Introduction
The choice, order, and volume (e.g., intensity, repetitions, sets, and rest periods) of exercise are variables that describe all possible single resistance exercise sessions (15). Knowledge of the effects that each variable has on a training session is important to maximize results and to help the individual achieve his or her respective health and fitness goals.
Exercise order refers to the sequence of resistance exercises in a training session. The order of exercises used depends on an individual's training goals. Traditionally, exercises involving large muscle groups have been recommended to be placed at the beginning of training sessions so that large muscle movements are not compromised by preexhausted smaller muscle groups (23). The practice of using an exercise order that involves alternating “push and pull” movements was one of the important early modifications in resistance training underlying large increases in strength (5,9). Exercisers, practicing this kind of exercise order, are most likely able to efficiently control unwarranted cocontraction between agonist and antagonist muscle groups. This type of exercise order is advantageous in that it allows the exerciser to work multiple opposing muscle groups with greater intensity. Another frequently used exercise order is to alternate between upper- and lower-body exercises. The benefit of this exercise order is that it facilitates recovery between exercises (4).
Sforzo and Touey (20) found that performance of exercises of the small muscle group before exercises of the large muscle group, in trained men, resulted in significantly less total force production in the exercises of the large muscle group and in the total training session. Other studies have been performed to determine the most optimal exercise order that will elicit favorable physiological adaptations.
Simao et al. (21) found no significant difference in ratings of perceived exertion (RPEs) between two different upper-body exercise sequences (large to small, small to large), suggesting that exercise order does not influence the sense of effort at the end of the session. However, they did find that performing exercises of both the large and the small muscle groups at the end of an exercise sequence resulted in significantly fewer repetitions in the three sets of a given exercise. More recently, Simao and colleagues (22) examined whether exercise order would have the same effect in trained women. Similar to the previous study, RPE was not significantly different between the sequences; however, the mean number of repetitions per set was always less when an exercise was performed later in the exercise sequence. Ultimately, both studies produced similar results regardless of the sex of the subjects.
A limitation of these studies is that they did not examine blood lactate concentration or affective responses as a result of these two exercise sequences. There could be some correlation between the amounts of lactate produced during a specific exercise order sequence and the number of repetitions completed. If lactate responses are similar between the two exercise sequences, this may provide a partial explanation for the maintenance of RPE seen by Simao and colleagues (21,22). Additionally, the measurement of affective responses after bouts of resistance exercise may provide useful information for researchers and practitioners.
The importance in studying affect and perceived exertion may reside in their propensity to influence exercise intensity and, consequently, impact program design and adherence (10). Most of the previous research in exercise science has examined the influence of aerobic exercise on affect and perceived exertion (7,11), but few studies have examined the influence of resistance exercise on these variables.
There has been some research providing evidence that resistance exercise can play a role in improving affect (2,16,18). Arent et al. (3) investigated the influence of intensity of resistance training on affect in correlation to RPE, salivary cortisol, and heart rate. They report that moderate intensity (70% of 10-repetition maximum [10RM]) elicited the most favorable affective responses in the participants compared with 40 and 100% of 10RM. As expected, heart rate, cortisol secretion, and RPE differed between intensity conditions. One limitation of the study was that they did not examine the role of blood lactate concentration and its effect on affect and RPE. Previous studies have shown a strong relationship between lactic acid and RPE (7), but the effects of blood lactate concentration on affective responses are unknown because of limited research examining these variables.
This project will investigate the influence of exercise order and its influence on blood lactate, affect, and perceptual responses to acute bouts of resistance exercise.
Methods
Experimental Approach to the Problem
The purpose of this investigation was to examine the effect of two different exercise orders on blood lactate concentrations, affective and perceptual responses. Data were collected during three sessions. During the first session, the 10RM was determined for all nine exercises being used in the study. Participants were asked to return two more times with 48-72 hours of rest between visits to ensure proper muscle recovery from the previous session. For sessions 2 and 3, exercise order was randomly determined so that participants either lifted with a large to small (Order A) or small to large muscle group order (Order B) during the second session and the opposing order during the third session. Order A consisted of the 1) seated machine chest press, 2) machine leg press, 3) seated machine rows, 4) seated machine leg extension, 5) seated machine overhead press, 6) seated machine hamstring curl, 7) seated machine biceps curl, 8) calve raises performed on machine leg press, and 9) standing cable triceps extension. The reverse order of the exercises used in Order A was used for Order B. Therefore, the order of exercises used in Order B was 1) triceps extension, 2) calve raise, 3) biceps curl, 4) hamstring curl, 5) overhead press, 6) leg extension, 7) rows, 8) leg press, and 9) chest press.
