Comparing the kinematics of back squats performed with different heel elevations

Purpose: The barbell squat is fundamental in strength and conditioning, with two principal variants; the back and front squat. Unfortunately, the propensity for injury is high particularly at the knee. The aim of the current investigation was examine the influence of front and back squat variations on patellofemoral joint load. Methods: Patellofemoral loads were obtained from thirty-five experienced male participants, who completed both back and front squats at 70% of 1 RM. Differences between squat conditions were examined using Bonferroni adjusted (P = .008) paired t-tests. Results: The results showed that significant differences (P < .008) in patellofemoral load were identified between both conditions with the highest load being experienced during the back squat exercise. Conclusions: Given the proposed relationship between the magnitude of the load experienced by the patellofemoral joint and associated injury pathology, the back squat appears to place lifters at greater risk from injury. Therefore, it may be prudent therefore for lifters who are predisposed to patellofemoral pain syndrome to utilize the front squat in their training.

The study compared the effects of back squat (BS) and hip thrust (HT) exercises on muscle strength and hypertrophy in well-trained women. Twenty-two participants were divided in two groups: BS group (n=12, 26.4±1.32 years, 171.8±3.79 cm, and 69.5±4.9 kg) performed the BS exercise and HT group (n=10, 27.5±1.42 years, 170.8±4.4 cm, 67.5±4.7 kg) performed the HT exercise. Training was performed for 12 weeks. Before and after the training period, participants were assessed for quadriceps femoris and gluteus maximus muscle thickness (MT) and 1 repetition maximum (1RM) test on the BS and HT. Both groups significantly increased hip extensors MT and HT 1RM; however, the improvements in BS group were higher than in HT group on quadriceps femoris (12.2% for BS and 2% for HT, P<0.001) and gluteus maximus MT (9.4% for BS and 3.7% for HT, P=0.001) and BS 1 RM (35.9% for BS and 4.3% for HT, P<0.001). BS was more efficient than HT, since it resulted in greater muscle hypertrophy of the quadriceps femoris and gluteus maximus, increases in BS 1RM and similar increases in HT.

The aim of this study was to determine the validity, reliability, and sensitivity of a new linear position transducer (LPT) device (RepOne) to a previously validated LPT (Tendo) during the barbell back squat and bench press exercises. Fourteen recreationally resistancetrained individuals (7 males and 7 females) performed three repetitions for the back squat and bench press at loads ranging from 30–90% 1RM. Both devices recorded average (ACV) and peak (PCV) concentric velocities concurrently for every repetition at each load. Significant correlations were observed between RepOne and Tendo during the back squat (PCV: r = 0.90–0.99, p < 0.01; ACV: r = 0.84–0.99, p < 0.01), bench press (PCV: r = 0.74–0.99, p < 0.01; ACV r = 0.81–0.99, p < 0.01). ICCs reveal good to excellent reliability between devices for back squat (PCV, 0.85–0.99; ACV, 0.83–0.99) and bench press (PCV, 0.79–0.99; ACV, 0.83–0.99). Bland-Altman plots revealed greater bias during PCV for both exercises across intensities (back squat, 0.072 to 0.110 m/s; bench press, 0.039 to 0.107 m/s), although ACV bias was lower for both exercises (back squat, −0.002 to −0.029 m/s; bench press, −0.022 to 0.015 m/s). The RepOne device generally exhibited higher smallest detectable change (SDC) values compared to the Tendo, except for specific loads in certain conditions. Additionally, the RepOne device demonstrated higher smallest worthwhile change (SWC) values than the Tendo unit for most loads in back squat ACV. Collectively, the RepOne exhibits strong validity and reliability comparable to the Tendo across both barbell back squat and bench press exercises, despite some variations in sensitivity metrics like SDC and SWC, indicating its efficacy for resistance training application.

