A review of the available studies regarding training frequency suggests training a muscle group twice a week was superior to training a muscle group once a week for muscle growth. What if we decide to increase the frequency even more? There seems to be a threshold in which more frequent training is not beneficial.
IS HIGH TRAINING FREQUENCY THE KEY TO GAIN MUSCLE SUMMARY
- Training volume seems to be the driving force behind increased muscle mass with high training frequency.
- Trained athletes have less of an increase in protein synthesis after exercise than untrained athletes and less damage.
- If they have recuperated properly, trained athletes can likely train a muscle group after 48 hours because protein synthesis has returned to baseline. This depends on their recovery capacity.
- Muscle growth is better correlated with volume than training frequency.
- Well-trained athletes may need to train less frequently and gain greater muscle mass and strength increases.
- Training twice a day does not increase muscle growth when the volume is similar between groups.
- Twice a day seems to favor better strength gains.
UPDATE 4/12: HOW OFTEN SHOULD YOU GO TO THE GYM?
Originally, when I wrote this article, the research suggested that twice-per-week training was optimal for muscle growth. Still, a recent article suggested that trained athletes may need lower training frequencies to increase muscle hypertrophy and strength.
The review article examined the literature on well-trained athletes and removed all the studies with untrained athletes and training frequency. The study reviewed four studies that provided moderate to strong evidence for greater improvements in strength and hypertrophy with lower-frequency training.
A similar article suggested that frequency does not influence strength or hypertrophy if training is performed to muscular failure, even though the total training volume differs significantly.  Older adults (>60 years of age) seem to benefit from training less frequently, as there was no relationship between training frequency and muscle mass. 
4/25: INCREASED TRAINING FREQUENCY DOES NOT INCREASE MUSCLE GROWTH
Thirty-four resistance-trained men and women were randomized into a high-frequency (HF) and low-frequency (LF) training group for nine weeks. The HF completed four weekly sessions, and LF completed two weekly sessions. Volume was matched at 32 weekly sets per week. There were no differences in strength or muscle growth between the two groups. This study confirms that training frequency is less important once training volume is matched. (25)
4/28: GREATER RECOVERY & INTENSITY WITH A TWO-A-DAY SPLIT.
It was mentioned that breaking a training program into two-a-day workouts can result in a higher training volume. If you are training with a large number of sets, fatigue sets in, and workout intensity drops.
Researchers had resistance-trained men divided into two groups. One group performed eight sets of 10 reps on the bench press at 70% of one-repetition maximum (1RM) once per day in the afternoon, and the other group performed four sets of 10 at 70% in two sessions (i.e., the first session in the morning, then the second session performed four hours later).
All sets were taken to failure. The lifters training twice a day were able to train at a higher intensity than the one-a-day group. This was accomplished by the second training session, allowing for higher training intensities.
The twice-per-day group also had a faster recovery, but both groups had recovered by 48 hours. The group that did the once-a-day training had greater pec swelling in the once-per-day group. This could be local edema from tissue damage that occurred with 8 sets of bench presses. Training twice a day may be helpful for lifters who are trying to incorporate more volume into their routine.(26)
EVERYONE SHOULD TRAIN WITH THE SAME FREQUENCY FOR MUSCLE GROWTH?
Training frequency is often a topic of conversation for increasing muscle growth. Is it better to train a muscle once, twice, or even three times a week? Most bodybuilders will break their workouts into splits, so they will do a major body part, such as the chest, and combine it with a smaller bodypart, such as the triceps. Others will work their entire body in one workout.
Another popular topic is training twice daily (morning and evening sessions). By breaking your workout into morning and evening sessions, the theory is that greater protein synthesis and anabolic hormones will be stimulated than one workout per day, leading to greater increases in muscle growth. A 2013 survey reported that 70% of bodybuilders trained each body part once per week, whereas 31% trained each muscle group twice per week.
TRAINING FREQUENCY AND PROTEIN SYNTHESIS
Going to the gym stimulates muscle growth by causing tension in muscle fibers, followed by recuperation and muscle protein synthesis. Beginners experience much more damage to exercise than trained athletes. If you are a beginner, once-a-week training is sufficient to stimulate muscle growth. Still, as you continue to train, your body adapts to the exercise program and becomes more resilient to muscle damage. This process of muscle adaptations to exercise is called the repeated bout effect.
The ability to train a muscle group again is determined by whether you have recuperated from your previous exercise bout. Your ability to train a muscle again depends on your genetic ability to recuperate (i.e., number of Type II fibers), which muscle group is being trained (i.e., calves can be trained more often than hamstrings), and the type of workout (i.e., an eccentric overload program will take longer to recuperate between workouts than a traditional resistance exercise protocol).
Trained athletes have less of an increase in muscle protein synthesis and less muscle damage after exercise than untrained athletes, which means trained athletes need more training stimulus to build muscle.
If you train a muscle group once a week and the muscle has recuperated, waiting an additional week may result in subpar muscle gains. It should also be mentioned that after 10 weeks of resistance exercise, untrained athletes also have a dampening of muscle protein synthesis. This shows that after 10 weeks, they have reached an adaptation process.
