Effect of front and back squat techniques on peak loads experienced by the Achilles tendon

Background A primary technique in the discipline of strength and conditioning the squat has two principal ‘back and front’ variants. Despite the physiological and strength benefits of the squat, the propensity for musculoskeletal injury is high. The current investigation examined the influence of the front and back squat variations on the load experienced by the Achilles tendon. Material/Methods Achilles tendon loads were obtained from eighteen experienced male participants as they completed both back and front squats. Differences between squat conditions were examined using Bonferroni adjusted (p = 0.0125) paired t-tests. Results The results showed that the peak Achilles tendon load was significantly greater in the back squat (2.67 ±0.74 B.W) condition compared to the front squat (2.37 ±0.69 B.W). Conclusions Given the proposed relationship between the magnitude of the load experienced by the Achilles tendon and tendon pathology, the back squat appears to place lifters at greater risk from Achilles tendon injury. Therefore, it may be prudent for lifters who are predisposed to Achilles tendon pathology to utilize the front squat in their training

Static loads on the knee and ankle for two modalities of the isometric smith squat

Introduction: The back squat is a popular strength training exercise that recruits approximately 75% of the muscular system. However, knowledge of muscular and joint loads incurred when performing two variations of the back squat, namely the high bar and the low bar isometric parallel-depth Smith squat, is limited. Therefore this study aims to determine the lower limb muscle forces and the compressive and shear joint forces at the knee and ankle incurred in these two subtle variations of the one repetition maximum (1RM) isometric Smith squat. Method: Eight healthy male 400-m sprinters participated in the study. The participants performed the two modalities of the squat using a 7° backward-inclined Smith machine. The bottom of the squat corresponded to a position in which the thighs are parallel to the ground. The mean ± SD 1RM external load for the eight participants was 100.3 ± 7.2 kg. During the squat, the participants paused for 2-3 s at the bottom of the squat. This was, therefore, considered a static position for the calculation of isometric muscle forces and joint loads using static mechanical analysis. Moment arms, and joint and segmental angles were calculated from video images of the squat obtained at 25 Hz. Internal forces were computed using a geometrical model of the lower limb. Results: Quadriceps muscle and knee joint forces were higher in the high bar squat; where, the mean patellofemoral joint reaction force was 3.7 body weights (BW). The ankle extensor muscle and ankle joint forces were larger in the low bar squat; whereby, the mean compressive force at the ankle joint was 3.0 BW. Discussion: The high bar squatting modality may be avoided in the rehabilitation of ACL injury. Conversely, the low bar technique may be discouraged in conditions of ankle joint instability, strained Achilles tendon, and damaged gastrocnemius and soleus muscles. The findings of the static biomechanical evaluation provide an in-depth understanding of the musculoskeletal loads associated with the two squat modalities in isometric conditions and offer a foundation for the dynamic modelling of the high bar and low bar Smith squat. Further, the knowledge gained can be used for the prevention of injury in strength training and in the design of rehabilitation programs that control muscle recruitment and joint loads

Static loads on the lower back for two modalities of the isometric smith squat

Introduction: The squat is one of the most effective exercises in athletic training. However, there is a scarcity of research that reports the muscular and joint loads in the lumbar region incurred when performing the high bar and the low bar isometric squat modalities in a Smith machine. Therefore, this study aims to determine the muscle force of the lower back extensors, and the compressive (Rc) and shear (Rs) forces at the lumbosacral joint for the one repetition maximum (1RM) high bar and low bar isometric parallel-depth Smith squats. Methods: Eight healthy male well-trained 400-m sprinters participated in the study. The athletes performed the two modalities of the isometric squat on a 7° backward-inclined Smith machine using a mean ± SD 1RM external resistance of 100.3 ± 7.2 kg. During the squat, the participants paused for 2-3 s at the bottom of the squat, corresponding to a position in which the thighs are parallel to the ground. This was, therefore, considered a static position for the calculation of isometric muscle forces and joint loads using static mechanical analysis. Moment arms, and joint and segmental angles were calculated from video images of the squatting performance. Internal forces were computed using a geometrical model of the trunk and lower limb. Results: Spinal extensor muscular forces and lumbo-sacral joint forces were higher when using the low bar technique; with the exception of Rs which was approximately equal. The mean Rc were 10.2 body weights (BW) or 8,014 N (high bar) and 11.1 BW or 8,729 N (low bar). Discussion: The low bar technique yields higher Rc and may therefore be avoided in the rehabilitation of spinal injuries. Increased bone mineral density and well-developed trunk musculature due to long term squat training can provide protection against passive spinal tissue failure. Therefore, the Rc found for the 1RM isometric parallel-depth Smith squat do not appear excessive for healthy well-trained athletes. The presence of Rs at the lumbo-sacral joint in both squat modalities suggests potential for damage to the intervertebral disc. The findings provide an in-depth understanding of the two squat modalities in isometric conditions for the prevention of lower back injury and the design of rehabilitation programs

