Secondary Logo

Journal Logo


Individual Muscle Hypertrophy and Strength Responses to High vs. Low Resistance Training Frequencies

Damas, Felipe1; Barcelos, Cintia1; Nóbrega, Sanmy R.1; Ugrinowitsch, Carlos2; Lixandrão, Manoel E.2; Santos, Lucas M. E. d.1; Conceição, Miguel S.2; Vechin, Felipe C.2; Libardi, Cleiton A.1

Author Information
Journal of Strength and Conditioning Research: April 2019 - Volume 33 - Issue 4 - p 897-901
doi: 10.1519/JSC.0000000000002864
  • Free



Resistance training (RT)-induced increases in muscle mass (i.e., hypertrophy) and strength have significant impact in overall health, diseases prevention (29), and athletic performance (2). The effect of RT weekly frequency on muscle hypertrophy and strength development has been given special attention lately (6,12,14,16,25,30). The rationale for examining the impact of different frequencies on RT outcomes relies on recent studies showing the time course of increases in muscle protein synthesis after RT session (lasting ∼24–48 hours after an RT session) (10,11,28). In addition, higher RT frequencies could result in greater training volumes, which in turn would positively affect muscle hypertrophy and strength gains (16,26).

Notwithstanding, our group recently showed that performing RT 2, 3, or 5 times per week resulted in similar gains in muscle hypertrophy and strength after 8 weeks in untrained individuals, even with a higher 8-week accumulated total training volume (TTV) for the higher frequency (sets × reps × load) (3). Other reports also showed similar RT outcomes after distinct RT frequencies both in untrained and trained individuals, irrespectively of matching TTV (4,6,8,14). However, these findings are not universal, especially when higher training frequencies result in greater TTV (16,25,30). These discrepancies could be due, at least in part, to interindividual differences in responsiveness to distinct RT frequencies. A large variability has been reported for muscle strength and hypertrophy outcomes even when subjects perform standardized RT programs (1,9,20). However, no study has evaluated the effects of manipulation of RT frequency within the same individual.

The present short communication compared individual muscle hypertrophy and strength gains with high (HF, 5× per week) vs. low (LF, 2 or 3× per week) RT frequencies in the same subjects (unilateral design) over 8 weeks of RT using data from our previous study (3). We hypothesized that the intersubject variability would be high, but a per-individual analysis would show that most of the subjects would respond better to the high RT frequency, as it results in greater TTV over the training period.


Experimental Approach to the Problem

This is a follow-up short communication to analyze individual responses to HF (RT performed 5× per week) and LF (RT performed 2 or 3× per week) from our previous publication (3). In short, a within-subject approach was used in which each subject performed RT after an HF with one leg and an LF with the other leg. Subject's legs were randomly allocated in 1 of the 2 experimental protocols in a counterbalanced way. Specifically, one leg of each subject was allocated in the HF (10 dominant and 10 nondominant legs), and the contralateral legs were then randomized in LF (10 dominant [5 in each low frequency, i.e., 2 or 3× per week] and 10 nondominant legs [5 in each low frequency]). The vastus lateralis muscle cross-sectional area (CSA) was assessed using ultrasound and the maximum dynamic strength by a unilateral 1 repetition maximum (1RM) test, both before and after 8 weeks of RT.


The subjects included in this short communication were the same from our previous article (3) (young untrained men, mean ± SD: n = 20,23 ± 4 years [18-30 years old]; 174 ± 6 cm; 72 ± 8 kg). However, one participant was excluded from the analyses because he did not complete the experiment protocol because of personal reasons. The study was approved by the Federal University of São Carlos Ethic Committee, and each participant signed informed consent before participation. All procedures performed in the study were in accordance with the ethical standards of the institutional research committee and with the Helsinki declaration.


Muscle Cross-Sectional Area and Maximal Dynamic Strength (1 Repetition Maximum)

Vastus lateralis muscle CSA was assessed using sequential images acquired by a B-mode ultrasound with a 7.5-MHz linear probe (MySono U6; Samsung, São Paulo, SP, Brazil) and an image-fitting technique that our group has validated previously (23). Maximal dynamic strength was assessed using the 1RM test on the leg extension machine following previously described criteria (7).

