Smith Machine Squat Research Articles

Muscle Hypertrophy and Strength Adaptations to Systematically Varying Resistance Exercises

ABSTRACT We compared the effects of varied and constant resistance exercises on muscular adaptations in young women. Seventy young women (21.8 ± 3.4 yrs, 62.0 ± 12.3 kg, 162.3 ± 5.7 cm) were randomly divided into two groups: constant resistance exercises (CON-RE, n = 38) or varied resistance exercises (VAR-RE, n = 32). The resistance training (RT) was performed thrice a week over 10 weeks. CON-RE performed a 45º leg press and stiff-leg deadlift in every training session, while VAR-RE performed 45º leg press and stiff-leg deadlift in the first training session of the week, hack squat and prone leg curl in the second, and Smith machine squat and seated-leg curl in the third. Both groups performed two sets of 10–15 repetitions maximum per resistance exercise. We measured the muscle thickness of the thigh’s anterior, lateral, and posterior aspects by ultrasonography at different muscle sites (proximo-distal). Muscular strength was analyzed from the one-repetition maximum (1RM) tests in the 45° leg press and leg extension (non-trained exercise). The muscle thickness increased similarly in both groups for all muscles and sites (CON-RE: +7.8–17.7% vs. VAR-RE: +7.5–19.3%, p > .05). The 1RM increased similarly in both groups (CON-RE: +24.4–32.1% vs. VAR-RE: +29.0–30.1%, p > .05). Both RT routines resulted in virtually similar muscular strength gains and hypertrophy. Therefore, both strategies should be considered for the improvement of strength and muscle growth.

4-6 Repetition Maximum (RM) and 1-RM Prediction in Free-Weight Bench Press and Smith Machine Squat Based on Body Mass in Male Athletes.

Dhahbi, W, Padulo, J, Russo, L, Racil, G, Ltifi, M-A, Picerno, P, Iuliano, E, and Migliaccio, GM. Four- to 6-repetition maximum and 1-repetition maximum estimation in free-weight bench press and smith machine squat based on body mass in male athletes. J Strength Cond Res 38(8): 1366-1371, 2024-This study aimed to explore the feasibility and face validity of predicting maximum strength 1 repetition maximum (1-RM) and 4-6 RM in athletes across different sports specialties, based on the relationship between muscle strength and BM. One hundred fifteen male athletes, aged 23.63 ± 6.77 years and participating in diverse sports specialties, were included in this study. Muscle strength was assessed using the 4-6 RM and 1-RM tests in free-weight bench press (BP) and Smith machine squat (SQ) exercises, whereas BM was measured using a portable digital scale. A linear regression equation based on muscle strength and BM was performed. The 4-6 RM and 1-RM scores showed excellent intersession relative reliability (intraclass correlation coefficient (2,1) : 0.946-0.989) and absolute reliability (CV: 3.4-4.7%) in both BP and SQ exercises. In addition, the magnitude of the relationship and the coefficients used to estimate the 4-6 RM and 1RM, based on BM, differed among the subjects when they are grouped according to their sports specialties ( R2 ranged from non-significant to 0.998). Overall, the 4-6 RM test showed a stronger correlation with BM ( R : 0.655 for SQ and R : 0.683 for BP) than the 1RM ( R : 0.552 for SQ and R : 0.629 for BP), and the general (i.e., not sport-specific) 4 to 6-RM prediction equations should be preferred over sport-specific ones because they are statistically more robust due to the larger sample size. In conclusion, the 4-6 RM can be predicted from BM with high reliability, a moderate association, and a prediction error that, when considering the 4-6 RM as a starting point for estimating of the 1RM, can be considered entirely acceptable in practical settings.

Heavier loads in flywheel exercise induce greater post-activation performance enhancement in countermovement jumps compared to heavy Smith machine squats in males.

