The Journal of Strength and Conditioning Research: Vol. 18, No. 3, pp. 660???667.
Single- vs. Multiple-Set Resistance Training: Recent Developments in the Controversy
Daniel A. Galvão and Dennis R. Taaffe
School of Human Movement Studies, University of Queensland, Brisbane, Australia
ABSTRACT
Galvão, D.A., and D.R. Taaffe. Single- vs. multiple-set resistance training: recent developments in the controversy. J. Strength Cond. Res. 18(3):660???667. 2004.???The number of sets in a resistance training program remains a major point of discussion and controversy. Studies prior to 1998 demonstrated inconsistent findings between single-set and multiple-set programs; however, recent evidence suggests that multiple sets promote additional benefits following short- and long-term training. The rationale supporting multiple sets is that the number of sets is part of the exercise volume equation, and the volume of exercise is crucial in producing the stimulus necessary to elicit specific physiological adaptations. The purpose of this paper is to present an overview of recent resistance training studies comparing single and multiple sets. However, it should be noted that studies to date have been conducted in young and middle-aged adults, and it remains to be determined if the additional benefits accrued with multiple-set training also occurs for older adults, especially the frail elderly.
Key Words: training volume, muscle strength, training duration
Introduction Return to TOC
It is well established that resistance training is the most effective method available for improving muscle strength and lean body mass (17, 24, 29, 34, 47). Resistance training has been prescribed by many major health organizations for improving fitness and health (1, 2, 18, 29, 39). The effectiveness of a resistance-training program depends on several factors including intensity of training (load); volume of training (number of sets and repetitions); order of exercise; rest period length between sets and exercises; frequency of training; and repetition velocity (3, 13, 17, 29, 30, 54, 58). However, controversy exists as to which training protocols most effectively increase maximum strength (8???10, 13, 27, 54). Comparison between single-set and multiple-set training regimes in previously untrained (6, 7, 11, 12, 26, 28, 32, 33, 35, 37, 38, 40, 41, 49, 52, 55, 59, 60) and trained (5, 25???28, 42, 50, 51, 53) subjects have shown conflicting results. It is worthy to note that all the published studies that found no difference between single and multiple sets were short-term in duration, not exceeding 14 weeks. The short-term nature would likely limit the ability to detect differences, especially in previously untrained subjects who respond favorably to all resistance training protocols.
Many experts maintain that adults would obtain greater benefits from multiple-set programs (5, 8, 17, 27??? 29, 32, 33, 37, 42, 49, 50, 54). The rationale for this view is that the number of sets is part of the exercise volume equation, and the volume of exercise helps to create the exercise stimulus necessary to elicit specific physiological adaptations (4, 5, 22, 27, 28, 33, 34, 53, 54). However, a number of studies reported that multiple sets do not lead to additional strength benefits (11, 12, 25, 26, 35, 40, 51, 52, 59) or muscle hypertrophy (25, 38, 40, 41, 52, 59, 60). These studies reported that 1 set was equally effective as multiple sets and more time efficient for increasing muscle strength and muscle hypertrophy.
A review paper by Feigenbaum and Pollock (13) published in 1997 comparing single- and multiple-set protocols suggested that a single set was as advantageous as multiple sets to develop muscle strength in young and middle-aged adults. Further, in 1998 Carpinelli and Otto (10) published a review on the topic and reported no significant difference in strength gains between training protocols in the majority of the studies undertaken. However, Byrd et al. (8) contested this conclusion by Carpinelli and Otto (10) maintaining that scientific evidence was omitted and that the results were not well interpreted. Recently, Carpinelli (9) published another review on the topic suggesting that evidence supporting the superiority of multiple-set training was still extremely weak. However, 7 out of 8 recently published studies and 1 abstract have reported that multiple-set and periodized multiple-set programs are superior to single-set programs following short- (37, 42, 49, 50) or long-term (7, 32, 33) training for improvements in muscle strength (6, 7, 32, 33, 37, 42, 50); hypertrophy (32, 33); and vertical jump performance (32, 33, 49). Moreover, 2 meta-analyses recently undertaken by Rhea et al. (43, 44) concluded that multiple-set training was superior to single-set training for the development of muscle strength in both trained and untrained individuals. Due to the number of studies published in the area since the reviews by Feigenbaum and Pollock (13) and Carpinelli and Otto (10), it appears prudent to review the recent developments in the area. Thus, the purpose of this paper is to present an overview of studies reported since the review of Carpinelli and Otto (10) that support either single- or multiple-set programs for developing muscle strength. To provide an overview and temporal perspective of developments in the area, studies undertaken prior to 1998 will first be briefly discussed.
