The effect of wearing a weight belt on one-repetition maximum for the parallel back squat and its relation to performance measures

Abstract

Background

The use of a weight belt reportedly increases intra-abdominal pressure (IAP), which, in turn, increases the one repetition maximum (RM) of squatting. However, the effect of a weight belt on 1RM of squatting, and the correlation between 1RM with and without a weight belt and athletic performance is unclear.

Objective

This study aimed to determine the effect of using a weight belt on the 1RM for parallel back squats (BSQs), and to examine the relationship between 1RM and 1RM/body weight (BW) with and without a weight belt and performance measures.

Methods

This cross-sectional study included 26 male college athletes. The 1RM for BSQs with and without a weight belt, and its correlations with performance tests, such as the 30-m sprint, 505 agility test, and vertical jump (VJ), were assessed. The 1RM for parallel BSQs was measured by a certified strength and conditioning specialist.

Results

The 1RM for BSQs with the weight belt (116.35 ± 18.03 kg) was significantly higher than without the weight belt (113.56 ± 17.48 kg, mean difference = 2.79 ± 6.13 kg [95%CI, 0.314–5.266], p = 0.029). A significant correlation was only found between the 1RM/BW for BSQs without a weight belt and VJ height (p = 0.045, r = 0.396 [95%CI, 0.010–0.697]).

Conclusions

Use of a weight belt improves the 1RM of the parallel BSQ, although the relationship between 1RM/BW of parallel squats and other performance metrics might be slightly masked when a belt is used during measurement of squat strength.

Keywords

Strength training athletic performance athlete

1. Introduction

The back squat (BSQ) is one of the most popular resistance training exercises and has been reported to be associated with several performance measures.^1–3 Hartmann et al.¹ observed favorable adjustments in squat jump and countermovement jump (CMJ) performance subsequent to deep squat training. Wisløff et al.² found a strong correlation between the one repetition maximum (1RM) for half squats and vertical jump (VJ) height and sprint performance. Pallares et al.³ reported that engaging in full-squat training resulted in the most substantial enhancements across all performance parameters (CMJ, 20-m sprint, and Wingate tests) compared to parallel and half-squat depths. In recent years, health club members have been using weight belts during resistance training to prevent injury and improve performance measures.⁴ In addition, many athletes also use a weight belt while doing weight training with heavy weights to increase their maximal muscle strength and improve their performance on certain measures.

Core stability is defined as the foundation of dynamic trunk control, which allows the production, transfer, and control of force and motion to the terminal segments of the lower body kinetic chain.^5–7 Previous studies have reported the relationships between core stability and muscle strength and power.^8,9 Significant correlations have been reported between core endurance, assessed using the McGill test, and performance tests, such as sprint times and the 1RM of squatting.⁸ Intra-abdominal pressure (IAP) is defined as the pressure concealed within the abdominal cavity, which is relative to the respiratory phase and abdominal wall resistance.¹⁰ Previous studies reported that maximum IAP during parallel BSQs¹¹ and deadlifts¹² is greater with than without a weight belt. In addition, Tayashiki et al.⁹ reported that maximal hip extension torque correlates significantly with IAP. However, although IAP provides stability to the core, the correlation between core stability and athletic performance remains unclear.

For athletes who need to be able to freely manipulate their limbs while stabilizing their core, increases in 1RM with a weight belt are not considered important factors. Especially in competitions where it is not permitted to use a weight belt or similar equipment, it is necessary to stabilize the core using one's own core muscles. Nonetheless, whether or not a weight belt should be used during BSQs to improve athletes’ performance measures has not yet been examined. Therefore, examining the correlation between the 1RM for squatting with or without a weight belt and performance measures may have implications in terms of weight belt use during training.

Previous studies have reported that the use of a weight belt increases IAP, which would likely increase the 1RM of squatting. However, the effect of a weight belt on 1RM and its correlation with athletic performance is unclear. This study aimed to determine the effect of a weight belt on the 1RM for BSQs and to examine the correlations between 1RM and 1RM/body weight (BW) with and without the use of a weight belt with performance measures. We hypothesized that use of a weight belt during BSQs would allow for a higher 1RM, but might have a lower correlation with performance measures.

