Impact of Augmented Feedback and Music During the Bench Press Resistance Exercise: Does Their Combination Compromise Mechanical Performance?

Abstract

Background:

Verbal feedback (knowledge of results [KR]) and listening to music are common ergogenic strategies used to boost athlete performance during resistance exercise. No previous research has explored their effects when both strategies are combined in the same exercise session (KR+music). This study aimed to examine the impact of providing KR, listening to music, and their combined effects on: (1) mechanical responses (number of repetitions, fastest velocity, and average velocity in a set), and (2) perceptual responses (feeling scale [FS], rating of perceived exertion [RPE], and rate of perceived discomfort [RPD]) when a determined percentage of velocity loss (%VL) is prescribed.

Hypothesis:

Providing KR or listening to music would provide an ergogenic effect on these outcomes whereas KR+music can compromise mechanical performance.

Study Design:

Cross-sectional study.

Level of Evidence:

Level 3.

Methods:

Fifteen recreational resistance-trained men were tested on 5 occasions separated by a 48 to 72 hour washout period. The first session was used to determine the bench press 1-repetition maximum (1RM) strength. The 4 experimental sessions were identical (4 sets at 70% 1RM with a 20%VL during bench press exercise) except for the intervention (ie, control, KR, music, and KR+music) used randomly on each session.

Results:

The findings revealed that: (1) mechanical performance was significantly greater for the music condition (from 5.7% to 20.4%), followed by the KR+music (from 4.9% to 15.4%) and KR (from −0.4% to 8.1%) condition, and (2) greater FS values were found for music compared with control condition, while no significant differences were reported for RPE or RPD.

Conclusion:

Listening to music enhances bench press performance and mood; adding KR does not compromise these benefits.

Clinical Relevance:

Recreational athlete performance may benefit from listening to music, and KR+music does not compromise this effect. However, athlete preference should take priority when implementing these ergogenic strategies.

Resistance training (RT) is the most effective intervention for inducing favorable adaptations in muscle hypertrophy, strength, and power.^28,35 These training adaptations are pivotal for enhancing athletic performance and overall health.^1,25 Nevertheless, to optimize the benefits of RT, precise adjustments of key training variables such as volume (eg, repetitions) or lifting velocity, are essential.^9,24 In fact, training at maximum intended velocity has been shown to significantly enhance athletic performance and neuromuscular adaptations (eg, selective and greater recruitment of fast-twitch muscle fibers and higher motor unit firing frequency).^10,22,30 In this regard, velocity-based training (VBT) has emerged in strength and conditioning as an objective methodology that allows a more precise prescription of the training stimulus by using the maximal intended concentric velocity.^27,34 Although there are different approaches to prescribing training volume, monitoring velocity loss (ie, percentage difference in velocity between the fastest and last repetition of the set; %VL) is the most common approach reported in the VBT literature.^13,19 However, it remains uncertain whether the adaptations from the %VL prescription method can be enhanced by ergogenic strategies such as receiving augmented feedback, listening to music, or the combination of both strategies. Previous results suggest that these strategies have the potential not only to improve lifting velocity but also to reduce perceptions of fatigue, possibly allowing a higher volume for a given %VL.^4,6,38

The type and amount of feedback provided to the athlete can significantly enhance the kinetic, kinematic, and perceptual outcomes. ³⁸ In the context of VBT, the proliferation of technology has allowed real-time measurement of movement velocity (ie, augmented feedback) that can give immediate knowledge of results (KR).^17,18,31 The provision of KR immediately after each repetition has been shown to be an effective strategy for inducing acute mechanical improvements in strength and power during the bench press and back squat exercises.^6,18,36,39 Moreover, these mechanical improvements have been found to occur alongside increases in motivation and competitiveness. ⁴⁰ Despite the mechanical and perceptual improvement, it is unknown whether the KR effects can be compromised when subjects listen to music at the same time during the RT sessions.

