The Effects of Lifting Lighter and Heavier Loads on Subjective Measures

Abstract

Background: Despite the progress made in the study of subjective measures in resistance training, some questions remain unanswered. Here the authors investigated if ratings of perceived exertion (RPE) can predict task failure and bar velocity across exercises and loads as a primary outcome and whether a battery of subjective measures differ as a function of the lifted loads as a secondary outcome. Methods: In this preregistered study, 20 resistance-trained subjects (50% female) first completed a 1-repetition-maximum test of the barbell squat and bench press. In the second and third sessions, they completed 2 sets of squats followed by 2 sets of bench press to task failure, using 70% or 83% of 1-repetition maximum, while bar velocity was recorded. RPE scores were recorded after every repetition. In addition to RPE, rating of fatigue, affective valence, enjoyment, and load preferences were collected after set and session completion. Results: Across conditions, RPE was strongly correlated with reaching task failure (r = .86) and moderately correlated with bar velocity (r = −.58). The model indicates that an increase in 1 RPE unit is associated with an 11% shift toward task failure and a 4% reduction in bar velocity, with steeper slopes observed in the heavier condition. Negligible differences were observed between the load conditions in rating of fatigue, affective valence, enjoyment, and load preference. Conclusion: RPE scores, collected on a repetition-by-repetition basis, accurately reflected reaching task failure across loads and conditions. Hence, RPE can be used to prescribe repetition numbers during ongoing sets. The negligible differences between load conditions in rating of fatigue, affective valence, enjoyment, and load preference indicate that when sets are taken to task failure, loads can be selected based on individual preferences.

“Just One More Rep!” – Ability to Predict Proximity to Task Failure in Resistance Trained Persons

“…The internal meta-analysis echoed the results of Experiment 2 supporting that participants under predicted. These results are mostly in line with previous findings (Hackett et al, 2012(Hackett et al, , 2016Giessing et al, 2016a,b;Altoé Lemos et al, 2017;Steele et al, 2017a;Zourdos et al, 2019;Emanuel et al, 2020;Hughes et al, 2020;Mansfield et al, 2020). However, in contrast with prior research this study is the first to examine predictive ability at the sdRM/0RIR.…”

“…The overall results of these studies suggest participants generally under predict the number of repetitions they can perform to MF whether predictions are made a priori to initiation of exercise, or at varying degrees of proximity to actual MF. Improved accuracy, which has been shown with subsequent sets (Hackett et al, 2012;Emanuel et al, 2020;Mansfield et al, 2020) or heavier loads (Altoé Lemos et al, 2017;Emanuel et al, 2020;Hughes et al, 2020), would suggest proximity to MF may play a role, though accuracy may still be imperfect. Indeed, Zourdos et al (2019) found that, despite improved accuracy of predictions with closer proximity to MF, participants still under predicted when they thought they were 5, 3, and 1 repetition away from MF (difference between predicted and actual of 5.15 ± 2.92, 3.65 ± 2.46, and 2.05 ± 1.73 for 5RIR, 3RIR, and 1RIR, respectively).…”

“…Many authors have examined the accuracy of participants' ability to predict proximity to MF across different exercises using both single and multiple sets, varying relative loads, and predictions both a priori and during sets at varying proximities to MF (Hackett et al, 2012(Hackett et al, , 2016Altoé Lemos et al, 2017;Steele et al, 2017a;Emanuel et al, 2020;Hughes et al, 2020;Mansfield et al, 2020). The overall results of these studies suggest participants generally under predict the number of repetitions they can perform to MF whether predictions are made a priori to initiation of exercise, or at varying degrees of proximity to actual MF.…”

“…An assumption inherent in use of RIR scales to provide valid control of intensity of effort is that participants can accurately predict their number of repetitions until MF. Several recent studies have examined this predictive ability under a variety of conditions, including a priori to beginning the exercise (Steele et al, 2017a;Emanuel et al, 2020), and at varying proximities to MF during the exercise (Hackett et al, 2012(Hackett et al, , 2016Altoé Lemos et al, 2017;Zourdos et al, 2019;Hughes et al, 2020;Mansfield et al, 2020). Most have shown that people are inaccurate in their predictions suggesting that, when using an RIR based prescription, they may be training at a lower actual effort than intended.…”

“…Indeed, prediction has been shown to be more accurate when using heavier loads (i.e., where fewer repetitions are possible such that any given repetition is closer to MF; Altoé Lemos et al, 2017;Steele et al, 2017a). Further, accuracy increases with subsequent sets possibly due to practice, or lingering fatigue (Hackett et al, 2012;Emanuel et al, 2020;Mansfield et al, 2020). However, only one study has examined varying proximities to failure (Zourdos et al, 2019).…”