On the subsequent testing days, participants performed two sets of each lift; the first set was a warm-up at 80% 10RM, followed by a set at 100% 10RM. A minimum of a 1-minute rest interval, of passive recovery, took place in between each set, except after sets in which blood lactate samples were taken and affect was measured. After all second sets (100% of 10RM) of each exercise, heart rate and RPE were measured and recorded. Each subject's RPE was assessed using Borg's CR-10 Rating of Perceived Exertion Scale (7).
This study used a common protocol that is often used in training subjects, such that push-pull as well as upper- and lower-body exercises were alternated. This training stimulus allows for appropriate recovery between sets for muscle groups, and it meets training recommendations proposed for gaining fitness and health benefits (1).
Subjects
Eleven men (age, 20.8 ± 2.0 years; height, 179.1 ± 6.4 cm; body mass, 81.7 ± 9.4 kg; body fat, 12.9 ± 3.4%) and 18 women (age, 20.9 ± 1.8 years; height, 168 ± 4.6 cm; body mass, 63.0 ± 7.3 kg; body fat, 21.8 ± 3.2%) participated as subjects in the study. Percent body fat was determined using the Omron Hand Held Body Fat Analyzer. Eighty percent of the men and 77.8% of the women reported engaging in resistance training (one man did not complete the questionnaire). Men reported more sessions per week of resistance exercise compared with women (3.2 ± 1.9 and 1.9 ± 1.3 sessions per week, p = 0.042) as well as more metabolic equivalents (METs) per week from resistance exercise (22.1 ± 16.5 and 8.3 ± 8.0, p = 0.006). Overall physical activity was measured by the Aerobics Center Longitudinal Study Physical Activity Questionnaire (14) and was not different between men and women (76.4 ± 39.5 and 63.4 ± 37.4 METs per week, p > 0.05). All subjects answered the Physical Activity Readiness Questionnaire (25) and signed an informed consent form that was approved by the university's institutional review board before participation in the study.
Ten-Repetition Maximum Testing
The 10RM was determined during session 1. The 10RM protocol followed the same 10RM testing format as suggested by the National Strength and Conditioning Association (4). The total duration of this session was significantly longer compared with sessions 2 and 3 because of increased recovery time between sets of each test exercise. The order of exercises for the 10RM determination during session 1 followed the large to small order (Order A). All exercises were performed on Body Master Resistance training machines except the standing triceps extension. The standing triceps extension was performed on the cable pulley attachment of a universal machine setup. An inverted V-bar was used for the triceps extensions. The order of exercises also ensured an alternation of upper- and lower-body exercises, as well as push and pull exercises, so that a sufficient level of recovery occurred before the next determination of 10RM (4).
To prevent significant error or injury during the 10RM determination of each exercise, the following actions took place. 1) Participants received instructions in proper lifting technique for each exercise. Proper technique for each exercise was evaluated based on standards proposed by the International Weightlifting Association (8). 2) Participants were monitored for correct technique during each exercise test. 3) Participants received spots from the researchers. 4) Participants were provided motivational verbal encouragement to perform at maximal effort. Improper lifting techniques during a trial attempt were strongly discouraged, and an attempt was terminated immediately if the participant was executing the test exercise with improper technique.
The 10RM tests were administered after each subject warmed up by performing a few sets of the test exercise with lighter loads. The first attempt was with about 50% of the participant's estimated 10RM weight. After the participant had about 2-4 minutes of passive recovery to feel recovered from the previous attempt, the weight was then increased to be somewhat more difficult. The increase in load was based on the ease with which the previous trial was performed. Determination of 10RM, for each test exercise, never took more then five attempts. The five attempts did not include the very light warm-up attempt. These stipulations concerning the amount of attempts executed were necessary to negate any effect fatigue could possibly have on the final result. If participants, while performing a trial attempt, sensed they could perform 10 repetitions with the designated load, the trial attempt was quickly terminated. This ensured that participants would spare themselves from any unnecessary muscular fatigue, thus allowing for the most accurate 10RM to be determined for each exercise.
