Resistance training has been recommended in the context of weight management programs because of its impact on the energy expenditure (EE), lean body mass (5), and resting metabolic rate (5,25). Consequently, previous studies have investigated the specific contribution of different training variables on these aspects within and after exercise sessions. Variables such as muscle mass (27), session format (circuit or consecutive sets) (32), number of sets (25), lifting velocities (15), number of repetitions (26,32), workload (15,16,31), and training volume (16) have been investigated. However, although relevant in terms of acute responses that cause accumulated fatigue and higher perceived exertion, the order of selection of resistance exercises has been generally neglected in previous studies, particularly in older subjects.
A significant decrease in performance has been reported during the last prescribed exercise when the resistance training sequence is reversed (29,30). In these studies, the performance was demonstrated to be impaired for the exercises placed later in the sequence, regardless of the order of selection or the size of muscle mass group. No difference was found for the rate of perceived exertion (RPE) at the end of both sequences. These results were probably considered by the last ACSM's Position Stand on Progression Models in Resistance Training for Healthy Adults (5), which was the first to recognize that multiple-joint exercises should be performed early in a training session to maximize their performance and strength gains. The concept that an exercise of primary importance within a training session should be performed early in a given sequence seems to be reasonable. Nonetheless, it contradicts the premise that large-muscle group exercises should be always performed first to enhance the training volume and diminish the accumulated fatigue in resistance training sessions, if one were to consider a smaller muscle group to have primary importance over a larger muscle group (28).
Previous studies have analyzed the EE during resistance exercises through oxygen uptake (V[Combining Dot Above]O2) assessment, showing that the V[Combining Dot Above]O2 kinetics along successive sets may reflect the accumulated fatigue (12,16,26). It has been proposed that an increase in V[Combining Dot Above]O2 in a given exercise may be caused by anaerobic metabolism strain in the previous sets or exercises. In this context, we have recently demonstrated in young women that the exercise order within a training session for the upper body had no effect on the total work volume, overall V[Combining Dot Above]O2, and EE (12). Nonetheless, the V[Combining Dot Above]O2 presented an increased pattern throughout all the sequences, being always higher during the last exercise of a given sequence. Considering that the V[Combining Dot Above]O2 increase reflects the accumulated fatigue (13,18,27) from the previous exercises, it has been proposed that the exercise order selection would be a variable to consider when this issue is paramount.
The aforementioned studies (12,29,30) were mainly designed for young trained women. It is unknown whether the training volume, perceived exertion, and physiological responses would remain the same in untrained sedentary subjects. For instance, it is unknown whether the same results would be observed in older subjects, because the decline of strength and fiber type 2 cross-sectional area (4) may lead to a higher fatigue compared with younger subjects as the resistance training session evolves. It is feasible to think that because of lower strength and higher susceptibility to muscle fatigue (1,18,22), older subjects may exhibit different physiological responses compared with younger counterparts to a sequence of resistance exercises performed to exhaustion. In that case, the V[Combining Dot Above]O2 kinetics (and therefore the overall EE) and the effort perception may be different in older and younger groups.
Considering the well-known benefits of resistance training on the functional fitness in older adults and the lack of information on the effect of exercise order on the overall performance, energy cost, and perceived exertion during resistance training in a such population, this study aimed to compare the V[Combining Dot Above]O2 and associated caloric expenditure, work volume reflected by the number of repetitions, and RPE in younger and older adults performing 2 different and mirrored sequences of upper-body exercises. It has been hypothesized that the number of repetitions, total V[Combining Dot Above]O2 and V[Combining Dot Above]O2 kinetics within the sets and intervals, net EE, and RPE would be influenced by age and sequence. To find a possible mechanism for differences in these variables, the V[Combining Dot Above]O2 and number of repetitions in each set and exercise have been also compared across sequences and age groups.
Experimental Approach to the Problem
To investigate the effect of 2 different exercise orders on the fatigue (number of maximum repetitions) and EE estimated from V[Combining Dot Above]O2, data from younger and older subjects were assessed on 5 nonconsecutive days. On the first day, anthropometric measurements and a maximal cardiopulmonary exercise testing were performed using either a ramp treadmill (younger subjects) or a cyclo-ergometer protocol (older subjects). On the second day, the workload corresponding to 10RM was determined for all exercises, being retested on the third day. On the fourth and fifth days, the 2 exercise sequences were performed. The V[Combining Dot Above]O2 was continuously measured during all sets and exercises.
