Article

A three-dimensional biomechanical analysis of sumo and conventional style deadlifts

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  • American Sports Medicine Institute
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Abstract

Strength athletes often employ the deadlift in their training or rehabilitation regimens. The purpose of this study was to quantify kinematic and kinetic parameters by employing a three-dimensional analysis during sumo and conventional style deadlifts. Two 60-Hz video cameras recorded 12 sumo and 12 conventional style lifters during a national powerlifting championship. Parameters were quantified at barbell liftoff (LO), at the instant the barbell passed the knees (KP), and at lift completion. Unpaired t-tests (P < 0.05) were used to compare all parameters. At LO and KP, thigh position was 11-16 degrees more horizontal for the sumo group, whereas the knees and hips extended approximately 12 degrees more for the conventional group. The sumo group had 5-10 degrees greater vertical trunk and thigh positions, employed a wider stance (70 +/- 11 cm vs 32 +/- 8 cm), turned their feet out more (42 +/- 8 vs 14 +/- 6 degrees). and gripped the bar with their hands closer together (47 +/- 4 cm vs 55 +/- 10 cm). Vertical bar distance, mechanical work, and predicted energy expenditure were approximately 25-40% greater in the conventional group. Hip extensor, knee extensor, and ankle dorsiflexor moments were generated for the sumo group, whereas hip extensor, knee extensor, knee flexor, and ankle plantar flexor moments were generated for the conventional group. Ankle and knee moments and moment arms were significantly different between the sumo and conventional groups, whereas hip moments and moments arms did not show any significantly differences. Three-dimensional calculations were more accurate and significantly different than two-dimensional calculations, especially for the sumo deadlift. Biomechanical differences between sumo and conventional deadlifts result from technique variations between these exercises. Understanding these differences will aid the strength coach or rehabilitation specialist in determining which deadlift style an athlete or patient should employ.

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... Previous work has also investigated biomechanical differences between the sumo deadlift (SD) and the conventional-style deadlift (CD). With a greater stance width and slightly more narrow grip width for the SD compared with the CD, there are differences in the amount of mechanical work and stress placed on various joints between the SD and CD (5). Electromyography recorded during the 2 deadlift styles suggests greater knee extensor muscle activity during the SD compared with the CD (6). ...
... With a larger LD for the CD compared with the SD, this would allow for a greater velocity to be achieved between the sticking point of the lift and the end LD. In agreement with our findings, previous work has shown a greater bar velocity for the CD compared with the SD in national level powerlifters during competition lifts (5). However, the results of Escamilla et al. (5) demonstrated differences in ACV between the SD and CD at maximal loads, whereas we observed differences in ACV at submaximal loads between the SD and CD. ...
... In agreement with our findings, previous work has shown a greater bar velocity for the CD compared with the SD in national level powerlifters during competition lifts (5). However, the results of Escamilla et al. (5) demonstrated differences in ACV between the SD and CD at maximal loads, whereas we observed differences in ACV at submaximal loads between the SD and CD. One potential difference for these findings is due to differences in the subjects' characteristics between the studies. ...
... For this reason, rate of force development should not strictly be a limiting factor within powerlifting. The development of maximal muscle tension is likely to take 0.6 -0.8 seconds (Zatsiorsky, 2003) with competition lifts typically lasting 2-5 seconds (McGuigan & Wilson, 1996;Escamilla et al., 2000;Miletello et al., 2009). ...
... However, there is minimal correspondence or carryover between the two lifts. During deadlifting the largest moment is commonly observed at the hip (Brown & Abani, 1985;Cholewicki et al., 1991;Escamilla et al., 2000;Escamilla et al., 2001). However, Swinton et al. (2011) has reported a greater moments at the lower back. ...
... However, Swinton et al. (2011) has reported a greater moments at the lower back. Moments at the knee are widely demonstrated to be lower than at the hip (Brown & Abani, 1985;Cholewicki et al., 1991;Escamilla et al., 2000;Escamilla et al., 2001;Swinton et al., 2011), highlighting why the deadlift is recognised as a hip and back dominant exercise. ...
... Previous kinetic studies limited assessing lumbosacral, hip and knee joint moments in the standing resistance exercises [32][33][34][35][36][37][38][39][40][41][42]; for instance, deadlift is conducted by hip extensor moment, while back squat is conducted by knee extension moment [43]. One possibility of hip or knee domination is likely to be caused by the different joint angles in which the peak joint moments were generated in the lower limb. ...
... Three-dimensional analysis was recruited for a more accurate kinetic calculation rather than two-dimensional analysis [36,37]. Joint angle and angular velocity were three-dimensionally calculated by the standard calculation [58]. ...
... These may demonstrate that a barbell hip thrust can be a lower back and hip extension exercise for strength training, accompanied by a slight knee extension. Few previous studies calculated the lumbosacral, hip and knee joint moments during the resistance exercises [32][33][34][35][36][37][38][39][40][41][42]. It is not easy to discuss whether our calculated value of the joint moment is valid, compared to that in previous studies on the resistance exercise. ...