Activation of the <i>gluteus maximus</i> during performance of the back squat, split squat and barbell hip thrust and the relationship with maximal sprinting

The purpose of this research was to compare muscle activation of the gluteus maximus and ground reaction force between the barbell hip thrust, back squat, and split squat and to determine the relationship between these outcomes and vertical and horizontal forces during maximal sprinting. Twelve male team sport athletes (age 25.0 ± 4.0 years, stature 184.1 ± 6.0 cm, body mass 82.2 ± 7.9 kg) performed separate movements of the three strength exercises at a load equivalent to their individual three repetition maximum. The ground reaction force was measured using force plates and the electromyography (EMG) activity of the upper and lower gluteus maximus was recorded in each leg and expressed as percentage of the maximum voluntary isometric contraction (MVIC). Participants then completed a single sprint on a non-motorized treadmill for the assessment of maximal velocity, horizontal and vertical forces. Although ground reaction force was lower, peak EMG activity in the gluteus maximus was higher in the hip thrust than the back squat (p = 0.024; 95%CI = 4 – 56%MVIC) and split squat (p = 0.016; 95%CI = 6 – 58%MVIC). Peak sprint velocity was correlated with both anterior-posterior horizontal force (r = 0.72) and peak ground reaction force during the barbell hip thrust (r = 0.69) but no other variables. The increased activation of gluteus maximus during the barbell hip thrust and the relationship with maximal running speed suggests that this movement may be optimal for training this muscle group in comparison to the back squat and split squat

Task‐specific strength increases after lower‐limb compound resistance training occurred in the absence of corticospinal changes in vastus lateralis

Neural adaptations subserving strength increases have been shown to be task‐specific, but responses and adaptation to lower‐limb compound exercises such as the squat are commonly assessed in a single‐limb isometric task. This two‐part study assessed neuromuscular responses to an acute bout (Study A) and 4 weeks (Study B) of squat resistance training at 80% of one‐repetition‐maximum, with measures taken during a task‐specific isometric squat (IS) and non‐specific isometric knee extension (KE). Eighteen healthy volunteers (25 ± 5 years) were randomised into either a training (n = 10) or a control (n = 8) group. Neural responses were evoked at the intracortical, corticospinal and spinal levels, and muscle thickness was assessed using ultrasound. The results of Study A showed that the acute bout of squat resistance training decreased maximum voluntary contraction (MVC) for up to 45 min post‐exercise (−23%, P < 0.001). From 15–45 min post‐exercise, spinally evoked responses were increased in both tasks (P = 0.008); however, no other evoked responses were affected (P ≥ 0.240). Study B demonstrated that following short‐term resistance training, participants improved their one repetition maximum squat (+35%, P < 0.001), which was reflected by a task‐specific increase in IS MVC (+49%, P = 0.001), but not KE (+1%, P = 0.882). However, no training‐induced changes were observed in muscle thickness (P = 0.468) or any evoked responses (P = 0.141). Adjustments in spinal motoneuronal excitability are evident after acute resistance training. After a period of short‐term training, there were no changes in the responses to central nervous system stimulation, which suggests that alterations in corticospinal properties of the vastus lateralis might not contribute to increases in strength

A biomechanical analysis of the heavy sprint-style sled pull and comparison with the back squat

This study compared the biomechanical characteristics of the heavy sprint-style sled pull and squat. Six experienced male strongman athletes performed sled pulls and squats at 70% of their 1RM squat. Significant kinematic and kinetic differences were observed between the sled pull start and squat at the start of the concentric phase and at maximum knee extension. The first stride of the heavy sled pull demonstrated significantly (

