Stark differences in muscle and strength gain have been reported between individuals performing the same standardized resistance training program.[1][2][3][4] For example, one study reported that changes in muscle size and strength varied from –11% to 30% and –8% to 60%,[1] respectively, whereas another reported a variation of –2% to 59% and 0% to 250%,[3] respectively.
While genetic and physiological differences between individuals,[5] as well as lifestyle factors (i.e., nutrition, sleep, stress), help to explain a large proportion of the response to a given resistance exercise program, training history is another influential factor, and one that is rarely considered in resistance exercise studies. For example, it’s been shown that a resistance exercise program that increased volume by 20% over what participants previously performed was better for muscle gain than a nonindividualized program.[6]
On the other hand, a program containing a decrease in volume has also been shown to promote substantial muscle gain in some participants,[7] further demonstrating that the response to resistance exercise is highly individual.
Besides interindividual differences in the response to resistance exercise, evidence suggests that particular styles of resistance exercise can produce substantially different effects within an individual. In one study that had participants perform high-frequency (5x per week) resistance exercise with one leg and low-frequency (2x or 3x per week) resistance exercise with the other leg, it was found that some individuals gained more muscle and strength on the leg assigned to the high-frequency condition and some individuals gained more muscle and strength on the leg assigned to the low-frequency condition, while others experienced no difference between conditions.[8]
To throw another monkey wrench in the works, only about 32% of individuals displayed an aligned response, i.e., one in which the same resistance training frequency was better for both muscle gain and strength. This suggests that, within an individual, not only are certain resistance exercise programs more effective than others, but also that the best program to increase strength is likely different from the best program for muscle gain, so it may be prudent for the individual to prioritize one goal over the other.
In a nutshell, the best resistance exercise program for one person is unlikely to be the best for another, so each person will have to experiment to find what works best for them. When a plateau in progress occurs, some individuals will benefit from increasing their training frequency and/or volume, while others will benefit from decreasing one or both of these variables.
References
- ^Ahtiainen JP, Walker S, Peltonen H, Holviala J, Sillanpää E, Karavirta L, Sallinen J, Mikkola J, Valkeinen H, Mero A, Hulmi JJ, Häkkinen KHeterogeneity in resistance training-induced muscle strength and mass responses in men and women of different agesAge (Dordr).(2016 Feb)
- ^Erskine RM, Jones DA, Williams AG, Stewart CE, Degens HInter-individual variability in the adaptation of human muscle specific tension to progressive resistance training.Eur J Appl Physiol.(2010-Dec)
- ^Monica J Hubal, Heather Gordish-Dressman, Paul D Thompson, Thomas B Price, Eric P Hoffman, Theodore J Angelopoulos, Paul M Gordon, Niall M Moyna, Linda S Pescatello, Paul S Visich, Robert F Zoeller, Richard L Seip, Priscilla M ClarksonVariability in muscle size and strength gain after unilateral resistance trainingMed Sci Sports Exerc.(2005 Jun)
- ^Bamman MM, Petrella JK, Kim JS, Mayhew DL, Cross JMCluster analysis tests the importance of myogenic gene expression during myofiber hypertrophy in humans.J Appl Physiol (1985).(2007-Jun)
- ^Roberts MD, Haun CT, Mobley CB, Mumford PW, Romero MA, Roberson PA, Vann CG, McCarthy JJPhysiological Differences Between Low Versus High Skeletal Muscle Hypertrophic Responders to Resistance Exercise Training: Current Perspectives and Future Research Directions.Front Physiol.(2018)
- ^Maíra C Scarpelli, Sanmy R Nóbrega, Natalia Santanielo, Ieda F Alvarez, Gabriele B Otoboni, Carlos Ugrinowitsch, Cleiton A LibardiMuscle Hypertrophy Response Is Affected by Previous Resistance Training Volume in Trained IndividualsJ Strength Cond Res.(2022 Apr 1)
- ^Aube D, Wadhi T, Rauch J, Anand A, Barakat C, Pearson J, Bradshaw J, Zazzo S, Ugrinowitsch C, De Souza EOProgressive Resistance Training Volume: Effects on Muscle Thickness, Mass, and Strength Adaptations in Resistance-Trained Individuals.J Strength Cond Res.(2022-Mar-01)
- ^Damas F, Barcelos C, Nóbrega SR, Ugrinowitsch C, Lixandrão ME, Santos LMED, Conceição MS, Vechin FC, Libardi CAIndividual Muscle Hypertrophy and Strength Responses to High vs. Low Resistance Training Frequencies.J Strength Cond Res.(2019-Apr)