Each subject accomplished 2 exercise sessions, separated by 48 hours in a counterbalanced design. The sessions consisted of the same exercises, performed in a mirrored order: machine bench press (BP), seated machine shoulder press (SP), and standing pulley triceps extension (TE). Sequence A (SEQA) started with large-muscle group exercises, progressing to small-muscle group exercises (BP, SP, and TE), whereas Sequence B (SEQB) adopted and inverted order, starting with small-muscle group exercises and progressing to large-muscle group exercises (TE, SP, and BP). Three sets to volitional fatigue were performed for all exercises in both sequences using the predetermined 10RM workloads. Sets and exercises were separated by 3-minute rest intervals of passive recovery.
The total number of repetitions was counted in each set of the exercises for SEQA and SEQB. The rate of perceived exertion (RPE) was assessed immediately after the completion of each sequence by using the Borg CR-10 Scale with emphasis on local fatigue (8). All the exercise sessions were performed at the same period of the day (9:00–11:00 PM). Adequate hydration was provided in all exercise sessions, and the mean ± SD ambient temperature and relative humidity during testing were 22.6 ± 1.0° C (range 20–23° C) and 62.5 ± 4.1 % (range 50–70%), respectively.
Ten young women (YG: 22 ± 2 years; 64 ± 11 kg; 166 ± 7 cm) with at least 2 years of recreational resistance training and 8 sedentary older women with no previous experience in resistance training (EG: 69 ± 7 years; 65 ± 8 kg; 154 ± 6 cm) participated as subjects in the study. The experimental approach had institutional ethical board approval, and all the subjects signed an informed consent form before participation in the study. Additional exclusion criteria were (a) use of drugs that could affect the cardiorespiratory responses and (b) blood pressure abnormalities, heart disease, pulmonary function limitation, locomotion impairment, as any bone, joint, or muscle problems that could limit the performance of the exercises; (c) body mass index >35 kg·m−2.
Oxygen Consumption Assessment
A maximal cardiopulmonary exercise testing was performed to determine the peak V[Combining Dot Above]O2, using individualized ramp protocol (8–12 minutes; YG—treadmill; EG—cyclo-ergometer). Criteria for testing interruption followed the recommendations of the ACSM (3). The test was considered maximal when at least 2 of the following criteria were observed: (a) respiratory exchange ratio (RER) > 1.15; (b) V[Combining Dot Above]O2 plateau despite an increase in workload (increase < 2.0 ml·kg−1·min−1 between the last 2 loads); and (c) maximum volitional exhaustion. The V[Combining Dot Above]O2 was assessed every 10 seconds (Medical Graphics VO2000; Medical Graphics, Saint Louis, MO, USA), using a medium flow pneumotachometer (10–120 L·min−1). Before each test, all the equipment was calibrated in standard fashion with reference gases. The heart rate was continuously monitored (Polar Accurex Plus; Polar Electro Oy, Kempele, Finland). Ambient temperature and humidity were between 20 and 25° C and 40 and 65%, respectively, for all tests.
The choice of different ergometers to assess the maximal cardiorespiratory capacity in younger and older subjects deserves explanation. Although treadmill tests are known to engage larger muscle mass and therefore may elicit higher peak V[Combining Dot Above]O2 (3,21,23), some authors have proposed that cyclo-ergometer tests would be more appropriate to assess the cardio-respiratory fitness in older subjects, mainly for safety reasons (14), which has been endorsed by the American College of Sports Medicine (3) and the American Heart Association (7). Moreover, the poor mechanical efficiency while running seems to reduce the performance of older compared with younger subjects during treadmill exercise (11), which would very likely limit the peak V[Combining Dot Above]O2 in maximal cardiopulmonary tests. Such limitation has been considered by previous research that adopted cyclo-ergometer protocols to assess the cardio-respiratory fitness in older populations (9,10,13). In brief, we have adopted different strategies to assess the peak V[Combining Dot Above]O2 to contemplate the different characteristics of our samples and to assure that the obtained values would actually represent the maximal cardio-respiratory fitness in each group. In the present case, applying a cyclo-ergometer protocol in the younger group and a treadmill protocol in the older group would probably underestimate the V[Combining Dot Above]O2max and jeopardize the subjects' characterization.
