Self-selection of exercise intensity requires that individuals rely on their own sensory effort cues and perceptions. Research examining self-selecting aerobic exercise training intensity has shown that individuals are able to self-select work rates that are appropriate for cardiovascular conditioning (9,16). The nature of aerobic conditioning is such that submaximal work intensities between 50 and 80% of o2max are ideal for conditioning (1). Resistance training, however, differs in that ideal results are achieved when the muscle experiences overload. Load intensities beyond 60% of 1 repetition maximum (1RM) appear adequate to invoke the strength training response. In fact, self-selection of exercise intensity appears to be a preferred method of exercise intensity selection (13). Research regarding self-selection of resistance training intensity is very limited. Rate of perceived exertion (RPE) has been shown to be helpful as a tool to distinguish weight training intensity. Gearhart et al. (8) showed that when external work was held constant, subjects rated resistance training at 90% 1RM significantly harder than 30% 1RM. Likewise, Day et al. (5) showed that rating effort according to an entire training session also showed differences according to training load. However, these studies did not examine the load naturally selected by individuals, but instead used assigned workloads.
Glass and Stanton (10) had novice lifters self-select loads over 2 days of resistance training. 1RM was estimated after the self-selection trials. Results showed that novice lifters chose resistance loads that were <60% of 1RM. This was seen in both men and women and meant that subjects were selecting loads too light to induce hypertrophy. They also showed that subjects did not lift to fatigue, as evidenced by a low number of repetitions despite a light load. This was seen despite their indication of hard efforts based on RPE. Therefore, while self-selection of aerobic training intensity appears appropriate, resistance training may require initial learning intervention. Effort sense is based on sensory “anchors” that help define the parameters of easy or difficult effort. It may be that effective anchors are in place for most individuals regarding submaximal aerobic exercise, but deficient for the supramaximal effort required with resistance training.
1RM testing within the typical training environment is time-consuming and also increases injury potential. However, novice lifters may benefit from a learning trial that helps extend the perceptual anchor of “heavy” to a higher intensity, thus increasing the load that an individual will self-select for resistance training. The purpose of the present study was to determine the effect of a resistance training learning trial on self-selected strength training intensity. It was our intent to determine whether a single learning intervention using a large muscle exercise (seated bench press) would be an adequate stimulus to increase the self-selected resistance training load.
Experimental Approach to the Problem
Past research has shown that individuals self-select resistance training loads that are too light to promote strength gain. Testing for 1RM for each lift is cumbersome and time-consuming, while self-selection relies on the individuals' own effort sense. We wanted to determine whether a minimal intervention learning trial using a large muscle group exercise would be adequate to provide sensory information adequate to promote a heavier self-selected load for all lifts. Subjects were divided into control and learning groups, using both men and women novice lifters. These were healthy and otherwise active individuals who were not accustomed to strength training. Control subjects self-selected with no previous learning, while the learning group self-selected after they had been exposed to a 2-set training bout at 75% 1RM using the seated bench press. All subjects were subsequently tested for estimated 1RM. This load was chosen since it represents the intermediate lifting load suggested by the American College of Sports Medicine (1).
Sixteen subjects (7 men, 9 women) were recruited for the study. Subjects provided signed consent in accordance with the Institutional Review Board and were individuals who had not performed any resistance training for the past 6 months. The study was conducted in accordance with the institutional policy for research with human subjects. Based on previous work by Glass and Stanton (10), who saw no differences in load selection between gender, we chose to combine gender and use a heterogeneous group. Subjects were divided into a control group (5 women, 3 men; age, 21.0 ± 2.4 years) and a learning group (4 women, 4 men; age, 20.9 ± 3.5 years). Recruited subjects had not been strength training for the past 6 months, and most had little or no lifting experience. All subjects completed an initial orientation day, where resting characteristics were measured and subjects were provided a weight training orientation. Subjects were set properly for the variable resistance exercises (Badger Magnum Selecterized Equipment) and instructed as to the proper form. Cadence was standardized (2 seconds up, 2 seconds down) for lifting. Subjects were alternately assigned to either a control or learning group.