We evaluated the effects of post-activation performance enhancement through flywheel exercise with varying inertial loads compared to traditional resistance exercise on countermovement jump performance and muscle recruitment. In a randomized crossover design, 13 trained men completed four main experimental trials after three familiarization sessions. These conditions included a traditional trial consisting of 5 sets of 1 repetition using the Smith machine (SM) squat at 90% 1RM, and three flywheel ergometer trials. Each flywheel protocol consisted of 3 sets of 8 repetitions with 3-minute rest intervals between sets, utilizing one of three inertial loads (0.0465, 0.0784, and 0.1568 kg · m2 for light, moderate, and heavy, respectively). Participants performed countermovement jumps before (baseline), immediately after (0 minute), and at the fourth (+4 minutes), eighth (+8 minutes), and twelfth (+12 minutes) minute following exercise. Compared to baseline, jump height was higher at +4 minutes for SM squats (p = 0.009). All flywheel conditions exhibited higher jump heights at +4 minutes (p < 0.05), +8 minutes (p < 0.001), and +12 minutes (p < 0.001) compared to baseline. Additionally, moderate and heavy loads resulted in higher jump heights at 0 minute (both p < 0.001). Integrated electromyographic activity values, a proxy for muscle recruitment, were significantly higher for the gluteus maximus muscle at both +8 minutes and +12 minutes for moderate (both p = 0.004) and heavy loads (p ≤ 0.002) compared to SM squats. Overall, flywheel protocols produce greater post-activation performance enhancement, extend the time window for improvement, and recruit more active musculature compared to heavy-load SM squats, particularly with heavier loads acting as a stronger preload stimulus.

Reliability and concurrent validity of the PUSH Band™ 2.0 to measure barbell velocity during the free-weight and Smith machine squat exercises

The aim of this study was to examine the test-retest reliability and concurrent validity of the PUSH Band™ 2.0 to measure barbell’s velocity during unconstrained (free-weights) and constrained (Smith machine) squat exercises. After an initial assessment of the Smith machine squat one-repetition maximum (1RM), 24 resistance-trained males completed one or two testing sessions separated by 7 days. In one session, the squat was performed with free-weights ( n = 22), while in another session, the Smith machine was used ( n = 16). Both testing sessions consisted of two blocks of eight repetitions (three repetitions at 45%1RM, three repetitions at 65%1RM, and two repetitions at 85%1RM). The mean velocity of the lifting phase was simultaneously recorded with the PUSH Band™ 2.0 and a gold-standard linear velocity transducer (T-Force® System). The PUSH Band™ 2.0 generally revealed an acceptable reliability (CVrange = 5.81%–13.14%), but the reliability was always greater for the T-Force® System (CVrange = 2.95%–7.86%). Regardless of the squat exercise, the concurrent validity of the PUSH Band™ 2.0 with respect to the T-Force® System was generally low at 45%1RM (ESrange = 0.18–0.33; rrange = 0.58–0.75; SEErange = 0.04–0.05 ms−1 and 4.2%–6.0%), 65%1RM (ESrange = 0.26–0.44; rrange = 0.63–0.82; SEErange = 0.04–0.06 ms−1 and 6.0%–9.2%), and 85%1RM (ESrange = 0.61–0.64; rrange = 0.66–0.82; SEErange = 0.05–0.07 ms−1 and 11.4%–16.0%). Taken together, these results suggest that the PUSH Band™ 2.0 is a reliable, but not valid, wearable technology to measure the barbell velocity during the free-weight and Smith machine squat exercises.

Is the Occurrence of the Sticking Region in Maximum Smith Machine Squats the Result of Diminishing Potentiation and Co-Contraction of the Prime Movers among Recreationally Resistance Trained Males?

This study compared the kinetics, barbell, and joint kinematics and muscle activation patterns between a one-repetition maximum (1-RM) Smith machine squat and isometric squats performed at 10 different heights from the lowest barbell height. The aim was to investigate if force output is lowest in the sticking region, indicating that this is a poor biomechanical region. Twelve resistance trained males (age: 22 ± 5 years, mass: 83.5 ± 39 kg, height: 1.81 ± 0.20 m) were tested. A repeated two-way analysis of variance showed that Force output decreased in the sticking region for the 1-RM trial, while for the isometric trials, force output was lowest between 0–15 cm from the lowest barbell height, data that support the sticking region is a poor biomechanical region. Almost all muscles showed higher activity at 1-RM compared with isometric attempts (p < 0.05). The quadriceps activity decreased, and the gluteus maximus and shank muscle activity increased with increasing height (p ≤ 0.024). Moreover, the vastus muscles decreased only for the 1-RM trial while remaining stable at the same positions in the isometric trials (p = 0.04), indicating that potentiation occurs. Our findings suggest that a co-contraction between the hip and knee extensors, together with potentiation from the vastus muscles during ascent, creates a poor biomechanical region for force output, and thereby the sticking region among recreationally resistance trained males during 1-RM Smith machine squats.