Resistance Training

All RT protocols were performed in a leg extension machine (Effort NKR; Nakagym, Diadema, SP, Brazil). Training protocol consisted of 3 sets of 9RM–12RM to muscular failure. A 2-minute rest interval was allowed between sets because it was showed to be sufficient to promote increases in muscle hypertrophy (15) and strength in untrained individuals (17). Total training volume was calculated as sets × repetitions × load (kg).

Statistical Analyses

For the analyses, each leg (experimental unit) was grouped into either an HF (legs previously allocated to the 5× per week RT) or LF (legs previously allocated to 2 or 3× per week RT) (3). For group analyses, the accumulated TTV and changes in muscle CSA and 1RM values were compared between HF and LF using paired t-tests. For individual analyses, if an individual that showed a difference in the response (for CSA or 1RM increases) from HF or LF (or vice versa) within 2 typical errors (CSA typical error = 1.38%, 1RM typical error = 3.64%; values extracted from Ref. 3), no difference in the response between RT frequencies was considered. Relationships between variables were assessed using the Pearson's correlation. In addition, we defined an individual as “responder” to RT as one with a response greater than 2 typical errors from zero for increases in muscle CSA and 1RM; if not, he was considered as “nonresponder” (19). A chi-square test was performed to compare the proportion of individuals (responders) that had higher CSA and 1RM gains (greater than 2 typical errors) after training between HF and LF. In case of significant p values, standard residuals were analyzed to determine which proportions were significantly different in the contingency table. Differences in the estimated proportions were considered significantly different if standard residuals were outside the interval [−2, 2]. Significance was established as p ≤ 0.05.


Total Training Volume, Changes in Muscle Cross-Sectional Area, and 1 Repetition Maximum

Group analyses showed that HF resulted in higher 8-week accumulated TTV (p < 0.0001) compared with LF (Figure 1A). However, similar changes were found in CSA and 1RM changes comparing legs that trained at HF vs. LF (p > 0.05; Figure 1B, C, respectively).

Figure 1.:
A) Individual 8-week accumulated total training volume (TTV, sets × reps × load [kg]), % changes in (B) muscle cross-sectional area (CSA) and (C) 1 repetition maximum (1RM) at week 8 relative to baseline for high and low resistance training frequencies. Pointed lines in panels (B) and (C) indicate “zero” value, and dashed lines indicate “cut-points” for responsiveness: 2.76% for CSA and 7.28% for 1RM (see Methods for details). *Significant difference from lower resistance training frequencies (p < 0.0001).

The individual analyses showed that all subjects depicted higher TTV for HF vs. LF (Figure 1A). For muscle hypertrophy, 6 individuals (31.6% of the sample) responded more HF, 7 individuals (36.8% of the sample) responded more for LF, and the other 6 individuals (31.6% of the sample) showed no difference in the hypertrophic responses between training frequencies (the difference was within 2 typical errors) (Figure 1B). Regarding muscle strength, 5 individuals (26.3% of the sample) increased more the 1RM value for HF, 3 (15.8% of the sample) for LF, and the other 11 (57.9% of the sample) showed similar responses between RT frequencies (Figure 1C). No significant correlations were found between TTV and CSA (p = 0.59; r = 0.09) or 1RM (p = 0.17; r = 0.22). Importantly, after manipulation of the RT frequency (i.e., HF-to-LF or LF-to-HF), only one individual (marked as “white upside-down triangle”) was still considered “nonresponder” for muscle hypertrophy. For muscle strength, after RT frequency manipulation, no individual was still considered a “nonresponder.” The chi-square test showed that there were no significant differences between the proportion of individuals who become responders after HF or LF for both CSA and 1RM gains (p > 0.05).


This is the first study to analyze individual responses to different RT frequencies. As hypothesized, our results showed a large intersubject variability to HF and LF, but contrarily to what we proposed, most subjects did not show greater responses (muscle hypertrophy and strength) to the RT frequency that resulted in a larger TTV.

