Training Each Bodypart Once or Twice a Week? What’s Best for Muscle Mass?

Aug 4, 2022

Training Each Bodypart Once or Twice a Week? What’s Best for Muscle Mass?

by: Robbie Durand
Casey Viator was a beast, yet he trained three times a week, working the whole body in one workout. Who trains like that these days? Nobody in the current bodybuilding circles follows full body workouts anymore. Regular resistance training has consistently been shown to produce rapid and marked increases in both muscle strength and hypertrophy across a wide variety of populations. Optimization of muscular adaptations is influenced by the prescription of resistance training variables including load, volume, and rest interval. There has always been a debate among bodybuilders as to how many days per week is optimal for muscle growth and strength. For years, bodybuilders did workouts three days per week, whole body training. Then, gradually in the 80’s and especially the 90’s people started to move into body part splits and training a muscle once per week. A recent survey of 127 competitive male bodybuilders found that more than two- thirds of respondents trained each muscle group only once per week. Compared to full body routines, it is believed that a split routine allows total weekly training volume per muscle group to be maintained with fewer sets performed per training session and greater recovery afforded between sessions.

Whole vs. Split-Body Training- Study # 1
A new study published ahead of print in the Journal of Strength and Conditioning Research sought to compare traditional hypertrophy training (body part split, muscles trained once per week) to a higher frequency training protocol (full-body workouts, muscles trained three times per week). Researchers examined the impact of a full body vs. a split routine on muscle mass and strength.

Twenty well-trained college-aged males were divided into one of the two training programs (whole body vs. split training). The training program lasted eight weeks and involved three training sessions per week on non-consecutive days. The groups were matched for baseline strength and body mass. Before and after the training program, the researchers evaluated muscle thickness of the forearm and the vastus lateralis (i.e. quadriceps) in addition to 1 rep max in the bench press and parallel back squat. Volume was equated, and nutrition was monitored to control for confounding variables. Collectively, these results suggest that training muscles three times per week is likely superior to training them once per week for strength and hypertrophy gains.

After the eight week training period the results tended to favor the higher frequency training group. 1RM bench press improved by 10.6% in the high-frequency group (3 days per week training) compared to a 6.3% increase in the body part split group. Improvements in 1RM squat strength did not differ between groups (~11% increase in both). Though not all reached significance, muscle thickness measures were greater in the high-frequency training relative to the body part split group. Collectively, these results suggest that training muscles three times per week is likely superior to training them once per week for strength and hypertrophy gains. The authors suggest periodizing training by varying training frequency to maintain the effectiveness of the stimulus. In sum, the researchers found that training muscle more frequently resulted in greater gains in strength and muscle hypertrophy.

Whole vs. Split-Body Training- Study #2
training frequency, infinite_labs A new study in the Journal of Biology in Sport examined the effects of two equal-volume resistance training protocols upon strength, body composition and salivary hormones in male rugby union players. Using a crossover design, 24 male rugby players completed either a:

– 4-week full-body. The prescribed exercises included; back squats, leg curls, leg press, bench press, bent-over row, pull downs, shoulder press, bicep curls and calf raises.
and
– 4- week split-body training protocol of equal volume during the competitive season.

training frequency, infinite_labs The groups then crossed over to complete the other training protocol after an 8-week washout period. Training involved eight repetition maximum lifts for selected exercises, performed for 3-6 sets with rest periods of 60-90 seconds between sets and exercises. At the end of the study, both training methods increased 1RM strength to a similar extent and facilitated positive changes in body composition (bodyfat and lean muscle mass) after only four weeks. The full-body and split-body protocols improved upper (7.3% and 7.4%) and lower body 1RM strength (7.4% and 5.4%), whilst reducing body fat (-0.9% and -0.4%) and fat mass (-5.7% and -2.1%), respectively. The two training protocols improved various aspects of body composition (i.e. bodyfat decreased, fat-free mass increased), with full body training producing more favorable bodyfat and increases in fat-free mass. This could be due to the activation of more muscle groups per training session. This study was fascinating because I would have assumed that the split body training would have resulted in greater increases in muscle mass and strength, but both full and split body routines resulted in similar increases in muscle mass and strength. Based on the suggestions, full body routines may be something to try out for a few weeks for variety.

training frequency, infinite_labs

Training Frequency: Meta-Analysis
A meta-analysis is a collection of studies in which reviewers can analyze a large number of studies and can draw conclusions. Research muscle guru Brad Schoenfeld conducted a systematic review and meta-analysis to determine the effects of resistance training frequency on hypertrophic outcomes. He wanted to look if training more often had an impact on muscle growth. He found that after going thru all the data when comparing studies that investigated training muscle groups between 1 to 3 days per week on a volume-equated basis, the current body of evidence indicates that frequencies of training twice a week promote superior hypertrophic outcomes to once a week. He was quoted as saying, “It can therefore be inferred that the major muscle groups should be trained at least twice a week to maximize muscle growth; whether training a muscle group three times per week is superior to a twice-per-week protocol remains to be determined.”

Key Points: The research seems to point to training major muscle groups twice a week for maximal muscle growth.