Should you workout twice a day to gain muscle? Will doing so build muscle faster than training once a day? Or will it lead to a bad case of fitness burnout, leaving you tired and overtrained?
Here’s a closer look at what the science has to say on the subject of two-a-day workouts and muscle growth.
Can I Workout Twice a Day to Gain Muscle?
Two-a-day-workouts should, in theory at least, lead to a faster rate of muscle growth than training once a day.
There are two main reasons why.
First, separating your workouts into two distinct blocks allows for a higher volume of training . This in turn should lead to more muscle being built.
For instance, let’s say that you’re doing three full-body workouts a week, working your whole body in a single training session.
One of the downsides of total-body training is that a typical workout can end up lasting anywhere between 1-2 hours, which doesn’t suit everyone.
Some people will run out of steam towards the end of an intense workout. The muscles being worked towards the end of a workout receive less effort than the ones trained at the start, which in turn can mean a slower rate of muscle growth.
You’re not going to have the same amount of energy at the end of that training session as you did at the start, especially if you’re doing compound lifts like squats, deadlifts, barbell rows and bench presses.
But if you were to do some of those exercises at a different time of day, fatigue from the previous exercises wouldn’t be a problem. Your energy and focus is distributed across fewer muscle groups, which makes for a higher quality workout.
You’d be stronger, fresher and able to lift a heavier weight, or do more reps with the same weight, which in turn generates a larger stimulus for growth.
For example, rather than hitting your entire body in a single workout, you might do the pushing movements in the morning, hitting the quads, chest, shoulders and triceps.
Then, in the afternoon or evening, you do the pulling movements, working the back, biceps and hamstrings.
Here’s what your AM and PM workouts might look like:
Or you could train the upper body and lower body in separate sessions. That is, you’d work your upper body in the morning, then come back to the gym later in the day to train your lower body.
Two-a-day workout plans are also employed by some advanced lifters who have hit a plateau, and are finding it hard to put on muscle mass.
There’s a link between the number of hard sets you do for a muscle and the speed at which that muscle grows. Put differently, a higher volume of training, up to a point at least, will typically lead to a faster rate of muscle growth.
For advanced lifters, increasing your weekly training volume (the number of hard sets you do for a muscle group) is sometimes all the stimulus your muscles need to start growing again.
Bodybuilders, for example, will typically perform a high volume of training to ensure that every muscle is developed to its full potential.
Problem is, more sets will mean longer workouts. For a lot of people, longer workouts are neither practical nor convenient.
Moving to a two-a-day workout routine allows you to get some extra volume in while still keeping each training session down to a reasonable length.
Arnold Schwarzenegger, for example, found that two shorter workouts worked better than one longer session (which isn’t surprising, given the huge number of sets he was doing).
Here’s what he had to say on the subject:
“I worked out from 9-11 in the morning and then again from 7-9 at night. In the Army, when I had trained six hours continuously, I found that I could never handle the kind of weight I wanted to use. But by splitting up my schedule, training arms and shoulders in the morning, resting for a few hours and eating at least two substantial six-course meals, then going back to train my legs, chest and abdominals in the evening, I discovered I had plenty of energy to handle a lot of poundage. It was like a whole new workout on a different day. I was rested, my energy was back, and my mind was ready for it.”
So, on paper at least, training twice a day should lead to muscle being built more quickly than once a day.
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However, there isn’t a great deal of research to look at how training twice a day affects gains in muscle size and strength.
However, these studies were conducted in competitive strength athletes, over a period of just 2-3 weeks.
Should You Workout Twice a Day to Gain Muscle?
How does working out twice a day affect muscle growth? Does it speed it up, slow it down, or have no effect at all?
To answer that question, a team of Brazilian scientists set up a very simple experiment .
They rounded up a group of trained men, and assigned them to 1 of 2 groups:
- 1 daily session per muscle group, where every muscle group was trained once
- 2 daily sessions per muscle group, where every muscle group was trained twice
Here’s what the training program looked like:
- Monday: Push Workout
- Tuesday: Pull Workout
- Wednesday: Rest Day
- Thursday: Push Workout
- Friday: Pull Workout
- Saturday: Rest Day
- Sunday: Rest Day
- Bench Press 8 sets x 8-10
- Dumbbell Flyes 8 sets x 8-10
- Triceps Pressdown 8 sets x 8-10
- Squats 8 sets x 8-10
- Leg Extension 8 sets x 8-10
- Lat Pulldown 8 sets x 8-10
- Straight-Arm Pulldown 8 sets x 8-10
- Biceps Curl 8 sets x 8-10
- Lying Leg Curl 8 sets x 8-10
As you can see by the high number of total sets, this was a high volume training program, with a whopping 40 work sets being performed in each workout.