Single- and Multiple-Set Training Studies to 1998 Return to TOC
A summary of the published studies to 1998 comparing single- and multiple-set training regimes is shown in Table 1 . Out of 13 studies, 6 supported single sets to be as beneficial as multiple sets, whereas 7 suggested that multiple-set protocols produced additional strength development. In addition to the published papers, 4 abstracts (11, 12, 38, 60) supported similar strength gains using either single or multiple sets.
An influential study on the optimal number of sets in a resistance exercise program was published by Berger in 1962 (5), which examined different combinations of sets and repetitions for the bench press exercise in college-aged men. Superior strength gains for the bench press exercise were reported with a regime using 3 sets of 6 repetitions. In contrast, several studies reported in the 1980s indicated that a single set was similar to multiple sets for developing muscle strength (26, 35, 41, 51, 59), whereas only 1 published study reported additional benefits with multiple-set training (55). These studies reported comparable strength gains for upper- (35, 41, 51, 59) and lower- (26, 35, 41, 59) body muscles following short-term (<10 weeks) training using either single or multiple sets. Subsequently, 4 published abstracts and 2 papers by Pollock et al. in the 1990s reported similar strength gains with both single- and multiple-set protocols (11, 12, 38, 40, 52, 60), reinforcing the concept that similar strength gains accrue regardless of the use of single or multiple sets. However, the subjects in these studies were previously untrained. In contrast, Kraemer in 1997 reported data from 4 studies (27, 28) supporting further strength gains with multiple-set protocols for upper- (28) and lower-body (27, 28) exercises subsequent to short- (27, 28) and long-term periods (28) of training. Therefore, conflicting findings among studies fueled the controversy as to the most advantageous protocol for strength development. Although similar strength gains were reported for both single- and multiple-set protocols in several studies (11, 12, 26, 35, 38, 40, 41, 51, 52, 59), no study found that single sets were superior to multiple sets for promoting strength in any muscle group.
When comparing strength gains from different training protocols, several important variables such as intensity of training (% 1 repetition maximum [RM] or repetitions until failure), order of exercise, rest period length between sets, frequency of training, and repetition velocity should be kept constant between training groups; thus, differences in strength response would be directly related to the number of sets performed. To 1998, 7 studies did not use similar intensities between training groups (26???28, 35, 41, 53, 55), and 8 did not report the rest interval used between sets (5, 11, 12, 38, 41, 51, 59, 60). Moreover, some studies used different exercises (28, 35, 53) and equipment (28, 35, 51, 53) between training groups. However, for a number of these studies (26???28, 35, 41, 53, 55), the investigators were examining the efficacy of specific training programs, rather than the number of sets performed. It is interesting to note that studies supporting multiple-set protocols used dynamic 1RM tests to assess muscle strength (5, 27, 28, 53, 55), whereas other studies supporting a single set used a different strength assessment (isometric) than the training regimen (dynamic; 41, 52). Thus, considering the methodological differences in studies undertaken prior to 1998, it is difficult to draw a definitive conclusion regarding the superiority of either single- or multiple-set training, and these differences among studies contributes to confusion in the area.
Single- and Multiple-Set Training Studies Since 1998 Return to TOC
Support for Single-Set Training
Recently, the only study supporting a single set as being as effective as multiple sets for strength gain was conducted by Hass et al. (25) using a circuit training program (see Table 2 ). Forty-two adults who previously had performed 1 set of exercise for a minimum of 1 year continued to perform 1 set or performed 3 sets of 8???12RM 3 d·wk−1 for 13 weeks. The single-set group increased leg extension 1RM by 7.4% at week 7 and 6.2% from week 7 to week 13. In comparison, the multiple-set group increased leg extension strength by 7.4% at week 7 and a further 5.4% by week 13. Similar changes were observed for the chest press, overhead press, and biceps curl exercises. The continual increase in strength in the single-set group, without change to any training variable, was surprising. Although the multiple-set group improved significantly more for the leg curl, it should be pointed out that the strategy of using multiple sets in a circuit training program leads to prolonged rest intervals between sets and does not correspond to the usual situation where 1 muscle group is stressed with multiple sets with a short rest interval of 1???2 minutes between sets. Thus, overloading the same muscle group using short intervals between sets was not addressed in this study.