2. Methods

2.1. Research design

Previous studies reported that maximum IAP during resistance training is greater with than without use of a weight belt.^11,12 Thus, the presence of a difference in 1RM for BSQs with and without a weight belt would indicate that core stability contributes to weight lifting performance. This study used a repeated-measures, within-subjects design to examine the effect of using a weight belt on the 1RM for BSQs in collegiate athletes. For this, subjects had their 1RM measured with and without the use of a weight belt. We also examined the correlation between 1RM and 1RM/BW with and without a weight belt, and sprint time, agility and jump performance, to determine whether athletes should use a weight belt during strength training. All the 1RM tests and performance tests were conducted by certified strength and conditioning specialists (CSCS), and core stability tests were conducted by athletic trainers certified by the Japan Sport Association.

2.2. Population

This cross-sectional study included 26 male collegiate athletes (mean ± standard deviation (SD); age, 19.19 ± 0.90 years; height, 1.74 ± 0.06 m; body weight, 67.40 ± 5.31 kg; and duration of resistance training, 3.73 ± 1.40 years). The subjects were sprinters and jumpers. The inclusion criteria comprised being a male collegiate athlete, having a minimum of 6 months of consistent resistance training (which included BSQs), and currently engaging in ongoing training. The exclusion criteria included experiencing pain in the lower back, lower limbs, or other parts of the body during measurements. The required sample size was determined using statistical software (G*Power Version 3.1.9.4), based on the analysis during the preliminary experiment for correlation data (Tails = Two, Effect size = 0.5, α=0.05, Power = 0.8), which indicated a required sample size of 26 subjects. All subjects were informed of the benefits and risks of participation in this study, and provided written, informed consent for participation. Approval for the study was obtained from the Research Ethics Committee of Chukyo University (approval no. 2022-108; dated January 6, 2023).

2.3. Procedures

Measurements were performed over a span of two days, ensuring a minimum interval of 72 h between consecutive measurements. The 1RM on any one of the BSQs, with or without a weight belt, 30-m sprint time, 505 agility test time, VJ height, and body composition were assessed, and a questionnaire on usual training was administered, on day 1. On the second assessment day, only the 1RM for BSQs in the other weight belt condition was measured. A minimum of 10 min was allowed between tests. The athletes were given 30 min to warm up and were instructed to be ready to sprint at full speed. Athletes had unrestricted access to training, except during the measurement sessions. Subjects maintained their normal intake of food and fluids, but drank no caffeine-containing beverages for 4 h before testing, and ate no food for 2 h before testing.^13,14 Data on subject age, duration of resistance training, their usage of a weight belt in their normal strength training, and whether they routinely performed core stability training was obtained from the self-reported questionnaires mentioned above. The subjects’ body weight was measured using a body composition analyzer (InBody 470; InBody Japan, Tokyo, Japan).

2.3.1 1RM test

1RM weight testing for the parallel BSQ: Assessment of the 1RM for BSQs was carried out according to the 1RM test protocol outlined by the National Strength and Conditioning Association (NSCA).¹⁵ With safety as a priority, the test was conducted using a squatting rack equipped with safety bars in case of a failed attempt. The researcher, who was a CSCS, verified subjects’ attainment of the parallel position in squats by ensuring that their buttocks made contact with a positioned plastic bar.^1,16 The location at which the subjects performed the squat and the location of the plastic bar were marked with tape. A basic leather weight belt (G3326; Gold's Gym, Tokyo, Japan) was used while performing the BSQ, and it was applied leaving enough space for one finger on the lower back. The order of testing with and without a weight belt during measurement of the 1RM for the BSQ was randomly determined. In accordance with the 1RM test protocol of the NSCA, athletes were given a two- to four-minute break between BSQ 1RM measurement trials, and completed the measurement within five trials. The technique for the BSQ exercise adhered to the guidelines set forth by the NSCA.¹⁵ Briefly, the subjects placed their feet shoulder-width apart, with the toes turning slightly outward. Subjects descended from the standing position, lowering their buttocks until they contacted the bar. Care was taken to ensure that the knees did not extend beyond the toes during this movement. Upon reaching the position where their buttocks contacted the bar with lowered buttocks, subjects extended their knees to return to the standing position. The researcher, located beside the subject, ensured that the descent of the buttocks was sufficient and that the subjects maintained proper posture during the movement. Among the subjects, nine athletes used weight belts in their usual strength training, and 25 athletes did core stability training during their regular training.

2.3.2 Performance tests

30-m sprint: The 30-m sprint time was measured using timing gates (Brower TCi Timing System Set; Brower Timing Systems, Draper, UT, USA). Subjects started in the crouching position and sprinted as quickly as possible. Athletes were given a two- to four-minute break between measurements. The test was performed three times, and the best time (sec) was used for statistical analysis.

