Your time in the gym is valuable. It takes so much motivation to even walk through the door some days that you want to make sure your workouts are actually going to get you to your goals. And though both cardio and strength training are essential for your health, most fitness regimens will skew one way or the other.
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If you're not sure whether you should focus your sweaty efforts on strength training or classic cardio, look no further. Here, two fitness gurus break down whether spending more time on the treadmill or in the weight room will best support your health and fitness goals — from just getting of the couch to supporting strong bones to de-stressing.
When Cardio Is King
Aerobic exercise (aka cardio) includes any movement or activity that increases your heart and breathing rate. (Two popular options: running and cycling.) Cardio directly trains your heart, lungs and the rest of your cardiovascular system — but its benefits don't end there.
In addition to improving your heart health, cardio also supports your brain health, blood sugar and overall mobility, according to the Cleveland Clinic. It even supports sexual well-being and can help you maintain a healthy weight.
Because of its widespread benefits, regular cardio exercise can ultimately help you live longer, according to a June 2017 study published in Progress in Cardiovascular Disease.
Where Strength Training Shines
Though strength training (technically called resistance training) had the reputation of being solely reserved for bodybuilders until recently, this type of exercise is crucial for everyone — especially as you age.
"As we age, growth hormones in the body decrease, which contributes to muscle loss," says Amanda Murdock, CPT, director of fitness for Daily Burn. "Strength training helps us maintain and build muscle tissue."
In addition to keeping your body physically strong, strength training can also support your overall cardiovascular health and help you maintain a healthy weight. According to the Mayo Clinic, strength training can also help you maintain strong bones and improve quality of life and independence in your later years.
How to Decide Between Cardio or Weights
In a perfect world, everyone would incorporate both cardio and strength training into their workout routines. Depending on your unique goals, though, you might want to focus more on one over the other. Follow this guide to figure out where you should be spending the majority of your gym time.
If You: Are Training for a Race
Go for: Cardio
Whether you want to run a 5K or bike 100 miles, if you want to compete in some sort of race, "you need to do the exact thing you're trying to get good at in training," says Bret Contreras, PhD, CSCS, author of Glute Lab: The Art and Science of Strength and Physique Training.
"If you want to get good at running, you have to run; if you want to get good at cycling, you have to cycle," he says. Yep, that means you'll want to focus your training on cardio — specifically on whatever form of cardio you'll be doing come race day. This way, you train the right muscles through the right movements to help you perform at your best.
If You: Want to Burn More Body Fat
Go for: Strength Training
While cardio burns calories and can help you lose weight in the short-term, strength training best supports fat-loss long-term, Contreras says. Strength training builds muscle, which then increases your metabolism, helping you become leaner over time.
Though results may take a couple of months, Contreras recommends focusing on strength training for sustainable fat loss. (Though, since cardio can have an appetite-suppressing effect in some people, it can support your goals, too.)
If You: Are Looking to Get Stronger and Build Muscle
Go for: Strength Training
There's a reason they call it strength training. "We can build muscle mass quickest with weighted exercises," Murdock says.
"Though cardio exercise like cycling and running will build some muscle in your legs, it can only really get you so far," Murdock says.
Contreras agrees: "If you want to get stronger, there's only so much stress you can put on your body just using your body weight." When you strength train, you can progressively overload your body to continue making gains, he says.
The only way to continually put enough tension on the muscles to stimulate muscle growth, is strength training, Contreras says. "As you increase the tension you put on your muscles, they continue to respond by growing bigger and bigger over time," he says. (This process is called muscle hypertrophy.)
You don't need to lift big, hulking weights, either. Training with both light and heavy weights can promote muscle growth, according to an October 2015 Journal of Strength and Conditioning Research study (which Contreras co-authored).
If You: Just Want to Be More Active
Go for: Both Cardio and Strength Training
Though more experienced exercisers can strength train at an intensity that provides both its muscle- and cardiovascular-related benefits, that's not the case with beginners, Contreras says.
If you're just getting moving, aim for a balance of "three weight-training sessions and two to three cardiovascular sessions per week," he says. Focus on full-body strength-training sessions to reap the most benefits.
For those without gym access (or who just don't feel comfortable sweating in that setting), "going outside for a walk or jog is convenient and free," Murdock says. You can also ease your way into resistance training with body-weight exercises like push-ups, squats and lunges.
If You: Need to Reduce Chronic Disease Risk
Go for: Cardio or Strength Training
"Exercising in general has been shown to reduce chronic disease," Murdock says. "Whatever makes you move works!"
Both cardio and strength training offer notable benefits when it comes to protecting long-term health. According to the Mayo Clinic, strength training can help ward off arthritis, obesity, heart disease, depression and diabetes. Cardio offers similar benefits — and may even help ward off strokes and certain types of cancer.
If You: Want to Support Strong Bones
Go for: Strength Training
According to August 2013 research published in the Journal of Sports Medicine and Physical Fitness, both power and resistance training effectively support bone mineral density.
"Weight-bearing exercises, which force you to work against gravity, help build bone mass and density," Murdock says.
Though certain types of cardio — like running and jumping — are considered weight-bearing, they only increase bone density in certain parts of the body, like the hips, Contreras says. Instead, strength training offers the most notable full-body bone benefits.
Just as lifting weights stimulates muscle growth, it also stimulates bones to grow stronger. "When you lift a load, gravity acting on that load itself stimulates the body," Contreras says. "On top of that, the muscles that contract in order to lift that weight pull on the bones, further stimulating them."
If You: Need to De-Stress
Go for: Cardio (But Keep It Light)
If you want a workout to help you simmer down, stick to lower-intensity exercise, like a light jog, that doesn't shoot your heart rate through the roof, Contreras says. Extra points if you do it outside.
"When we're stressed or don't sleep enough and go pedal to the metal when we exercise, it can promote this sympathetic ['fight-or-flight'] state," Contreras says. Low-intensity cardio, which doesn't require too much effort or mental concentration, can help the body shift into a more parasympathetic ("rest and relax") state.
Case in point: a July 2015 study published in PNAS found that nature walks can reduce rumination (aka anxious thinking) and quiet activity in the parts of the brain associated with risk of mental illness.
If You: Only Have 20 Minutes a Day to Work Out
Go for: Strength Training
"People don't realize that you can get in an awesome workout in 20 minutes," Contreras says. To make the most of that time, though, opt for full-body strength training. "You'll be more functional, you'll have more total-body strength, muscle mass and bone density, and build a better shape."
To turn the benefits up a notch, Murdock recommends performing your workout HIIT-style, which involves alternating between periods of high-intensity work and rest. (HIIT workouts are more efficient than workouts you perform at a steady, consistent pace.)