The Science Will Surprise You.
One of the seemingly endless choices facing those who lift weights is whether to train using full-body workouts, or to use split routines.
Full-body (aka total-body, whole-body) workouts involve performing exercises for all the main muscle groups of the upper and lower body at each workout.
Split routines, as the name suggests, involve dividing up one's workouts so that different muscle groups are trained on separate days.
Each format has its pros and cons. With whole-body routines, there's no obsessing over which muscle grouping to train on what day, because everything is trained in the one workout. Simple.
I like simple. The older I get, the more I appreciate the value of simplicity. Whether it's a weight training routine or an electrical appliance, it's a beautiful thing to be able to jump right in and use something productively with a minimum of fuss, head-scratching and cursing.
Turns out I'm a bit of an oddity. At least in the world of resistance training, that is, where a lot of other people clearly don't share my love of the uncomplicated. Total-body protocols have long been looked upon as "beginner" routines; in the minds of many, they are the apprenticeship that newbies briefly serve before coming of gym age and embarking on more 'advanced' split routines.
In fact, it's quite common nowadays for beginning lifters to bypass total-body routines completely and start right away on split protocols. Many begin training with routines that work each muscle group only once per week - a protocol widely known as "The Bro Split." Whether someone who struggles to get reps with 80 kg on the bench press should be training pecs only once per week is highly questionable, but that hasn't stopped Bro Splits from becoming standard fare in gyms worldwide.
Where's The Science Behind All This?
Split routines have by far enjoyed the most muscle media coverage over the years, and are the go-to choice for gym rats all around the world. But is there any actual evidence that split routines lead to greater strength and muscle gains than full-body routines?
The answer to that question will no doubt come as a surprise to many people.
Incredibly, prior to the turn of the millennium there was only one published English-language trial comparing a full-body routine to a split routine. Despite the worldwide popularity of weight training and the global thirst for getting buffed, resistance training has remained a poorly-researched topic until recently, leaving instructors and gym-goers to rely on anecdote, broscience and the sometimes ridiculous articles in muscle magazines and websites.
Thankfully, after 2010 researchers around the world began comparing total-body and split routines in controlled trials. To minimize confounding, the routines they compared featured a similar weekly volume in terms of the number of sets performed. That's not always how it works in real life, of course, as people often adopt split routines so they can increase the number of exercises and sets they perform for given bodyparts. Increasing volume is not always a good thing; often, it's downright counterproductive. I've previously addressed the numerous flaws in the research claiming superiority for multiple sets over single set training, and it's a subject I'll surely discuss again in future.
For now, let's look at whether splitting your routine, per se, offers any strength and hypertrophy (muscle growth) advantages over whole body training. The following is a quick rundown of the relevant studies conducted so far; I've linked to the full texts where possible for those who want more details on the methods employed in each study.
The content below was originally paywalled.
This is the seminal study on the topic, conducted by researchers from McMaster University, Ontario. Thirty young, healthy, female undergraduate kinesiology students were recruited for the study. They were physically active but had no previous strength training experience.
The women were assigned to follow a total-body routine, a split routine, or to serve in a control group.
The full-body group trained twice per week. The split routine group trained four times per week, with 2 sessions for upper body and 2 for lower body.
Training was done on weight stack machines. Both routines were comprised of seven upper and lower body exercises, each performed for 5 sets.
Thanks to the high set count, the full-body training sessions lasted 60 to 90 minutes whereas each split workout lasted 45 to 60 minutes.
The study was comprised of two 10-week training periods, separated by a 2-week Christmas recess.
Both the full-body and split groups experienced significant 1RM increases for the bench, curl and leg press, with no significant differences between groups.
Only the full-body group increased leg lean tissue mass significantly (4.9 versus 1.7% in the whole and split groups, respectively).
Whole-body lean tissue mass increased in both the whole and split groups (4.1% versus 2.6%). Percent body fat decreased similarly (-1.1 versus -1.3%).