The same environmental conditions were kept and the same data assessment devices were used for the V[Combining Dot Above]O2 during the resistance exercise sequences and during postexercise oxygen consumption (EPOC). The device was calibrated before each individual test according to the manufacturer's guidelines. In the 24 hours before an exercise session day, the subjects were required to (a) avoid caffeine or other metabolic-altering supplements and drugs, (b) engage in no physical activity, (c) be well hydrated and do not change their habitual diet, and (d) be well rested. Before the exercise session, they remained seated for 10 minutes until the RER was considered acceptable (R ≤ 0.82) and to assess the V[Combining Dot Above]O2 at rest.
Measurements of V[Combining Dot Above]O2, carbon dioxide production (V[Combining Dot Above]CO2), and minute ventilation (VE) were made for each of 3 complete respiratory cycles at rest, during all the exercise periods, and for 20 minutes after the exercise sequences. The reliability of respiratory gas parameters (V[Combining Dot Above]O2, V[Combining Dot Above]CO2, VE) during high-intensity resistance training has been previously determined by Katch et al. (17) for shoulder, chest, and leg exercises (r = 0.41–0.83 for gas measures, and r = 0.72–0.89 for heart rate). In a recent study, the reproducibility of the V[Combining Dot Above]O2 assessed by a protocol similar to the presently adopted was determined in subjects performing the bench press (at the end of 3 sets performed with 10RM and following 20 minutes of postexercise recovery). The intraclass correlation (ICC) ranged from 0.78 (within sets values) to 0.90 (20 minute EPOC) (p < 0.05) (12).
Ten Repetition-Maximum Testing
In both young and older groups, the 10RMs were assessed on 2 nonconsecutive days, using Life Fitness equipment (Life Fitness, Franklin Park, IL, USA). The 10RM tests were performed in the following order: BP, SP, and TE. Standard exercise techniques were adopted for all exercises. No pause was allowed between the eccentric and concentric phase of a repetition or between repetitions. For a repetition to be successful, a complete range of motion, as normally defined for the exercise, had to be completed. The following is a brief description of the range of motion used to define a successful repetition for each exercise: BP, moving the bar from a chest touch to a fully extended elbows position; SP, starting with the bar slightly above shoulder height and moving the bar to a fully extended elbows position; and TE, starting with the elbows at a 90° angle and fully extending the elbows.
Aiming to minimize possible errors, the following strategies were adopted: (a) all the subjects received standard instructions on the general routine of data assessment and the exercise technique of each exercise before testing, (b) the exercise technique of the subjects during all testing sessions was monitored and corrected whenever appropriate, and (c) all the subjects were given verbal encouragement during the test. The subjects had a maximum of 5 10RM attempts of each exercise with 2- to 5-minute rest intervals between successive attempts. After the 10RM load in a specific exercise has been determined, an interval not shorter than 10 minutes was allowed before the 10RM determination of the next exercise.
The tests were repeated after a 48-hour interval to confirm the test-retest reliability. The subjects were not allowed to practice any exercises during the interval between the testing sessions. Excellent day-to-day 10RM workload reliability for each exercise was shown by this protocol. The ICC coefficients for the young and older group (p < 0.05) were, respectively, BP (ICC = 0.91 and ICC = 0.90), SP (ICC = 0.93 and ICC = 0.90), and TE (ICC = 0.94 and ICC = 0.91). Despite this strong concordance, the higher 10RM workload assessed in the 2 testing sessions was adopted as reference to determine the workload the exercise sessions.
The choice of only 3 upper-body exercises must be justified. Even though in most cases actual resistance training sessions are composed of exercises for both lower and upper body, this is not always the case, especially when we are dealing with high-intensity programs (e.g., split body workouts, preexhaustion, or priority systems). In the case of a protocol designed to investigate the specific effects of exercise ordering on the V[Combining Dot Above]O2 and fatigue, we considered that the effects of accumulated fatigue on the performance would be more likely to occur for an expressive number of sets with high volume (high intensity and repetitions), and exercises involving primary and secondary related muscle groups (24). Additionally, it is very difficult to design a 10 RM 3-set program with exercises for the whole body, especially in older populations, and at the same time to isolate the effects of a given sequence on the fatigue and V[Combining Dot Above]O2. In short, it is true that only 3 upper-body exercises may result in a less total V[Combining Dot Above]O2 and caloric expenditure than a total-body workout or a leg workout, but such a protocol should show if exercise order does affect V[Combining Dot Above]O2 and caloric expenditure. This rationale supported the procedures that were adopted in a similar previous study of our group, including young trained women (12).
