High and Low responders' energy intake, protein intake, sleep, etc., were identical. Hard gainers made equal strength gains to hyper responders based on their body weight. Hard gainers did not have differences in protein synthesis or ribosome content compared to hyper responders. Protein synthesis was not associated with gains in muscle mass. Hyper responders had a greater satellite cell response than low responders.
SUMMARY OF HARD GAINERS VS. HYPER MUSCLE RESPONDERS
- Hard gainers did not have differences in protein synthesis or ribosome content compared to hyper responders.
- High and Low responders’ energy intake, protein intake, sleep, etc., were identical.
- Hard gainers made equal strength gains to hyper responders based on their body weight.
- Protein synthesis was not associated with gains in muscle mass.
- Hyper responders had a greater satellite cell response than low responders.
HOW DO MUSCLES GROW?
Some people can’t grow muscle as fast as they want while weight training. Scientists may have an answer if you are one of the many people who are seeing no results working out and not gaining muscle mass. So how do you know if your muscles are growing while lifting weights?
An easy way to track muscle growth and fat loss is using tape circumference measurements to track increases in muscle size regularly. If your clothes fit a little tighter, that’s a good sign you are adding muscle and hopefully minimal fat.
Before going into the study, a few mechanisms have been suggested to influence muscle tissue growth. Researchers have suggested higher responders gain more muscle because of a greater increase in muscle cell ribosome content increases, satellite cell activation, and increased protein synthesis. (Mobley et al., 2018; Roberts et al., 2018)
HARD GAINERS: WHY ISN’T MY WORKOUT WORKING?
Hyper-responders or extreme muscle responders grow muscle easily in response to weight lifting. They are genetically blessed to gain muscle faster than most people.
Contrary to hyper-responders, there are those classified as low responders or a true hard gainer. Low responders can’t seem to gain muscle fast despite doing the same workout as a high responder. (Davidsen et al., 2011) The typical low responder has the body type of an ectomorph (i.e., skinny).
One study found high responders experienced a 30% increase in muscle growth, whereas low responders gained no muscle or a small ~4% increase in muscle size. The hyper-responders gained more muscle despite using the same routine. (Franchi et al., 2018)
A study of 585 subjects who followed the same training program looked at the differences in muscle growth responses: 232 subjects gained increases in muscle size between 15-25%, 10 subjects gained 40%, and 36 subjects gained less than 5%. (Chung et al., 2021)
Hyper-responders gain muscle fast, but they also lose it faster! After quitting exercise, high responders lost 10.5% of their muscle mass, whereas low responders only lost .6% of their muscle mass. (Räntilä et al., 2021)
A NEW STUDY LOOKED AT MUSCLE GROWTH BETWEEN HARD GAINERS AND MUSCLE RESPONDERS
Researchers took people from a study and analyzed those that were hyper muscle responders vs. slow responders. The resistance training protocol was a 10-week progressive overload program. This study looked at everything!!! They examined protein synthesis, gene responses (i.e., ribosome content), satellite cells, etc.
They wanted to know what exactly made the hyper-responders different from those who couldn’t gain muscle. The high and low responders were those in the top and bottom 25% for muscle gains. (Smith et al., 2023)
GYM MYTH #1: HARD GAINERS DON’T TRAIN HARD:
The researchers found that the hyper-responders had more muscle at baseline or right when they entered the study. The high responders trained with a heavier weight throughout the study, but this was because they weighed more. The hyper responders had greater pre and post-bench press, leg press, and deadlift strength metrics.
However, when the researchers equalized the weights used while training based on body weight, there were no differences between the high and low responders. The low responders made comparable strength gains based on their body weight. So low responders are not gaining muscle because they don’t train hard enough. They had equal strength increases based on their relative body weight.
GYM MYTH #2: HARD GAINERS HAVE REDUCED MUSCLE PROTEIN SYNTHESIS.
The study found muscle protein synthesis was the same between high and low responders. There was no difference from pre to post-training for 24-hour protein synthesis and changes in leg muscle size. Another interesting finding was that protein synthesis after exercise has not correlated with muscle growth.