In this Iranian trial, thirty-nine healthy males with no resistance training experience were randomly divided into four groups;
Total-body (12 exercises for one session per week);
Total-body (12 exercises spread over two sessions per week);
Split routine (the same 12 exercises split into three training sessions per week: 1) Legs; 2) Upper back, triceps; 3) chest, biceps).
Control group
The researchers don't mention the number of sets per exercise, so total set volume is unknown. All we are told is that the volume was equal between groups.
All groups increased 1RM bench press, 1RM leg press, body weight, body composition, and bench and leg press endurance to a similar degree.
For thigh circumference, only the increases seen in the split and twice-weekly full-body groups attained statistical significance. For arm circumference, only the increases seen in the split and once-weekly full-body groups attained statistical significance.
Despite admitting "no significant differences" between groups at pre- and post-training for all variables, the researchers recommended "novice individuals had better use the split routine training for improving performance and promoting muscular adaptations."
A curious conclusion for a study that detected no clinically meaningful differences between groups.
Brad Schoenfeld and colleagues compared two different 3-day-a-week routines. One involved a full-body routine performed on each of the three training days. The other was a 3-way split routine, structured as follows:
Day 1 - Chest, Upper back;
Day 2 - Thighs, Hamstrings/Lower Back;
Day 3 - Shoulders, Biceps, Triceps.
Nineteen young, resistance-trained, male volunteers (mean body mass 78 kg; age 23.5 years; mean lifting experience 4.5 years) completed the eight-week intervention.
The full-body subjects performed 2-3 sets per muscle group per workout. The split group performed all 6 sets for smaller muscles and 9 sets for larger muscles at each of their allocated weekly workouts.
In an attempt to maximize post-workout muscle anabolism, subjects were given a supplement on training days containing 24 grams of whey protein (and a mighty 1 gram of carbohydrate).
After eight weeks, ultrasound imaging showed muscle thickness of the forearm flexors increased by 6.5% and 4.4% in the full-body and split groups, respectively. After adjusting for baseline, the difference was statistically significant.
While numerically greater percentage increases in forearm extensor and vastus lateralis thickness were found for the total-body group, the differences were not significant.
The researchers noted that although forearm extensor muscle thickness was not statistically different between groups, the effect size for total-body was 96% greater than that of split (0.90 vs. 0.46, respectively). Similarly, the effect size for quadriceps thickness markedly favored the higher frequency total-body protocol (0.70 vs. 0.18, respectively).
(In simple terms, statistical significance estimates the likelihood of a finding being due to chance, while effect size estimates the 'strength' of a finding).
Both groups experienced an increase in 1RM bench press; 10.2 kg (10.6%) and 6.3 kg (6.8%) for total-body and split, respectively.
1RM squat increased by 13.8 kg (11.3%) and 12.1 kg (10.6%) for total-body and split, respectively.
No significant between-group differences were noted.
Effect sizes for 1RM bench press favored total-body compared with split (0.57 vs. 0.41, respectively), "suggesting a meaningful difference in results." Effects sizes for 1RM squat were identical between groups.
The researchers concluded the "findings suggest a hypertrophic benefit to higher frequencies of training when volume is equated between conditions" and "provide evidence that well-trained individuals benefit from including periods of training muscle groups 3 days-per-week when the goal is to maximize muscle hypertrophy."
The authors posited an important factor that may help explain why the higher-frequency full-body routine trended towards better results: "During prestudy interviews, 16 of the 19 subjects reported training with a split routine on a regular basis. Although the topic has not been well studied, there is some evidence to indicate that muscular adaptations are enhanced when program variables are altered outside of traditional norms."
Indeed there is; it's the entire premise underpinning periodization, where variables such a training volume, intensity and frequency are deliberately and periodically altered to prevent staleness and overtraining.
"Thus," continue the researchers, "it is conceivable that those in [total-body group] benefited from the unaccustomed stimulus of training more frequently.