505 agility test: Subjects sprinted forward from the 15-m cones and the timer was started once they passed the 5-m cones. When the subjects reached the 0-m cones, they made a 180-degree change in direction and sprinted back through the 5-m cones, at which point the timer was stopped. Athletes were given a two- to four-minute break between measurements. The timing gate at 5 m was placed 1 m above the ground. The test was performed three times, and the best time (sec) was used for statistical analysis.

Vertical jump: The VJ was measured with the subject standing on a digital measurement unit (Multi Jump Tester II; PTS-2400A, DKH Co. Ltd, Tokyo, Japan). Maximum effort VJs were performed after a rapid countermovement. The subjects were allowed to go from the crouching to the standing position and swing their arms during the VJ measurements. Athletes were given a two- to four-minute break between measurements. The test was performed three times, and the best height value (cm) was used for statistical analysis.

2.3.3 Core stability tests

Modified double leg lowering test (mDLLT): The subjects lay supine with their arms across their chest and their legs bent at 90 degrees at the knee and hip joints. With the researcher's hand placed below the subject's lower back, the subjects slowly lowered their legs. The researcher turned on a flashlight when the subject's spine extended beyond the neutral position. The trial was recorded using a high-speed camera (GC-LJ20B; JVC, Kanagawa, Japan) at 240 Hz, and image analysis software (NIH ImageJ ver. 14.4) was used to analyze the angle between a line connecting the greater trochanter and the lateral epicondyle of the femur and the horizontal axis when the flashlight was turned on.^17,18 A certified athletic trainer affixed two markers to the lateral epicondyle and greater trochanter of the femur before measurement. In this test, a lower value on this measurement indicated a more stable core. This measurement was performed only once.

Plank with arm lift test (PALT): The plank with arm lift is a training program in which the subject raises one arm after adopting the plank posture, resists the rotational load generated by the decrease in the number of points of support, and maintains their posture to stimulate the muscles related to core rotational stability. The load increases with narrowing of the foot width in the plank posture. The PALT uses this principle to assess core rotation stability. During the test, the subject assumed the plank posture with the elbow joint positioned below the shoulder joint and the ankle joint in 0 degrees of plantar dorsiflexion (ankle at 90 degrees), so that the body was in a straight line (Figure 1). The subject then slowly raised one arm from the plank position. During the test, the researcher lightly touched the subject's pelvis to assess pelvic movement as the subject raised their arm. If the subject was able to raise his arm without pelvic sway, the foot width was narrowed. The subject self-reported the leg width at which the pelvis did not sway when the arm was raised to one side in the plank posture, and this was used as the leg width for the first trial. The narrowest leg widths when raising each of the arms were recorded, and the average value was used for statistical analysis.¹⁹ In this test, a lower value on this measurement indicated a more stable core. This measurement was performed only once.

Figure 1.

Plank with arm lift test. A) Start position. B) End position.

2.4. Statistical analyses

Statistical analyses for all data were conducted utilizing SPSS (ver. 26, IBM Corp., Armonk, NY, USA). Normality of the entire dataset was assessed using the Shapiro–Wilk test. Results are presented as the mean ± SD with 95% confidence interval (CI). The paired t-test was used to compare 1RM values with and without the weight belt. Pearson's correlation analysis was used to test the correlation between 1RM and 1RM/BW for BSQs and performance measurements. The 1RM relative to the subject's BW was used in previous studies^20–24 because a previous study²⁵ reported that the 1RM relative to BW was more meaningful than the absolute 1RM for examining the relationships between maximum strength, power, and athletic performance. Results were considered statistically significant at the 5% level (p < 0.05).

3. Results

All measurement values are shown in Table 1. No subject was excluded because of pain during the measurement. The use of a weight belt increased the 1RM for parallel BSQs to 116.35 ± 18.03 kg compared to 113.56 ± 17.48 kg without a belt, with a mean difference of 2.79 ± 6.13 kg (95%CI, 0.314–5.266, p = 0.029). Twelve subjects demonstrated an increase in their 1RM with the use of a weight belt, nine subjects showed no change, and five subjects experienced a decrease in their 1RM (Figure 2). The use of a weight belt increased the 1RM/BW for parallel BSQs to 1.72 ± 0.20 kg/kg compared to 1.68 ± 0.20 kg/kg without a belt, with a mean difference of 0.040 ± 0.001 kg/kg (95%CI, 0.003–0.077, p = 0.033).

Figure 2.

Difference between the 1RM for parallel BSQs with and without a weight belt.

Table 1.

Subject characteristics and one-repetition maximum weight (1RM) during parallel back squats with and without a weight belt.