Article
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Joint kinetic characteristics during the eccentric phase are important in resistance exercises because eccentric actions with elastic potential energy storage lead to the energy recoil with large joint moment and power generation during the subsequent concentric phase. Previous studies assessed the force production capacity in the barbell hip thrust; however, these were reported by the methodology using only surface electromyographic amplitudes recorded in the lower back and thigh muscles and did not focus on eccentric action. This study aimed to determine kinetic characteristics of lumbosacral, hip and knee joints of sprinters during the eccentric and concentric phases in a barbell hip thrust, compared to those of deadlift and back squat. Eleven well-trained male sprinters participated in this study. Each participant performed two full ranges of motion repetition using their previously determined six-repetition maximum loads. During strength exercises, reflective marker displacements attached to the body and a barbell were captured using 22 high-speed cameras, and ground reaction forces were captured using 4 force plates simultaneously. In the barbell hip thrust, as well as deadlift, the peak values of the lumbosacral and hip extension moments were generated almost immediately after the eccentric phase and were 24% and 42% larger than those in the back squat, respectively. In the knee joint, the largest was the peak extension moment in the back squat (155 ± 28 Nm), followed in order by that in the barbell hip thrust (66 ± 33 Nm) and that in the deadlift (24 ± 27 Nm). These demonstrated that a barbell hip thrust, as well as deadlift, can be a resistance exercise to strengthen the lower back and posterior thigh muscles. Thus, these resistance exercises may be able to be used separately according to their intended purposes, enabling transformations of strength training to specific dynamic motions such as sprint running.
... 5 Another study compared lower extremity joint kinetics between the CD and the SD and indicated that the CD had significantly greater plantarflexor and knee flexor torques while the SD had greater dorsiflexor and knee extensor torques. 13 For achieving desired training goals, understanding biomechanical differences among the deadlift exercises is important for coaches and athletes to select the most appropriate deadlift technique. ...
... However, the hamstrings and gluteals are also agonists during the CD since those muscles serve as knee stabilizers and hip extensors. 3,13 Furthermore, in order to identify in-depth biomechanical differences between the variations of the deadlift, joint kinetics, such as net joint torque (NJT), need to be concurrently analyzed with the myoelectric activities of the lower extremity muscles. This is because joint kinetics enables us to identify muscle dominance throughout the deadlift. ...
... This is because joint kinetics enables us to identify muscle dominance throughout the deadlift. 13 It is expected that the CD will show different muscle dominance as well as myoelectric activities of the lower extremity muscles from those of the RD. Thus, in-depth electromyographic and kinetic comparisons between the CD and the RD need to be performed to provide coaches and athletes with a better insight into the deadlift variation. ...
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Background/objective Significant biomechanical differences were found among deadlift variations. However, little is known about the differences between the conventional and the Romanian deadlifts. Therefore, the purpose of this study was to determine which deadlift technique is a better training protocol between the conventional and the Romanian deadlifts as indicated by the greater demand in muscle activities and joint kinetics. Methods 21 males performed each deadlift with 70% of the Romanian deadlift one repetition maximum (1RM) determined using a 1RM testing. Myoelectric activities of the rectus femoris, biceps femoris, and gluteus maximus and lower extremity net joint torque (NJT) were compared. The variables were extracted through an electromyography system (EMG) and a three-dimensional motion analysis. The EMG values were normalized to the peak EMG activation from a submaximal non-isometric voluntary contraction. A two-way repeated measures analysis of variance was conducted for statistical analysis. The level of significance was set at 0.05. Results Significantly greater normalized EMG values were found from the rectus femoris and gluteus maximus (58.57 ± 13.73 and 51.52 ± 6.08 %peak) of the conventional deadlift than those of the Romanian deadlift (25.26 ± 14.21 and 46.88 ± 7.39 %peak). The conventional deadlift indicated significantly greater knee and ankle NJTs (0.21 ± 0.13 and −0.33 ± 0.08 Nm/kg cm) than those of the Romanian deadlift (−0.28 ± 0.1 and −0.29 ± 0.06 Nm/kg cm). Conclusion The conventional deadlift would be a better technique for training the rectus femoris and gluteus maximus than the Romanian deadlift as indicated by the greater EMG and NJT values.
... Due to the technical differences in the sumo and conventional style, the vertical displacement of the bar is greater in the conventional [5]. The SD's wider stance and relative joint angles result in the barbell travelling a significantly shorter distance from lift off (LO) to lift completion (LC) [6,7]. Vertical displacement has a direct effect on mechanical work, where the CD had a significantly higher total work, while maintaining a relatively similar peak vertical ground reaction force (VGRF) in comparison to the SD [6][7][8]. ...
... The SD's wider stance and relative joint angles result in the barbell travelling a significantly shorter distance from lift off (LO) to lift completion (LC) [6,7]. Vertical displacement has a direct effect on mechanical work, where the CD had a significantly higher total work, while maintaining a relatively similar peak vertical ground reaction force (VGRF) in comparison to the SD [6][7][8]. Establishing the concept of mechanical work is important as it, in-part, dictates the amount of effort for a given exercise. Identifying the variable which alters the amount of mechanical work is also important as it establishes where the changes to the work occur, therefore exploring both the force levels and displacement is important. ...
... In a comparison of the CD with the SD, it was found that mechanical work, vertical displacement, and peak VGRF were increased in the CD while lift time was reduced. The increased vertical displacement and mechanical work in the CD are congruent with past studies [6,7], as is the reduced vertical displacement in the SD [4,5]. The SD employs a wider stance width which moves the center of mass of the lifter closer to the ground, thereby making the distance from the beginning of the lift to full standing a shorter distance, leading to reduced vertical displacement. ...
Article
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Barefoot weightlifting has become a popular training modality in recent years due to anecdotal suggestions of improved performance. However, research to support these anecdotal claims is limited. Therefore, the purpose of this study was to assess the differences between the conventional deadlift (CD) and the sumo deadlift (SD) in barefoot and shod conditions. On day one, one-repetition maximums (1 RM) were assessed for thirty subjects in both the CD and SD styles. At least 72 h later, subjects returned to perform five repetitions in four different conditions (barefoot and shod for both CD and SD) at 70% 1 RM. A 2 × 2 (footwear × lifting style) MANOVA was used to assess differences between peak vertical ground reaction force (VGRF), total mechanical work (WORK), barbell vertical displacement (DISP), peak vertical velocity (PV) and lift time (TIME) during the concentric phase. The CD displayed significant increases in VGRF, DISP, WORK, and TIME over the SD. The shod condition displayed increased WORK, DISP, and TIME compared to the barefoot condition. This study suggests that lifting barefoot does not improve performance as no differences in VGRF or PV were evident. The presence of a shoe does appear to increase the DISP and WORK required to complete the lift, suggesting an increased work load is present while wearing shoes.