Exercise Sessions
Between 48 and 72 hours after the 10RM determination session took place, participants were asked to participate in two more exercise sessions in which they would perform one of two exercise sequences in a randomized, counterbalanced design. Fifteen subjects participated in Order A first, and 14 subjects participated in Order B first. The exercise sequence for Order A was 1) chest press, 2) leg press, 3) rows, 4) leg extension, 5) overhead press, 6) hamstring curl, 7) biceps curl, 8) calve raise, and 9) triceps extension. The exercise sequence for Order B was 1) triceps extension, 2) calve raise, 3) biceps curl, 4) hamstring curl, 5) overhead press, 6) leg extension, 7) rows, 8) leg press, and 9) chest press. For consistency, a similar alternating upper/lower body, push/pull pattern was used. (4)
Two sets of each exercise were performed. The first set was a warm-up set in which the participant performed a set of 10 repetitions at 80% of his or her 10RM for the specific exercise. A minimum of 1 minute of passive recovery was allowed before the execution of the second set, in which the participant performed a set of 10 repetitions at 100% of his or her 10RM for the specific test exercise. After the second set of each test exercise, heart rate and RPE were measured and recorded. A minimum of a 1-minute rest interval, of passive recovery, took place between exercises, except after sets where blood lactate samples were taken and affect was assessed. Blood lactate via finger stick was recorded preexercise, after exercises 1) chest press or triceps extension, 5) overhead press, and 9) triceps extension or chest press, and 10 minutes postexercise in both sessions. Blood was collected in a capillary tube and then placed in the Accusport portable blood lactate analyzer (Sports Resource Group, Boehringer Mannheim, Hawthorne, NY). This portable lactate analyzer has been found to be valid and reliable (6). Affect was measured by two single-item scales, the Feeling Scale (13) and the Felt Arousal Scale (24), which represents the two major dimensions of the circumplex model of affect (19). The Feeling Scale measures affective valence, and the Felt Arousal Scale measures activation/arousal dimensions of the circumplex model of affect.
During the exercise sessions, subjects were verbally encouraged to perform all second sets with maximal effort, and the same definitions of a complete range of motion used during the 10RM testing were used to define completion of a successful repetition. Verbal cues were made to reemphasize control of repetition velocity during specific test exercises. The total number of repetitions for each set of each exercise was also recorded.
Statistical Analyses
Repeated-measures general linear modeling (RM GLM) was used to determine main and interaction effects of exercise order and time (within-subjects repeated measure) on lactate, repetitions, RPE, and affective responses. Gender was used as a between-subjects factor in all analyses. Correlation analyses examined the relationship between blood lactate, RPE, and affective responses during and immediately after resistance exercise. A significance level of p ≤ 0.05 was selected a priori. A Bonferroni correction was performed for all post hoc analyses.
Results
Lactic Acid Responses to Resistance Exercise
Results from the RM GLM for lactate revealed a significant effect for gender (p = 0.008), time (p = <0.001), time × gender (p = 0.018), and condition × time (p = 0.046). Men had greater lactate responses when compared with women. The interaction effects were attributable to significant differences in lactate production after overhead press, with the large to small exercise order having greater lactate (p = 0.013), but this effect was only significant in women (p = 0.024). A pictorial depiction of the lactate responses is provided in Figure 1.
Figure 1: Time course of lactate responses in men and women for two different exercise orders. EX1 = chest press in large to small and triceps extension for small to large; EX5 = overhead press in both conditions; EX 9 = triceps extension in large to small and chest press for small to large. *Significant difference between two sequences for that time point in the total group (p = 0.013) and in women (p = 0.024).
Number of Repetitions and Ratings of Perceived Exertion
Comparison between sequences showed a significant difference (p = 0.01) for the average number of repetitions between the large to small (9.8 ± 0.3) and small to large condition (9.9 ± 0.1). However, there was not a significant difference (p > 0.05) in the mean RPE between the large to small (8.0 ± 1.0) and small to large condition (7.9 ± 1.1). There were no gender differences for repetitions or RPE.
Affective Responses to Resistance Exercise
Results from the RM GLM for affect (Feeling Scale and Felt Arousal Scale) revealed a significant effect for condition (p = 0.047), time (p = < 0.001), and condition × time (p = 0.036). In the large to small exercise order, there was no change in Feeling Scale with time; however, there was a change in Felt Arousal Scale (p < 0.001). In the small to large exercise order, there was a significant effect for time in both Feeling Scale (p < 0.001) and Felt Arousal Scale (p < 0.001). See Figure 2 for a pictorial depiction of the temporal dynamics of the affective responses to resistance training.
Figure 2: Feeling Scale (FS) and Felt Arousal Scale (FAS) responses to the two different exercise orders. During is after overhead press in both conditions.
A paired-sample t-test was conducted to examine differences in Feeling Scale and Felt Arousal Scale for the two exercise orders at the different time points. Significant differences were only found for Feeling Scale during exercise (after overhead press; p = 0.002) and at 10 minutes postexercise (p = 0.039), with the small to large exercise order having greater Feeling Scale responses (see Figure 3).
Figure 3: Feeling Scale responses to the two different exercise orders. “During” = after overhead press in both conditions. *Significant difference between two sequences for that time point (p < 0.05).