RETRACTED ARTICLE: Load–velocity relationship 1RM predictions: A comparison of Smith machine and free-weight exercise

ABSTRACT This study aimed to determine differences in the validity and reliability of 1RM predictions made using load–velocity relationships in Smith machine and free-weight exercise. Twenty well-trained males attended six sessions, comprising the Smith machine and free-weight squat, bench press, prone row and overhead press. Load-velocity relationship-based 1RM predictions were performed using minimal velocity threshold (1RMMVT), load at zero velocity (1RMLD0) and force-velocity (1RMFV) methods, with 5- or 7-loads. Measured 1RM did not differ from 1RMMVT or 1RMLD0 for any of the Smith machine exercises, while it was higher than 1RMFV for all exercises except the prone row. For the free-weight variations all 1RM predictions differed from measured 1RM for the squat and overhead press, while measured and predicted 1RM did not differ in the bench press and prone row. No differences were observed between 7-and 5-load predictions. 1RMMVT was the most reliable and valid of the methods. Smith machine exercises resulted in more reliable predictions than free weight exercises. 1RMMVT provides valid and reliable predictions for the Smith machine, squat, bench press, prone row and overhead press and free-weight bench press and prone row. Practitioners must be aware of the poor validity of free-weight squat and overhead press predictions.

URINARY INCONTINENCE AND EXERCISE: KINESIOLOGICAL DESCRIPTION OF AN INTERVENTION PROPOSAL

ABSTRACT Introduction Research shows that symptoms of urinary incontinence are common among women who engage in physical activity. Objective To conduct a kinesiological analysis of specific exercises for the pelvic floor muscles (PFM), proposing correspondences of these postures through resistance exercises. Methods This research project is of a descriptive nature with level of evidence V. Videos and photos were taken to obtain an image for the collection of data based on the accomplishment of the specific postures. Results The kinesiological study revealed that the muscles involved in the postures of exercises targeting the prevention of urinary incontinence beyond those specific to the pelvic floor were: trunk flexors; spinal erector; adductors and hip extensors. The resistance exercises corresponding to these positions in bodybuilding apparatus were the machine hack squat; sitting adductor exercises; sitting abductor exercises; the smith machine squat and the free squat or machine squat. Conclusion This study showed that it is possible to construct correspondence between exercises for the pelvic floor muscles and resistance exercises with bodybuilding equipment and free weights. A new strategy is suggested for the physical education professional, based on resistance exercises: taking a coadjuvant approach to the treatment and prevention of urinary incontinence during physical and sports exercises. Level of evidence V, Case series.

A Comparison of Compound Set and Traditional Set Resistance Training in Women: Changes in Muscle Strength, Endurance, Quantity, and Architecture

The purpose of the study was to investigate the effects of using compound sets during a 12-week lower body resistance training program on muscle strength, endurance, hypertrophy, architecture, and soreness. Thirty-one recreationally active females were randomly assigned to one of three groups: traditional sets, compound sets, or control. The training groups performed Smith Machine squat and leg press at matched intensities, volumes, and cumulative rest per session. During compound sets, the squat was performed immediately prior to the leg press, while 1 min rest separated the exercises during traditional sets. A non-exercise control group did not perform resistance training. One-repetition maximum strength, muscle endurance, muscle thickness, cross-sectional area, pennation angle, training session time, and soreness were compared from pre- to post-training (α level 0.80), 24 (P > 0.50), or 48 (P > 0.30) h post-workout. In conclusion, compound set training, with equated rest, is a method of resistance training that elicits gains similar to traditional sets in young females.

The Effect of In-Season Traditional and Explosive Resistance Training Programs on Strength, Jump Height, and Speed in Recreational Soccer Players

ABSTRACTPurpose: Resistance training is often performed in a traditional training style using deliberate relatively longer repetition durations or in an explosive training style using maximal intended velocities and relatively shorter repetition durations. Both improve strength, “power” (impulsivity), and speed. This study compared explosive and traditional training over a 6-week intervention in 30 healthy young adult male recreational soccer players. Method: Full body supervised resistance training was performed 2 times a week using 3 sets of each exercise at 80% of one repetition maximum to momentary failure. Outcomes were Smith machine squat 1 repetition maximum, 10 meter sprint time, and countermovement jump. Results: Both groups significantly improved all outcomes based on 95% confidence intervals not crossing zero. There were no between-group differences for squat 1 RM (TRAD = 6.3[5.1 to 7.6] kg, EXP = 5.2[3.9 to 6.4] kg) or 10 meter sprint (TRAD = −0.05[−0.07 to −0.04] s, EXP = −0.05[−0.06 to −0.03] s). Explosive group had a significantly greater increase in countermovement jump compared to the traditional group (TRAD = 0.7[0.3 to 1.1] cm, EXP = 1.3[0.9 to 1.7] cm). Conclusion: Both the traditional training and explosive training performed to momentary failure produced significant improvements in strength, speed, and jump performance. Strength gains are similar independent of intended movement speed. However, speed and jump performance changes are marginal with resistance training.

