focus on maintaining an upright position -- ears, shoulders, and hips in alignment -- and try to sit back into the lunge rather than worrying about where your knees go.

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