The protocols adopted for the exercise sessions were exactly the same in the 2 age groups. Forty-eight hours after the retesting of the 10RMs for each exercise, subjects performed 1 of the 2 exercise sequences in a counterbalanced design. The second exercise sequence was performed 48 hours after the first session. The V[Combining Dot Above]O2 mask and equipment were put on the subject after they were positioned to perform the first exercise in the sequence and before performing the standardized warm-up. A facemask (Hans Rudolph V Mask; Hans Rudolph Inc., Shawnee, KS, USA) that covered the mouth and nose of the participant was attached to a bidirectional digital flow valve and fastened to the participant by the use of a mesh hairnet and Velcro straps.
Data collection began by assessing V[Combining Dot Above]O2 at rest for 5 minutes. After this, a warm-up was performed consisting of 20 repetitions of the first exercise of the session (BP for SEQA and TE for SEQB) with 40% of the 10RM load. A 2-minute interval was allowed after the warm-up before the subjects performed the assigned exercise sequence. Both exercise sequences consisted of 3 sets of each exercise to failure using 10RM with 3-minute rest intervals between sets and exercises. During the exercise sessions, the subjects were encouraged to perform all sets to concentric failure, and the same limits of range of motion used during the 10RM testing were used to define the completion of a successful repetition. All the subjects were specifically asked to avoid the Valsalva maneuver.
The number of repetitions for each set and exercise was recorded. The absolute V[Combining Dot Above]O2 (liters per minute) during each exercise set, recovery intervals, and along a 20-minute postexercise period (EPOC) were measured and averaged to be expressed in liters per minute. The V[Combining Dot Above]O2 within the exercises and intervals were compared using the mean V[Combining Dot Above]O2 obtained during the exercise performance and the last minute of each interval (expressed in liters per minute). The overall V[Combining Dot Above]O2 (liters) associated with each exercise and interval were compared multiplying the V[Combining Dot Above]O2 (liters per minute) by the time expended to perform the exercises and the whole intervals.
The total V[Combining Dot Above]O2 for both sequences was also calculated. The total V[Combining Dot Above]O2 for a given sequence was defined as the overall V[Combining Dot Above]O2 during exercise performance, the 3-minute recovery intervals between sets and exercises, and the 20-minute EPOC period. The EE from both sequences was estimated based on the net V[Combining Dot Above]O2 defined as the resting V[Combining Dot Above]O2 subtracted from the total V[Combining Dot Above]O2. The energy cost in kilocalories estimation was based on a caloric equivalent of 5.05 kcal·L−1 (32). This method has been used in other studies investigating the energy cost of resistance training (12,16,17,32). Net kilocalories were estimated by multiplying net V[Combining Dot Above]O2 by the corresponding RER value for kilocalories per liter of oxygen.
Univariate analysis was used to ratify data normality. The body mass and V[Combining Dot Above]O2 peak between age groups were compared by the Student t-test. The hypothesis that age and sequence could influence the total V[Combining Dot Above]O2, net EE, number of repetitions, and RPE was tested by means of 2-way analysis of variance (ANOVA) with repeated measures (age and sequence). Possible V[Combining Dot Above]O2 differences between sets and rest intervals within each sequence and age group were tested by 1-way repeated measures ANOVA.
Finally, the hypothesis that the V[Combining Dot Above]O2 within the sequences would be affected by age and sequence was tested by a 3-way ANOVA with repeated measures (age, sequence, and either sets or rest intervals). Fisher post hoc tests were applied to determine pairwise differences when significant F ratios were obtained. In all cases, a probability level of p ≤ 0.05 was adopted for statistical significance. The effect sizes were calculated by dividing the difference between mean values associated with each sequence or age group by the pooled standard deviation. The same statistical software was used for all calculations (Statistica 6.0; StatSoft, Tulsa, OK, USA).
