Abstract

• Purpose: This study aimed to compare the effects of free-weight resistance with and without elastic band (EB) tension on upper-body maximal strength and strength endurance during bench press (BP) exercise.

  Methods: Twenty-six trained males (age: 26 ± 2.4 years; body mass: 73 ± 7.6 kg; stature: 172 ± 5.8 cm) were randomly assigned to two groups, CON (n = 13) and EXP (n = 13). BP sessions were performed twice weekly over 12 weeks. Both groups followed the same training program except that the EXP group executed BP with 30% of the prescribed load originating from the use of EB. BP one repetition maximum (1RM) and the maximum number of repetitions (MNR) for muscular fatigue were tested before and after the intervention.

  Results: Analysis of covariance with the pretest value as the covariate revealed that both the CON and EXP groups demonstrated improvements in maximal strength and muscular endurance. However, the EXP group exhibited significantly greater improvements in 1RM (14% vs. 12%) and MNR (27% vs. 7%) than the CON group.

  Conclusion: A combination of free weight and EBs may provide a greater training stimulus than free-weight resistance alone to improve upper-body strength and muscular endurance in trained adult men.

🏷️Keywords: muscle strength, resistance training, athletic performance, accommodating resistance

Introduction

Constant external resistance (CR) is the most commonly used resistance mode for inducing musculoskeletal adaptation and is characterized by exercise in which the total resistance depends on the mass of the object to be lifted (Frost et al., 2010), demanding uniform resistance to the muscles and joints, despite the considerable strength of muscle changes throughout this range of motion (ROM). Alternatively, accommodating resistance (AR) (i.e., elastic bands [EBs] or chains attached to the barbell) has been used to provide variation in the resistance (load) throughout the ROM when performing movement (McMaster et al., 2009) by overcoming the mechanical disadvantages related to specific joint angles during exercise (Ebben & Jensen, 2002; Smith et al., 2019; Wallace et al., 2006). Training by applying EB in addition to free weights can augment the range of the concentric portion of the lift in which the barbell is accelerated and therefore cope with the deceleration at the end of the concentric phase of the lift, during which the skeletal muscles are not optimally contracting because the lifter unintentionally decelerated the barbell [6]. Consequently, this action induced by EB causes a variety of stimuli and thus provokes neuromuscular adaptations, which enhance different expressions of strength (Joy et al., 2016).

Previous studies have demonstrated that AR is more effective than CR at increasing maximal muscular strength [8] and speed-strength (Rhea et al., 2009) when performing a bench press (BP) with EBs in both athletes (Anderson et al., 2008) and untrained lifters [11]. However, the results from other studies, in which AR was used have been inconclusive (Shoepe et al., 2011). After performing a 7-week training intervention program, in which top-tier athletes performed BP with EB, they experienced greater improvement in their one-repetition maximum (1RM) than did those using CR (Anderson et al., 2008). Similarly, significant increases in maximal upper-body strength were observed in second-tier basketball players after a 5-week training intervention using a banded BP compared with one free-weight barbell BP (Joy et al., 2016). Conversely, after a 24-week training program for novice college lifters, a combination of free weights and EB was found to be similar but not more effective than free weights alone for developing maximum BP strength (Shoepe et al., 2011).

To the best of our knowledge, only one study has demonstrated the effect of free weight in combination with AR techniques using EB to enhance muscular endurance rather than strength and power in the upper body (Kashiani & Geok, 2020). This study revealed that AR was more effective than CR in improving strength and muscular endurance after a 12-week intervention. However, these effects were tested on untrained participants using the overhead press exercise. No studies have used trained participants or traditional BP exercises for such comparisons. The present study aimed to compare the effects of free weight with and without EBs on both upper-body maximum strength and muscular endurance in healthy resistance-trained males using BP.

Methods

Study design

This study followed a randomized trial with a pre- and posttest repeated measures design and was conducted in 14 weeks (Figure 1). Preintervention testing was completed within 1 week, followed by a 12-week training program, after which the participants performed postintervention testing. The training program intervention consisted of two weekly training sessions. The participants were randomly and equally assigned to one of two parallel groups following simple randomization procedures (computer random numbers in 1:1 ratio), the CON group (n = 13) or the EXP group (n = 13) (Figure 2). All training sessions were completed under the supervision of a certified strength and conditioning specialist.