Athletes and recreationally active people often use music to boost their performance and motivation during workouts. ²⁰ Therefore, the effects of music on sports performance have been studied extensively, and evidence largely supports its use as an ergogenic aid.^2,4,14,20 This phenomenon can be attributed to a mental diversion effect in which music shifts focus away (ie, external focus) from the physical strain of exercise.^4,6,8 As a result, the influence of music in RT sessions can benefit both mechanical and perceptual outcomes.^3,4,6,36 For example, previous research suggests a higher isometric maximal strength, ³⁶ lifting velocity and power, ⁶ greater strength-endurance (eg, repetitions to failure against a given load), ³⁶ and lower rating of perceived exertion (RPE) for music compared with the control group during RT sessions. ³⁶ However, no previous study has explored whether a higher kinematics performance and repetitions can be achieved for a given %VL prescription method when listening to music.

Attention allocates neural resources to the most relevant stimuli based on immediate environmental demands, allowing quick responses and efficient goal achievement by filtering out less relevant information ²¹ . Previous research showed that stimuli can be identified simultaneously, but selecting an appropriate response for multiple stimuli may cause interference (see cocktail-party problem for further details). ⁷ In particular, this phenomenon is crucial when multiple ergogenic strategies are intended to be used at the same time. To address the current research gaps, we aimed to examine the effect of providing KR or listening to music separately, as well as their combined effects (KR+music) on: (1) mechanical responses (number of repetitions, fastest velocity [fastest mean concentric velocity of the set], and average velocity [average of all mean concentric velocities of the set] in a set); and (2) perceptual responses (feeling scale [FS], RPE, and rate of perceived discomfort [RPD]) when a determined %VL is prescribed. It was hypothesized that an ergogenic effect on mechanical and perceptual outcomes for providing KR or listening to music whereas KR+music can compromise the mechanical performance.^{17,18,31,39,40} The study’s findings are expected to yield significant information about how coaches can combine the effects of providing KR or listening to music to increase the acute performance of their athletes.

Methods

Study Design

This study used a repeated-measures within-groups study design to compare the acute effects of providing KR, listening to music, or KR+music effects on RT mechanical performance and perceptual responses. Subjects were tested on 5 occasions separated by a 48 to 72 hour washout period to avoid excessive fatigue in the subsequent sessions. The first session was used for anthropometric measures and to determine bench press 1-repetition maximum (1RM) strength. The remaining 4 experimental sessions were identical (4 sets at 70% 1RM with a 20%VL during bench press exercise) except for the intervention (ie, control, KR, music, and KR+music) allocated randomly (through an excel function) to be performed at each session to avoid potential learning effects. All sessions were conducted at the university’s research laboratory at the same time of the day for each subject and under similar environmental conditions (approximately 22 ºC and 60% humidity).

Participants

A total of 15 recreational resistance-trained men (age, 22.1 ± 1.6 years [range, 20-25 years]; body mass, 75.8 ± 8.5 kg; body height, 1.75 ± 0.04 m; bench press 1RM relative to body mass, 1.16 ± 0.24 [range, 0.70-1.63]; absolute bench press 1RM, 88.1 ± 21.0 kg [range, 57-129 kg]) volunteered to participate in this study. Subjects had 2.8 ± 1.3 years of RT experience and were accustomed to performing the bench press exercise (‘Tier 1: Recreationally Active’ based on the performance caliber of McKay et al ²⁶ ). Most participants (13 out of 15) were already familiar with the maximal intended lifting velocity, but all underwent a familiarization session with a researcher experienced in VBT methods. Of note, a single familiarization session has proven sufficient to detect KR effects during the subsequent RT sessions.^17,18 Subjects did not have any physical limitations or injuries that could impact their performance in the bench press exercise. They were not allowed to perform any additional strenuous physical activity over the course of the study. Before beginning the study, subjects were briefed on the study procedures and provided written informed consent. However, the study’s objectives were intentionally kept undisclosed to prevent any potential interference with the outcomes being tested. The study protocol adhered to the tenets of the Declaration of Helsinki and was approved by the University of Almeria Review Board (IRB approval no. UALBIO2023/016). To quantify the effects of augmented feedback and music on the primary outcome measures (ie, mechanical responses), an a priori sample size calculation conducted using G*Power Version 3.1.9.6 (effect size [ES] of 0.20, alpha of 0.05, statistical power of 0.95, 2 number of groups, 4 number of measurements, and a correlation among repeated measurements of 0.90 revealed a total sample size of 14 participants).