An achieved statistical power of 0.899 for an effect size of 0.25 was obtained by performing a post hoc power analysis (GPower version 3.0.10, Kiel, University of Kiel, Germany) based on the given sample size, p value, number of repeated measures and groups. No difference was found for the body mass across the age groups (YG = 64.4 ± 11.4 kg vs. EG = 65.8 ± 7.6 kg; p = 0.54). As expected, the peak V[Combining Dot Above]O2 was significantly different between groups (YG = 42.2 ± 2.9 ml·kg−1·min−1 vs. EG = 22.7 ± 2.5 ml·kg−1·min−1; p < 0.001).
Table 1 presents the results for the number of repetitions in each exercise and sequence. The number of repetitions showed a steady decrease throughout the exercises regardless the age group and sequence (main effects—exercise: p = 0.02; age: p = 0.01; sequence: 0.30; interaction: p = 0.31). The total number of repetitions was always higher in YG than in EG regardless of the sequences. However, no significant difference for the total number of repetitions was detected between SEQA and SEQB in both age groups. The number of repetitions in each exercise consistently declined from BP to TE in SEQA, whereas in SEQB, the repetitions declined from TE to BP.
Table 2 presents data for the total V[Combining Dot Above]O2 (exercise sequences + EPOC) and estimated EE (ANOVA main effects—age: p = 0.48; sequence: p = 0.04; interaction: p = 0.71). In both sequences, the V[Combining Dot Above]O2 was slightly higher in EG than in YG, but no significant difference was found between the age groups (p > 0.05). Contrary to YG, in EG, the V[Combining Dot Above]O2 and EE were a little higher in SEQB compared with SEQA, albeit no statistical significance has been detected (p > 0.05). There were also no significant differences for the total V[Combining Dot Above]O2 and EE in the within-group (SEQA vs. SEQB) comparisons. However, the net EE, which takes into account the V[Combining Dot Above]O2 at rest, was significantly higher during SEQB in EG compared with YG (ANOVA main effects—age: p = 0.05; sequence: p = 0.04; interaction: p = 0.05).
The V[Combining Dot Above]O2 (liter) within the 3 sets of each exercise (exercise + intervals) in SEQA and SEQB is exhibited in Figure 1 (ANOVA main effects—age: p = 0.007; sequence: p = 0.01; exercise: p = 0.65; total interaction: p = 0.05). The V[Combining Dot Above]O2 was significantly different for BP and TE when comparing the sequences. The exercise placed in the middle of the sequences (SP) exhibited similar V[Combining Dot Above]O2 in SEQA and SEQB, whereas the V[Combining Dot Above]O2 assessed for BP and TE was always higher when the exercise was performed last in a given sequence. In brief, the V[Combining Dot Above]O2 measured for TE in SEQA was higher over TE in SEQB (p = 0.04 for YG and EG) and BP in SEQA (YG: p = 0.04 and EG: p = 0.05), while the V[Combining Dot Above]O2 for BP in SEQB was higher over BP in SEQA (YG: p = 0.04 and EG: p = 0.03) and TE in SEQB (p = 0.05 for YG and EG). These results suggest a significant effect of the exercise order on the V[Combining Dot Above]O2 kinetics along the training sessions. There were also between-group differences indicating an age-related effect on the V[Combining Dot Above]O2–a significant difference between YG and EG was detected for the TE in SEQA (p = 0.04).
Figure 2 presents the V[Combining Dot Above]O2 (liters) measured in each set and rest interval along SEQA and SEQB. The 1-way repeated measures ANOVA showed that the V[Combining Dot Above]O2 assessed in the rest intervals was always higher than in the sets regardless of the age group, sequences, and exercises (p < 0.0001). Actually, in all cases, the V[Combining Dot Above]O2 increased immediately after the end of a set before declining during the rest intervals. The 3-way ANOVA did not detect V[Combining Dot Above]O2 differences between the sets in both sequences (ANOVA main effects—age: p = 0.92; sequence: p = 0.44; set: p = 0.60; interaction: p = 0.89). On the other hand, differences were found in the V[Combining Dot Above]O2 assessed during the rest intervals (ANOVA main effects—age: p = 0.05; sequence: p = 0.04; interval: p = 0.33; total interaction: p = 0.78). In both age groups, the V[Combining Dot Above]O2 was always higher (p < 0.01) in the intervals subsequent to the exercise performed last in a given sequence (e.g., BP in SEQA and TE in SEQB). However, in the YG, no difference was found for SP between SEQA and SEQB, whereas in the EG, this exercise, placed in the middle of the sequences, exhibited higher V[Combining Dot Above]O2 in the third set of SEQB compared with SEQA.