Jump Training Analysis: An Application in Strength and Conditioning

Force development is a crucial part of sports performance. Jumping is a mechanical movement used in various sports to analyze force production. Strength and Conditioning coaches work with athletes on improving sports performance through a variety of exercises. The mechanical principles utilized in jump training will help coaches train athletes to excel. Research has analyzed the various components of jumping that could substantially improve the rate of force development. Studies about the mechanisms of jumping will consist of devices used to measure force, phases of the jump, neuromuscular control of jumping and exercises to help athletes improve. The following thesis will include a review of jumping as well as an application strength and conditioning coach’s use in the weight room

Barbell back squat:How do resistance bands affect muscle activation and knee kinematics?

ObjectivesThis study aimed to determine whether looped resistance bands affect knee kinematics and lower body muscle activation during the barbell back squat.MethodsTwenty-six healthy participants (13 female, 13 male) calculated their one repetition maximum (RM) prior to data collection. Each participant performed three squats at both 80% and 40% 1RM wearing a light resistance band, an extra-heavy resistance band and no resistance band.Vicon 3D motion analysis cameras were used to collect the kinematic data, and Delsys Trigno Lab wireless electromyography (EMG) system was used to measure vastus medialis, vastus lateralis, gluteus maximus, gluteus medius and biceps femoris muscle activity. Peak knee flexion angle, peak knee valgus angle and maximum tibial rotation values were examined. Peak EMG values were also analysed after being normalised and expressed as a percentage of maximum voluntary contraction (MVC).ResultsGluteus maximus (GM) activity is significantly increased when a resistance band is used during squatting. However, squatting with a resistance band is detrimental to knee kinematics as it leads to an increase in knee valgus angle and maximum tibial rotation angle. A direct correlation is recorded between an increase in resistance and an increase in these two angles.ConclusionsSquatting with resistance bands is likely to increase the risk of knee injury. Coaches and clinicians who already implement this technique are advised to remove resistance band squats from training and rehabilitation programmes. Further research evaluating the long-term effects of using resistance bands during the barbell back squat should be considered

The sit up test to exhaustion as a test for muscular endurance evaluation

AIMS/HYPOTHESIS The aim of this study was to examine the sit up test to exhaustion as a field test for muscular endurance evaluation in a sample of sedentary people of both sexes. METHODS: A cross-sectional study was performed. Three-hundred-eighty-one participants volunteered for the study (28.5 \ub1 10.0 years; 168.2 \ub1 8.9 cm; 65.1 \ub1 11.1 kg), of which 194 males (27.5 \ub1 10.2 years; 173.6 \ub1 7.0 cm; 71.2 \ub1 5.2 kg) and 187 females (29.6 \ub1 10.1 years; 162.6 \ub1 7.1 cm; 58.7 \ub1 8.9 kg). Each subject voluntarily and randomly performed: a sit up test (SUT), a push up test (PUT), and a free weight squat test (ST), all till exhaustion. A multiple regression analysis was adopted for data analysis. Subsequently a percentile model for muscle endurance was developed. The 25th, 50th, and 75th percentile were identified as upper limit for low muscular endurance, average muscular endurance, and lower limit for high muscular endurance, respectively. RESULTS: Considering the sit up test as the dependent variable, the coefficients (R(2) = 0.23; r = 0.49; p < 0.001), and (R(2) = 0.31; r = 0.57; p < 0.001) emerged from a multiple regression analysis applied with respect to the push up test and the squat test, respectively. Gender stratification showed regression coefficients of (R(2) = 0.19; r = 0.44; p < 0.001) for SUT vs. PUT, and (R(2) = 0.30; r = 0.56; p < 0.001) for SUT vs. ST in male; and (R(2) = 0.23; r = 0.49; p < 0.001) for SUT vs. PUT, and (R(2) = 0.34; r = 0.59; p < 0.001) for SUT vs. ST in female. CONCLUSIONS/INTERPRETATION: The SUT showed low inter-relation with the other proposed tests indicating that the adoption of a single test for the global evaluation of muscle endurance is not the optimal approach. Moreover, the SUT was found to be inexpensive, safe, and appropriate for core muscle endurance measurement for both male and female