Procedures

Body Composition and 1RM Assessment (Session 1)

Body mass (Seca 899, Seca Ltd) and body height (Seca 202, Seca Ltd) were measured at the beginning of the session. Then, a standard incremental loading test was used to determine the bench press 1RM strength. ¹² The general warm-up consisted of jogging, dynamic stretching, upper-body joint-mobilization exercises, and 1 set of 5 repetitions with an external load of 20 kg. Thereafter, the external load was progressively increased in 10 kg increments until the mean velocity was <0.50 m s⁻¹. From that moment, the load was increased in increments of from 5 to 1 kg until the 1RM load was reached. The average number of loads tested was 7.7 ± 2.0. Two repetitions were executed with light-medium loads (mean velocity > 0.50 m s⁻¹) and 1 repetition with heavy loads (mean velocity ≤ 0.50 m s⁻¹). The mean concentric velocity (ie, average velocity from the first positive velocity of the barbell until the velocity of the barbell was 0 m s⁻¹) of each repetition was recorded at 1,000 Hz using a validated linear velocity transducer (T-Force System; Ergotech).^11,33 The rest between loading conditions was fixed to 4 minutes.

The bench press exercise was performed with a standard Olympic barbell and calibrated bumper weight plates (Ruster). Subjects initiated the task holding the barbell with a self-selected grip width and their elbows fully extended. ³² From this position, they lowered the barbell in a controlled manner until touching the chest at the level of the sternum, and then they lifted the barbell as fast as possible until their elbows reached full extension (ie, touch-and-go technique).^12,32 Subjects used the standard 5-point body contact position technique (head, upper back, and buttocks placed firmly on the bench, and both feet flat on the floor) and were not allowed to bounce the barbell off their chests or raise the trunk off the bench. Velocity performance feedback was provided verbally after completing each repetition to encourage maximal effort.^18,31

RT Conditions (Sessions 2-5)

Each session began with the same general warm-up described above. The specific warm-up consisted of 1 set of 6, 4, and 2 repetitions at 40%, 60%, and 80% of 1RM, respectively. Thereafter, subjects performed 4 sets at 70% 1RM during the bench press. The sets ended when a 20%VL threshold was exceeded for 2 consecutive repetitions. The fastest repetition on the first set was used to define the target %VL threshold.^13,19 Inter-repetition rest was set at 1 second so that feedback could be received by the subject while the inter-set rest was fixed at 4 minutes. Subjects were instructed to perform all repetitions with maximal intent. No verbal encouragement (eg, ‘Come on, push it!’) was provided for any RT condition and the same absolute load was maintained. Special care was taken to maintain consistent bench press technique (eg, grip width) across all experimental conditions. The only difference among the 4 RT conditions was as follows:

• - Control: subjects did not receive KR or listen to music during the RT session.

• - KR: subjects received KR immediately after each repetition. The mean velocity was provided by the lead investigator at a volume slightly louder than normal conversation volume.^17,18,31

• - Music: subjects listened to electronic dance music during the RT session. A playlist of 20 songs was created on the Spotify music platform: https://open.spotify.com/playlist/2Dbka1B4amOpGktV36fCzT?si=YCJwjDK0R6C2pnPhuX-7Og&nd=1&dlsi=78ad878f04bc4929. All songs had a tempo >120 bpm, the volume was set at ≈70 decibels using a loudspeaker and all the songs were randomized to prevent any specific effects to a particular training set.^4,8

• - KR+music: subjects received immediate KR while simultaneously listening to the music described above.