Preintervention testing (week 1) was divided into two sessions, each separated by 4 days. During the first session, anthropometric  measurements (i.e., body stature and weight) were conducted, followed by a 1RM test. The second session required participants to complete a maximum number of repetitions (MNR) test using 70% of the weight obtained in the 1RM test. The intervention programs (weeks 2–13) were identical, except that the EXP group realized flat BP using 30% of the load arising from the use of EBs, whereas the CON group performed resistance training with no added band tension. All baseline tests were repeated at week 14 after the intervention program.

Participants

This study included 26 male participants (age: 26 ± 2.4 years; body mass: 73 ± 7.6 kg; stature: 172 ± 5.8 cm). The inclusion criteria were as follows: 20–30 years of age, having at least 3 years of consistent resistance training experience, being free from a current or previous injury that may be aggravated by participating in upper-body physical exercises, and being technically proficient in the BP technique. Participants were advised to avoid training for 72 h before data collection. All individuals were informed of the advantages and inherent risks related to the investigation, and they signed written informed consent before starting the investigation. The study adhered to all relevant national and institutional guidelines and the Declaration of Helsinki and ethical standards in sport and exercise science research.

Procedures

1RM assessment

A conventional flat BP was used to evaluate 1RM. The measuring protocol followed the guidelines indicated by Mayhew et al., (1992). Briefly, the participants grasped the bar at a position that was slightly greater than the biacromial width, lowered the bar in a smooth and controlled manner to the lower portion of the pectorals, and then rapidly extended the arms to full extension. The participants completed five repetitions with 50% of the estimated 1RM (based on previous training history) during the first set. After a 2-min interval, 2.5–5 kg was added, and the participants executed the second set with three repetitions. The participants then rested for 3 min. Subsequently, 2.5–5 kg was added, and the participants performed one repetition. A series of single attempts was completed until the participant achieved their 1RM, with a 3-min interval between each trial.

MNR assessment

This evaluation was performed 4 days after the strength assessment and consisted of one set of as many repetitions as possible, without stopping between repetitions, using a submaximal load (70% 1RM) in the BP. Only those repetitions performed using the correct technique were considered valid.

Intervention program

The intervention program consisted of four weekly sessions for 12 weeks, totaling up to 48 training sessions. These sessions used a split routine (upper- and lower-body) training format, allowing 48 h of recovery between sessions for the same body part. All participants performed lower-body exercises on Mondays and Thursdays and upper-body exercises on Tuesdays and Saturdays. Each of these four sessions included 2 main lifts and 2–3 secondary exercises. The training program was divided into four periodized mesocycles of 3 weeks, with increasing training intensity and decreasing volume at each mesocycle. In the first mesocycle (weeks 2–4), the participants had to perform 3–5 sets of 8–12 repetitions at 72%–77% of the 1RM, with 2–3 min of interset rest. In the second mesocycle (weeks 5–7), the participants performed 3–5 sets of 5–10 repetitions at 80%–85% of the 1RM, with 2–3 min of recovery between sets. In the third mesocycle (weeks 8–10), the participants performed 3–5 sets of 3–8 repetitions at 87%–92% of the 1RM, with 3–5-min rest intervals between sets. In the last mesocycle of training (weeks 11–13), the participants completed a descending load scheme of distributing the training load. In this approach, the load increased progressively to a higher intensity (85%–98% of 1RM), whereas the number of repetitions decreased with complete recovery between sets (See also Table 1).

Table 1. 12-week upper-body training intervention programme. *Both groups completed the same training programme, except that the EXP group performed the bench press with 30% of the prescribed load arising from the utilisation of elastic bands and the other 70% from free-weight.

