Always remember that one study never proves a training principle works! It certainly adds new knowledge to the scientific literature, but never base your training beliefs on a single study. The same holds true for any new supplement studies that are released.


It is not uncommon to see conflicting research studies regarding a specific training principle or protein supplementation studies. For example, a recent study on dropsets found greater increases in muscle growth in a specific thigh region than traditional training. It looks like adding drop sets can promote more muscle growth, but if you examine the study, there were some key findings why dropsets may have resulted in greater muscle growth.

The resistance training study lasted eight weeks, with the drop set protocol comprising a 5RM load to failure, reducing the load by 20% to failure again, then reducing the load by 10-15% to failure. The traditional strength protocol comprised 15RM to failure. At the end of eight weeks, although both had similar increases in leg muscle mass, drop-sets resulted in a superior increase in the rectus femoris (front middle region of the thigh).[1]

Upon analysis of the training volume, the drop set group resulted in a higher training volume. The greater exercise volume with dropsets was suggested to enhance hypertrophy of the targeted rectus femoris compared to the traditional strength training group. More than likely, if the traditional group did more sets to equal the training volume of the dropset group, muscle growth would have been similar.

Is it the Specific Exercise or More Volume Driving Muscle Growth?

Researchers do their best to standardize protocols, but these issues sometimes happen. Sometimes research studies comparing the effects of two different resistance exercise protocols for muscle growth are not equal, and the sets or total workload for two workouts are different so that one group is doing more exercise.

The subjects did not gain muscle because they used some magic training principle. They grew more muscle because they did more exercise, resulting in greater muscle tension and muscle growth. In the study mentioned above, the researchers suggested that the greater increase in rectus femoris growth was because of greater workout volume.


When studies are designed to make sure that both groups are doing the same amount of total workload (sets x reps), muscle growth results are often similar. A similar occurrence can occur in protein supplementation studies, in which one group consumes a protein supplement after exercise gains more muscle. Was it because the group consuming the protein supplement after exercise caused more muscle growth? It could be that the protein supplement group consumed more total protein per day than the control or experimental group, which resulted in greater muscle growth.

Total protein intake is a better predictor of muscle hypertrophy than the timing of protein.[2] Total protein intake comprising a complete spectrum of essential amino acids is more important than the protein source.[3] A 2019 meta-analysis found that protein supplementation above 1.6 g/kg/bw (.7 grams per pound of body weight) provided no further increases in lean muscle mass.[4] However, later studies have suggested that more protein is needed on training days (i.e., 2.0 g/kg/bw or 1 gram per pound of body weight) to maximize the anabolic response to resistance exercise.[5]

The International Society of Sports Nutrition recommends for building muscle mass, an overall protein intake of 1.4-2.0 grams per kg of body weight per day (i.e., .6-1 gram per pound of body weight) and for fat loss, higher protein intake at 3.0 g/kg/day (i.e., 1.4 grams per pound of body weight).[6] Thus, it is recommended that at least 1 gram of protein per pound of bodyweight be consumed on training days.

Always remember that one study never proves a training principle works! It certainly adds new knowledge to the scientific literature, but never base your training beliefs on a single study. The same holds true for any new supplement studies that are released.


When analyzing a research study, many factors can affect the study’s outcome. Some factors are:

  • ·      Training status of a subject (i.e., trained vs. untrained)
  • ·      Age (i.e., young vs. elderly adults)
  • ·      Genetics (i.e., a hyper-responder can affect the mean outcome of the study)
  • ·      Exercise selection (multi-joint vs. single-joint exercises)
  • ·      Were the subjects consuming the same macronutrients (Protein, fat, and carbohydrates)?
  • ·      Were the sets taken to complete muscular failure or not?
  • ·      How did they assess body composition? (i.e., DEXA, BIA, MRI, etc.)
  • ·      The sample size of the study (i.e., how many subjects)
  • ·      Were the total training loads equated in the study (i.e., was one group doing more than the other?)?
  • ·      Training adherence (i.e., were the training groups supervised in a laboratory, or were they unsupervised and told to perform the program on their own)
  • ·      Type of statistics used to analyze the results
  • ·      Duration of the study
  • ·      Lifestyle factors (i.e., sleep, life stress, etc.)
  • ·      Author bias (Does the lead author have a vested interest in the study’s outcome?)

Any of these variables can affect the outcome of the study. Many factors can affect the outcome of a study, and human studies are difficult to control. Human test subjects are notorious for not correctly reporting things regarding self-reporting data, especially regarding diet. For example, a college student is in a resistance training study determining the effect of a particular training principle, but he is sleeping 4-6 hours a night, eating a subpar diet, and drinking alcohol and not reporting it. What do you think the outcome of the results will be? The outcomes of using college students are hard to extrapolate to serious athletes and bodybuilders eating 4-6 meals a day, sleeping 8 hours a night, and adhering to a well-designed periodized resistance training protocol.


A valuable takeaway from this article is that one study does not mean it’s the definitive answer. It’s not uncommon for an investigation to find positive results, and another study will test the same variables and find negative or contradictory results. There are many instances where results show beneficial findings in one study and contradictory studies regarding the same exercise principle. Unfortunately, this is the research process for muscle growth; there is no simple answer. The key to reading research is to be objective.


[1] Dorian Varović et al., “Drop-Set Training Elicits Differential Increases in Non-Uniform Hypertrophy of the Quadriceps in Leg Extension Exercise,” Sports (Basel, Switzerland) 9, no. 9 (August 29, 2021): 119.

[2] Brad Jon Schoenfeld, Alan Albert Aragon, and James W. Krieger, “The Effect of Protein Timing on Muscle Strength and Hypertrophy: A Meta-Analysis,” Journal of the International Society of Sports Nutrition 10, no. 1 (December 3, 2013): 53.

[3] Victoria Hevia-Larraín et al., “High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores,” Sports Medicine (Auckland, N.Z.) 51, no. 6 (June 2021): 1317–30.

[4] Robert W. Morton et al., “A Systematic Review, Meta-Analysis and Meta-Regression of the Effect of Protein Supplementation on Resistance Training-Induced Gains in Muscle Mass and Strength in Healthy Adults,” British Journal of Sports Medicine 52, no. 6 (March 1, 2018): 376–84.

[5] Michael Mazzulla et al., “Protein Intake to Maximize Whole-Body Anabolism during Postexercise Recovery in Resistance-Trained Men with High Habitual Intakes Is Severalfold Greater than the Current Recommended Dietary Allowance,” The Journal of Nutrition 150, no. 3 (March 1, 2020): 505–11.

[6] Ralf Jäger et al., “International Society of Sports Nutrition Position Stand: Protein and Exercise,” Journal of the International Society of Sports Nutrition 14, no. 1 (June 20, 2017): 20.

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