Subjects completed the felt arousal scale at the beginning of the session to ensure consistent valence and activation conditions before the experimental sessions. The felt arousal scale is a 6-point numerical rating scale used to measure affective responses along the arousal dimension. ¹⁵ Subjects also sequentially completed the FS, RPE, and RPD scales after the last training set. The FS is an 11-point numerical bipolar rating scale designed to assess the subject’s current mood along the valence dimension. ¹⁵ The RPE (Question: ‘How hard do you think you are working?’) and RPD (Question: ‘How much discomfort do you feel?’) scales are an 11-point numerical rating scale used to assess perceptions of effort and perceptions of discomfort where 0 indicates “no exertion” or “no discomfort,” and 10 indicates “maximal effort” or “maximal discomfort,” respectively. ³⁷

Statistical Analyses

The normal distribution of the data was confirmed using the Shapiro-Wilk test (P > .05), except for felt arousal, FS, and RPE, and RPD. A 2-way repeated-measures analysis of variance (ANOVA) (condition [control, KR, music, and KR+music] × set number [first, second, third, and fourth]) was conducted on each RT performance indicator (numbers of repetitions, fastest velocity, and average velocity). Pairwise comparisons were identified using Bonferroni post hoc corrections. The Friedman test was used to compare the felt arousal, FS, RPE, and RPA scales during different conditions. The Wilcoxon signed-rank test with Bonferroni post hoc corrections was used for pairwise comparisons. The magnitude of the differences was quantified through the standardized mean difference (Cohen’s d effect size [ES] calculated as means difference divided by the pooled standard deviation) with their respective 95% confidence interval (CI). The ES was interpreted as follows: trivial (<0.20), small (0.20-0.59), moderate (0.60-1.19), large (1.20-2.00), and extremely large (>2.00). ¹⁶ Statistical analyses were performed using SPSS (IBM SPSS Version 25.0). Statistical significance was set at P < .05.

Results

A main effect of condition was reported for the number of repetitions, fastest velocity, and average velocity (F_(3,42) ≥ 7.9; P < .01) (Table 1). The number of repetitions was significantly greater for the music and KR+music conditions compared with the control condition (P = .03 and P < .01, respectively). The fastest velocity was significantly greater for the music condition compared with the KR condition (P = .01). The average velocity was significantly greater for the music and KR+music conditions compared with the control condition (P = .01 and P = .04, respectively) and for music condition compared with the KR condition (P < .01) (Figure 1). The main effect of set number was only observed for the number of repetitions (F_(3,42) = 3.1; P = .04) because it tended to be lower for set 4 than for sets 1 and 2 (P = .21 and P = .20, respectively). None of the condition × set number interactions reached statistical significance (F_(9,126) ≤ 1.8; P ≥ .07). The standardized differences between the control and experimental conditions for the number of repetitions, fastest velocity, and average velocity are depicted in Figure 2.

Table 1.

Comparison of the number of repetitions, fastest velocity, and average velocity between RT condition and set number

Variable	Set number	Condition				Condition		Set number		Interaction
		Control	KR	Music	KR+music	F (3,42)	P value	F(3,42)	P value	F (9,126)	P value
Number of repetitions	1	7.7 ± 1.8	8.1 ± 2.2	8.9 ± 2.1	9.0 ± 2.4	5.1	<.01	3.1	.04	0.3	.99
	2	7.7 ± 2.7	8.3 ± 2.2	8.9 ± 1.8	8.5 ± 2.5
	3	7.1 ± 2.3	7.9 ± 1.7	9.1 ± 2.6	8.5 ± 2.5
	4	7.1 ± 1.9	7.5 ± 1.9	8.5 ± 1.7	7.9 ± 1.9
Fastest velocity (m s−1)	1	0.62 ± 0.06	0.61 ± 0.06	0.63 ± 0.08	0.64 ± 0.07	5.2	<.01	0.9	.43	1.8	.07
	2	0.62 ± 0.06	0.61 ± 0.07	0.65 ± 0.09	0.63 ± 0.06
	3	0.59 ± 0.05	0.61 ± 0.07	0.64 ± 0.10	0.64 ± 0.07
	4	0.60 ± 0.06	0.60 ± 0.07	0.65 ± 0.06	0.65 ± 0.08
Average velocity (m s−1)	1	0.55 ± 0.05	0.54 ± 0.06	0.58 ± 0.08	0.58 ± 0.06	7.9	<.01	0.5	.66	0.8	.66
	2	0.55 ± 0.05	0.55 ± 0.07	0.58 ± 0.08	0.57 ± 0.06
	3	0.53 ± 0.04	0.55 ± 0.07	0.59 ± 0.09	0.57 ± 0.07
	4	0.53 ± 0.06	0.54 ± 0.06	0.59 ± 0.06	0.57 ± 0.07