Leg Press vs. Smith Machine: Quadriceps Activation and Overall Perceived Effort Profiles.

First aim was describing Smith machine squat and leg press exercise as nominal load, knee extensors activity, and rating of perceived exertion. Second aim was developing predictive equations to provide same muscular activation and same perceived exertion nominal loads during the two exercises. To do that, vastus lateralis and vastus medialis activation, as their summed surface electromyography signal integrals, and overall perceived exertions were measured at different nominal loads during Smith machine squat and leg press exercise in adult male athletes experienced in weight training. Correlation and multistep stepwise analyses were performed. Then, two different results-driven predictive equations to provide same electromyography signals and same perceived exertion nominal loads were developed. The same electromyography signal equation results were less accurate (i.e., less predictive) due to high inter-individual differences, whereas the same perceived exertion equation results were more accurate, because perceived exertion is more related to the Smith machine squat and leg press exercise overall level of exertion than to the two single muscles that were investigated. In conclusion, these two equations represented an initial attempt to provide athletes and coaches with a new tool to mutually convert equivalent nominal loads during Smith machine squat and leg press exercise over a training period.

The Effect of Caffeine Supplementation on Power and Fatigue in Recreationally Trained College Aged Males

Caffeine (CAF) is consumed regularly by approximately 90% of adults worldwide, primarily to reduce fatigue and increase wakefulness. The benefit of caffeine consumption on athletic performance in large doses (3-9 mg/kg body weight or BW) is well documented in aerobic athletes. However, the benefits of caffeine consumption on resistance training (RT) variables such as power are less clear. PURPOSE:The purpose of this study was to investigate the effect of consumption of 7 mg/kg BW of CAF on power production in experienced, resistance trained college-aged males, who are habitual caffeine consumers. METHODS:Eighteen young, healthy college aged males (21.7 ± 2.0 yrs) were included in this double blind, placebo controlled study. Subjects performed a battery of tests that included a vertical jump (VJ), isometric squat (ISO), and Smith Machine squat (SQF) and Smith Machine bench press (BPF) to failure at 60% 1RM. Subjects consumed either 7 mg/kg BW of CAF or placebo (P), 60 minutes prior to testing. Test sessions were separated by a minimum of 7 days. Power production during VJ, SQF and BPF exercises was evaluated. Power obtained during SQF and BPF was used to find the fatigue index (F.I.). Also, force production during an ISO was assessed. A repeated measures ANOVA was used to determine differences between treatments. Significance for all analysis was set at p≤ 0.05. RESULTS:There were no significant differences between treatments (CAF vs P) in measures of VJ (3924.2 ± 617.1 vs 3930.9 ± 627.5W, p=0.925), ISO (2512.3 ± 555.8 vs 2585.3 ± 528.2N, p=0.270), SQF (36.9 ± 12.6 vs 33.6 ± 10.6%, p=0.234), or BPF (40.5 ± 12.5 vs 42.0 ± 8.3%, p=0.591). CONCLUSION:7 mg/kg BW of CAF does not improve measures of force, power, or fatigue during single-set to failure resistance training exercises in habitual caffeine users. These results indicate that CAF supplementation may be affected by training bout volume (sets x reps), due to the lack of improvement in F.I., i.e. local muscular endurance.

Changing the stability conditions in a back squat: the effect on maximum load lifted and erector spinae muscle activity

The aim of this study was to identify how changes in the stability conditions of a back squat affect maximal loads lifted and erector spinae muscle activity. Fourteen male participants performed a Smith Machine (SM) squat, the most stable condition, a barbell back (BB) squat, and Tendo-destabilizing bar (TBB) squat, the least stable condition. A one repetition max (1-RM) was established in each squat condition, before electromyography (EMG) activity of the erector spinae was measured at 85% of 1-RM. Results indicated that the SM squat 1-RM load was significantly (p = 0.006) greater (10.9%) than the BB squat, but not greater than the TBB squat. EMG results indicated significantly greater (p < 0.05) muscle activation in the TBB condition compared to other conditions. The BB squat produced significantly greater (p = 0.036) EMG activity compared to the SM squat. A greater stability challenge applied to the torso seems to increase muscle activation. The maximum loads lifted in the most stable and unstable squats were similar. However, the lift with greater stability challenge required greatest muscle activation. The implications of this study may be important for training programmes; if coaches wish to challenge trunk stability, while their athletes lift maximal loads designed to increase strength.