Band tension measurement

This study used the protocol of Shoepe et al., (2010) to determine the exact loading of EBs at different lengths. EBs (GFC Power Band, Japan) of different thicknesses were affixed to the top of a stationary bar. Dumbbells of differing weights were gradually added (balanced independently from human contact) to the free end of the band, and the deformation was measured in centimeters. All assessments were registered to the nearest centimeter as measured from the top of the stationary bar to the opposite side of the middle point of the dumbbell handle. This process was replicated with all EBs to compile a chart of tension for different band lengths. Band tension measurements were retested at weeks 5 and 10 to confirm that elasticity and tension were unchanged.

Data Processing and Analysis

The collected data were processed using Jamovi (The Jamovi Project, 2021, Version 1.6). An analysis of covariance (ANCOVA) with the pretest value as the covariate was applied to determine the effect of free weight with and without EB on muscular fitness. The pre- and postintervention values were linear for each group, as confirmed by a visual examination of a scatterplot. The regression slopes demonstrated homogeneity. Within-group and overall model residuals were normally distributed, as determined by the Shapiro–Wilk test. Homoscedasticity and homogeneity of variance were observed and determined by visual examination of a scatterplot and Levene’s test, respectively. Dataset inspection revealed no outliers, as confirmed by the absence of cases with standardized residuals of greater than ±3 standard deviations. Post-hoc analysis was performed with Bonferroni correction whenever a statistically significant value was identified. The level of statistical significance was set at a p-value of <0.05.

Results

1RM assessment

Expectedly, the ANCOVA results indicated that both groups demonstrated improved 1RM BP performance. However, a significant difference in the postintervention upper-body maximal strength was found between the groups after correction for preintervention (F [1,23] = 11.2, p = 0.002, $\eta_{p}^{2}$ = 0.341). Postintervention, the 1RM values were significantly greater in the EXP group than in the CON group ($M_\textit{diff}$ = 5.6 kg, 95% CI [2.3, 9.0], p = 0.002) (Table 2).

MNR assessment

The outcomes of the MNR analysis revealed a significant difference in upper-body strength-endurance between the two groups after adjustment for preintervention than the CON group (F [1,23] = 11.3, p = 0.003, $\eta_{p}^{2}$ = 0.329). Postintervention, the improvement in muscular endurance was significantly greater in the EXP group (Table 2).

Table 2. Changes in muscular fitness in response to the 12-week training intervention (mean ± SD).

Discussion

This study revealed that both free-weight exercises with and without EBs effectively increase the amount of force produced using maximal external loads and the total number of repetitions performed using submaximal loads in the BP exercise. However, the EXP group demonstrated superior improvements from pretesting to post-testing.

In terms of the maximal strength measure, the participants experienced an increase of 14.4% in EXP and 12% in CON. These findings are in line with the results reported by a previous study in which 7-week training of banded BP in Division I-A athletes produced an increase of +8% compared with +4% in the group without added EB tension (Anderson et al., 2008). Additionally, banded BP during a 7-week training program in a sample of Division I-AA football players increased 1RM values by +7.8%, while free weight alone increased by +5.4% [8]. Similarly, 5 weeks of banded BP training in NCAA Division II basketball players produced a significant difference in upper-body strength (+7.6%) compared with that in CR (+2.7%) (Joy et al., 2016). The higher reported 1RM values would appear plausible in both groups, considering the 12-week timeframe of this study, as the aforementioned studies may not have been long enough to have allowed for larger increases.

Accordingly, this study reveals that combined elastic and free-weight tension may provide a supplementary advantage compared with free-weight alone for increasing maximum strength in resistance-trained individuals. The greater improvement in the 1RM BP could be attributed to several factors. First, the external force provided by the EB potentiates eccentric contractions. The EB attempts to recoil and thus provides an assistive descending force during the eccentric component of the BP exercise. Consequently, the strength required to slow down or stop the weight at the end of the eccentric action induced greater loading in the muscle. This greater lengthening loading has been proven to improve eccentric muscle activity (Aboodarda et al., 2014; Cronin et al., 2003) and induce a relevant increase in eccentric strength (Jensen et al., 2012; Wallace et al., 2018). Therefore, training using free weights with EB may differentially affect the neuromuscular system during each repetition. In conformity with these data, this assistance descending force may result in higher initial eccentric velocities and thus greater force during the final portion of the eccentric phase, inducing greater force early in the shortening contractions (Bosco & Komi, 1979; Doan et al., 2002; Siegel et al., 2002).