Several psychological factors have been linked to acute strength performance through a variety of psychometric analyses. Recent research suggests that the “grittier” a person is, the greater their perseverance and passion for long-term goals. Although grit has shown promise in predicting long-term performance, the association between grit and acute strength performance is yet to be determined. PURPOSE: Therefore, the purpose of this investigation was to examine the relationship between grit as determined by the Short Grit Scale (Grit-S) and total repetitions performed to volitional failure at 70% of one-repetition maximum in the back squat. METHODS: Fifty-eight resistance-trained males and females (age: 23±3yrs; body mass: 80.64±16.49 kg) completed Grit-S prior to performing a one-rep max back squat (1RM). Following a 5-minute dynamic warm-up, subjects completed a validated 1RM back squat protocol. Following 1RM testing, subjects had a standardized rest period of 10 minutes prior to completing two single-repetition sets on the squat at 30%, 40%, 50%, 60%, 70%, 80% and 90% of the established 1RM for which the data is included elsewhere. After the submaximal single repetition sets, subjects had a 10-minute rest period before completing one set on the back squat to volitional failure at 70% of the established 1RM. A Pearson’s product moment correlation was utilized to determine any relationships between Grit-S total repetitions performed at 70% of 1RM. RESULTS: There was a wide range of repetitions performed across all subjects (6-28) with an average of 14±4 repetitions. However, grit as determined by the Grit-S was not significantly related to total repetitions performed at 70% of 1RM in the back squat (r=-0.11, p=0.42). CONCLUSIONS: These results indicate that higher levels of grit are not associated with repetitions performed to failure and submaximal back squat intensities. However, we suggest that the Grit-S should be used to assess long-term commitment to athletic training as well as a possible indicator of chronically improved performance.

The aim of this study was to compare the musculature activity and kinematics of knee and hip joints during front and back squat with maximal loading. Two-dimensional kinematical data were collected and electromyographic activities of vastus lateralis, vastus medialis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus and erector spinae were measured while participants (n = 12, 21.2 ± 1.9 years old) were completing front and back squat exercises with maximum loading. Paired sample t-test was used for comparisons between two techniques. Results showed that the electromyographic activity of vastus medialis was found to be greater in the front squat compared to the back squat during the ascending phase (P < 0.05, d = 0.62; 95% CI, −15.0/−4.17) and the whole manoeuvre (P < 0.05, d = 0.41; 95% CI, −12.8/−0.43), while semitendinosus (P < 0.05, d = −0.79; 95% CI, 0.62/20.59) electromyographic activity was greater in the back squat during the ascending phase. Compared to the front squat version, back squat exhibited significantly greater trunk lean, with no differences occurring in the knee joint kinematics throughout the movement. Results may suggest that the front squat may be preferred to the back squat for knee extensor development and for preventing possible lumbar injuries during maximum loading.

INTRODUCTION: The back squat (BS) and the front squat (FS) are mainstay exercises of strength training programs. However, not much is known about joint-specific kinematic and kinetic changes during the execution these two exercises as the external load is varied. In addition, the Relative Muscular Effort (RME), which quantifies a muscle groups operating level with respect to its maximum capacity, of the knee extensor muscle group during both exercises is not well characterized. PURPOSE: To investigate load-dependent RME of the knee extensor muscles during the BS and FS. METHODS: Seven collegiate athletes (4 male, 3 female) participate in this study. Each athlete completed motion analysis and isometric muscle strength testing. During motion analysis testing each athlete performed, in counterbalanced order, both the BS and FS at loads of 40, 60, and 80% of their FS one-repetition maximum (1-RM). Kinematic and kinetic data were captured from markers placed on anatomical landmarks (Plug-in Gait marker set) and from two force plates underneath the athletes’ feet. These data were used to calculate the net joint moments (NJM) during each exercise and at each load. During the isometric strength testing sessions each athlete performed maximal voluntary isometric contractions (MVIC) at 30, 60, and 90 degrees of knee flexion. A moment-angle curve was fitted to the MVIC data and used to calculate the theoretical peak NJM during the squats, which was then compared against the actual NJM during the execution of the BS and FS to calculate the RME. A 2x3 ANOVA ([Exercise: Front, Back] x [Load: 40, 60, 80]) was used to determine the effects of exercise and load on RME. RESULTS: : The interaction (p = 0.025) and load main effect were significant (p = 0.004). Post-hoc testing, however, indicated that only the exercise-pooled RME differed across loads (40% RME: 51.6±0.05, 60% RME: 61.3±0.06, 80% RME: 69.3±0.06). Specifically, the RME differed significantly between 40% and 60% (p = 0.049), 40% and 80% (p = 0.015), and 60% and 80% (p = 0.008). CONCLUSIONS: : RME did not differ between BS and FS at any load, but increased linearly from 40% through to 80% of FS 1-RM. These results suggest that at the same absolute load both exercises impose similar demands upon the knee extensor muscle groups, and that greater loads increase that demand.