Reliability of one-repetition maximum test in untrained young adult men and women

BACKGROUND: The one repetition maximum (1RM) test is the most widely used method to analyze muscular strength. However, the 1RM reliability may be dependent on gender. OBJECTIVE: The purpose of the study was to investigate the reliability of one-repetition maximum (1RM) test in untrained young adult men and women. METHODS: Thirteen men and eleven women between 18–35 years were recruited. All subjects performed the 1RM tests in the bench press (BP), Smith machine squat (SQ), and arm curl (AC) in four sessions separated by 48 to 72 hours of recovery. At each measurement session, the subjects performed exercise-specific warm-ups and were given three attempts to reach a peak strength level for each exercise. RESULTS: There was a significant session-by-time interaction ( P< 0.05) in BP and SQ, while men reached a stabilized load between sessions 2–3, women stabilized their load between sessions 1–2. Significant increases ( P< 0.05) in maximal strength occurred between session 1 and 4 in BP (men =+ 10.5%, women =+ 13.1%), SQ (men =+ 17.6%, women =+ 20.7%), and AC (men =+ 7.5%, women =+ 11.7%). CONCLUSION: We conclude that the reliability of the 1RM tests in multiple-joint exercises may be gender dependent.

Effects of Adding Whole Body Vibration to Squat Training on Isometric Force/Time Characteristics

Resistance training interventions aimed at increasing lower-body power and rates of force development have produced varying results. Recent studies have suggested that whole-body low-frequency vibration (WBLFV) may elicit an acute postactivation potentiation response, leading to acute improvements in power and force development. Potentially, the use of WBLFV between sets of resistance training rather than during training itself may lead to increased recruitment and synchronization of high-threshold motor units, minimize fatigue potential, and facilitate the chronic adaptation to resistance exercise. The purpose of this study was to determine the effects of applying TriPlaner, WBLFV, prior to and then intermittently between sets of Smith machine squats on short-term adaptations in explosive isometric force expression. Thirty recreationally resistance trained men aged 18-30 were randomly assigned to 1 of 3 groups: resistance training only (SQT, n = 11), resistance plus whole-body vibration (SQTV, n = 13), or active control (CON, n = 6). An isometric squat test was performed prior to and following a 6-week periodized Smith machine squat program. Whole-body low-frequency vibration was applied 180 seconds prior to the first work set (50 Hz, 2-4 mm, 30 seconds) and intermittently (50 Hz, 4-6 mm, 3 x 10 seconds, 60 seconds between exposures) within a 240-second interset rest period. Subjects were instructed to assume a quarter squat posture while positioning their feet directly under their center of mass, which was modified using a handheld goniometer to a knee angle of 135 +/- 5 degrees . Instructions were given to subjects to apply force as fast and as hard as possible for 3.5 seconds. Isometric force (N) and rates of force development (N.s(-1)) were recorded from the onset of contraction (F(0)) to time points corresponding to 30, 50, 80, 100, 150, and 250 milliseconds, as well as the peak isometric rate of force development (PISORFD), and rate of force development to initial peak in force (RFDinitial). Repeated measures analysis of variance and analysis of covariance revealed no significant group by trial interactions for isometric rate of force development (ISORFD) between 0-30, 0-50, 0-80, 0-100, 0-150, and 0-250 milliseconds and PISORFD (p > 0.05). A significant group x trial interaction was seen for RFDinitial with SQTV >CG (p = 0.04, mean difference 997.2 N.s(-1)) and SQTV >SQT (p = 0.04, mean difference 1,994.22 N.s(-1)). Significant trial by covariate interactions (week one measures for ISORFD) and main effects for trial were observed for ISORFD between 0-80, 0-100, 0-and 150 milliseconds; PISORFD; and RFDinitial (p < 0.01). A significant trial effect was seen for Finitial (%) when expressed as a relative percentage of maximal voluntary contraction (MVC) (MVC = 100%) (p = 0.015; week 1 > week 7, mean difference, 5.82%). No significant differences were seen for any other force variables from the onset of contraction to MVC between weeks 1 and 7 (p > 0.05). The data suggest that there was a significant benefit afforded by adding WBLFV to a short-term resistance training protocol with regard to "explosive" strength expression. The addition of vibration prior to and between sets of resistance exercise may be a viable alternative to vibration applied during resistance exercise when trying to improve "explosive" isometric strength.