HOW MANY TIMES SHOULD I GO TO THE GYM FOR OPTIMAL MUSCLE GROWTH?
A review of the available studies regarding training frequency suggests training a muscle group twice a week was superior to training a muscle group once a week for muscle growth. What if we decide to increase the frequency even more? There seems to be a threshold in which more frequent training is not beneficial. Using high-frequency, low-volume sessions to stimulate muscle growth is called micro-dosing.
It is assumed that small frequent increases in protein synthesis and anabolic signaling pathways can result in a larger muscle growth response. There are mixed results regarding the optimal frequency, as more does not always result in greater muscle growth. For example, training six days a week results in no greater strength and muscle growth than three days a week.
A Canadian study found that training 2 days per week vs. 3 days a week resulted in similar muscle growth when the group volume of resistance exercise was similar. Whether you do a full-body workout or a split workout, as long as the total volume is similar, both will increase muscle mass equally.
DOES HIGH-FREQUENCY TRAINING RESULT IN GREATER MUSCLE GROWTH
The advantage of adding frequency or extra days is that it is often difficult to add extra sets in a single session without fatigue. Increased frequency with a whole-body workout training each muscle group three days a week resulted in greater muscle growth than the typical bodybuilding split, training each muscle group once a week. However, other studies have found similar increases in muscle growth between split workout routines and whole-body workouts when the volume is equal.. Check out the newest study, which found that higher training frequency resulted in greater muscle growth.
HOW OFTEN SHOULD YOU TRAIN LEGS?
In another study, when subjects trained their legs to complete failure either 2, 3, or 5 times weekly, there was no difference in muscle size, regardless of the training frequency.
Interestingly, the five times per week trained with a higher volume yet muscle size was identical, suggesting volume thresholds for muscle growth. More is not always better!
INCREASED TRAINING FREQUENCY BENEFITS FOR MAXIMAL MUSCLE
In 2017, an article titled “Frequency: The Overlooked Resistance Training Variable for Inducing Muscle Hypertrophy?” suggests the following benefits for increasing working frequency:
a.) Trained individuals should train similar muscle groups more frequently while reducing the number of sets performed in each training session. This is based on earlier research suggesting increasing the number of sets beyond a certain point has negligible effects on muscle hypertrophy, given the relatively low volume appears to maximally stimulate muscle protein synthesis;
b) The duration of the time when muscle protein synthesis is elevated in trained individuals appears to be shortened. The authors hypothesized that increasing training frequency, rather than training load or sets performed, maybe a more effective strategy for trained individuals to increase muscle size.
STUDY FINDS INCREASED WORKOUT FREQUENCY RESULTS IN BETTER MUSCLE GROWTH: WORKING OUT 6 DAYS A WEEK IS BETTER THAN WORKING OUT 3 DAYS TIMES A WEEK
An exciting abstract titled “Norwegian Frequency Project” found that increased training frequency was advantageous. Elite competitive Norwegian powerlifters were divided into two groups. One group trained 3 days per week, while another trained 6 days per week. Both groups performed the resistance training program for 15 weeks using the same exercises, weekly volume, and intensity.
At the end of the study, the 6 weekly training sessions, which used shorter but more frequent workouts, gained more strength and muscle mass than the 3 days per week group. The average increase in muscle mass for the 6 days per week group was almost 10% in the vastus lateralis and nearly 5% in the quadriceps. Remember that this was just an abstract and has never gone through the peer-review process.
The typical bodybuilders hit each body part once per week. It’s smarter to break a workout into two parts and space them over the week than try to do it all in one day. For example, you will get a more effective workout if you break a chest workout into 8 sets on Monday and 8 sets on Friday instead of doing 16 sets all on Monday.
After the first 5 sets, an enormous amount of fatigue can diminish the workout quality, reducing training volume. A study on female athletes found increased muscle size when the total resistance training volume was split into two sessions per day instead of one.
This suggests that distributing the volume of a resistance exercise program into smaller units, such as two daily sessions, may create more optimal conditions not only for muscular hypertrophy but by producing effective training stimuli, especially for the nervous system.
MORE ON HIGH TRAINING FREQUENCY STUDIES
One of the most common questions is how many sets per workout are recommended. It’s recommended that you perform anywhere from 6 to 8 hard sets per muscle group each session. It’s been found that 4 sets taken to complete muscular failure took 48 hours for complete muscle recovery.
This suggests that the standard bodybuilding practice of training a muscle once per week is sub-par for increasing muscle growth for advanced trainers. It’s beneficial to break a large volume workout into parts over the week to reduce fatigue.
There is no added benefit to increasing workout frequency per muscle group greater than 2–3 days a week. Total volume seems to be the determining factor for muscle growth rather than training frequency. If you do 20 sets per week, it does not seem to matter whether it’s done in 2 sessions of 10 sets or 4 sessions with 5 sets. The driving factor for increasing workout frequency is to increase the weekly total workout volume per bodypart.