Height and weight of subjects (control: 169.5 ± 7.4 cm and 64.5 ± 18.4 kg, respectively; learning: 176.0 ± 9.8 cm and 78.5 ± 25.3 kg, respectively) were measured using a Stadiometer (to the nearest centimeter) and a Health-o-meter scale (to the nearest 0.01 kg), respectively. Skinfold body density was determined (Lange calipers) using the 3-site Jackson et al. equations (14), and body fat was calculated (control: 16.0 ± 4.8%; learning: = 20.1 ± 8.2%) using the Siri equation (15). Resting systolic (control: 105.9 ± 11.7 mm Hg and learning: 115.0 ± 9.1 mm Hg) and diastolic (control: 72.4 ± 10.9 mm Hg and learning: 79.8 ± 8.7 mm Hg) blood pressure was measured with the subject seated using a standard stethoscope and sphygmomanometer. Resting heart rate (control: 71.8 ± 11.8 beats·min−1 and learning = 73.3 ± 11.8 b·min−1)was measured by manual palpation of the radial artery. There were no statistical differences between groups.
Control Group Weight Training Trials
Testing consisted of 3 separate days, with a minimum of 48 hours apart. The first day was an orientation day. Subjects were introduced to the Borg 6-20 RPE scale (3), completed a health history questionnaire, and were also given an orientation as to proper fitting and technique for lifting using selecterized weight equipment. On a second day, subjects reported to the gym for a self-selected strength training workout. Subjects were given an initial warm-up weight and asked to complete 10 repetitions as a warm-up. Following the warm-up, they were asked to self-select a load that they felt would contribute to a gain in strength. Subjects were allowed trial lifts of different loads as they attempted their self-selection. Subjects were blinded to the weight stack and the researcher adjusted load based on subject request. Two sets of the lifts were completed by the subjects. They were not given feedback concerning the suggested number of repetitions and could stop at any time. The opportunity to adjust load for the second set was given. Load and number of repetitions as well as immediate post-RPE were recorded. Lift order consisted of seated bench press, leg extension, seated back row, triceps extension, biceps curl, overhead shoulder press. On day 3, 48-72 hours later, subjects reported to the gym and an estimate of their 1RM was made for each lift using the equation of Brzycki (2). Relative lift intensity during self-selected trials was then calculated based on the estimated 1RM.
Learning Group Weight Training Trials
While control subjects completed 3 days of testing, learning group subjects completed 4. The learning group subjects completed the same orientation as the control group subjects with 1 exception. Subjects were tested for estimated 1RM for the seated bench press. Subjects began lifting at a light load, then the load was repeatedly increased until they completed between 5-10 repetitions to fatigue. Subjects remained blinded to the loads that they were lifting. 1RM was estimated. On the second day, subjects completed the learning trial. This consisted of exercise only on the seated bench. After a warm-up set, subjects were asked to complete 2 sets of 75% of 1RM. Subjects were encouraged to lift to fatigue. The RPE was obtained immediately after. Subsequent test days 3 and 4 were identical to those of the control group; that is, subjects completed 2 sets of a self-selected workout on all 6 lifts on day 3, followed by 1RM testing on day 4.
The second set of each lift was used in the data analysis. Independent means t-tests were used to determine differences between control and learning group subjects for all variables. Bonferroni's adjustment was used to minimize α error. Significance was set at p ≤ 0.01.
There were no differences in strength between the control and learning groups. Strength data are presented in Table 1.
Comparisons of self-selected load revealed that the learning group selected 21% more weight for the seated bench press (63.4 ± 6.4% 1RM) than the control group (50.3 ± 12.0% 1RM). However, this was not statistically different. This was the same lift used for the learning trial; all other lifts showed no significant difference in self-selected load. Self-selected loads are shown in Figure 1.