Support for Multiple-Set Training
Seven recent studies (7, 32, 33, 37, 42, 49, 50) and 1 abstract (6) demonstrated additional improvements in muscle strength, (6, 7, 32, 33, 37, 42, 50); hypertrophy (32, 33); and vertical jump performance (32, 33, 49) both in untrained (6, 7, 33, 49) and trained individuals (32, 37, 42, 50) subsequent to short- (6, 37, 42, 49, 50) or long-term (7, 32, 33) training (Table 2 ).
Short-Term Studies (6???12 weeks). Evidence supporting a greater volume of resistance training was reported by Sanborn et al. (49) comparing the effects of a single-set (8???12RM) and multiple-set variation regimen (2???10RM) in 17 untrained women for 8 weeks. The multiple-set group performed faster velocity repetitions than the single-set group using maximum repetitions twice per week and reduced weight (20% less of the maximal) in the third training session of the week. Although there was no statistical difference in 1RM parallel squat performance between training groups (24.2 and 34.7% for the single and multiple set, respectively), significant differences were found in muscle power (countermovement vertical jump test performance) with the multiple-set group improving by 11.2% and no change in the single-set group. Thus, considering that the multiple-set group performed faster velocity repetitions, the response in muscle power is likely to be related not only to the additional sets but also to the specificity of the repetition velocity. It should also be noted that the small sample size limited the ability to detect a significant difference between training groups.
Schlumberger et al. (50) examined the effects of single- and multiple-set training in 27 women with resistive exercise experience for 6 weeks. Subjects were randomly assigned to either a single-set group, a 3-set group, or a nontraining control group. Intensity was set for both training groups at 6???9 repetitions until failure for several upper and lower body exercises. Both training groups significantly improved in bilateral leg extension strength (3-set group, 15%; single-set group, 6%). However, in the seated bench press exercise, only the multiple-set group demonstrated significant improvement in strength (10%). Training variables such as intensity of training, level of activity of the subjects, repetition velocity, frequency of training, and strength test specificity were similar between training groups. Thus, the additional improvements in strength are likely the result of the greater amount of stimulus induced by the multiple-set protocol.
Rhea et al. (42) examined the effects of single- and multiple-set training in 16 recreationally trained men. Participants trained twice weekly for 12 weeks for the bench press and leg press exercise. Daily undulating periodization using similar intensity (4???10RM) was used for both groups. The multiple-set group increased lower- and upper-body strength significantly more than the single-set group from baseline to posttest: bench press increased by 20% and 33%, whereas the leg press increased by 26 and 56% for the single- and multiple-set group, respectively. Similar to Schlumberger et al. (50), training groups underwent similar training conditions (intensity, frequency, and repetition velocity).
Recently, Paulsen et al. (37) assigned untrained men to a single-set (7RM) lower-body and 3-set (7RM) upper-body group or a 3-set (7RM) lower-body and 1-set (7RM) upper-body group for thrice weekly training for 6 weeks. The results demonstrated that 3 sets were superior to 1 set for increasing maximal strength in leg exercises, and 1 set was as effective as 3 sets for improving upper-body strength. This suggests that differences in threshold stimulus between the upper and lower body may exist and are likely to affect the training response during a short-term period of exercise. This is in agreement with the results from Rhea et al. (42) who found that gains in lower-body strength were greater than that for the upper body. In contrast, Schlumberger et al. (50) found additional strength gains only for the upper body and not for the lower body in their study of trained women.
Long-Term Studies (24???36 Weeks). Kraemer et al. (32) examined over 9 months the effect of resistance training volume on the development of physical performance abilities in competitive collegiate women tennis players. Twenty-four subjects were randomly assigned to a control group, a periodized multiple-set resistance training group, and a single-set circuit resistance training group. Maximal muscle strength was assessed for the leg press, shoulder press, and the bench press exercises. The single-set group trained with 8???10RM for each exercise, whereas the periodized multiple-set group used a range of 4???10RM for 2???4 sets. The single-set group increased strength only at 4 months of training, whereas the periodized multiple-set group increased strength at 4, 6. and 9 months of training for all exercises. Furthermore, the multiple-set group increased countermovement vertical jump by 51.2%, whereas the change in the single-set group was only 2.5%. However, it is possible that the superior results achieved by the multiple-set group may not only be the result of the greater volume used for this group, but also the differences in training intensities applied.