Ruck marching is a key performance indicator for tactical preparation; however, marching under load causes changes in biomechanics, which can increase injury risk. Although this risk of injury from changes is known, current methods commonly used for assessing physical fitness have not adequately identified how to minimize these changes. In this observational study, 14 ROTC cadets underwent a series of physical muscular fitness tests prior to performing a six-mile ruck march. These included an evaluation of postural endurance via the Biering Sorenson hold, lower body strength via the back squat, and upper body strength via bench press. After the tests were performed, ruck march performance was evaluated by total time to completion and running dynamics. Multiple regression analysis was performed to determine if bench press maximum, back squat maximum, or Sorenson hold were predictors of the performance of the ruck March. Average cadence shared a positive significant relationship with the Sorenson hold (r = 0.76, p = 0.02) and a negative significant relationship with the back squat (r = -0.76, p = 0.02). Additionally, the Sorenson hold did not share any significant relationships with total ruck time (r = -0.3, p = 0.29) or ground contact time (r = -0.41, p = 0.31). The back squat did not share significant relationships with ground contact time (r = -0.37, p = 0.37) or average smoothness (r = -0.38, p = 0.31). This study highlights the potential relationship that the Sorenson hold and back squat can have on running cadence, which has shown significant changes in previous research evaluating the changes in running performance and characteristics from weight ruck marching. Further investigation of the relationship of these assessments on the performance of ruck marching should be performed with larger numbers of cadets in the future.

Houlton, LJ, Moody, JA, Bampouras, TM, and Esformes, JI. Acute effects of intracomplex rest after back squats on vertical jump performance during complex training. J Strength Cond Res 38(11): e645-e655, 2024-Postactivation performance enhancement and complex-contrast sets are prevalent in sports science research. Typical complex-contrast sets consist of heavy back squats, an intracontrast rest period (ICRP) and vertical jumps (countermovement jumps [CMJs], or squat jumps [SJs]). Propulsive impulse (J prop ) is considered the leading indicator of jump performance. However, studies evaluating jump performance during complex-contrast sets use jump height as the primary performance measure, limiting insight into ICRP's effect on jump performance. We assessed the effect of a 3 repetition maximum (3RM) back squat and 6 ICRPs on vertical jump J prop and associated force-time components. Fourteen subjects completed 12 experimental conditions, assigned equally to 4 testing sessions. Independent variables, in a 6 × 2 randomized, counterbalanced design, were ICRP (0, 60, 120, 180, 240, 300 seconds; ICRP0, ICRP60, ICRP120, ICRP180, ICRP240, ICRP300, respectively) and vertical jump (CMJ and SJ). Conditions consisted of baseline vertical jumps, followed by 3 back squat repetitions at 100% 3RM, an ICRP and experimental jumps. Symmetrized percentage changes between experimental and baseline jumps were assessed using repeated measures analysis of variance (ANOVA) and pairwise effect sizes. Results showed significant effects ( p ≤ 0.05) on CMJ average rate of force development (RFD) between ICRP0 and ICRP120 and ICRP0 and ICRP300. Pairwise comparisons showed medium and large effect sizes for and increases in CMJ RFD ( g = 0.83-2.69) whereas SJ RFD decreased ( g = 0.81-2.57). Small effect sizes were found for J prop , peak force, and mean force. Results suggest limited change in J prop ( g = 0.01-0.58), but back squats may potentiate RFD via the stretch-shortening cycle.