KR, knowledge of results; RT, resistance training.

Data are presented as means ± SD.

Figure 1.

Comparison of the number of repetitions (upper panel), fastest velocity (middle panel), and average velocity (lower panel) between RT conditions. The average value of the 4 training sets is depicted, whereas numbers represent the P value obtained through the analysis of variance with Bonferroni correction. KR, knowledge of results; RT, resistance training.

Figure 2.

Standardized differences (95% confidence interval) in the number of repetitions (upper panel), fastest velocity (middle panel), and average velocity (lower panel) between the control condition and KR (filled circles), music (open triangles), and KR+music (filled squares). RT performance indicators of each set (1, 2, 3, and 4) or of the entire session (grand mean) are depicted. %Δ, percent difference ([experimental − control]/control] × 100); KR, knowledge of results; RT, resistance training.

Significant differences were observed between RT conditions for the FS (χ²_{(3, N = 15)} = 8.1; P = .04), but not for the felt arousal (χ²_{(3, N = 15)} = 3.2; P = .367) or RPE and RPD (χ²_{(3, N = 15)} = 1.8 and 4.6; P = .61 and P = .20, respectively). FS values were significantly greater for the music condition than for the control condition (P = .01; ES = 0.85) (Figure 3).

Figure 3.

Box-and-whiskers plots for felt arousal (upper left panel), feeling (upper right panel), RPE (lower left panel), and RPD (lower right panel) scales. Boxes correspond to the 25th and 75th percentile (top and bottom of the box, respectively) and the line in the box marks the median (50th percentile). Whiskers correspond to the 10th to 90th percentiles. Data not included between the whiskers are plotted as outliers (dots). Numbers represent the Pvalue obtained through the Wilcoxon signed-rank test with Bonferroni correction. RPD, rating of perceived discomfort; RPE, rating of perceived exertion.

Discussion

This study compared the acute impact of providing KR, listening to music, or KR+music on mechanical RT performance and perceptual responses. The study’s main findings revealed that: (1) mechanical performance (number of repetitions, and fastest and average velocity) was greater for the music condition (increased from 5.7% to 20.4%), followed by the KR+music condition (from 4.9% to 15.4%), and KR condition (from −0.4% to 8.1%), (2) greater FS values were found only for the music compared with control condition, whereas no significant differences were reported for the RPE and RPD values. Taken together, listening to music can be a simple and effective strategy to improve bench press mechanical performance while positively affecting people’s feelings. In addition, the KR+music combination does not provide additional ergogenic effects compared with music alone.

Providing verbal velocity feedback right after each repetition has been shown to be an effective method to enhance mechanical performance in strength and power during bench press and back squat exercises.^18,31,40 However, contrary to our first hypothesis, providing KR did not reveal significant effects on mechanical performance compared with the control condition. Nevertheless, a positive trend was observed for the number of repetitions performed as reflected in the increasing percentage values in Figure 2. The lack of significant differences can be explained by the interaction of 3 factors: (1) feedback form (visual vs verbal), (2) participants training status and muscle mass involved in the exercise, and (3) lack of motivation. First, it was found that conscientiousness (ie, a personality trait characterized by being responsible and persistent) showed a higher association with average velocity improvements for visual compared with verbal conscientiousness. ³⁹ These results suggest that people with lower conscientiousness may experience greater benefits from receiving verbal encouragement during RT. Second, training status and exercise selection can affect motor unit recruitment, suggesting that highly trained athletes can show greater improvements from feedback, specifically when performing exercises that engage larger muscle groups (eg, lower-body exercises).^39,40 Third, our results showed no motivation effect when KR was provided, despite feedback being widely reported to improve mood and perceptions of effort. Taken together, the interplay of these 3 factors might account for the lack of improvement in both mechanical and perceptual variables for the KR condition.