HOW OFTEN SHOULD I GO TO THE GYM TO GAIN MUSCLE (SEE WHAT THE SCIENCE SAYS)
CAN YOU STILL MAKE GAINS BY TRAINING ONE BODYPART PER WEEK?
The answer is a solid yes! Some studies have found similar gains in muscle mass training one bodypart per week compared to training each muscle group five times per week. In a weekly volume-matched resistance training study, well-trained subjects were randomized into two groups: low-frequency (i.e., bodypart trained once per week) or high-frequency (i.e., bodypart trained five times per week).
The low-frequency group performed a split-body routine, training each specific muscle group once a week, while the high-frequency group trained all muscle groups five times per week. For example, the once-per-week group did 10 sets of bench press on one day, whereas the high-frequency group did two sets of bench press every day.
Another important consideration was that the high-frequency group trained with 2-3 sets to failure to equal the number of sets to the low-frequency group. At the end of the study, similar increases in muscle growth occurred despite the high-frequency group performing more volume.
The author stated, “Our findings suggest a set number (≥10 sets) per week performed to volitional failure (8-12 RM), instead of training frequency, is an important “stimulus” to promote muscle mass and strength gains in well-trained subjects when the sets and intensity are equated per week.” The once-per-week group also experienced more soreness than the high-frequency group. The researchers suggested that high-frequency training is an alternative to increase muscle mass without soreness.
DOES WORKING OUT EVERY OTHER DAY INCREASE MUSCLE GROWTH?
Muscle protein synthesis and repair occur after exercise, not during exercise. Logic dictates that having a day of recovery after an intense exercise session would facilitate muscle growth. Although this seems logical, science does not support this.
Researchers compared lifters that did the same workout, trained to failure, and used the same rest periods and volume. The only difference was that one group trained consistently for 3 days in a row (~24 hours between sessions), whereas another group had a rest day after each workout (~48–72 hours between sessions) for 12 weeks.
At the end of the study, both groups had similar muscle growth and strength increases. When all training variables, such as volume, intensity, rest periods, etc., are equated, there is no difference in whether you train 3 days in a row or space it out over the week.
WILL HIGH TRAINING FREQUENCY DOUBLE YOUR MUSCLE GROWTH?
Training twice a day does not increase muscle growth compared to once a day when the volume is similar between groups. Some suggest that training twice per day could increase anabolic hormones, leading to greater increases in muscle protein synthesis and anabolic signaling pathways.
The rationale was that if resistance exercise provides an anabolic response, breaking sessions into two smaller sessions over the day could provide a greater stimulus for muscle growth. If you examine the studies regarding muscle protein synthesis, volume seems to be the driving factor, not frequency.
For example, research had subjects perform 10 sets of leg exercises consisting of leg presses and leg extensions once per week. The other group did the same exercises every day for 5 days (1 set of 10 reps for leg press and extensions). Thus, the weekly set volume was 10 sets in both conditions; they performed it once or spread it across multiple days.
At the end of the study, muscle protein synthesis and anabolic signaling pathways were the same between the groups. The author concluded that training frequency does not impact protein synthesis when the volume is similar.
STUDIES ON HIGH TRAINING FREQUENCY
Another study had subjects train for 8 weeks and divided into one group who trained once per day (performing 8 sets per exercise). One group trained twice daily (performing 4 sets per exercise, once in the morning and in the evening).
At the end of the study, the gains in muscle were the same between training twice per day and training once per day. Another study compared once-a-day and twice-a-day training and found similar gains in strength.
Strength gains are slightly better with twice-a-day training, so splitting your workouts into two sessions is an option if you want to maximize strength. In a study on male weightlifters, athletes who trained twice daily had greater isometric strength, muscle activation, testosterone, and testosterone: cortisol ratio than those who did once-daily training.
Despite these positive changes, muscle growth was the same but favored the group that trained once a day (+3.2%) versus twice-a-day training (+2.1%).
There is no advantage to training multiple times per day compared to a single session for muscle growth. Bodybuilders should not ask, “how often do you need to train a muscle group, but what volume of exercise do you need to optimally stimulate muscle growth?
If you love being in the gym and want to train twice a day, that’s fine, but it does not appear to serve any extra muscle growth stimulus when training once per day when the total exercise volume is similar. Multiple training sessions per day seem to elicit more favorable strength changes.
HIGH TRAINING FREQUENCY AND MUSCLE MASS KEY POINTS
- · Trained athletes have less of an increase in protein synthesis after exercise than untrained athletes and less damage.
- · If they have recuperated properly, trained athletes can likely train a muscle group after 48 hours because protein synthesis has returned to baseline. This depends on their recovery capacity.
- · Well-trained athletes may need to train less frequently and gain greater muscle mass and strength increases.
- · Training twice a day does not increase muscle growth when the volume is similar between groups.
- · Twice a day seems to favor better strength gains.
- · Training volume seems to be the driving force behind increased muscle mass with increasing frequency.
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