Rosa, A, Coleman, M, Haun, C, Grgic, J, and Schoenfeld, BJ. Repetition performance, rating of perceived discomfort, and blood lactate responses to different rest interval lengths in single-joint and multijoint lower-body exercise. J Strength Cond Res 37(7): 1350-1357, 2023-The purpose of this study was to examine the effects of different rest interval lengths (RILs) on repetition performance, rating of discomfort, and blood lactate responses during lower-body single-joint and multijoint exercises. This study used a counterbalanced design where each subject performed the Smith machine back squat (BS) and leg extension (LE) using 3 different RIL configurations (1, 2, and 3 minutes) in a randomized fashion. Data collection occurred over the span of 3 separate days. Volunteers were randomly allocated to perform the independent variables (RILs and exercises) in 1 of 12 potential configurations. The initial session was allotted for familiarization with the rating of discomfort scale and 10 repetition maximum testing. The other 2 sessions involved training with the different configurations of RIL length using both the BS and LE. Randomization ensured that the BS was performed first in one of the training sessions and the LE was performed first in the other session. Results indicated that longer RILs had a small positive effect on repetition performance, with longer rest durations allowing for more repetitions compared with shorter durations. The largest difference in repetition performance between RILs was observed between 1 minute and 2-3 minutes rest; there were trivial differences in repetition performance between 2 and 3 minutes rest for both the BS and LE. Blood lactate levels were slightly higher with longer RILs. Overall, BS showed greater increases in blood lactate compared with LE, and these differences were magnified over time. Exercise selection and RIL both influenced rating of discomfort, with LE producing less discomfort than BS and longer RILs reducing perceived discomfort. Our findings suggest that RIL influences the repetition performance, blood lactate, and rating of discomfort responses between single-joint and multijoint exercises.

BACKGROUND: Deadlift (DL) and back squat (BSQ) are considered different exercises because of their kinematic and kinetic characteristics. However, there are similarities, such as joint movement and the maximal muscle strength generated. Although there are differences and similarities, it is unclear which is more related to athletic performance. OBJECTIVE: This study aimed to determine the relationship between DL and jump, acceleration, and change of direction and compare whether DL or BSQ differ in their relationship to jumping, acceleration, and change of direction. METHODS: Eighty male volleyball players (age: 19.6 [Formula: see text] 0.9 years, height: 179.2 [Formula: see text] 6.7 cm, mass: 71.9 [Formula: see text] 9.4 kg) volunteered to participate in this study. Countermovement jump (CMJ), 10-m sprint, and 1–5 repetition maximum (1–5 RM) BSQ were measured on day 1. The T-test and 1–5 RM DL were measured on day 2. RESULTS: DL had a significant and moderate relationship with all parameters of CMJ ([Formula: see text] 0.328, [Formula: see text] 0.01), 10-m sprint ([Formula: see text] [Formula: see text]0.471, [Formula: see text] 0.01), and T-test ([Formula: see text] [Formula: see text]0.441, [Formula: see text] 0.01). BSQ showed a significant and moderate relationship with the 10-m sprint ([Formula: see text] [Formula: see text]0.489, [Formula: see text] 0.01) and T-test ([Formula: see text] [Formula: see text]0.356, [Formula: see text] 0.01), but a significant and weak relationship only with CMJ ([Formula: see text] 0.289, [Formula: see text] 0.01). In addition, no significant differences were found in the comparison of correlation coefficients ([Formula: see text] 0.05). CONCLUSIONS: Deadlift may be introduced as an alternative exercise to BSQ when there are limitations in the training environment, such as the lack of a squat rack to safely perform BSQ or home confinement due to external factors like pandemics.