Adaptation to low-volume circuit-type resistance training vs. periodized high-volume resistance training was examined by Marx et al. (33). Subjects were 34 untrained women randomly assigned to 1 of 3 groups for 24 weeks: control, single-set circuit, or a periodized multiple-set group. The intensity for the single-set group was set at 8???12RM, whereas the multiple-set periodized group performed 2???4 sets per exercise at 3???15RM using moderate-to-explosive movements. Both training groups improved bench press and leg press 1RM significantly during the first 12 weeks of training. However, only the multiple-set group increased 1RM strength during the second half of the training program. At posttest, the single-set group increased vertical jump performance by 10.3%, whereas the multiple-set group improved by 39.7%. Small but significant increases in resting serum testosterone occurred for both training groups, whereas resting serum cortisol concentration decreased at the 12th and 24th week only in the multiple-set group. It was concluded that a high-volume periodized multiple-set protocol of resistance training was superior to a low-volume, single-set protocol for improving muscular performance in untrained women. An important factor to be addressed is that only the periodized multiple-set group continued to improve strength from mid- to posttest, supporting the role that higher volumes of training facilitate gains in muscle strength and hypertrophy subject to prolonged training (7, 32, 33). In addition, the decrease in resting serum cortisol concentrations for the periodized multiple-set group would contribute to an improved anabolic environment for the muscle cell. However, the superiority of the multiple-set group may not be exclusively explained by the fact that a greater volume of training was undertaken. The intensity, frequency, exercises, and speed of movement were different between training groups; thus it is likely that these differences in addition to greater training volume contributed to the results.
Finally, Borst et al. (7) examined the impact of resistance training volume on strength as well as insulin-like growth factor-I (IGF-I) and their binding proteins (IGFBP-1, IGFBP-3) over 25 weeks in healthy adults aged 25???50 years. Participants were stratified by sex and initial leg strength into 1 of 3 groups: 3-set, single-set, or a nonexercising group. The absolute improvements in strength for the 3-set group were approximately 50% greater than the single-set group. Resistance training was associated with a significant increase in circulating IGF-I after 13 weeks (18.5 and 20.5% in multiple-set and single-set groups, respectively), with no further increase between weeks 13 and 25. IGFBP-3 concentration decreased 20% during the second half of the investigation in the multiple-set group, with no change in the single-set group. These results suggest that an improved anabolic environment accompanied both resistance-training protocols; however, the multiple-set group had lower IGFBP-3 concentrations and significantly greater improvements in upper- and lower-body strength. These findings in muscle strength are in contrast to previous findings from this laboratory (11, 12, 38, 60), which has repeatedly reported no difference between single- or multiple-set training. The differences between studies cannot be accounted for by training status, subject age, or study duration. Therefore, it is unclear why this research group has found divergent results.
Discussion Return to TOC
The purpose of this paper was to present studies published since the review by Carpinelli and Otto in 1998 (10) supporting either single- or multiple-set programs for improving muscle strength. Although it is difficult to make comparisons among the studies because of confounding variables such as program duration, frequency of training, muscle groups trained and assessed, test procedures, repetition velocity, and training status of the subjects, 7 out of 8 recently published studies and 1 abstract support the position that multiple-set and periodized multiple-set programs are superior to single-set programs under both short- (6, 37, 42, 49, 50) and long-term periods (7, 32, 33) for improvements in muscle strength (6, 7, 32, 33, 37, 42, 50); hypertrophy (32, 33); and vertical jump performance (32, 33, 49). Only 1 study (25) demonstrated that individuals with 1 year of resistance training experience had similar improvements in upper-and lower-body muscle strength when using either a single- or multiple-set circuit training regime. Moreover, when intensity was constant between training groups (6, 7, 25, 37, 42, 50), the majority of studies (6, 7, 37, 42, 50) found that a greater number of sets promote additional strength gains in young and middle-aged adults. Furthermore, 2 meta-analyses recently undertaken by Rhea et al. (43, 44) found greater strength gains with multiple-set training, regardless of initial training status. This is supported by all, except 1 (25), of the studies recently published (6, 7, 32, 33, 37, 42, 49, 50).