Our unilateral RT protocol elaborated to minimize between-subject variability, allowed to compare the leg that performed an HF (RT 5× per week) with the contralateral leg, which performed an LF (RT 2 or 3× per week). In accordance with our previous article (3), group analyses showed higher TTV for HF (Figure 1A), but similar hypertrophic (Figure 1B) and muscle strength (Figure 1C) outcomes between HF and LF. An interesting hypothesis is that there might exist a training volume threshold beyond which there is no further increase in muscle mass and strength, as discussed in more detail recently (13). In fact, the individual analyses demonstrate that a significant proportion of subjects showed no difference in their responses manipulating RT frequency (31.6% of the subjects for muscle hypertrophy and 57.9% for muscle strength). Even so, some individuals greatly increased the muscle CSA and 1RM values in response to an HF, but, surprisingly, other responded better to LF, despite all subjects had greater TTV after HF (Figure 1). Corroborating with the results above, when RT frequency is manipulated, we report no correlation between TTV and CSA or 1RM increases. These results do not fully support the hypothesis that the magnitude and duration of elevated muscle protein synthesis in response to RT bout and the greater accumulated TTV would favor training muscles with a greater frequency. Specifically, for muscle hypertrophy, ∼31.6% of the sample responded more for HF, and for muscle strength, ∼26.3% of the sample benefited more from HF. We suggest that some individuals might be “less sensitive” to RT stimulus, requiring a higher RT frequency (or TTV) to maximize their RT-induced adaptations. Some studies with endurance training indicate that individuals considered as low responders (e.g., have small or no increase in maximal oxygen consumption [V̇o2max]) may better respond to higher training volumes (18,27). The same concept does not seem to hold for RT, as some subjects (36.8% for muscle hypertrophy and 15.8% for muscle strength) in this study were more responsive to LF (and consequent smaller TTV). These results could indicate that these subjects might require a longer time to recover between sessions or even that they are more sensitive to inhibitory mechanisms of hypertrophy and strength gains performing larger weekly TTV. These suggestions require further investigation. In addition, we expand the TTV threshold hypothesis, indicating that should it really exists, it is to some extent individual-dependent, and further increases in TTV can even impair muscle mass and strength development with RT in some individuals.

Interestingly, 3 subjects (of 19) were considered as “nonresponders” for muscle hypertrophy considering HF and LF separately, but only 1 subject was considered a “nonresponder” after the manipulation of RT frequency (HF-to-LF or LF-to-HF) (Figure 1B). For muscle strength, also 3 subjects were considered as “nonresponders” after HF or LF separately, but all were considered as “responders” when RT was manipulated (Figure 1C). However, it should be highlighted that despite the manipulation of RT frequency can alter intraindividual responsiveness to RT, the interindividual responses are dependent on each individual's genetic predisposition to respond to RT. Other factors as nutritional patterns, daily activities, etc., could also have an impact on intersubject responsivity to RT. Our data show that some individuals presented greater responses in comparison with other subjects irrespectively of RT frequency, i.e., even the smallest increase that some subjects achieved was still higher than the largest increase of other. Overall, the individual manipulation of RT frequency is relevant because it can improve the intrasubject responsiveness to training, but the effect is limited to each individual capacity to respond to RT.

It should also be noted that the intrasubject muscle hypertrophy and strength responses were not aligned between RT frequencies, i.e., a given individual can show a better hypertrophic response to HF, but increase more muscle strength for LF (or vice versa, Figure 1). Our results showed that only 6 of 19 subjects (∼32% of our sample size) showed an aligned response for muscle strength and hypertrophy after the same RT frequency (whether HF or LF). This suggests that the biological mechanisms regulating individual responsivity to different RT frequencies regarding muscle strength and mass gains are distinct. Future studies should investigate the individual's biological mechanisms behind the effect of manipulations of RT variables, as it is plausible to consider that not only frequency and TTV, but also load, muscle actions, repetition duration, and rest, for example, could modulate individual responsiveness to muscle hypertrophy and strength adaptations.

Importantly, the results of this study can be specific to previously untrained young men performing RT for 8 weeks. Both sex and age could alter the effect of training frequency because of differences in fatigability, time to recover from training, and required RT weekly dose (5,21,22). It is also possible that longer RT periods and the use of previously trained subjects could modulate the individual responses to distinct RT frequencies. Trained individuals depict a shorter increase in muscle protein synthesis (10), and longer training periods (e.g., 6 months) was showed to result in a dosed response of weekly training volume in muscle hypertrophy (24). Thus, it is possible that trained individuals, in general, would require more frequent training stimulus (and maybe higher weekly volumes), decreasing interindividual variability as subjects become more trained. These speculations require further scrutinization. In addition, the use of unilateral exercise was specifically chosen to evaluate the intraindividual variability to distinct RT frequencies performed during the same time frame (i.e., 8 weeks), but other research are commended to investigate this research question using, e.g., bilateral exercises and a wash-out period. Also, upper-body and additional exercises could be tested, as maybe a different pattern of response could emerge.