This study evaluated impulse (I), peak ground reaction forces (GRF), and the rate of force development (RFD) of a variety of exercise modes for the purpose of estimating the magnitude and rate of mechanical loading as a measure of osteogenic potential. Twenty-three subjects participated in this study (mean +/- SD, age 21.2 +/- 1.4 years; body mass 77.8 +/- 16.2 kg). Kinetic data were obtained via a force platform for the test exercises modes, which included walking, jogging, depth jumps, loaded jump squats, and the back squat. Repeated measures analysis of variance revealed significant main effects for I, GRF, and RFD (p < or = 0.001). Bonferroni-adjusted post hoc analyses demonstrated that I and GRF were different between each exercise mode and that RFD was different between all exercise modes except for jogging and the back squat. The depth jump demonstrated the highest GRF and RFD, while the back squat produced the highest I. The jump squat produced the second highest value for all the variables assessed. Thus, the depth jump, jump squat, and back squat appear to offer the greatest potential as osteogenic stimuli and a mixed mode training strategy including exercises such as these is recommended. These results suggest that walking and jogging may have less osteogenic potential.

A 30-year-old person with a unilateral transtibial amputation (TTAmp) was assessed performing an Olympic-style back squat with an energy storage and return prosthetic foot. Determine joint-level movement strategies of an individual with TTAmp while performing an Olympic-style back squat. Case study design. Back squat mechanics are evaluated in an individual with TTAmp by comparing the contribution of the ankle, knee, and hip joint to total positive and negative amputated and sound limb work. The hip joint was the greatest contributor to total positive limb work compared with the knee and ankle, respectively, in the amputated (55.0% hip vs. 30.8% knee, P < 0.001; vs. 14.2% ankle, P = 0.001) and sound limbs (52.2% hip vs. 38.9% knee, P < 0.001; vs. 8.9% ankle, P < 0.001). The hip joint was the greatest contributor to total negative limb work compared with the ankle in both the amputated (51.0% hip vs. 15.9% ankle, P < 0.001) and sound limbs (47.3% hip vs. 10.0% ankle, P < 0.001) and the knee in the amputated limb (51.0% hip vs. 32.5% knee, P < 0.001). Ankle joint power demonstrated an atypical bimodal negative/positive/negative/positive pattern. The individual with TTAmp used a hip-dominant joint strategy in both the amputated and sound limbs while demonstrating more potential to optimize the prosthetic foot's energy storage and return capabilities when performing a back squat.

The aim of this study was to investigate the effects of wearing knee wraps on mechanical output and performance characteristics of back squat exercise. Ten resistance trained men (back squat 1 repetition maximum [1RM]: 160.5 ± 18.4 kg) performed 6 single back squats with 80% 1RM, 3 wearing knee wraps, 3 without. Mechanical output was obtained from ground reaction force, performance characteristics from digitized motion footage obtained from a single high-speed digital camera. Wearing knee wraps led to a 39% reduction (0.09 compared with 0.11 m, p = 0.037) in horizontal barbell displacement that continued during the lifting phase. Lowering phase vertical impulse remained within 1% across conditions; however, the lowering phase was performed 45% faster (1.13 compared with 1.57 seconds). This demonstrated that vertical force applied to the center of mass during the lowering phase was considerably larger and was likely a consequence of the generation and storage of elastic energy within the knee wrap. Subsequent vertical impulse applied to the center of mass was 10% greater (192 compared with 169 N·s, p = 0.018). Mechanical work involved in vertically displacing the center of mass was performed 20% faster and was reflected by a 10% increase in peak power (2,121 compared with 1,841 W, p = 0.019). The elastic properties of knee wraps increased mechanical output but altered back squat technique in a way that is likely to alter the musculature targeted by the exercise and possibly compromise the integrity of the knee joint. Knee wraps should not be worn during the strength and condition process, and perceived weakness in the knee joint should be assessed and treated.