Each set involved 8-10 reps with 90 seconds of rest between sets and 180 seconds of rest between exercises.
The once-a-day group did all 40 sets in a single workout. The group training twice a day did 20 sets in one workout, then came back to the gym later in the day to do another 20 sets.
They did their first workout between 6-8 am, and made sure to leave at least eight hours before the second session.
- Bench Press 4 sets x 8-10
- Dumbbell Flyes 4 sets x 8-10
- Triceps Pressdown 4 sets x 8-10
- Squats 4 sets x 8-10
- Leg Extension 4 sets x 8-10
- Bench Press 4 sets x 8-10
- Dumbbell Flyes 4 sets x 8-10
- Triceps Pressdown 4 sets x 8-10
- Squats 4 sets x 8-10
- Leg Extension 4 sets x 8-10
What happened? Who saw the best results?
In terms of muscle growth, both groups made similar gains.
After eight weeks of training, ultrasound scans show no difference in muscle thickness in the biceps, triceps, quadriceps or pecs.
In other words, training twice a day didn’t lead to muscle being built any faster.
However, there were some small benefits in terms of both strength and endurance associated with two-a-day workouts.
Muscular endurance (number of reps with 60% of 1-RM) was not significantly different between groups. However, the two-a-day group did see the largest gains.
Subjects in the two-a-day workout group also saw their squat strength increase to a greater extent than the one-a-day group. This wasn’t the case with the bench press, where strength gains weren’t significantly different between groups.
Here’s how the researchers sum up their findings:
“The primary and novel finding of this study was that training a muscle group only once a day is as efficient as training twice a day to promote an increase in upper-body maximal strength, muscular endurance and muscle size. The increase in lower-body maximal strength seems to be more pronounced when this portion of the body is stimulated with twice-daily sessions.”
All things considered, it was the group training twice a day that saw the best results.
However, there was no benefit in terms of hypertrophy. Whether a muscle was trained once or twice a day, the rate of growth was much the same.
Benefits of Working Out Twice a Day
Working out twice a day isn’t for everyone. Most people are doing well to train once a day, let alone twice.
However, training twice a day isn’t something reserved solely for professional athletes preparing for a competition.
If you have the time, as well as the motivation, there are benefits of working out twice a day.
If you need rapid results in a short period of time, and you’re able to devote many hours to training, good nutrition and recovering properly, going to the gym twice a day is one of the best ways to go about it.
Movie stars, for example, will sometimes train twice a day, 5-6 days a week for hours at a time in order to get in shape for a film role.
If you’re being paid millions of dollars to show up on set with a body to rival that of the Farnese Hercules, you’ll want to do everything in your power to drop fat and gain muscle as fast as humanly possible.
For example, I remember reading about the training Josh Brolin did when he was preparing for his role as Cable in Deadpool 2.
Brolin was in the gym 5-6 days a week for around three hours in total, split between two daily workouts.
His training consisted of mobility work and circuit training in the morning and more traditional bodybuilding-style workouts in the afternoon.
Many bodybuilders will employ two daily workouts to help them get ripped for a contest, doing fasted cardio first thing in the morning before breakfast, before lifting weights in the afternoon or evening.
Going to the gym twice a day can also be useful if you’re training for different fitness goals at the same time, such as gaining muscle and improving your cardiovascular fitness.
That’s because training to improve both qualities in a single workout can end up compromising your results.
Here’s what I mean:
If you do cardio before you lift weights, it can compromise the quality of a lifting session, which in turn reduces the strength of the muscle-building stimulus generated by that lifting session.
For example, let’s say you go to the gym, do a bout of high-intensity interval training (HIIT) on the bike, then train your legs immediately afterwards.
Chances are it’s not going to go well.
You won’t be able to do as many reps, or lift as much weight, because of the residual fatigue from the HIIT.