In conclusion, this short communication highlights that interindividual variability to different RT frequency (and consequent TTV) is high, and, surprisingly, some individuals showed greater muscle hypertrophy and strength gains after lower RT frequencies, which resulted in lower TTV. Importantly, intrasubject responsiveness to training can be modulated through the manipulation of RT frequency; however, the effect is limited to each individual's capacity to respond to RT. Finally, the individual response to different frequencies and resulted TTV does not necessarily agree between distinct RT-related outcomes (i.e., muscle hypertrophy and strength gains).

Practical Applications

Considering individual responses, some subjects respond better after a higher RT weekly frequency and consequent accumulated RT volume, others might benefit more from lower RT weekly frequencies and accumulated RT volume, and even others show similar responses irrespective of RT frequency manipulation. Importantly, this occurred despite the fact that previously untrained subjects were studied in the present investigation, challenging the notion (based on average group values) that any training scheme maximally stimulates RT-related outcomes in this population. In addition, manipulation of RT frequency has an impact on intrasubject responsiveness to training, but this effect is limited to the each individual's capacity to respond to RT. Finally, care should be taken on which RT outcome (e.g., muscle hypertrophy or strength) should be the training focus, as individual responsiveness to different RT outcomes may differ among RT frequencies and volumes chosen.


This work was supported by the São Paulo Research Foundation (FAPESP) (#2016/24259-1 to F.D., #2016/22635-6 to M.E.L., and #2013/21218-4 and #2017/04299-1 to C.A.L.) and the National Council for Scientific and Technological Development (CNPq) (#406609/2015-2 to C.U.) grants.


