Are Twice-a-Day Workouts the Fast Track to Fitness—or Injury?

Sound familiar?

For fitness fiends, it can be tempting to double up on daily workouts, whether that means a morning run and then an evening Spin, or following your favorite fitness instructor from her yoga class to her session at Barry’s Bootcamp. And while—yay!—the benefits of a daily double can be rewarding, there are also loads of potential risk factors (think injury, overuse, or workout burnout). We got Jonathan Cane, an exercise physiologist and owner and head coach at City Coach Multisport in NYC, to give us the lowdown on doubling down.

Is there any good reason to double up on daily workouts?

If you’re trying to nail a new PR in an upcoming race, two-a-days might actually pay off. Also, as Jessie Spano once famously said on Saved by the Bell, “No time! There’s never any time!” “Sometimes people double up because they don’t have enough time to get in everything they want to do before work,” says Cane, who has been coaching athletes for more than 25 years. “Other times, it’s an effective way for a goal-oriented athlete to diversify and pack in some extra workouts.” Take triathletes, for example: During a triathlon, these athletes have to compete in three different disciplines (swimming, cycling, and running). That’s a lot of training to cram into just seven days a week, so many triathletes will complete a cycling workout in the morning followed by a swim or strength-training session in the evenings. 

But if you’re exercising twice a day to lose weight, it can go either way. “If it’s just pouring on more and more in an effort to burn calories, it may not be sustainable, in which case it’s probably not a great long-term solution,” says Cane. But if you break up your sessions intelligently (more on that later), it could potentially pay off. 

RELATED: What Happens to Your Body When You Do the Same Workout Over and Over Again 

But surely there has to be a risk factor, right?

“It’s easy to overdo it,” says Cane. “Even the most ambitious athlete with a lot of experience needs to be careful.” Cane doesn’t prescribe double workouts more than three times per week for his athletes. “In most cases, anything more than that risks overtraining, injury, or burnout,” he says.

Let’s break it down: Which workouts can you double up on, and which should you never do in a single day?

Cane’s rule of thumb is to keep it diverse. “If you do a hard run in the morning, opt for an easy swim or yoga session in the evening,” he says. “Avoid doing two hard workouts in the same day, and be sure to balance orthopedically stressful workouts—like running—with non-weight bearing or lower impact activities.” If it’s volume you’re after—say if you’re a marathoner trying to maximize time on your feet—Cane suggests doing a harder run in the morning followed by an easy jog on soft terrain in the evening.

RELATED: The High-Intensity Workout That’ll Wake You Up, Even at the Crack of Dawn 

Which comes first: the easy or the hard?

Or rather, which should you do first: the easy workout or the more challenging one? “I prefer hard followed by easy,” says Cane. “I think it’s mentally easier to get the challenging workout out of the way and then use the later one as more of a recovery or restorative session. If the supposedly easy session is the first one of the day, there’s a tendency to overdo it, which in turn compromises the evening’s scheduled hard session.” (Crank up your sweat sessions with the Ignite routine by Women’s Health’s Next Fitness Star Nikki Metzger!) 

The bottom line 

“Double workouts can be an effective way to pack in some extra sessions while still giving your body a chance to recover in between,” says Cane. “They should be used sparingly, but for someone looking for an additional challenge, or even someone with scheduling limitations, incorporating one to three doubles per week can be beneficial.” The key, though, is to do it safely. Heed Cane’s advice for daily doubles: 

If you do a Spin class in the morning, swim or lift in the evening.

If you run in the morning, go for a swim or do yoga in the evening.

If you start your day with yoga, pack in a workout with a significant cardio component later on, like a run, bike ride, or swim.

If you’re into CrossFit or bootcamp-style classes first thing in the morning, pick an evening workout that’s steady and less intense, like a swim or a spin class.

And remember: Don’t forget to squeeze in a rest day at least once a week.