The authors also lamented on a problem common to most of the studies discussed here: Small sample size and less-than-optimal statistical power. A high degree of individual variability in results was noted between subjects, which limited the ability to detect significant differences in several outcome measures.
Crewther et al 2016 (New Zealand)
This study also involved trained subjects: 24 male rugby players competing in a premier club competition in New Zealand. Their mean age was 29.8 years; height 179.5 cm; body mass 92.9 kg; the players each had at least 2 years of resistance-training experience (3-4 times per week). At the start of the study, their mean 1RM bench press and squat was 103 kg and 130 kg, respectively.
The participants were matched according to initial strength into 2 groups. One group started out on a 4-week full-body protocol, the other began the study with a 4-week split training protocol of equal volume.
The groups then crossed over to complete the other training protocol after an 8-week washout period. This means every player spent 4 weeks on both the full-body and split routine, in random order. This means that any differences in the results are unlikely due to baseline disparities between the participants of each group, because all participants spent equal time on both routines, in random order.
During the washout period, the athletes maintained their normal club skill and fitness conditioning, but all forms of resistance training were avoided.
Both training approaches involved three weekly sessions (Monday, Wednesday and Friday). The full-body group obviously trained all major muscle groups at each workout. The format of the split routine is not described in the paper; the researchers simply write that "only a sub-set of the muscle groups was exercised during each session."
The prescribed exercises included back squats, leg curls, leg press, bench press, bent-over row, pull downs, shoulder press, bicep curls and calf raises.
The full-body and split protocols both improved 1RM bench press (7.3% and 7.4%) and 1RM squat (7.4% and 5.4%), respectively.
Fat free mass increased by 1.1 kg and 0.4 kg with the whole-body and split routines, while body fat (-0.9% and -0.4%) and fat mass (-5.7% and -2.1%) declined.
The split protocol elevated testosterone (21%) and cortisol (50%) concentrations, but a higher testosterone:cortisol ratio (28%) was seen after full-body training.
The improvement in T:C ratio and the greater decline in fat mass and body fat percentage seen with the whole-body routine was statistically significant, as was the greater rise in cortisol seen on the split routine.
Seven women and 12 men with resistance-training experience (mean age 34.6 years, mean strength training age 4.3 years) completed this study.
The full-body group trained 3 times per week, with 3 sets per muscle group per session.
The split group also trained thrice weekly, using the following format:
Day 1 - Chest, deltoids, and triceps;
Day 2 - Upper back and biceps;
Day 3 - Quadriceps, hamstrings, calves, and abdominals.
So both groups performed 9 sets per muscle group per week. All work sets were performed to momentary muscle failure. Repetitions per set were 8-12RM. Daily workouts lasted around 45-60 minutes.
After eight weeks, total-body training increased lean mass by a mean 1.06 kg (1.9%), and split training increased lean mass by 0.99 kg (2.0%).
Total-body group 1RM improvement on the chest press was 9.1 kg (11%), and hack squat 20.2 kg (21%). The split routine group 1RM improvements on chest press was 5.8kg (7%), while hack squat increased 21.8 kg, (24%). There were no statistically significant differences between groups.
This study is where things start getting interesting. So far, all of the studies utilized programs where the subjects were required to train 1-3 times a week. As a result, none of these studies examined the effect of training individual muscle groups more than three times weekly.
In modern gym culture, training a muscle group 3 x a week is considered "high frequency". So high, in fact, that few people do it. Training the same muscle group five times a week, therefore, is almost unheard of. Ask around at your local gym and the consensus will be that training muscle groups on a daily basis is a sure-fire route to burnout, injury and wrecked joints.
Like so much broscience, this sentiment is based on no science. It's just a belief that has been handed down and unquestioningly accepted by generations of gym rats.
Thankfully, sports scientists have begun questioning the narrative. Starting in 2018, they began reporting on trials comparing traditional routines with very high-frequency routines, where muscles groups were trained directly 4 to 6 times per week.