There were no significant differences in repetitions completed between the control and learning groups. Repetitions across lifts were between 11 and 15. Individual as well as mean repetition data are presented in Table 2.
There were also no differences in RPE between control and learning groups across all lifts. Of note is that the RPE for seated bench press was not significantly different despite a significantly greater self-selected load for the learning group. Individual and mean data for RPE are presented in Table 3.
A common scenario with health and fitness facilities is the initial client orientation to strength training. Clients receive an initial explanation of strength training principles, are measured to fit the resistance training machines, and then are mostly left to themselves to select load and progress, unless they use the services of a personal trainer. Previous work has shown that novice lifters self-select load intensities that are insufficient to induce strength gains (10). It was hypothesized that the reason for underselection of load is due to the limit of the perceptual range of the client. While aerobic training is submaximal in nature, resistance training requires working a muscle to fatigue with a load adequate to induce muscular stress. The aim of the present study was to determine whether a minimal learning trial intervention, where a client experiences a load and repetition effort sufficient to induce strength gain, could provide sufficient effort information to promote self-selection of appropriate resistance loads. Our results show that subjects showed a trend toward heavier load selection for only the seated bench press, the lift from which they received learning information. For all other lifts, the learning group subjects chose loads that were similar to the control group. Examination of individual results shows that the underselection occurs in men and women equally.
Strength gain is dependent on imposing load demands on the muscle sufficient to induce tissue adaptation (4,6,7). It is generally accepted that 60% of 1RM is the minimal load for strength gains (11). Previous research (10) and the present study show that subjects self-select loads that are too light for inducing strength gain. The learning trial, which provided the subjects perceptual feedback on the seated bench press at 75% 1RM and repetitions to fatigue, resulted in only a modest and insignificant increase in load selection and only for the seated bench press. Clearly, the learning trial was not sufficient to provide perceptual cues for load selection.
It is unclear whether the perceptual range of the subjects was extended as a result of the learning trial. Perceptual effort ranges are based on anchors that define the range of effort sensation (8). While the self-selected load for the learning group seated bench press was showing a trend toward increased load compared to the control group, the RPE was not different. Perhaps some perceptual learning did indeed take place, but this learning did not spillover to the other lifts.
In addition to training load, strength gain is also linked to muscular fatigue through adequate repetitions (6,12). Training loads of 50-60% of 1RM would be expected to elicit 15-25 repetitions prior to the onset of fatigue (11). Our data show that subjects were not only lifting light loads, they were also not lifting to fatigue. Both learning and control groups lifted around 12 repetitions for each muscle group. Perceptual information or anchoring regarding the fatigue sense is therefore also important in resistance training and may be even more difficult than load effort sense to learn.
The results of the present study, we believe, are the first to show that self-selection of weight training load is not a simple task. The perceptual range of what is heavy or overload, as well as the fatigue sense, is difficult to learn. These sensations may also differ by muscle group, adding to the complexity. While testing an individual's 1RM is time-consuming and cumbersome, self-selection of training load is not advisable. The value and benefit of a personal trainer, especially for strength training, seem clear; clients simply do not have the perceptual information to self-select load and require outside intervention to assist them with proper loading and effort. Additional research needs to examine the degree of intervention needed to provide the exerciser adequate anchors for training intensity so that the proper load and effort are self-selected. Without this training, many individuals will train at insufficient loads, will not lift to fatigue, and will see minimal improvements in strength.
Clients begin weight training programs typically with technique orientations and minimal feedback perceptually regarding load and effort unless working consistently with a personal trainer. As such, clients left to themselves will choose intensities that are too light and will not lift to fatigue. Providing a training trial of only 1 muscle group appears to be inadequate to increase load selection beyond the lift on which they received instruction. Trainers must keep this in mind as they work with clients and encourage adequate load selection as well as volitional fatigue.
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