One of the biggest debates currently surrounding muscular hypertrophy is training frequency. That is, how many times per week you train a particular muscle group. Given the current research, it is becoming increasingly clear that training volume, intensity and interval rest times all play a significant role in the hypertrophy process. What is more: research has shown that
⇒ More volume (up to a point) is essential for more gains in muscular growth.
⇒ Muscular hypertrophy can be induced across a range of intensities
⇒ Shorter and longer rest-intervals play a great role in the hypertrophy process.
But, what about training frequency? Originally, many people thought that higher frequencies would be better for muscle growth and many still hold this opinion. But why? The theory is that by training each muscle group more often during the week, you stimulate more regular elevations in muscle protein synthesis and hence the subsequent activation of downstream process that ultimately lead to muscular hypertrophy over the longer-term. However, research is coming out which suggests that higher frequencies might not lead to greater muscular gains over those that utilise lower training frequencies.
The 2018 Study
Colquhoun et al. (2018) investigated the effect of training 6x per week and 3x per week in resistance trained men on muscular hypertrophy and strength over a 6-week period. In both groups, volume, intensity and time spent between training were equated in order to investigate only the impact of training frequency. After 6 weeks, it was found that both 3x and 6x resistance training per week caused significant increases in 1RM squat, bench and deadlift and fat free mass. There were no significant differences between groups. The conclusion was that training each muscle group 6x per week did not generate any significant improvements over those training 3x per week in resistance-trained men when volume and intensity are equated.
Colquhoun et al. (2018). Figure showing the % change in 1RM strength and body composition values following a 6-week training period in response to 3x and 6x resistaining training per week. As you can see, the % change amongst values between 3x and 6x per week training are very similar.
What Is This Study Saying?
Looking at the results of the study, it is clear that training 6x per week does not offer any additional benefits in terms of maximum strength and muscular hypertrophy gains over those that are training 3x per week. In line with this, previous studies have shown that 3x per week (full body) muscle training produces significantly greater increases in muscular thickness of the elbow flexors (with volume equated) over those that train each muscle group 1x per week (split program).
However, something to keep in mind is that the total volume in this study was kept fixed between groups. Given that frequency is one way of allowing those to increase their total weekly volumes, you could ask if there perhaps would have been greater gains in the 6x per week group if volume was allowed to increase? This was however not tested in this study. It is possible however that by allowing total volume to increase, the 6x per week group might have displayed more muscular gains. More volume would have provided the stimulus necessary for further muscular adaptations. There is also another possibility in that the 6x per week group with more volume would have seen no further improvements or possibly regression. Why? They might have hit their exceeded maximum recoverable volume threshold. In other words, they would simply be overtraining rather than allowing for more muscle growth. Without answers to these questions it is difficult to say for sure whether 3x per week is really the optimal training frequency.
Giving my opinion, it would seem that training 3x per week for each muscle group is a good target to aim for if you are an intermediate or advanced lifter looking to optimise muscular hypertrophy gains. But, it is just one piece of the muscle building puzzle. Even if you do train with a frequency of 3x per week, you still have to consider total weekly training volumes, ensuring that this allows for maximum muscular adaptations while preventing the risk of burnout. 3x per week is good, but only if you regulate your weekly volumes. If you don’t, you won’t see the growth you want to see.