Effects Of Six Weeks Periodized Squat Training With Or Without Whole Body Vibration Upon The Relationship Between Isometric And Dynamic Performance

Resistance training interventions aimed at increasing lower body power and rates of force development have produced varying results. Potentially, the use of WBLFV in between sets of resistance training may increase high-threshold motor unit recruitment and synchronization leading to greater adaptations in both isometric and dynamic performance. The relationship between isometric force/time characteristics and dynamic performance and their respective changes in response to resistance training is of practical importance to strength and conditioning practitioners. To determine the effects of applying whole body vibration prior to and then intermittently between sets of Smith Machine squats upon training induced changes in isometric and dynamic performance and their relationships to one another. Twenty four recreationally resistance trained men were randomly assigned to one of two groups, resistance only (SQT n = 11), or resistance plus whole body vibration (SQTV n = 13). An isometric squat test as well as Squat Jumps (SQJ) and Depth Jumps (DJ) were performed prior to, and following a six-week, periodized Smith Machine squat program. WBLFV was applied 180 s prior to the first work set (50Hz 2-4mm, 30 s) and intermittently (50Hz 4-6mm, 3 × 10 s, 60s between exposures) within a 240s inter-set rest period. Subjects were instructed to assume a quarter squat posture while positioning their feet directly under their center of mass which was modified using a hand held goniometer to a knee angle of 135 ± 5°. Measures of isometric force (N) and isometric rates of force development (N·s−1) were recorded from the onset of contraction (F0) to time points corresponding to F30ms, F80ms, F250ms, Force at initial peak (Finitial), Force at 50% of MVC (MVC50) Time Finitial (ms) as well as the Peak Isometric Force (MVCp) and Peak Isometric Rate of Force Development (PISORFD). Squat jumps were performed with a 20kg Olympic barbell with a linear position transducer attached while the DJ utilized body mass as resistance while dropping from a height of 30cm onto a switch mat. Measures recorded during jumps included jump height (cm) peak power (PMax,W), peak power per kg of body mass (PMax/kg, W/kg) and mean power (Pav,W) for both jump conditions. Correlation matrices matching isometric force/time variables and dynamic (SQJ, DJ) performance within group between weeks 1 and 7(Pre- Post training) revealed multiple significant positive, and negative correlations (p = *<.05 and**<.001, range, r = −.624 to .859). A greater total amount of positive correlations were seen for SQTV (24) compared to SQT (2). Correlation coefficients (r) calculated between percent change (%Δ) scores for similar variables revealed small to moderate r values with the only significant correlation seen for the SQTV group between F30ms and DJ height (cm) (r = −.589, R2 = −.347, p <.05). More positive correlations were seen for isometric and dynamic %Δ variables that for SQTV (9) compared to SQT (7). The addition of WBLFV to the SQTVgroup appeared to effect neuro-muscular training adaptation differently from SQT as reflected in the percent change relationship between isometric and dynamic performance measures following six weeks of exposure. WBLFV may help facilitate early phase adaptations to resistance exercise with a tendency to improve early force time components of isometric and dynamic performance.

A Comparison of Free Weight Squat to Smith Machine Squat Using Electromyography

The purpose of this experiment was to determine whether free weight or Smith machine squats were optimal for activating the prime movers of the legs and the stabilizers of the legs and the trunk. Six healthy participants performed 1 set of 8 repetitions (using a weight they could lift 8 times, i.e., 8RM, or 8 repetition maximum) for each of the free weight squat and Smith machine squat in a randomized order with a minimum of 3 days between sessions, while electromyographic (EMG) activity of the tibialis anterior, gastrocnemius, vastus medialis, vastus lateralis, biceps femoris, lumbar erector spinae, and rectus abdominus were simultaneously measured. Electromyographic activity was significantly higher by 34, 26, and 49 in the gastrocnemius, biceps femoris, and vastus medialis, respectively, during the free weight squat compared to the Smith machine squat (p < 0.05). There were no significant differences between free weight and Smith machine squat for any of the other muscles; however, the EMG averaged over all muscles during the free weight squat was 43% higher when compared to the Smith machine squat (p < 0.05). The free weight squat may be more beneficial than the Smith machine squat for individuals who are looking to strengthen plantar flexors, knee flexors, and knee extensors.