As a result, the intensity of the “growth signals” sent to your muscles will be weaker than they otherwise would be, which in turn means a slower rate of muscle gain .
There’s also some evidence to show that doing cardio immediately after lifting weights is less effective than keeping the workouts separate.
In one study, researchers looked at the effect of separating strength and endurance training by 6 hours, 24 hours or combining them in the same workout .
After seven weeks of training, it was the group combining the workouts who saw the smallest gains in both strength and cardiovascular fitness.
To quote the authors directly:
“Daily training without a recovery period between sessions and, to a lesser extent, training twice a day, is not optimal for neuromuscular and aerobic improvements. Fitness coaches should avoid scheduling 2 contradictory qualities, with less than 6-hour recovery between them to obtain full adaptive responses to concurrent training.”
By keeping the workouts separate, you run less risk of interfering with the adaptive responses to each session.
That said, even doing the workouts at a different time of day is no guarantee that your rate of muscle growth will remain unaffected, and you’ll need to be mindful of the total amount of endurance training you’re doing if you’re trying to maximize hypertrophy.
Working out twice a day can also make for shorter workouts.
That is, instead of doing all your training in one hit, you distribute the same amount of work across two shorter sessions.
For some people, separating one block of training into a couple of shorter ones is a more practical way to fit that training into your day.
Let’s say you’re following the Arnold split, which involves three different workouts — one for your chest and back, one for your shoulders and arms, and one for your legs.
But rather than train both muscle groups in the same workout, you might spend 30-45 minutes in the morning training the first muscle group (such as your chest or shoulders).
Then, later in the day, you come back and train something else (such as your back or arms).
Exercising Twice a Day FAQ
Is it OK to workout twice a day?
From a physiological point of view, there’s no reason why you can’t perform two daily training sessions. In most cases, lack of time and or enthusiasm are going to be the limiting factors, rather than your body’s ability to recover from and adapt to working out twice a day.
Will working out twice a day lead to overtraining?
Working out twice a day certainly increases the potential for overtraining compared to training once a day.
However, it’s the total amount of exercise you’re doing, rather than how that exercise is distributed throughout the day, which poses the biggest risk as far as overtraining is concerned.
In fact, research to compare the same amount of resistance training spread over 1 or 2 training sessions shows no difference in various signs of overtraining, including fatigue, sleep patterns, muscle soreness, stress levels and mood .
Entering a true state of overtraining can take months of excessive exercise, far more than most people are doing in the gym. It’s nowhere near as common as some would have you believe.
There is a form of temporary overtraining, known as overreaching, where your performance stagnates, or even gets worse, and you end up digging yourself into a hole that can take weeks to recover from.
But most people will end up skipping a few workouts if they’re feeling a bit frazzled. That’s usually all they need to get things back on track before they get anywhere close to overreaching, let alone overtraining.
If you feel tired, or have a few crappy workouts, it doesn’t automatically mean you’re overtrained. Maybe your diet wasn’t quite right, or you’ve been under a lot of stress, or you haven’t been sleeping well, all of which can lead to burnout, and your performance in the gym taking a dive.
Can I work out twice a day for weight loss?
Any form of exercise can make a contribution to the calorie deficit required for weight loss. However, weight loss is more a function of your diet than what you do in the gym.
In fact, despite the boost in calorie expenditure, working out twice a day for weight loss has the potential to cause more problems than it solves.
Sometimes, a workout routine that burns lots of calories will stimulate your appetite, so you end up replacing the calories you’ve worked so hard to burn.
There’s also a phenomenon known as moral licensing, where being good gives you permission to be bad. In other words, you may end up eating more food on a two-a-day workout plan because you feel like you earned it. As a result, any fat you burn off by going to the gym twice a day will end up getting replaced.
There’s also some interesting research to show that if you burn lots of calories via exercise, your body adjusts by spending less energy elsewhere .
If your typical couch potato ramps up their activity levels, their daily calorie burn will rise. But if you take someone who is already moderately active and increase their activity levels still further, you don’t see the same effect.
Daily calorie expenditure appears to plateau at higher activity levels as the body adapts to maintain total energy expenditure within a narrow range.
I’m not saying that working out twice a day for weight loss can’t work, because it can. But you do need to be mindful of how those two daily workouts affect your calorie intake and activity levels outside of the time you spend in the gym.
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