In Brazil, Gomes et al reported on twenty-three resistance-trained subjects (mean age 26.2 years; mean training experience 6.9 years) who trained five days a week, Monday to Friday on one of 2 routines:
A total body routine, training all muscle groups at every one of the 5 weekly sessions;
A split routine, training each specific muscle group once a week.
In the split routine group, 5-10 sets were performed for each muscle group, in the one weekly workout for that muscle.
In the total-body routine, every muscle group was worked daily for 2-3 sets per workout.
All volunteers consumed a nutritional supplement containing 24 grams of whey protein and 6.4 g of carbohydrate immediately after all workouts.
After eight weeks, there were no significant differences between groups in any endpoint excepting muscle soreness.
Mean fat-free mass gains were 0.8 kg and 0.5 kg in the whole-body and split groups, respectively. Muscle mass index (kg/m²) improved by 0.1 in both groups.
1RM squat improved by 12 kg and 8 kg in the whole-body and split groups, respectively. The corresponding improvements in 1RM bench press were 9.7 kg and 5.6 kg.
The split group, working each muscle grouping only once per week, showed more delayed-onset muscle soreness (DOMS) than the high-frequency, whole-body group at the beginning, middle and end of the study.
So, apart from greater soreness in the split group, there were no discernible differences in the results obtained on each routine.
Eighteen healthy men with an average 6.5 years of resistance training experience were recruited for this study, and assigned to either a total-body or split routine.
Both groups trained five days per week. As with the Gomes study, the whole body group trained all five muscle groupings every day from Monday to Friday, while the split routine trained each muscle group once weekly.
At each workout, the full-body group performed three sets of a single exercise for each muscle group. A different exercise was used for each muscle group at each of the weekly workouts.
The split group performed three sets each of all 5 exercises per muscle group in the one weekly workout for that muscle group.
So both groups performed a weekly total of 15 sets per muscle group and 75 sets in total.
Despite the whole body group training to failure 5 days a week, no injuries were reported and the adherence to the program was 100% for both groups.
After eight weeks of training, 1RM increases on the bench pess and seated row machine were near identical between groups, while squat 1RM increased by 18.5% and 8.8% in the total-body and split groups, respectively. The difference was not statistically significant.
Forearm flexor, triceps and outer thigh muscle thickness increased by 8.5%, 11.2% and 9.7%, respectively, in the total-body group. The corresponding increases for the split routine group were 3.8%, 5.8% and 5.4%. In this case, the differences in forearm and outer thigh thickness between groups were statistically significant.
As with Schoenfeld et al 2015 (Brad Schoenfeld was also a co-author of this study), the researchers posited that the results may have been influenced by the novelty of changing training programs. Pre-study interviews revealed all the subjects regularly trained with a frequency between 1 and 2 sessions per muscle group per week. Therefore, the subjects who were randomized to the full-body group were exposed to a new stimulus in the form of a much higher weekly frequency (5 times per muscle group per week), whereas the split group trained with their usual frequency (1 time per muscle group per week).
Perhaps because of the subjects' untrained status, in this trial the researchers gradually increased the volume and frequency of training. Both groups started with 2 weekly workouts, progressing to 5 workouts by week 4. Between weeks 4-8, the total-body routine involved training each muscle grouping every day from Monday to Friday, while the split routine worked each muscle group once a week. Between weeks 4-8, both groups performed 10 sets per week for each of the 7 exercises, using 8–12RM.
Despite the step-wise progression, the study was marred by a high dropout rate. Twenty-seven untrained males were initially randomized to one of the 2 groups, with only 18 completing the study.
Total lean body mass increased by 1.0 kg in the whole-body group, and 1.5 kg in the split group.
Appendicular lean mass (arms and legs) increased by 0.3 kg and 0.5 kg in the total-body and split groups, respectively.
Bench press 1RM increased 7.1 kg and 4.5 kg in the whole-body and split groups, respectively.