... Previous work has also investigated biomechanical differences between the sumo deadlift (SD) and the conventional-style deadlift (CD). With a greater stance width and slightly more narrow grip width for the SD compared with the CD, there are differences in the amount of mechanical work and stress placed on various joints between the SD and CD (5). Electromyography recorded during the 2 deadlift styles suggests greater knee extensor muscle activity during the SD compared with the CD (6). ...
... With a larger LD for the CD compared with the SD, this would allow for a greater velocity to be achieved between the sticking point of the lift and the end LD. In agreement with our findings, previous work has shown a greater bar velocity for the CD compared with the SD in national level powerlifters during competition lifts (5). However, the results of Escamilla et al. (5) demonstrated differences in ACV between the SD and CD at maximal loads, whereas we observed differences in ACV at submaximal loads between the SD and CD. ...
... In agreement with our findings, previous work has shown a greater bar velocity for the CD compared with the SD in national level powerlifters during competition lifts (5). However, the results of Escamilla et al. (5) demonstrated differences in ACV between the SD and CD at maximal loads, whereas we observed differences in ACV at submaximal loads between the SD and CD. One potential difference for these findings is due to differences in the subjects' characteristics between the studies. ...
Article
Full-text available
fferences between the front and back squat and conventional and sumo deadlift. J Strength Cond Res XX(X): 000-000, 2019-The average concentric velocity (ACV) of a resistance exercise movement is inversely related to the load lifted. Previous work suggests that different resistance exercises differ in ACV at the same relative load. Currently, there is limited evidence to determine whether the style of exercise (e.g., front or back squat [BS]; sumo-style or conventional-style deadlift) also affects the load-velocity profile or other kinematic variables such as the peak concentric velocity (PCV) and linear displacement (LD). The purpose of this study was to compare the kinematics (ACV, PCV, and LD) between the front squat (FS) and BS as well as between the conventional deadlift (CD) and sumo deadlift (SD). In a randomized order, 24 men and women (22 ± 3 years) performed a 1 repetition maximum (1RM) protocol for the FS, BS, CD, and SD over 4 visits to the laboratory. Barbell kinematics were recorded during all submaximal and maximal repetitions performed during the 1RM protocol using the Open Barbell System. Kinematic data were pooled into categories based on the percentage of the 1RM lifted in 10% increments (e.g., 30-39% 1RM, 40-49% 1RM, etc.) and compared between exercises. Correlations between kinematic data for the FS and BS and for the CD and SD were examined at each relative load. No differences in kinematics were observed between the FS and BS at any load (p > 0.05). However, FS and BS ACV was weakly correlated (r < 0.4) at high (>80% 1RM) loads. Differences in LD were apparent between the SD and CD at all loads (30-100% 1RM) with the SD having a smaller LD compared with the CD (p < 0.05). Average concentric velocity was not different between the SD and CD at the 1RM (0.25 ± 0.09 vs. 0.25 ± 0.06 m·s; p = 0.962) but was different at 80-89% 1RM (0.35 ± 0.08 vs. 0.40 ± 0.07; p = 0.017), 70-79% 1RM (0.41 ± 0.08 vs. 0.46 ± 0.06; p = 0.026), and 40-49% 1RM (0.66 ± 0.09 vs. 0.77 ± 0.08; p < 0.001). In addition, SD and CD ACV values showed no relationships (p > 0.05) at any loads except at the 1RM (r = 0.433; p < 0.05). These results suggest individual load-velocity profiles for the FS and BS as well as for the CD and SD should be used for training purposes.
... Variations in lifting technique changes the moment arms and hence the forces acting on the primary joints. 13 16 60-68 It has been shown that different techniques can modulate the compressive, shear and rotational forces acting on the joints. 13 16 60-63 68-73 For example, the squat is often considered a safe exercise provided it is performed correctly. ...
... 13 16 60-68 It has been shown that different techniques can modulate the compressive, shear and rotational forces acting on the joints. 13 16 60-63 68-73 For example, the squat is often considered a safe exercise provided it is performed correctly. 10 74 However, there is still some disagreement among researchers, coaches and athletes as to what constitutes a correct technique 75 and whether aspects of technique such as squat depth, 75 stance width, 64 speed of movement, 72 barbell positioning 68 and direction of gaze 71 influence risk of injury and to what extent the lifting technique is modified by fatigue. ...
... 73 Instead, the ankle dorsiflexor and knee moments and moment arms are relatively larger with the sumo style compared with the conventional style. 13 In close association with lifting technique, the load itself is often considered an important risk factor in the development of injury. Especially, the combination of high loads and improper technique is said to increase the risk of injury. ...
Article
Full-text available
Pain and injuries are considered a common problem among elite athletes and recreational lifters performing the squat, bench press and deadlift. Since all three lifts engage multiple joints and expose the lifters’ bodies to high physical demands often several times a week, it has been suggested that their injuries might be related to the excessively heavy loads, the large range of motion during the exercises, insufficient resting times between training sessions and/or faulty lifting technique. However, no previous article has summarised what is known about specific injuries and the injury aetiology associated with the three lifts. Thus, the aim of this narrative review was to summarise what is known about the relationships between the powerlifting exercises and the specific injuries or movement impairments that are common among lifters and recreationally active individuals.