Squats are one of the most widely used weight training methods worldwide, and the single most ubiquitous with regard to multi-joint resistance training. The objective of the present study was to investigate kinematic and kinetic changes in the lower extremities as a result of load increases during a back squat exercise, and to propose an association between back squats and lower extremity injuries. Eight individuals with experience of back squat training were recruited. The subjects performed back squats with loads of 25%, 50%, 100%, and 125% of their body weight. During the performance, the center of pressure (COP) sway; vertical center of mass (COM) velocity; joint moment; joint range of motion (ROM) of flexion/extension and adduction/abduction; and rotation of the ankle, knee, and hip joints were measured. The participants' lower extremity joint ROM, vertical COM velocity, and COP variability did not change significantly with changes in weight loading. However, the moments applied to the lower extremity joints differed according to changes in barbell weight. The moments of plantar flexion (f= 54.362, p< 0.001), dorsiflexion (f= 8.475, p< 0.001), knee flexion (f= 12.013, p< 0.001), knee extension (f= 8.581, p< 0.001), hip flexion (f= 5.111, p< 0.001), and hip extension (f= 11.053, p< 0.001) increased in the sagittal plane (flexion/extension). There was also a significant increase in ankle eversion (f= 5.612, p= 0.004), hip abduction (f= 3.242, p= 0.037), and adduction (f= 5.846, p= 0.003) in the frontal plane (adduction/abduction). Among the moment variables in the transverse plane (rotation), there were significant differences in ankle internal rotation (f= 7.043, p= 0.001) and hip external rotation (f= 11.070, p< 0.001). As the barbell load increased, posture and performance were maintained, but rotational moments of the joints differed. It is expected that the joint directions that showed significant differences in this study are likely to be vulnerable to the risk of injury when an excessive load is applied to the body. Examples include the hip adduction moment, hip external rotation moment, and ankle internal rotation moment, and apply regardless of the increase in the rotational moments of joints from load increases.

This study aimed to determine the validity and between-day reliability of the mean velocity (MV), peak velocity (PV), mean power (MP), and peak power (PP) provided by the Vitruve linear position transducer at different submaximal loads in the free-weight and Smith machine back squat using GymAware as a reference point. Fourteen male sports science students (free-weight back squat one-repetition maximum [1RM]: 132.5 ± 28.5 kg, Smith machine back squat 1RM: 163.9 ± 30.4 kg) performed six experimental sessions, twice per week with 72 hours of rest. The first two included the assessment of the 1RM of both exercises. In the four remaining, both linear position transducers were simultaneously used to record MV, PV, MP, PP of each repetition during an incremental load test (i.e., 20, 40, 60, 80, 90% 1RM) with three minutes of rest between sets. Vitruve displayed both fixed and proportional bias for certain relative loads across all variables. Vitruve did not meet the validity criteria for all (MV, PP) or at least two (MP, PV) relative loads (Coefficient of variation [CV] > 10%; Pearson correlation < 0.70; Effect size > 0.60). MV, PV, MP, and PP recorded by Vitruve displayed acceptable reliability (CV < 10%) with superior reliability observed during a Smith Machine compared to free-weight back squat, and for velocity compared to power variables. Considering GymAware as a reference point, Vitruve was not valid for measuring velocity and power outcomes. Acceptable validity was observed only for PV in the Smith machine back squat, while the other variables-regardless of relative loads and exercise modes-were mostly inaccurate. All variables demonstrated acceptable reliability, with greater reliability noted in the Smith machine compared to the free-weight back squat exercise mode.