Right and left leg extension 1RM increased by 21.3 kg and 23.7 kg, respectively, in the total-body group. The corresponding increases for the split group were 19.7 kg and 18.1 kg.
None of these marginal differences were statistically significant.
Lasevicius et al 2019 (Brazil)
Twenty-eight resistance-trained men completed this study, after being randomly assigned to one of 2 groups:
A split-body training routine with muscle groups trained twice per week over 4 weekly sessions, or;
Total-body routine performed 3 times per week.
Depending on group assignment, 4-6 sets per exercise of 8-12RM were performed during each session, with a total weekly set count of 84.
After ten weeks of training, muscle thickness of the rectus femoris increased from by 7.9% and 12.3% for the total-body and split groups, respectively, with no statistical difference between groups.
Muscle thickness of the vastus lateralis increased from baseline to post-study by 12.2% and 16.9% for the total-body and split groups, respectively, with no statistical differences between groups.
Elbow flexor muscle thickness increased 1.6% and 7.3% for the total and split groups, respectively, with no statistical differences between groups.
Elbow extensor muscle thickness increased by 8.6% and 15.7% for the total and split groups, respectively, again with no significant difference between groups.
1RM bench press increased by 10.2% and 11.8% for the total and split groups, respectively, with no significant difference between groups.
1RM squat increased from baseline to post-study by 17.7% and 18.9% for the total and split groups, respectively, with no significant difference between groups.
In this study, the pattern was for larger percentage increases in muscle thickness in the split group. The findings were not statistically significant, and evinced small effect sizes. As with all the studies discussed here, this trial was limited by a small sample size. It was further marred by a hefty 22% dropout rate. Such small studies are inherently limited in their statistical power, which makes it even more difficult to determine whether small differences between groups are real and meaningful or simply random/chance findings.
Despite this, the authors wrote that "small, but potentially meaningful ES differences (ranging from 0.31 to 0.39) were observed in favor of training muscles two versus three days per week for every hypertrophy outcome measure studied. These findings suggest a potential hypertrophic benefit to the lower training frequency."
I'd say that's a tenuous conclusion given the study’s limitations and the overall body of evidence discussed here, but more on that later.
Evangelista et al 2021 (Brazil)
Sixty-seven untrained subjects completed this study. The full-body group performed the same routine at each of its four weekly sessions, using 4 sets of 8-12RM per muscle group. The split participants trained each muscle group twice per week, with 8 sets per session.
After eight weeks, both groups experienced near-identical increases in bench press and squat 1RM.
Both groups also experienced very similar increases in muscle thickness at the four measured sites (biceps, triceps, vastus lateralis, rectus femoris).
Johnsen and van den Tillaar 2021 (Norway)
In this study, twenty-one resistance-trained male subjects were randomly assigned to a full-body or split routine group, both training 4 times per week.
The split group performed two lower body and 2 upper body workouts per week.
After eight weeks, both groups significantly increased their squat 1RM (split group, +13.25 kg; full-body group, +14.31 kg) and bench press (split group, +7.75 kg; full-body group, +8.86 kg).
No hypertrophy or body composition outcomes were reported in this study.
Forty-four untrained women completed this 12-week study. The full-body group trained twice per week, while the split program involved 2 upper body and 2 lower body sessions each week.
The training intervention employed a linear periodization model: Throughout the study, participants performed 3 sets per exercise with a progressive increase in load and a concomitant decrease in the number of repetitions from 12RM to 8RM.
After 12 weeks, both groups increased their mean 1RM in the bench press, leg press and lat pulldown, with no statistically significant differences between groups.
Similar increases were also noted for muscle mass, countermovement jump height, and upper body power (as determined during a bench press using an empty bar with a sensor attached).
So ... What Does all this Mean?
First, a quick recap. The studies above encompassed a wide range of workout frequencies, from training one day a week to training 5 days a week, and training muscle groups from once weekly to 5 times weekly.