... Our results suggest that the SDL may be mechanically advantageous for deadlift naïve individuals with longer torsos, while the CDL may be best suited for those with shorter torsos. This is likely because during the SDL the center of mass is positioned over and closer to the barbell compared to the CDL, allowing for a more upright torso, which reduces the moment arms of resistance at the knee, hip and especially the lumber joints (Escamilla et al., 2000;Escamilla et al., 2002). Research has also indicated the hip extensors do not exceed the force exhibited by the erector spinae muscles in the SDL, possibly due to greater quadriceps femoris activity, making it easier to maintain lumbar lordosis (Escamilla et al., 2000;Escamilla et al., 2002). ...
... This is likely because during the SDL the center of mass is positioned over and closer to the barbell compared to the CDL, allowing for a more upright torso, which reduces the moment arms of resistance at the knee, hip and especially the lumber joints (Escamilla et al., 2000;Escamilla et al., 2002). Research has also indicated the hip extensors do not exceed the force exhibited by the erector spinae muscles in the SDL, possibly due to greater quadriceps femoris activity, making it easier to maintain lumbar lordosis (Escamilla et al., 2000;Escamilla et al., 2002). ...
Article
The barbell deadlift is a popular exercise and one of the three lifts in competitive powerlifting. While muscle activation has been tested between the sumo (SDL) and conventional deadlift (CDL), the relationships between anthropometrics and deadlift performance in the two styles is not yet known. The purpose of this study was to investigate the relationships between anthropometrics and SDL versus CDL performance (SDL:CDL strength ratio). Forty-seven (n = 28 male, n = 19 female) deadlift naïve subjects participated in this study. Anthropometric measurements were arm and hand length, wrist and ankle girth, seated height, thigh length, and lower leg length. Deadlift instructions for the two styles were provided on day 1 and 2. On day 3 and 4, deadlift 1RM was tested for the SDL or CDL in random order, and then deadlift repetitions to volitional fatigue with 60% of 1RM were measured. No significant differences between CDL 1RM and SDL 1RM were found. The only significant correlation found between the anthropometric predictors and the SDL:CDL strength ratio was an inverse relationship with the sitting height to total height ratio (r = 0.297, p = 0.043). Total repetitions to volitional fatigue was higher in females compared to males for both lifts (p = 0.041). Our findings suggest that the sumo deadlift may be slightly mechanically advantageous for deadlift naïve individuals with longer torsos, while the conventional deadlift may be better suited for those with shorter torsos.
... The examination of slight difference in movement on each side of the body is usually referred to as bilateral comparison and has been confirmed in the literature for deadlift [16]. We have not found it explicitly reported for squat and bench press, but it is safe to assume that this occurs for all of the lifts. ...
... • The lift is symmetrical and could be analysed in one plane, examining the lifter from his side. This two-dimensional (2D) analysis is appropriate when calculating spinal torques, especially for conventional deadlift [16]. (Note: there are two styles of deadlifting used in competition-conventional and sumo. ...
Article
The main contribution of this paper is didactic adaptation of the biomechanical analysis of the three main lifts in powerlifting (squat, bench press, deadlift). We used simple models that can easily be understood by undergraduate college students to estimate the values of various physical quantities during powerlifting. Specifically, we showed how plate choice affects the bench press and estimated spine loads and torques at hip and knee during lifting. Theoretical calculations showed good agreement with experimental data, proving that the models are valid.
... Our results suggest that the SDL may be mechanically advantageous for deadlift naïve individuals with longer torsos, while the CDL may be best suited for those with shorter torsos. This is likely because during the SDL the center of mass is positioned over and closer to the barbell compared to the CDL, allowing for a more upright torso, which reduces the moment arms of resistance at the knee, hip and especially the lumber joints (Escamilla et al., 2000;Escamilla et al., 2002). Research has also indicated the hip extensors do not exceed the force exhibited by the erector spinae muscles in the SDL, possibly due to greater quadriceps femoris activity, making it easier to maintain lumbar lordosis (Escamilla et al., 2000;Escamilla et al., 2002). ...
... This is likely because during the SDL the center of mass is positioned over and closer to the barbell compared to the CDL, allowing for a more upright torso, which reduces the moment arms of resistance at the knee, hip and especially the lumber joints (Escamilla et al., 2000;Escamilla et al., 2002). Research has also indicated the hip extensors do not exceed the force exhibited by the erector spinae muscles in the SDL, possibly due to greater quadriceps femoris activity, making it easier to maintain lumbar lordosis (Escamilla et al., 2000;Escamilla et al., 2002). ...
Article
Full-text available
The barbell deadlift is a popular exercise and one of the three lifts in competitive powerlifting. While muscle activation has been tested between the sumo (SDL) and conventional deadlift (CDL), the relationships between anthropometrics and deadlift performance in the two styles is not yet known. The purpose of this study was to investigate the relationships between anthropometrics and SDL versus CDL performance (SDL:CDL strength ratio). Forty-seven (n = 28 male, n = 19 female) deadlift naïve subjects participated in this study. Anthropometric measurements were arm and hand length, wrist and ankle girth, seated height, thigh length, and lower leg length. Deadlift instructions for the two styles were provided on day 1 and 2. On day 3 and 4, deadlift 1RM was tested for the SDL or CDL in random order, and then deadlift repetitions to volitional fatigue with 60% of 1RM were measured. No significant differences between CDL 1RM and SDL 1RM were found. The only significant correlation found between the anthropometric predictors and the SDL:CDL strength ratio was an inverse relationship with the sitting height to total height ratio (r = 0.297, p = 0.043). Total repetitions to volitional fatigue was higher in females compared to males for both lifts (p = 0.041). Our findings suggest that the sumo deadlift may be slightly mechanically advantageous for deadlift naïve individuals with longer torsos, while the conventional deadlift may be better suited for those with shorter torsos.
