Anyone who has spent a significant amount of time in the gym knows that there seems to be an unwritten list of “rules” that you need to follow in order to reach your fitness goals. The “Dos & Dont’s of Gains” if you may. However, many of these “rules” are based purely on bro-science or no science at all, and in some cases, actual science may show the exact opposite.
Below are 7 common training myths that we often hear in & around the gym.
1. You will over-train if you train muscle groups more frequently than once per week.
If you pick up any mainstream bodybuilding magazine, you will see the same generic split of Chest Monday, Back Tuesday, etc. with each body part trained once weekly. Moreover, if you go to a gym on any Monday, you will see nearly everyone battling for a bench to press on, so it is clear a large number of individuals take this advice.
Some of these individuals have good physiques so you can obviously get big training body parts once weekly; however, will you over-train and/or make less progress if you train more frequently?
Following a workout, skeletal muscle protein synthesis rate (the rate at which your body is building new proteins in your muscle) is elevated for 48 – 72 hours . For the other 4 – 5 days per week muscle protein synthesis levels are at baseline until the muscle group is trained again. This suggests training muscle groups every 48 – 72 hours may keep skeletal muscle protein synthesis rates elevated.
And most importantly, there is scientific evidence to support this.
A recent training study by Schoenfeld et al.  recruited trained young males and assigned them to either a ‘bro split’ or full body workout group for 8 weeks. Both groups trained 3 days per week and volume (weight x sets x reps) was matched between protocols. After 8 weeks, there was no difference in strength between the groups, however, the group that trained full body 3 times per week experienced more muscle growth, suggesting that training muscle groups more frequently than once per week is superior to training muscle groups once weekly.
Furthermore, the American College of Sports Medicine  and a research review of over 60 studies  on this topic both recommend training muscle groups more frequently than once per week.
Take Home Point:
Training muscle groups more than once per week is not detrimental and may be superior to the once-weekly training frequency commonly performed by most bodybuilders.
2. Doing 1 working set per exercise is superior to multiple working sets per exercise.
HIT training is a style of training that prescribes training one all-out working set to failure per exercise. This was popularized by Mike Mentzer and later Dorian Yates, both of whom built outstanding physiques proving that you can get big doing one working set per exercise.
So is their approach superior to doing multiple working sets per exercise?
Burd et al.  compared the effects of 1 vs 3 sets of leg extensions on skeletal muscle protein synthesis rates in the quads and found that 3 sets resulted in a greater increase in protein synthesis rate.
Acutely, multiple set training protocols appear to be superior to single-set protocols, but do multiple set training protocols results in more growth long-term?
Krieger et al.  performed a meta-analysis of studies (statistical analysis of multiple studies on the same topic) comparing single-set to multi-set training protocols and found greater strength and size gains when doing multiple working sets per exercise.
Take Home Point:
Performing multiple sets per exercise appear to be superior to performing a single working set for muscle growth.
3. You need to train in the _____ rep range for hypertrophy.
Every time I hear someone make this statement, it seems like they give a different rep range recommendation (4-6, 6-12, 8-12, 10-15…). So is there an ideal rep range for hypertrophy?
To address this question, Schoenfeld et al. performed a series of studies comparing the effects of various rep ranges on hypertrophy.
In the first study , participants performed either 7 sets of 3 reps or 3 sets of 10 reps on all exercises for 8 weeks. Volume (weight x sets x reps) was matched between groups and all participants trained 3 times weekly. No significant differences in muscle growth were observed between participants performing 3 reps per set and those performing 10 reps per set.
In a follow-up study , the authors compared the 8-12 rep range to the 25-35 rep range during a 12 week training protocol. No significant differences in muscle growth were observed between the 8-12 rep group and the 25-35 rep group.
Take Home Point:
There is no “best” rep range for muscle growth (hypertrophy). Incorporate a variety of rep ranges to maximize muscle growth and to keep your training fresh and interesting.
4. You need to train to failure on all sets for maximum muscle growth.
It is common to observe individuals in the gym training to failure, if not beyond failure (e.g. forced reps, drop sets, etc.) on a regular basis. The thought process behind training to and beyond failure is that you are training harder and really taxing the muscle so you should grow more.
So is training to failure required for muscle growth?
Training to failure increases muscle recruitment . In addition, taking low-load and high-load training protocols to failure produce similar increases in protein syntheses .
However, does this also mean you will grow more if you train to failure consistently?