A previous study found that increases in muscle protein synthesis were associated with muscle hypertrophy. Researchers suspect muscle damage stimulates muscle protein synthesis when starting a workout program, but now it is known that muscle becomes resistant to muscle damage. This study did not find any correlation between muscle protein synthesis and muscle gains.
GYM MYTH #3: HARD GAINERS USE GENETICS AS AN EXCUSE WHY THEY ARE NOT GAINING MUSCLE.
At entry into the study, there was no difference between low and high responders’ satellite cell numbers. The difference was that hyper-responders had a greater increase in satellite cell responses in response to training.
All the other variables that the researchers looked at were the same. Satellite cell activity was higher in response to those considered high responders than those that were low responders. Another interesting thing was that high and low responders’ energy intake, protein intake, sleep, etc., were identical.
To be clear, it is not that hard gainers’ muscles are not responding to exercise. They respond, just at a slower pace. You can’t change your genetics, so just focus on your training, nutrition, and recovery. The high responders had more muscle at baseline and gained more muscle from pre to post. Scientists are still trying to uncover why some people don’t gain muscle as quickly as others.
If your training is lagging, you may want a personal trainer to push you in the gym and ensure that the exercise stress and volume are high enough to drive muscle growth.
REFERENCES
Chung, H. C., Keiller, D. R., Roberts, J. D., & Gordon, D. A. (2021). Do exercise-associated genes explain phenotypic variance in the three components of fitness? a systematic review & meta-analysis. PLoS One, 16(10), e0249501. https://doi.org/10.1371/journal.pone.0249501
Davidsen, P. K., Gallagher, I. J., Hartman, J. W., Tarnopolsky, M. A., Dela, F., Helge, J. W., Timmons, J. A., & Phillips, S. M. (2011). High responders to resistance exercise training demonstrate differential regulation of skeletal muscle microRNA expression. J Appl Physiol (1985), 110(2), 309-317. https://doi.org/10.1152/japplphysiol.00901.2010
Franchi, M. V., Longo, S., Mallinson, J., Quinlan, J. I., Taylor, T., Greenhaff, P. L., & Narici, M. V. (2018). Muscle thickness correlates to muscle cross-sectional area in the assessment of strength training-induced hypertrophy. Scand J Med Sci Sports, 28(3), 846-853. https://doi.org/10.1111/sms.12961
Mobley, C. B., Haun, C. T., Roberson, P. A., Mumford, P. W., Kephart, W. C., Romero, M. A., Osburn, S. C., Vann, C. G., Young, K. C., Beck, D. T., Martin, J. S., Lockwood, C. M., & Roberts, M. D. (2018). Biomarkers associated with low, moderate, and high vastus lateralis muscle hypertrophy following 12 weeks of resistance training. PLoS One, 13(4), e0195203. https://doi.org/10.1371/journal.pone.0195203
REFERENCES
Räntilä, A., Ahtiainen, J., Avela, J., Restuccia, J., Kidgell, D., & Häkkinen, K. (2021). High Responders to Hypertrophic Strength Training Also Tend to Lose More Muscle Mass and Strength During Detraining Than Low Responders. Journal of Strength and Conditioning Research, 35, 1500-1511. https://doi.org/10.1519/JSC.0000000000004044
Roberts, M. D., Haun, C. T., Mobley, C. B., Mumford, P. W., Romero, M. A., Roberson, P. A., Vann, C. G., & McCarthy, J. J. (2018). Physiological Differences Between Low Versus High Skeletal Muscle Hypertrophic Responders to Resistance Exercise Training: Current Perspectives and Future Research Directions. Frontiers in Physiology, 9, 834-834. https://doi.org/10.3389/fphys.2018.00834
Smith, M. A., Sexton, C. L., Smith, K. A., Osburn, S. C., Godwin, J. S., Beausejour, J. P., Ruple, B. A., Goodlett, M. D., Edison, J. L., Fruge, A. D., Robinson, A. T., Gladden, L. B., Young, K. C., & Roberts, M. D. (2023). Molecular predictors of resistance training outcomes in young untrained female adults. J Appl Physiol (1985). https://doi.org/10.1152/japplphysiol.00605.2022
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