... More frequent performance of the deadlift was correlated to more injuries in the lower back and sacroiliac joint (p = 0.002; r = 0.398) which seems plausible knowing the high hip torque and lumbar shear force documented in research (Brown & Abani, 1985;Cholewicki, McGill, & Norman, 1991;Escamilla et al., 2000). Athletes using front squats more frequently, on the other hand, showed more injuries to the knee (p = 0.047; r = 0,266) and thigh (p = 0.006; r = 0,364). ...
... Further, more detailed analysis of different aspects in training periodization, methods, volume, exercise selection, equipment use, preventive and regenerative methods and lastly anthropometric measurements of athletes could be the foundation for a better understanding and consequently validation of causative factors for injuries in powerlifting as well as to validate proposed concepts to reduce these injuries in high risk areas like the lower back and shoulder region (Escamilla et al., 2000;Fees, Decker, Snyder-Mackler, & Axe, 1998;Green & Comfort, 2007;McGill, 1998;Reeves, Laskowski, & Smith, 1998). ...
Article
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The aim of this study was the analysis of incidence and type of injury in German elite powerlifters. A total of n = 57 competitive athletes of the German powerlifting federation completed a retrospective survey regarding acute and overuse injuries. With 224 total injuries, a mean incidence of 1.51 per 1.000 h or 0.49 per year was calculated. Most injuries affected the lower back (20.5%), elbow (11.2%), pelvic region (10.3) and the shoulder (9.8%). Regarding the type of injury acute inflammation (25.9%), muscle strains/sprains (20.5%) and skin lesions (13%) dominated. The mean incidence significantly declined with increasing age and training experience of the athlete. Athletes using a bench press shirt and various regenerative methods like sauna or swimming also showed decreased injury rates. There was no significant correlation between body weight, height or gender and injury incidence. Compared to other sports, the incidence of injuries and overuse syndromes is still low in powerlifting. Nonetheless, appropriate strategies in training, equipment, prevention and regeneration should be employed to protect the athlete from injury.
... Bei überhüftbreitem Stand sind die Füße leicht nach außen rotiert (ca. 7-15° Außenrotation [Escamilla et al., 2000[Escamilla et al., , 2002 (Whaley & McClure, 1997). ...
... Bei überhüftbreitem Stand sind die Füße leicht nach außen rotiert (ca. 7-15° Außenrotation [Escamilla et al., 2000[Escamilla et al., , 2002). Die Füße sind bei der gesamten Bewegung komplett zu belasten. ...
... A reduction in lower extremity skeletal muscle mass and strength is associated with a decline in physical function, while increased mass and strength are associated with increased athletic performance (10,15,36). Exercises such as the back-squat (23) and deadlift (12) recruit muscle groups with the largest cross-sectional area (CSA) and are associated with metabolic and hormonal responses that contribute to muscle strength and hypertrophy (19). Therefore, the back-squat and deadlift are commonly performed to increase lower extremity strength. ...
... Furthermore, individuals also use variations of the deadlift, such as the Romanian deadlift in rehabilitation settings, such as late-stage anterior cruciate ligament (ACL) injury recovery. The activation of the hamstrings in the deadlift may protect the ACL during knee rehabilitation because it provides an additional posterior force on the tibia (12,38). The back-squat also targets the hip and knee extensors and is effective in improving lower extremity strength and athletic performance (7,29,30). ...
Article
Choe, KH, Coburn, JW, Costa, PB, and Pamukoff, DN. Hip and knee kinetics during a back-squat and deadlift. J Strength Cond Res XX(X): 000-000, 2018-The back-squat and deadlift are performed to improve hip and knee extensor function. The purpose of this study was to compare lower extremity joint kinetics (peak net joint moments [NJMs] and positive joint work [PJW]) between the back-squat and deadlift. Twenty-eight resistance-trained subjects (17 men: 23.7 ± 4.3 years, 1.76 ± 0.09 m, 78.11 ± 10.91 kg; 11 women: 23.0 ± 1.9 years, 1.66 ± 0.06 m, 65.36 ± 7.84 kg) were recruited. One repetition maximum (1RM) testing and biomechanical analyses occurred on separate days. Three-dimensional biomechanics of the back-squat and deadlift were recorded at 70 and 85% 1RM for each exercise. The deadlift demonstrated larger hip extensor NJM than the back-squat {3.59 (95% confidence interval [CI]: 3.30-3.88) vs. 2.98 (95% CI: 2.72-3.23) Nm·kg, d = 0.81, p < 0.001}. However, the back-squat had a larger knee extensor NJM compared with the deadlift (2.14 [95% CI: 1.88-2.40] vs. 1.18 [95% CI: 0.99-1.37] Nm·kg, d = 1.44 p < 0.001). More knee PJW was performed during the back-squat compared with the deadlift (1.85 [95% CI: 1.60-2.09] vs. 0.46 [95% CI: 0.35-0.58] J·kg, d = 2.10, p < 0.001). However, there was more hip PJW during the deadlift compared with the back-squat (3.22 [95% CI: 2.97-3.47] vs. 2.37 [95% CI: 2.21-2.54] J·kg, d = 1.30, p < 0.001). Larger hip extensor NJM and PJW during the deadlift suggest that individuals targeting their hip extensors may yield greater benefit from the deadlift compared with the back-squat. However, larger knee extensor NJM and PJW during the back-squat suggest that individuals targeting their knee extensor muscles may benefit from incorporating the back-squat compared with the deadlift.
... Vergleichbar ist dieses Phänomen mit der "sumo-style"-Technik im Kreuzheben. Diese Technik dient ebenfalls dazu, die Hebelarme zwischen der Systemschwerpunktlinie und den Gelenkzentren zu verkürzen und somit die Belastungsmomente in den Gelenken zu reduzieren (Escamilla, Francisco, Fleisig, Barrentine, Welch, Kayes, Speer & Andrews, 2000). ...
