By now you know if you want to build a lean, fit body, you can’t stick to the treadmill or elliptical alone. It takes some heavy lifting to get that strong and chiseled physique. In fact, even if you want to be a better runner, you still need to incorporate strength training into your routine. But when you’re strapped for time, and need to squeeze cardio and weights into a single sweat session, which should you tackle first? Strength training, according to the research and fitness pros. Here’s why.
Why Weights Shouldn’t Wait
In one study published in The Journal of Strength and Conditioning Research, researchers pinned three workout tactics against each other: Strength training alone, running then strength, and cycling followed by strength. They found that exercisers did fewer weight lifting reps if they had just ran or cycled. Yet, doing strength training with no cardio beforehand resulted in more reps.
Another recent study found similar results. After research subjects performed different bouts of treadmill running, the number of reps they performed during resistance training decreased, as did muscle power. Their heart rate and rate of perceived exertion also increased during the strength training sessions that followed aerobic exercise, especially after a HIIT running workout.
“In my experience, I’ve found that most exercisers feel ‘stronger’ when they engage in resistance training first,” says Robert Confessore, PhD, clinical exercise physiologist at Summit Medical Fitness Center in Kalispell, MT. Many scientific studies also demonstrate that aerobic training can negatively affect strength development when performed prior to lifting (whereas research is lacking on the reverse effect), he says. This is due to physiological changes in the muscles that help you move. When you use those fibers to fatigue before you do resistance exercises, your form and drive will likely suffer.
And that can have a noticeable impact. According to Lacey Stone, an LA-based celebrity trainer, if you want the muscle-building benefits of strength training, it’s best to start with those exercises. “It’s vital that you lift before your cardio workouts, because you will have the most power and the most strength to lift heavier loads, which in turn will make you stronger,” she says.
When Cardio Matters Most
In terms of fighting off fat, both resistance exercises and anaerobic workouts are crucial. “When you gain muscle, it raises your metabolic rate, which helps you burn fat faster,” Stone explains. And according to research, doing both strength and cardio decreases body fat significantly more than each method alone. So you can probably stick to the same formula mentioned above, but keep in mind this caveat: That same study showed that while fat mass and waist circumference decrease when you do a combo of the two techniques or just aerobic activity. In other words, lifting alone didn’t lead to weight loss.
So if you want to slim down, you need to kick up your cardio — even if that means skipping some weights when you’re short on time. “Remember: Strength training changes your shape and cardio changes your size,” says Stone.
If it’s better cardio capacity you’re after, Stone says there are mixed reviews on what to tackle first. It’s still smart to strength train even if you want to be a better runner or biker. In fact, one study found that resistance exercises improved endurance athletes’ performance, muscle power and economy. You may just need longer and more frequent cardio moves (some of those being stand-alone aerobic sessions), with cross-training days sprinkled throughout your weekly schedule.
Research suggests taking ample recovery time between strength sessions, too, so you don’t mess with your endurance benefits. As shown in the study, the physiological stress from resistance training can fatigue muscles and potentially slow down the benefits of running or cycling sessions. Similarly, ACE-sponsored research shows that strength training before cardio increased heart rate by 12 beats per minute, which can increase your rate of perceived exertion. This makes your workout feel more vigorous and causes you to feel tired, faster. An important note to keep in mind if you’re aiming to go for a longer run or ride.
Finding Your Formula for Success
Of course every individual has different ideas for what they want to get out of their gym time. So tailor yours to your goals. “To the recreational exerciser, I recommend experimenting with the order of the two types of training within the same workout. Then gauge which works best for you,” says Confessore. If you’re still unsure of what to do, Confessore suggests scheduling these two types of workouts on different days. That way, you don’t have to worry about one affecting the other.
The bottom line… Do what works for your body, but if you need a place to start: Tackle strength, then cardio.
Originally published June 2015. Updated February 2018.