Data for RPE are exhibited in Figure 3 (ANOVA main effects—age: p = 0.003; sequence: p = 0.01; interaction: p = 0.05). Post hoc comparisons between sequences showed no significant differences for the Borg CR-10 scores in the YG (sequence A [SEQA], 6.3 ± 1.6 vs. sequence B [SEQB], 6.3 ± 1.8; p = 0.31; effect size = 0.0), suggesting that the exercise order did not influence the RPE. On the other hand, there was a significant effect of the exercise order on the Borg CR-10 scores in EG (SEQA, 4.6 ± 1.1 vs. SEQB, 6.3 ± 1.1; p = 0.02; effect size = 1.55).
This study aimed to compare the V[Combining Dot Above]O2 and associated caloric expenditure, work volume (number of repetitions), and RPE in younger and older adults performing opposite sequences of upper-body exercises. The main findings were as follows: (a) The number of repetitions in both young and older subjects decreased from the first to the last exercise regardless the exercise order. (b) The total V[Combining Dot Above]O2 and EE were similar in YG and EG and were not influenced by the exercise order. (c) The V[Combining Dot Above]O2 was always higher during the rest intervals compared with the exercises and increased from the first to last exercise within a given sequence regardless of the age group. (d) The V[Combining Dot Above]O2 assessed during the exercises and rest intervals increased along the sets and exercises in both sequences and age groups. However, in the EG, there were differences between SEQA and SEQB, especially in the third set, whereas no difference has been detected in YG. (e) The perceived effort was not influenced by the exercise order in YG but increased in EG, being significantly higher at the end of SEQB (smaller to larger muscle mass group order) in comparison with SEQA.
To the best of our knowledge, this is probably the first study comparing the influence of the exercise order on the performance, EE, and RPE (training volume, V[Combining Dot Above]O2, and Borg scale) during resistance exercise sessions in young and older subjects. The results obtained may help in designing training sessions considering the differences between those age groups. For instance, the ACSM recommendations regarding the exercise order (4,5) do not take into account the age and are quite alike for young and old persons. Our findings demonstrated that such groups responded differently to the exercise order and that at least their fatigue level and effort perception may be influenced.
Kraemer and Ratamess (20) claimed that the strength enhancement depends on the careful prescription of resistance training variables such as the intensity, volume, exercise selection, rest periods between sets, weekly frequency, and exercise order. For a long time, it has been recommended (2) that large-muscle group exercises should generally be performed first in a training session, to enhance the ability to use the heaviest resistances possible when performing the large-muscle group exercises and to increase the maximal number of repetitions and therefore the training volume. Such rationale was mainly based on the results by Sforzo and Touey (28) indicating that the performance of small-muscle group before large-muscle group exercises resulted in significantly less total force production in the large-muscle group exercises and in the total training session.
In a later Position Stand, the ACSM (5) recommended that to maximize the performance of multiple-joint exercises they should be placed first in a sequence, regardless the muscle group. Such review of the prior position was based on studies showing that whenever an exercise is performed last in an exercise sequence its performance will be perhaps negatively affected, whether the exercise sequence begins from large- to small-muscle groups or vice versa (29,30). These studies questioned the universal application of the Sforzo and Touey's results in all training circumstances.
The present results concur with the later ACSM's Position Stand (5) with regard to the training volume and overall performance—in both age groups differences between SEQA and SEQB were detected for the number of repetitions performed in BP and TE, which were placed at the beginning or the end of each sequence. No difference was found in SP performance, which was always in the middle of the sequences. Similar results were reported by previous research (12,29,30) indicating that regardless of the muscle group recruited by the exercises placed first and last in a given sequence, the maximal number of repetitions will probably decrease throughout the session.