1. Ahtiainen JP, Walker S, Peltonen H, Holviala J, Sillanpaa E, Karavirta L, et al. Heterogeneity in resistance training-induced muscle strength and mass responses in men and women of different ages. Age (Dordr) 38: 10, 2016.
2. American College of Sports Medicine. American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. Med Sci Sports Exerc 41: 687–708, 2009.
3. Barcelos C, Damas F, Nobrega SR, Ugrinowitsch C, Lixandrao ME, Marcelino Eder Dos Santos L, et al. High-frequency resistance training does not promote greater muscular adaptations compared to low frequencies in young untrained men. Eur J Sport Sci 18: 1077–1082, 2018.
4. Benton MJ, Kasper MJ, Raab SA, Waggener GT, Swan PD. Short-term effects of resistance training frequency on body composition and strength in middle-aged women. J Strength Cond Res 25: 3142–3149, 2011.
5. Bickel CS, Cross JM, Bamman MM. Exercise dosing to retain resistance training adaptations in young and older adults. Med Sci Sports Exerc 43: 1177–1187, 2010.
6. Brigatto FA, Braz TV, Zanini T, Germano MD, Aoki MS, Schoenfeld BJ, et al. Effect of resistance training frequency on neuromuscular performance and muscle morphology after eight weeks in trained men. J Strength Cond Res, 2018. Epub ahead of print.
7. Brown LE, Weir JP. ASEP procedures recommendation I: Accurate assessment of muscular strength and power. J Exerc Physiol Online 4: 1–21, 2001.
8. Candow DG, Burke DG. Effect of short-term equal-volume resistance training with different workout frequency on muscle mass and strength in untrained men and women. J Strength Cond Res 21: 204–207, 2007.
9. Churchward-Venne TA, Tieland M, Verdijk LB, Leenders M, Dirks ML, de Groot LC, et al. There are no nonresponders to resistance-type exercise training in older men and women. J Am Med Dir Assoc 16: 400–411, 2015.
10. Damas F, Phillips S, Vechin FC, Ugrinowitsch C. A review of resistance training-induced changes in skeletal muscle protein synthesis and their contribution to hypertrophy. Sports Med 45: 801–807, 2015.
11. Damas F, Phillips SM, Libardi CA, Vechin FC, Lixandrao ME, Jannig PR, et al. Resistance training-induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage. J Physiol 594: 5209–5222, 2016.
12. Dankel SJ, Mattocks KT, Jessee MB, Buckner SL, Mouser JG, Counts BR, et al. Frequency: The overlooked resistance training variable for inducing muscle hypertrophy? Sports Med 47: 799–805, 2017.
13. Figueiredo VC, de Salles BF, Trajano GS. Volume for muscle hypertrophy and health outcomes: The most effective variable in resistance training. Sports Med 48: 499–505, 2018.
14. Gomes GK, Franco CM, Nunes PRP, Orsatti FL. High-frequency resistance training is not more effective than low-frequency resistance training in increasing muscle mass and strength in well-trained men. J Strength Cond Res, 2018. Epub ahead of print.
15. Grgic J, Lazinica B, Mikulic P, Krieger JW, Schoenfeld BJ. The effects of short versus long inter-set rest intervals in resistance training on measures of muscle hypertrophy: A systematic review. Eur J Sport Sci 17: 983–993, 2017.
16. Grgic J, Schoenfeld BJ, Davies TB, Lazinica B, Krieger JW, Pedisic Z. Effect of resistance training frequency on gains in muscular strength: A systematic review and meta-analysis. Sports Med 48: 1207–1220, 2018.
17. Grgic J, Schoenfeld BJ, Skrepnik M, Davies TB, Mikulic P. Effects of rest interval duration in resistance training on measures of muscular strength: A systematic review. Sports Med 48: 137–151, 2017.
18. Gurd BJ, Giles MD, Bonafiglia JT, Raleigh JP, Boyd JC, Ma JK, et al. Incidence of nonresponse and individual patterns of response following sprint interval training. Appl Physiol Nutr Metab 41: 229–234, 2016.
19. Hopkins WG. Measures of reliability in sports medicine and science. Sports Med 30: 1–15, 2000.
20. Hubal MJ, Gordish-Dressman H, Thompson PD, Price TB, Hoffman EP, Angelopoulos TJ, et al. Variability in muscle size and strength gain after unilateral resistance training. Med Sci Sports Exerc 37: 964–972, 2005.
21. Hunter SK. Sex differences in human fatigability: Mechanisms and insight to physiological responses. Acta Physiol (Oxf) 210: 768–789, 2014.
22. Judge LW, Burke JR. The effect of recovery time on strength performance following a high-intensity bench press workout in males and females. Int J Sports Physiol Perform 5: 184–196, 2010.
23. Lixandrao ME, Ugrinowitsch C, Bottaro M, Chacon-Mikahil MP, Cavaglieri CR, Min LL, et al. Vastus lateralis muscle cross-sectional area ultrasonography validity for image fitting in humans. J Strength Cond Res 28: 3293–3297, 2014.
24. Radaelli R, Fleck SJ, Leite T, Leite RD, Pinto RS, Fernandes L, et al. Dose-response of 1, 3, and 5 sets of resistance exercise on strength, local muscular endurance, and hypertrophy. J Strength Cond Res 29: 1349–1358, 2015.
25. Schoenfeld BJ, Ogborn D, Krieger JW. Effects of resistance training frequency on measures of muscle hypertrophy: A systematic review and meta-analysis. Sports Med 46: 1689–1697, 2016.
26. Schoenfeld BJ, Ogborn D, Krieger JW. Dose-response relationship between weekly resistance training volume and increases in muscle mass: A systematic review and meta-analysis. J Sports Sci 35: 1073–1082, 2017.
27. Sisson SB, Katzmarzyk PT, Earnest CP, Bouchard C, Blair SN, Church TS. Volume of exercise and fitness nonresponse in sedentary, postmenopausal women. Med Sci Sports Exerc 41: 539–545, 2009.
28. Tang JE, Perco JG, Moore DR, Wilkinson SB, Phillips SM. Resistance training alters the response of fed state mixed muscle protein synthesis in young men. Am J Physiol Regul Integr Comp Physiol 294: R172–R178, 2008.
29. Wolfe RR. The underappreciated role of muscle in health and disease. Am J Clin Nutr 84: 475–482, 2006.
30. Zaroni RS, Brigatto FA, Schoenfeld B, Braz TV, Benvenutti JC, Germano MD, et al. High resistance-training frequency enhances muscle thickness in resistance-trained men. J Strength Cond Res, 2018. Epub ahead of print.

individual responsiveness; total training volume; 1 repetition maximum; muscle cross-sectional area

© 2018 National Strength and Conditioning Association