Sampson and Groeller  compared the effects of a 12 week training protocol in which subjects trained to failure or sub-failure and observed no difference in muscle growth between groups, indicating that failure is not required for muscle growth.
Similarly, a recent literature review  concluded that training to failure is not required for muscle growth. Additionally, it may increase the risk of injury and lead to over-reaching/over-training.
So is there a place for training to failure?
Training to failure may be an effective intensity technique for muscle growth in the context of a periodized training program. When training to failure, doing so on single-joint movements (e.g. leg extensions) may significantly reduce injury risk when compared to multi-joint movements (e.g. squats) .
Take Home Point:
Training to failure is not required for muscle growth and doing so on a regular basis may increase the risk of injury. However, it may be an effective intensifying technique resulting in muscle growth in the context of a periodized training program.
5. If you train for over ____ minutes you will go catabolic.
I’ve often heard individuals in the gym mention that they have been working out for 45 or 60 minutes so they need to leave the gym because they will go catabolic if they continue training. Usually, their rationale is based around the belief that cortisol (a catabolic hormone) will increase after a certain amount of time in the gym and at times they may cut their workouts short due to self-imposed time restrictions.
So is there any evidence that you will get better gains if you cut your workout time off at a certain point to avoid “going catabolic”?
West et al.  had subjects perform a 5 day per week resistance training protocol for 12 weeks. Changes in hormones pre and post-workout were measured around a single workout and correlated with muscle growth over the 12 week study. The only acute hormone change significantly correlated with muscle growth was that an increase in cortisol during a workout was correlated with more muscle growth.
That is not a typo.
The greater the cortisol increase during a workout, the more muscle growth observed after 12 weeks. This likely occurred because when you train hard cortisol increases – similarly when you train hard muscle grows.
Getting back to the original question, these results clearly show that worrying about cortisol increasing and “going catabolic” after a specific amount of time in the gym is not necessary.
Take Home Point:
There is no reason to cut your workout off at a certain point for fear of cortisol increasing and “going catabolic.” In fact, an increase in cortisol during a workout (the product of training hard) has actually been correlated with more muscle growth.
6. Rest periods should be ____ between sets for hypertrophy.
Similar to “ideal” rep range for growth, a number of different “ideal” rest periods between sets for growth are also commonly thrown around in gyms. In general, the notion most share is that limiting rest periods to a specific time will result in more muscle growth.
So is this supported by science?
Shorter rest periods have been shown to result in a greater increase in growth hormone following a workout . However, changes in growth hormone during a workout were not correlated with muscle growth over a 12 week training protocol .
Moreover, a recent literature review on rest periods concluded that rest periods had little impact on muscle growth . If anything, restricting rest periods may reduce training volume and result in less muscle growth.
Take Home Point:
Timing of rest periods between sets is not necessary for muscle growth. Take enough time to rest between sets so that you can perform quality working sets.
7. Super-slow rep tempo is the best rep tempo for hypertrophy.
Looking around the gym, it is not uncommon to see certain individuals training with extremely slow reps because they believe it will increase time-under-tension resulting in increased muscle growth.
So is there any evidence supporting this claim?
DeLacerda et al.  recruited healthy young men and had them perform a smith bench press under 2 conditions: 1) 6 reps with 3 second concentric and eccentric and 2) 12 reps with 1.5 seconds concentric and eccentric. This resulted in both groups being under tension for 36 seconds. In addition, the same weight and rest period were used in each condition so the only difference between conditions was rep tempo. They found that muscle activation and metabolic stress were significantly lower with slower reps.
This does not support the use of slow reps for muscle growth.
Moreover, training with a slow tempo will likely reduce the amount of weight that one is able to move during their sets resulting in a lower training volume and potentially less muscle growth.
Similarly, a recent meta-analysis on repetition duration  observed no differences in muscle growth when reps took 0.5 – 8 seconds to complete. However, muscle growth was significantly lower when reps took more than 10 seconds to complete.
Take Home Point:
Super-slow training is not superior for hypertrophy and may result in less muscle growth. With that being said, weight should be lifted using a controlled tempo for optimal muscle growth.
About the Author:
Peter Fitschen is a PhD Candidate in Nutritional Science at the University of Illinois. He has a BS in Biochemistry, MS in Biology with a Physiology Concentration, and is a Certified Strength and Conditioning Specialist (CSCS) through the National Strength and Conditioning Association. He is also an NGA Natural Pro Bodybuilder who has competing in natural bodybuilding since 2004 and a contest prep coach through Fitbody and Physique LLC.
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