Variables	Mean	±	SD
Height, m	1.74	±	0.06
Body weight, kg	67.40	±	5.31
Age, year	19.19	±	0.90
Duration of resistance training, year	3.73	±	1.40
mDLTT, deg	13.86	±	11.50
PALT, cm	67.69	±	17.51
VJ height, cm	57.27	±	6.82
30 m sprint, sec	4.24	±	0.13
5-0-5 agility test, sec	2.34	±	0.08
1RM Parallel BSQ with weight belt, kg	116.35	±	18.03
1RM Parallel BSQ without weight belt, kg	113.56	±	17.48
1RM Parallel BSQ with weight belt/BW, kg/kg	1.72	±	0.20
1RM Parallel BSQ without weight belt/BW, kg/kg	1.68	±	0.20

mDLLT, modified Double Leg Lowering Test; PALT, Plank with Arm Lift Test; VJ, vertical jump; RM, repetition maximum; BSQ, back squat; BW, body weight.

Significant correlations were found between the 1RM/BW of parallel BSQs without a weight belt and VJ height (p = 0.045, r = 0.396 [95%CI, 0.010–0.697], Figure 3). Significant correlations were found between the 1RM/BW for parallel BSQs with a weight belt and PALT (p = 0.016, r = −0.469 [95%CI, −0.725 – −0.100], Table 2). Significant correlations were also found between time in the 30-m sprint and mDLLT (p = 0.038, r = −0.409 [95%CI, −0.687 – −0.026]) and PALT (p = 0.004, r = 0.544 [95%CI, 0.198–0.769], Figure 4). Significant correlations were found between the 30-m sprint and VJ height (p < 0.001, r = −0.788 [95%CI, −0.901–−0.577], Table 2). There were no significant correlations between 1RM and 1RM/BW, and other performance measures.

Figure 3.

Correlation between the 1RM/BW for BSQs and vertical jump (VJ) height.

Figure 4.

Correlation between core stability and 30-m sprint time.

Table 2.

Correlations between 1RM and 1RM/BW for parallel BSQs and athletic performance measures.

	mDLLT	PALT	30 m sprint	505 agility test	VJ height
mDLTT	1
PALT	−0.333	1
30 m sprint	−0.409*	0.544**	1
505 agility test	−0.348	0.301	0.113	1
VJ height	0.186	−0.269	−0.788**	0.068	1
1RM with weight belt	−0.224	−0.324	−0.130	0.232	0.198
1RM without weight belt	−0.214	−0.240	−0.134	0.152	0.228
1RM/BW with weight belt	−0.140	−0.469*	−0.381	0.057	0.361
1RM/BW without weight belt	−0.118	−0.351	−0.383	−0.055	0.396*

mDLLT, modified Double Leg Lowering Test; PALT, Plank with Arm Lift Test; VJ, vertical jump; RM, repetition maximum; BSQ, back squat; BW, body weight; *p < 0.05; **p < 0.01.

4. Discussion

This cross-sectional study aimed to determine the effect of a weight belt on the 1RM for BSQs, and to examine the correlations between the 1RM and 1RM/BW with and without a weight belt, and performance measures in collegiate male athletes. Evaluation revealed a significant difference between 1RM and 1RM/BW for BSQs with and without a weight belt. There was, however, a significant positive correlation only between the 1RM/BW for BSQs without a weight belt and VJ height.

To the best of our knowledge, this is the first study to show that the 1RM and 1RM/BW for BSQs with a weight belt are significantly higher than those without a weight belt. In a previous study, myoelectric activity of the lower limb muscles and erector spinae was recorded using surface electrodes during squatting with 90% 1RM weight. The results indicated no significant difference in myoelectric activity between weight belt conditions for any of the muscle groups or for any joint angular kinematic variables during either phase of the lift.²⁶ Other studies reported that maximum IAP during the parallel BSQ¹¹ and deadlift¹² was greater with than without a weight belt. Therefore, the reason for the significantly higher 1RM for BSQs with a weight belt in the present study might be that the athletes’ efficiency in raising the bar was increased through stabilization of the core rather than through increased muscle activity in the lower limbs.

We observed a significant negative correlation between 1RM/BW for BSQs with a weight belt and PALT (p = 0.016, r = −0.469) in this study, although there was no significant correlation when BSQs were performed without a weight belt. A previous study reported that maximum IAP during the parallel BSQ was greater with than without a weight belt in six adult male volunteers.¹¹ IAP is considered an important factor for enhancing the stability and stiffness of the spine and generating force/torque in the limb muscles during kinetic chain activities involving trunk and hip extension, such as lifting.²⁷ In addition, it has been reported that use of a weight belt during squats²⁶ and deadlifts²⁸ allows for faster lifts as compared to when a weight belt is not used. Therefore, athletes who are able to stabilize their core on their own may be able to achieve greater core stability using a weight belt.