Whether the exercise order affected the total V[Combining Dot Above]O2 and EE was not unequivocal. Actually a significant main effect on the V[Combining Dot Above]O2 was found for the sequence. On the other hand, the post hoc tests also showed that the total V[Combining Dot Above]O2 and EPOC were not different between the sequences in both age groups, despite the significant increases in V[Combining Dot Above]O2 when an exercise was performed last compared with first in a sequence. These results are somewhat consistent with the findings from a previous study of our group with young women (12), which demonstrated that the total volume load would be more influential than the exercise order on V[Combining Dot Above]O2 or EE.
The metabolic demand is an important issue to increase the EE within weight management programs (2) and also as a stimulus to improve muscular endurance (5). In this sense, the capacity to endure substrate depletion and accumulation of metabolic waste products seems to be a necessary component of resistance training (19). The V[Combining Dot Above]O2 assessed during the intervals between sets and exercises has been shown to be a good indicator of the accumulated fatigue, reflecting the ability of the skeletal muscle to recover from the anaerobic exercise performed not just in the previous set of an exercise, but to recover from the additive effects of all sets of the exercises performed previously (12,26).
In this study, the V[Combining Dot Above]O2 increased systematically along the rest intervals after the successive exercises in a given sequence, which was probably because of the accumulated fatigue from the preceding exercises in both age groups. In YG, the exercise order did not influence the V[Combining Dot Above]O2. On the other hand, in EG, the V[Combining Dot Above]O2 at the end of SEQB was higher over SEQA, suggesting that the fatigue was more critical in this group when the protocol was organized from the smaller to the larger muscle group (Figure 2). The results for the RPE were consistent with the V[Combining Dot Above]O2 data—the sequences did not affect the perception in YG, but in EG, the Borg score was significantly higher at the end of SEQB.
As aforementioned, our results agreed with the ACSM Position Stand in which concerns the role of the exercise order on the training volume. However, it is worthy to mention that they challenge the concept that exercises which are priority should be always placed first in a resistance exercise session, because an equivalent decline in the volume is expected regardless of the exercise order, with no or little influence on the perceived effort (5). Such premise seems to fit very well in younger women but not necessarily in sedentary and untrained older women. Although a similar reduction in the performance was observed in both age groups, the accumulated fatigue reflected by the V[Combining Dot Above]O2 and RPE in EG was significantly higher in SEQB, which concurs with the idea that the fatigue level would be lower in exercise sessions beginning by exercises recruiting larger muscle groups. Hence, at least in untrained older women, the early results by Sforzo and Touey (28) regarding the exercise ordering seem to suit better than the more recent data published with young women (12,29,30).
However, it must be acknowledged that the observed sequences have included only 3 exercises for the upper-body, which is a major limitation of this study. The present data must be carefully extrapolated to benefits of an exercise program designed for the whole body. Performing only 9 sets of exercise, and limiting it to one region of the body, is in fact a very minimalist program, and not likely to be performed in actual resistive exercise programs. Despite these limitations, our findings introduce new issues to the topic of exercise order in resistance training and warrant future studies with protocols more closely related to the actual practice, including a larger number of exercises aiming the upper and lower body and organized in different sequences.
In conclusion, the exercise order did not affect the training volume across multiple sets of 3 resistance exercises for the upper body in younger and older women. The maximum number of repetitions declined similarly from the first to the last exercise regardless the sequence and age group. On the other hand, the V[Combining Dot Above]O2 and RPE were significantly higher in EG at the end of SEQB compared with SEQA, whereas no differences between sequences were found in YG. These results warrant further investigation on the influence of the exercise order on the training volume, accumulated fatigue, metabolic strain, and perceived effort within resistance exercise sessions performed by different trained and untrained populations.
The present results suggest that the exercise order may not be a major determinant of overall EE in resistance exercise sessions in younger and older women. On the other hand, the perceived effort in untrained older subjects during resistance training sessions may be reduced by placing first exercises for larger muscle groups, progressing toward smaller muscle groups. The same concern would not be important in the case of younger women with previous experience in resistance training. Additionally, further research should investigate whether resistance training sessions are capable to induce aerobic gains in older women with low fitness levels and without previous experience in resistance training.
The authors thank Dr. Ricardo Brandão de Oliveira for his critical reading and suggestions and the group of subjects for their participation. This study is supported by grants from the Carlos Chagas Filho Foundation for the Research Support in Rio de Janeiro (FAPERJ) and the Brazilian Council for the Research Development (CNPq).
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