It is well known that improvements in strength are more difficult to achieve after several months of training (21, 23). Strength gains during the initial stages of resistance training are principally due to neural factors with gains in muscle size becoming dominant as training continues (45, 46, 48). Thus, it is suggested (7, 32, 33) that once an initial level of muscle strength has been achieved, periodized multiple-set (32, 33) or multiple-set programs (7) become superior to a single-set training program. An increase in resting serum testosterone and IGF-I and a decrease in resting serum cortisol concentrations appears to contribute to an improved anabolic environment following long-term training (24???36 weeks; 21, 23, 31???33). Furthermore, it has been demonstrated by Gotshalk et al. (20) that the increase in circulating anabolic hormones (growth hormone and testosterone) during the recovery phase of a bout of resistance training are correlated with the number of sets performed; thus 3 sets induce higher circulating anabolic hormones than single sets subsequent to training.
Although current studies support additional strength gains with 3 (7, 37, 42, 50), 2???5 (32, 33), and 6 sets (6) compared with a single set, it has been proposed by Ostrowski et al. (36) that 6 and 12 sets do not lead to additional benefits in muscle strength and hypertrophy than 3 sets per exercise during 10 weeks of training in resistive-trained individuals. Thus, an optimal amount of stress is required to be applied to achieve maximal strength gains. The findings of Rhea et al. (44) suggest that multiple sets produce optimal strength gains. However, the results also suggest that performing 5 or 6 sets dramatically decreases the muscle response in untrained individuals. Current studies (31???33) support that alternating frequency, volume, and intensity through a periodization system may be the best strategy to maximize gains in strength and hypertrophy. Indeed, Fleck (16) concludes in a review paper that periodized resistance training results in substantially greater benefits in muscle strength, as well as lean body mass and motor performance, than conventional single- and multiple-set programs. However, it is important to note that when maximal strength gain is not the principal goal of the training program, a single-set protocol may be sufficient to significantly improve upper- (6, 7, 25, 32, 33, 37, 42) and lower-body (6, 7, 25, 32, 33, 37, 42, 49, 50) strength as well as being time efficient.
To date, studies comparing single- and multiple-set training have employed trained and untrained young and middle-aged adults as subjects. However, as a result of the seminal work of Frontera et al. (19) and Fiatarone et al. (14, 15) on the adaptations of older adults to resistance training, including the very old, resistance training is now endorsed as a training mode to preserve and enhance muscle strength in the elderly (2). Although some studies have examined various aspects of the exercise prescription in the elderly, such as exercise intensity (57, 61) and frequency (56) for improvements in muscle strength, none have examined the role of training volume on strength enhancement in this population. Thus, a requirement for future studies on this topic should include short- and long-term controlled trials using different populations such as older people and those with cardiovascular and orthopaedic limitations. In addition, these studies should attempt to establish a relationship between volume of resistance training and benefits related to health outcomes such as bone density, functional capacity, metabolic rate, glucose metabolism, cardiovascular adaptations, and enhancement of quality of life.
Practical Applications Return to TOC
Whether to use single or multiple sets in a resistance training program is dependent on the goals of the program and the time available for training. Independent of training status, multiple-set protocols should be incorporated when maximal strength gains are the primary goal of the exercise regimen. However, single-set programs also result in substantial improvements in strength, albeit not to the same level as that for multiple sets, and are recommended when exercise time is limited. At this stage it is unknown if superior gains in muscle strength are achieved with a multiple-set program in older adults; however, given that the older individual responds favorably to resistance training programs irrespective of intensity and frequency, single-set programs may be sufficient to significantly improve strength and physical function.
However, the number of sets is only 1 component of the exercise prescription. It is clear that training programs must be dynamic in nature with continual variation to induce physiological adaptation. Therefore, at different stages in an individual's program, especially when resistance exercise is viewed as a lifelong activity, variations in sets as well as the other components of the exercise prescription, including repetition velocity and systems of training, will be required. It may be time that we move on from a rather limited view of whether single or multiple sets should be performed to one of dynamic programs that incorporate variations in the many components of the exercise prescription.
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thanks bro.