Relationship Between Blood Lactate, Ratings of Perceived Exertion, and Affective Responses
The results indicate that there were no significant correlations (p > 0.05) between blood lactate and perceptual or affective responses at any time point and in either exercise order.
Discussion
The current study found that blood lactate production increased as a result of resistance exercise regardless of exercise order; however, further examination showed that during exercise (after overhead press), blood lactate was lower in the small to large exercise order. Additionally, men had a greater lactate response overall compared with women. This difference between men and women may be a result of previous resistance exercise experience. Even though there was not a difference in the percentages of men and women who reported resistance training, men reported engaging in more sessions per week of resistance exercise and expended more energy during these sessions than women. Therefore, it is likely that the men have experienced greater training adaptations and can produce and tolerate higher levels of lactic acid (12). As mentioned formerly, the previous studies examining exercise order have not examined blood lactate production as a result of the exercise session (20-22). Interestingly, blood lactate was not significantly correlated with either RPE or affective responses in this study. This finding is counter to traditional thinking that lactate influences affect and RPE.
Another finding from this study is that the average number of repetitions completed per exercise was greater in the small to large condition compared with the large to small condition. This suggests that a greater training volume could be achieved in the small to large condition, with the result of greater health and fitness benefits. Despite the difference in number of repetitions, there was not a difference in mean RPE by exercise condition. The inability to find a difference in mean RPE by condition is consistent with previous research by Simao and colleagues, who have not been able to demonstrate differences between exercise conditions. It is also noteworthy that there were not differences between men and women despite the fact that there were gender differences in lactic acid production.
Finally, changes in affect were observed as a result of resistance exercise. Similar to what has been reported in aerobic exercise (10,11), immediately after exercise there was an increase in affective valence and arousal indicating an activated pleasant state. This finding occurred regardless of exercise order. However, in the small to large exercise condition, affective valence as measured by the Feeling Scale was more positive during exercise, measured after overhead press, and at 10 minutes postexercise. This finding is of interest because, as has been suggested by Ekkekakis and colleagues (10,11), affective valence during exercise may be important in adherence to exercise programs. Two recent studies have found that affect was predictive of exercise adherence in the training program (17,26). These same findings might hold true in resistance exercise as well.
Few studies have examined affect as a result of resistance exercise. Arent and colleagues (3) found that affective responses were more positive after moderate-intensity resistance exercise compared with low- and high-intensity exercise. The results of the current study are consistent with these findings because the overall intensity of the exercise session could be considered moderate. The present study does provide an interesting addition by examining affect during the exercise session. No previous study has examined affective responses during resistance exercise.
One limitation of the study is that the training stimulus provided in this study would likely not be adequate for performance enhancement. The training stimulus used in this study would be deemed by many to be of moderate intensity. However, the stimulus is one that is likely to provide health benefits for the average person, and it would seem appropriate for our sample, which consisted of college-aged men and women who were physically active and recreationally fit. This stimulus meets with previous American College of Sports Medicine (ACSM) guidelines for health benefits and is one that would be beneficial for reducing chronic diseases (1). Specifically, this study incorporated exercises of all the major muscle groups and at an intensity that is consistent with the recommendations of ACSM for health benefits. Future studies that emphasize the influence of higher-intensity exercise prescriptions for performance enhancement are also needed. Manipulations of training volume (repetitions, sets, and intensity) may provide differing results than what the current study provided. Another avenue for future studies would be to incorporate free weight exercises instead of only machine exercises. Machine exercises were used in this study to ensure the safety of the subjects, but also because of availability for the researchers. However, the possible increased muscle activation with free weights may influence lactic acid production as well as perceptual and affective responses differently from what was seen in this investigation. In summary, the results from this study demonstrate that there are some differences that occur physiologically and psychologically during exercise, depending on which type of exercise order is used by the participant. The results from this study show that in the small to large exercise condition, participants were able to complete more repetitions, had lower blood lactate during the exercise session, and experienced more positive affect during the exercise session. Speculation based on these findings suggests that participants may be more likely to adhere to exercise when these training demands are in place.
Practical Applications
Applying the results to exercise prescription, a small to large muscle group order might be more beneficial for sedentary, elderly, or obese individuals when trying to improve health. On the basis of the recorded significant differences in affective responses, the small to large exercise order may lead to a more enjoyable workout, which, in return, will increase exercise adherence. However, using this kind of exercise order may not be desirable for performance enhancement because of a possible decreased force production on large muscle group exercises. Strength coaches should inform athletes of a possible performance decrement if a small to large exercise routine is being applied in their program.
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