None of the studies showed a clear, across-the-board, statistically significant advantage to either a split or full-body protocol.
Schoenfeld et al 2015 compared a 3-day whole-body versus 3-day split routine (muscle groups worked once per week), and wrote that the marginally more favourable results for the whole-body routine "suggest" a benefit for that protocol.
Lasevicius et al 2019, who compared a 3-day whole-body versus 4-day split routine (muscle groups worked twice per week), wrote that the marginally greater effect sizes for the split routine "suggest" a benefit for that protocol.
Interestingly, Brad Schoenfeld was a co-author of the Lasevicius et al paper (in fact, Brad was a co-author on many of the more recent studies discussed above).
Arazi and Asadi 2011, based on some rather tepid differences between groups, also recommended a split routine.
What the above results in their totality really suggest is that, if you conduct enough studies, marginally greater but non-significant results will be observed for a total-body routine in some studies, and a split routine in others. This heads-or-tails randomness is pretty much what you'd expect when comparing two different interventions of similar efficacy.
The safe, sensible and non-controversial summation of the above research is that, so long as volume is held equal, you'll probably get similar results from a split or total-body routine.
But as I pored through the studies above, something quickly caught my eye: Namely, the total-body routines in which muscle groups were trained 4-5 times weekly. While such high frequencies are not uncommon in Eastern bloc or Olympic weightlifting circles, they are almost unheard of in most Western gyms. Approach a group of broscientists at any local gym and tell them you're going to start working every bodypart 4-5 times a week (gasp!) in a total-body routine (what?!?), and the likely response will be:
"That's too much bro! You'll end up injured and overtrained!"
Your mental health may also be brought into question.
"Dude, are you crazy?!?"
The studies above, however, show there's nothing crazy or inherently dangerous about training muscle groups with such high frequency, at least when the set volume is kept low.
Not only did the subjects on the high-frequency, total-body routines not crash and burn, they tended to do just fine - at least as well as the subjects following split routines.
I'm going to write more about high-frequency, full-body routines in future, and what might happen if you follow one while eating for growth (i.e consuming sufficient protein and a caloric excess). All the studies above were free-living endeavours where the subjects either received no dietary advice or were told to simply eat their usual diet.
In the meantime, the evidence indicates that either a whole-body or split-routine will deliver similar results. Which you choose depends on factors such as your schedule and personal preference.
Because varying the training stimulus is an important requirement for continued progress, you may want to consider alternating between the two. If you've been flogging yourself for months on end with a high-volume split, a low-volume total-body routine performed 3 days a week may be just what the doctor ordered.
People switch from one routine to another, wondering why the initial positive results never last. They never stop to consider that it was not so much the new routine that got the results, but the change in routine.
As I mentioned at the start of this article, a big plus from total-body routines is their no-frills structure. You hit the gym, work all the major muscle groupings, then go home.
Full-body routines necessitate that you stop faffing around in the gym with single-joint movements like leg extensions and dumbell flyes, and instead focus on far more productive multi-joint compound movements like squats, leg presses, lunges, deadlifts and their variations, power cleans, bench/chest presses, rows, pulldowns and so on. These exercises utilize larger amounts of muscle than isolation movements and hence lead to more strength gains, hypertrophy and fat loss.
With whole-body routines, every workout matters. It’s not like a split workout for arms and calves, where you’ll get a bigger calorie burn from walking to the gym and back.
With whole-body routines, you can also add a moderate to vigorous cardio session at the end of every workout. You don't have to worry whether stationary bike sprints or rope flailing will interfere with recovery from a previous leg or upper body workout, because everything is being worked together in the one workout anyways.
Making the above changes is what this health writer did, upon the advice of her trainer. After switching to a full-body routine, her workouts took on a new lease of life and she reportedly lost 6% body fat in only 3 months. That’s what happens when you refocus and redouble, returning to the basics of training and giving them the respect and effort they deserve.
Leave a Reply