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Die Schnellkraftfähigkeit ist ein leistungsbegrenzender Faktor in den Wettkampfübungen des Gewichthebens. Zur Erhöhung der Schnellkraftfähigkeit im Gewichtheben werden im Trainingsprozess spezifische Trainingsübungen genutzt. Dieses Buch stellt einen methodischen Ansatz zu Beurteilung der potenziellen Wirkung einer spezifischen Trainingsübung auf die Wettkampfübung dar. Aus den gewonnen Ergebnissen werden praktische Empfehlungen für das Training im Gewichtheben abgeleitet und Vorschläge für die Optimierung der Trainingsgestaltung gegeben.
... Several studies have focused on joint and segment angles in deadlift variations (26,33), with two studies specifically focused on the comparison of kinematics and kinetics of the sumo deadlift and the conventional deadlift (9,11). Further research has been completed on muscle activation patterns via electromyography in both stable and unstable conditions (5,10,17,23). ...
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The kinetics of a conventional deadlift in shod (S) versus unshod (US) footwear conditions in 10 male participants (mean ± SD, age = 27.0 ± 5.8 years; weight = 78.7 ± 11.5 kg; height = 175.8 ± 8.2 cm; 1RM deadlift = 155.8 ± 25.8 kg) was assessed in two testing sessions. A counterbalanced, crossover experimental design was used with different loads (60% and 80% 1RM). Four sets of four repetitions were prescribed per session with two sets per shoe and with each shoe condition involving one set per load. Peak vertical force (PF), rate of force development (RFD), time to peak force (TPF), anterior-posterior (COP-AP) and medio-lateral (COP-ML) center of pressure excursion, and barbell peak power (PP) data were recorded during all repetitions. Except for RFD (F = 6.389; p = 0.045; ηp = 0.516) and ML-COP (F = 6.696; p = 0.041; ηp = 0.527), there were no other significant main effects of shoe. There were significant main effects of load for PF (p < 0.05), COP-AP (p = 0.011), TPF (p = 0.018) and COP-AP (p = 0.011). There were no significant interactions found between session, shoe and load (p range from 0.944 to 0.086). While the unshod condition may have produced changes in RFD and ML-COP compared with the shod condition, there is only limited evidence in the current study to support this lifting technique for the conventional deadlift. Further investigation is required to clarify any possible implications of this result and its benefit to lifters.
... 5 Though this lead to greater time under tension and volume-load, the authors made no suggestion about the potential benefits beyond competition specific training due to the acute study design and Powerlifting specific population. Unlike the deadlift which has a descending strength curve, 24 the bench press' ascending strength curve means that muscular tension is at its lowest when the leverage is greatest. 11 While the sticking point is the moment where velocity decreases as a result of inefficient leverage and variable resistance, 22 more recent literature has suggested that there is a sticking region where acceleration of the bar decreases 20 . ...
Article
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Objective: To examine whether using the Slingshot will enable participants to perform a greater volume-load during bench press repetitions with a maximal load and increase set volume-load compared to an unaided condition. Summary of Background Data: Literature suggests that increased volume-loads during training may aid in improving strength, and further maximises mechanical tension and metabolic stress potentially leading to increased hypertrophy. It has been suggested that a new piece of equipment, called the Slingshot could be used in training to improve performance in the bench press by enabling individuals to increase their training volume whilst using maximal loads. Method: Nine trained male participants volunteered to participate. Each participant performed a bench press one repetition maximum (1RM) test before completing repetitions to momentary failure using the Slingshot one week later. Volume-load for each condition was calculated as repetitions (n) x load (kg). Results: A paired samples t-Test comparing between conditions revealed a significant difference (p < 0.001) between volume loads performed unaided (96.1±14.6 kg) and with the Slingshot (350±103.7 kg). Conclusion: Using the slingshot in training does allow individuals to perform greater volume-loads with a maximal load; however longitudinal research must be conducted to ascertain the magnitude of any potential benefit from using it.
... Deadlifts, goodmornings and Split squats are all multijoint resistance exercises used to enhance athletic performance or for reducing the risk of musculoskeletal injury, but also for specific rehabilitation programmes during recovery from injury through targeted improvement of the dynamic stability of lower limb joints [18][19][20]. To optimize the training results with a reduced risk of injury, desired trained muscle part should be loaded while all the other parts of the body should be unloaded as much as possible. ...
Article
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Background To ensure an efficient and targeted adaptation with low injury risk during strength exercises, knowledge of the participant specific internal loading conditions is essential. The goal of this study was to calculate the lower limb muscles forces during the strength exercises deadlifts, goodmornings and splits squats by means of musculoskeletal simulation. Methods 11 participants were assessed performing 10 different variations of split squats by varying the step length as well as the maximal frontal tibia angle, and 13 participants were measured performing deadlift and goodmorning exercises. Using individualised musculoskeletal models, forces of the Quadriceps (four parts), Hamstrings (four parts) and m. gluteus maximus (three parts) were computed. Results Deadlifts resulted highest loading for the Quadriceps, especially for the vasti (18–34 N/kg), but not for the rectus femoris (8–10 N/kg), which exhibited its greatest loading during split squats (13–27 N/kg) in the rear limb. Hamstrings were loaded isometrically during goodmornings but dynamically during deadlifts. For the m. gluteus maximus, the highest loading was observed during split squats in the front limb (up to 25 N/kg), while deadlifts produced increasingly, large loading over large ranges of motion in hip and knee. Conclusions Acting muscle forces vary between exercises, execution form and joint angle. For all examined muscles, deadlifts produced considerable loading over large ranges of motion, while split squats seem to be highly dependent upon exercise variation. This study provides key information to design strength-training programs with respect to loading conditions and ranges of motion of lower extremity muscles.
... The deadlift is a compound full-body exercise that is fundamental in resistance training, rehabilitation and powerlifting (Escamilla et al., 2000;Hales, 2010). It is a complex movement that requires training to ensure correct form (Hales, 2010). ...