Music can enhance both mechanical and perceptual components during RT tasks.^4,8 Recent research suggests that these improvements occur because music boosts arousal (ie, state in which you feel excited), leading to improved task-focused attention. ²³ However, no previous research has explored how these effects can enhance performance when a determined %VL is prescribed. Our second hypothesis was accepted since our study’s findings show that music with a fast tempo enhances the number of repetitions, as well as the fastest and average velocity of the set. These results agree with previous literature that has shown that music can help maintain neuromuscular performance with loads between 60% and 80% 1RM,^3,5,29 and higher mean power and velocity against the 75%1RM during the bench press exercise. ³ Regarding the perceptual variables measured in this study, our second hypothesis was partly rejected since our study’s results did not find significantly higher RPE or RPD values. However, FS values were greater during the music condition, but it seems that this factor did not explain the increment of the mechanical performance (a posteriori analyses revealed no significant correlations (P ≥ 0.08) between FS values and mechanical performance during the music condition). Most of the scientific studies in this field to date have reported lower RPE values for the music condition when repetitions to failure are performed during the bench press and back squat exercises.^3,6,36 In contrast, Moss et al ²⁹ found slightly higher RPE values for different music genres compared with the control condition. Although our study did not find statistical differences in RPE values between different conditions, this could be explained by 2 factors: (1) the possibility that fatigue perceptions are masked during exercise (resulting in lower RPE) but not afterward (when RPE is queried), ²⁹ and (2) an increase in the number of repetitions (ie, higher level of effort) for the music condition might potentially “balance” the RPE values across both conditions (music vs control).

In applied practice, feedback and music are 2 ergogenic strategies that often occur simultaneously. For instance, athletes can be observed selecting their preferred tracks while the coach offers KR during the most demanding RT exercise. Despite their frequent co-occurrence, their combined effects remain unexplored. Drawing an analogy to the cocktail-party phenomenon, it is conceivable that KR+music condition could fragment an athlete’s attentional resources, thus potentially influencing both mechanical performance and perceptual outcomes. ⁷ However, our study revealed comparable results between the KR+music and music conditions. Further studies should aim to investigate the effects of various genres of music, form of feedback, and different KR frequency when combined with music. Such investigations are crucial for enhancing our understanding of how to optimize training methods in field conditions.

The present study provides novel results suggesting no interference when both feedback and music are supplied in the same training session. However, there are limitations that should be addressed when interpreting these findings. First, our sample consisted of physically active men with limited RT experience, and these results may differ from other populations. Second, the subjects’ preference was not considered for providing velocity performance feedback nor music. Since the effects of feedback and music depend on the subjects’ preferences, the magnitude of the differences with respect to the control condition may be increased/decreased in different circumstances. ⁴ Third, our study analyzed the effects of a specific %1RM combined with a predetermined %VL, as the authors adopted a balanced approach by selecting a moderate load and effort level (70% 1RM-20%VL). Further research should explore various training configurations (eg, different combinations of %1RM and %VL) to uncover additional effects. Finally, our findings may be applicable only to the bench press, highlighting the need for future studies to investigate other RT exercises.

Conclusion

Listening to music leads to improved mechanical performance and FS values compared with control (no music or feedback) conditions, whereas the combination of music and velocity feedback does not provide additional benefits. In practice, this finding is important, as it allows coaches to benefit from both strategies when used in the same exercise sessions (see Weakley et al ³⁸ and Ballman ² to further explore the benefits of feedback and music, respectively). However, since music preference (see Ballman et al ⁴ ) and forms of feedback (see Weakley et al. ³⁹ ) are key factors to consider, athlete preference and feasibility should still take priority when determining how and when these ergogenic strategies should be implemented.