In addition, the load is being lifted due to the coefficient of elasticity; thus, the force required to elicit movement proportionally increases with the amount of band deformation. Therefore, EB can increase the tension as the joint angle becomes more advantageous (Frost et al., 2010). Hence, EB has been shown to augment the range of the concentric portion of exercise in which the barbell is accelerated and therefore cope with deceleration at the end of the concentric phase of the lift, during which the skeletal muscles are not optimally contracting because the lifter unintentionally decelerated the barbell [6]. This action induces various stimuli and thus provokes neural adaptations that improve different expressions of strength (Joy et al., 2016). Free weight with EBs changes the pattern of force production across the movement and can induce a decrease in coactivation (antagonist muscle activation) and increase motor unit synchronization and recruitment and rate coding improvements, which may cause superior chronic adaptations (Cormie et al., 2011; Stone et al., 2002).

Conversely, regarding strength-endurance, the participants experienced an increase of 27% in EXP and 7% in CON in the maximum number of repetitions performed with 70% 1RM, indicating superior changes in fatigue resistance. This finding is consistent with the results of Kashiani & Geok (2020), who reported 13% increases in the number of repetitions to muscle fatigue in the group with added EB tension than that in the CR group after a 12-week training period.

Besides having favorable effects on maximal strength due to the continuous alterations in the load provided by EB, the neural adaptations elicited by AR may increase the number of working contracting muscle fibers and, consequently, augment anaerobic glycolysis. The skeletal muscle buffering capacity is its ability to cope with hydrogen (H+) ions generated during ATP hydrolysis and/or anaerobic glycolysis (Robergs et al., 2004; Sahlin, 2014). These processes are required to supply muscle fibers with energy to maintain the same levels of force output during sets of exercises. Anaerobic glycolysis generates equivalent amounts of lactate and H+. Most are buffered when H+ ions are released; however, those that remain free in the cytosol decrease muscle pH [26]. This decrease in muscle pH limits lactate production. Buffering of protons attenuates alterations in pH at a certain proton load, whereas a greater muscle buffering capacity increases the amount of lactate that accumulates in the muscle. The capacity for glycolytic ATP production is increased because of the augmented skeletal muscle buffering capacity and the enhanced removal of lactate/protons. This is associated with improved exercise performance and better fatigue resistance. Hence, by inducing greater fatigue during training sessions, the EXP group was exposed to a greater stimulus, which allowed it to adapt to fatigue resistance, in contrast to the CON group, although both groups completed an equal number of sets and repetitions and used the same 1RM percentage during the 12-week training program. This exposure to a greater stimulus may be beneficial for sports that require training in both neural and metabolic aspects.  In particular, not only strength but also muscular endurance of short- and medium-duration training are required in mixed martial arts, in which the performance time generally lasts longer than 2 min. AR may increase an athlete’s ability to cope with muscular fatigue without directly training it. This indicates that athletes can train in these capacities without an excessive volume of work and thereby spend more time developing their technical skills.

However, this study cannot confirm the exact cause of the improvement in muscular fatigue resistance in the EXP group. Future studies must elucidate the mechanisms through which the use of free weight with EB improves performance compared with free weight alone.

Conclusions

The results of the present study indicated that the addition of elastic tension to a free weight improved upper-body maximum strength and enhanced muscular endurance in resistance-trained men during a 12-week training program. These performance improvements may be related to the altered contractile properties associated with lifting and lowering a load when EB is used. Ultimately, the elastics tend to recoil and provide an accelerating component to the fixed load in movements with an ascending strength curve, such as BP, when the load is lowered. This facilitates certain aspects of the lengthening phase, thereby ultimately improving the shortening phase of a given exercise. However, further studies should be conducted to describe neuromuscular and metabolic adaptations induced by the addition of elastic tension.

Funding Information: This research received no specific grant from any funding agency, commercial, or not-for-profit sectors.

Conflict of Interest: The authors declare none.

Data Availability Statement: The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.