Article
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The deadlift is a compound full-body exercise that is fundamental in resistance training, rehabilitation programs and powerlifting competitions. Accurate quantification of deadlift biomechanics is important to reduce the risk of injury and ensure training and rehabilitation goals are achieved. This study sought to develop and evaluate deadlift exercise technique classification systems utilising Inertial Measurement Units (IMUs), recording at 51.2 Hz, worn on the lumbar spine, both thighs and both shanks. It also sought to compare classification quality when these IMUs are worn in combination and in isolation. Two datasets of IMU deadlift data were collected. Eighty participants first completed deadlifts with acceptable technique and 5 distinct, deliberately induced deviations from acceptable form. Fifty-five members of this group also completed a fatiguing protocol (3-Repition Maximum test) to enable the collection of natural deadlift deviations. For both datasets, universal and personalised random-forests classifiers were developed and evaluated. Personalised classifiers outperformed universal classifiers in accuracy, sensitivity and specificity in the binary classification of acceptable or aberrant technique and in the multi-label classification of specific deadlift deviations. Whilst recent research has favoured universal classifiers due to the reduced overhead in setting them up for new system users, this work demonstrates that such techniques may not be appropriate for classifying deadlift technique due to the poor accuracy achieved. However, personalised classifiers perform very well in assessing deadlift technique, even when using data derived from a single lumbar-worn IMU to detect specific naturally occurring technique mistakes.
... The CD resulted in a greater amount of work performed during the lift, which would relate to the further distance the bar needed to travel. The impact of a reduced bar displacement has been shown in comparisons between the CD and sumo deadlift, with Escamilla et al. (13) detailing that greater mechanical work resulted from the CD. This difference in work could influence how the CD and HHBD exercises are programmed. ...
Article
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The high-handle hexagonal bar deadlift (HHBD), a variation of the conventional deadlift (CD), is said to reduce the lift range of motion, which may change the mechanics of the lift. However, no research has investigated this. This study compared the mechanics between a one-repetition maximum (1RM) CD and HHBD. Thirty-one strength-trained subjects (21 males, 10 females) completed a 1RM CD and HHBD. A linear position transducer measured lift distance, duration, and work; and peak and mean power, velocity, and force. The presence of a sticking region (SR) was determined for each lift. A repeated measures ANOVA calculated differences between 1RM CD and HHBD mechanics. A one-way ANOVA compared the mechanics of each lift between subjects who exhibited a SR or not, and the SR between the CD and HHBD. Significance was set at p < 0.01. Subjects lifted a greater load in the HHBD (154.50 ± 45.29 kg) compared to the CD (134.72 ± 40.63 kg). Lift distance and duration were 22% and 25% shorter during the 1RM HHBD, respectively. The HHBD featured greater peak power and velocity, and peak and mean force; more work was done in the CD. Most subjects did not exhibit a CD (68%) or HHBD (77%) SR. There were no differences in CD or HHBD mechanics between subjects with or without a SR, and no differences in SR region distance or duration between the CD and HHBD. Greater force can be generated in the HHBD, which could have implications for strength training adaptations over time.
... The conventional deadlift style was used in this study. The conventional deadlift uses a narrower stance (feet about 32 to 35 cm apart) with hand/grip placement outside the stance feet compared to the sumo style (Escamilla, Francisco, Fleisig, Barrentine, Welch, Kayes, & Andrews, 2000;Escamilla Francisco, Kayes, Speer, & Moorman, 2002) which involves a placement of the hands outside the stance feet. Aside from the 5-week training program, separate days were provided each for the (1) Orientation and practice session of the deadlift, (2) pretesting of the 1-RM deadlift, (3) pretesting of the Bunkie test, (4) post testing of the 1-RM deadlift and (5) post testing of the Bunkie test. ...
Article
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The purpose of this study was to examine the effect of the deadlift, a heavy compound exercise, on core strength as determined through the 1-RM deadlift and the Bunkie tests. The deadlift is a multi-joint movement that involves picking up a barbell from the floor and standing up to an upright position. This movement includes plenty of muscle activation, mainly the lower back, upper back, quadriceps, hamstrings and abdominals. The core is a collection of muscles in the abdominal and lower back areas although it is commonly mistaken as simply the abdominal muscles. This study investigated the effect of deadlift training on core strength through a pretest-posttest comparison in the 1-RM deadlift to assess maximum muscular strength and the Bunkie test for core strength. 21 previously-untrained male college students participated in a 5-week deadlift strength program using progressive overload with no direct core training involved. The 5-week deadlift program resulted in significant increases in both the 1-RM deadlift, derived from the Brzycki formula, and Bunkie test scores most notably in the posterior stabilizing line and the medial stabilizing line. Deadlift strength training, even without direct core training, was able to produce significant improvements in core strength in previously-untrained male college students.
... According to the United States Powerlifting Association, overall deadlift records have been by both men and women in various weight classes when using both lifts ("National Records," 2016). While differences in muscle activation and biomechanics have been studied between the two styles with minimal differences in EMG readings in the lower limbs or hip extension range of motions reported in 3D analysis (Escamilla et al., 2000;Escamilla et al., 2002), and conversations with competitive lifters demonstrate a clear preference for one style over another, little is known about the anthropometrical determinants of deadlift performance between the two styles. This work is part of a larger, ongoing, study intended to: (1) identify relationships between anthropometrics and overall deadlift performance; (2) investigate the interaction between limb and height ratios and differences in performance between the conventional and sumo style deadlifts in untrained individuals; and (3) improve individualized resistance training exercise prescription. ...