This study revealed a significant positive correlation between the 1RM/BW for BSQs without a weight belt and VJ height (p = 0.045, r = 0.396), although there was no significant correlation between the 1RM/BW for BSQs with a weight belt and VJ. This may suggest that athletes should prioritize improving their 1RM without a weight belt over their 1RM with a weight belt when seeking to improve on certain performance measures. This is particularly important for athletes who are not allowed to use support equipment during competitions.

Several previous studies have reported the correlations between core stability and muscle strength and power. Significant correlations have also been reported between core endurance (using the McGill test) and performance tests, such as sprint time, and the 1RM for squatting exercises.^8,29 Although the difference in r-values, indicating the strength of the correlation between VJ and 1RM/BW of BSQs with and without a weight belt, in this study was not large, it is considered an important difference for athletes competing at higher levels where even a small difference in performance can substantially impact their standing. However, it is possible that these results were obtained because the performance measurements in this study were made without a weight belt. Therefore, future studies should also investigate whether the use of support equipment, such as a weight belt, improves performance measures.

Our study also indicated significant correlations between core stability measures and 30-m sprint time. Previous studies have reported significant correlations between 20- and 40-yard sprint times and total core strength using McGill's core endurance test.⁸ In the present study, the mDLLT was used to evaluate core stability against lumbar extension loading, and PALT was used to evaluate core stability against trunk rotation loading. A previous study reported that with an increase in running speed, lumbosacral axial rotation torque increases more markedly than do extension and lateral flexion torque, and that the increase in axial rotation torque is greater above 7.30 m/s.³⁰ Therefore, it appears important to be able to resist trunk rotational load when sprinting. In the 30-m sprint, early anterior pelvic tilt is a rather natural movement tendency and might be necessary for faster running.

4.1 Limitations

The present study has some limitations. First, this study only included male collegiate athletes. To avoid the effects of sex, we excluded female collegiate athletes as study subjects. Second, we did not assess the angles of the knee and hip during 1RM measurements. However, at the commencement of the 1RM assessment, the depth of the squat was verified, and the plastic bar was adjusted accordingly, and the 1RM measurement was conducted by a CSCS. Third, IAP was not measured and thus, its value was not known. However, the present study was based on the results of a previous study showing that IAP increases during squatting with a weight belt. In addition, because the relationship between core stability by mDLLT and PALT and IAP is unclear, it is necessary to develop a measure of core stability that is related to IAP in the future. However, it is worth noting that this was only an initial investigation to compare the 1RM for BSQs with and without a weight belt, and to show that the 1RM for BSQs without a weight belt correlates with VJ height.

5. Conclusions

In this study, using a weight belt significantly increased the 1RM for BSQs. Thus, a weight belt might be useful for lifting heavier weights. This study also indicated a significant correlation between 1RM/BW for BSQs without a weight belt and VJ height, although there was no significant correlation between the 1RM/BW for BSQs with a weight belt and VJ. The use of a weight belt improves the 1RM of the parallel squat, and the relationship between the 1RM/BW of parallel squats and other performance metrics might be slightly masked when a belt is used during measurement of squat strength. This suggests that athletes should prioritize improving their 1RM without a weight belt over their 1RM with a weight belt when seeking to improve certain performance measures.

Footnotes

Acknowledgements

This work was supported by a research grant from the National Strength and Conditioning Association Japan. None of the authors declare any conflict of interest. The authors thank FORTE Science Communications () for English language editing.

ORCID iD

Shota Enoki

Ethical considerations

All subjects were informed of the benefits and risks of participation in this study and provided written, informed consent. Approval for the study was obtained from the [institutional name masked for peer review] Research Ethics Committee (approval No. 2022-108).

Author contributions

Conception: Shota Enoki

Performance of work: Shota Enoki, Taisei Hakozaki

Interpretation or analysis of data: Shota Enoki

Preparation of the manuscript: Shota Enoki

Revision for important intellectual content: Shota Enoki, Junpei Shiba, Taisei Hakozaki, Kenji Kuzuhara

Supervision: Shota Enoki, Junpei Shiba, Kenji Kuzuhara

Funding

This work was supported by a research grant from the National Strength and Conditioning Association Japan. None of the authors declare any conflict of interest.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

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