Conference Paper
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INTRODUCTION: The barbell deadlift is a popular exercise employed to increase the strength of the posterior kinetic chain in athletes, recreational weight lifters, and the elderly (Thompson et al., 2015). The barbell deadlift is also one the three lifts tested during competition in competitive power lifting. The barbell deadlift is performed with two different styles: conventional and sumo. According to the United States Powerlifting Association, overall deadlift records have been by both men and women in various weight classes when using both lifts (" National Records, " 2016). While differences in muscle activation and biomechanics have been studied between the two styles with minimal differences in EMG readings in the lower limbs or hip extension range of motions reported in 3D analysis (Escamilla et al., 2000; Escamilla et al., 2002), and conversations with competitive lifters demonstrate a clear preference for one style over another, little is known about the anthropometrical determinants of deadlift performance between the two styles. This work is part of a larger, ongoing, study intended to: (1) identify relationships between anthropometrics and overall deadlift performance; (2) investigate the interaction between limb and height ratios and differences in performance between the conventional and sumo style deadlifts in untrained individuals; and (3) improve individualized resistance training exercise prescription. The purpose of this data is to investigate the relationships between anthropometrics and overall deadlift performance.
... Within the strength and conditioning fields, the deadlift is seen as an important part of an athletic training programme for the development of strength and power of the posterior chain i.e. back, hips and hamstrings (1)(2)(3). ...
... A detailed description of the technique can be found in [10]. There exist a total of eleven variations of deadlift movements as reported by [10,11]. However, the ones mostly used by athletes are the so called: conventional and nonconventional styles (i.e. ...
Article
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In this study, we assumed that correct functional movements for weightlifting can be learned with the help of a music-based biofeedback system. We compared musical feedback with verbal feedback from experienced trainers using two independent groups. The focus was on one specific movement called deadlift. Physical parameters under considerations were the spine (i.e. loss of midline stability resulting in flexion) and the forward displacement of the barbell during the repetitions relative to the mid-foot. We recruited 31 recreational weight lifters (21-42 years of age). Results revealed that both feedback types are effective in improving the movements for deadlift. No significant differences were found across the two feedback types, neither in terms of movement, nor in terms of clarity and motivation. The results suggest that the proposed feedback system is a valid tool for technology-aided training and self-training practices.
... Common ways for varying squat exercises include changing the standing width, foot position, hip depth, and extra load. In addition, the gender and ground environment when squatting may also be factors [17][18][19]. On the other hand, many people have examined the effects of these conditions on quadriceps femoris muscles. ...
Article
Background: Life in modern society has become convenient, but the lack of exercise due to a sedentary lifestyle has led to muscle weakness. The quadriceps femoris is essential for walking, standing, and using stairs in daily life. Muscle weakness can lead directly to impaired function. Squatting is the most representative exercise for effective muscle development and increasing the knee extensor strength. This study examined the effects of ankle angle during wall squats on the muscle activity of the vastus medialis oblique (VMO), vastus lateralis (VL), rectus femoris (RF), biceps femoris (BF), rectus abdominis (RA), and erector spinae (ES) to determine which ankle angle can better strengthen the vastus medialis oblique as a method of rehabilitation training after a knee joint injury. Methods: All subjects (n = 20) performed the following three types of wall squats randomly: (1) GWS (General Wall Squat), (2) WSD 10° (Wall Squat with dorsiflexion 10°), and (3) WSP 10° (Wall Squat with plantarflexion 10°). Each subject completed all three kinds of wall squatting exercises three different times, and the muscle activity data of the VMO, VL, RF, BL, RA, and ES were recorded. Results: Compared to GWS exercise, the VMO and RF muscle activity increased significantly under WSP 10° exercise (p < 0.05), whereas the VL, BF, RA, and ES activity did not increase significantly (p > 0.05). No significant change between WSD 10° and WSP 10° was observed (p > 0.05). Conclusions: WSP 10° can help increase the quadriceps muscle activity. Wall squat exercise with different ankle angles can be used for quadriceps muscle strengthening training for normal people and for recovery training for patellofemoral pain syndrome (PFPS) patients in the rehabilitation stage.
... A detailed description of the technique can be found in Bird and Barrington-Higgs (2010). There exist a total of eleven variations of deadlift movements as reported by Bird and Barrington-Higgs (2010) and Escamilla et al. (2000). However, the ones mostly used by athletes are the so called: conventional and nonconventional styles (i.e. ...
... Previous research investigated the biomechanical differences between the sumo DL and the conventionalstyle DL [17]. With a greater stance width and slightly more narrow grip width for the sumo compared with the conventional DL, there are differences in the amount of mechanical work and stress placed on various joints between the sumo DL and conventional DL [18]. ...
Article
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The competition in powerlifting has been divided into two divisions, with gear equipment (EQ) and without gear equipment (RAW). When competing in the EQ division, additional supportive gear can be worn by the athletes, while in the RAW division such gear is not allowed. The aim of the study was to compare the results of the RAW and EQ powerlifting divisions based on the results of world championships and current world records. One-hundred and twenty powerlifters (63 men, 57 women) were included to the analysis. Post hoc analysis for the results of men’s world championships indicated significantly higher results of the barbell squat (SQ; p < 0.001; ES = 1.31), bench press (BP; p < 0.001; ES = 1.27) and deadlift (DL; p < 0.001; ES = 0.37) for EQ compared to the RAW division. Post hoc analysis for the results of women’s world championships indicated significantly higher results of the SQ (p < 0.001; ES = 1.31), BP (p < 0.001; ES = 1.13) and DL (p < 0.001; ES = 0.71) for the EQ compared to the RAW division. Post hoc analysis for men’s world record indicated significantly higher results in the SQ (p < 0.001; ES = 1.32) and BP (p < 0.001; ES = 1.24) for the EQ compared to the RAW division. Furthermore, there were no significant differences in the results of world records in the DL (p = 0.901; ES = 0.26) between the EQ and RAW divisions. Post hoc analysis for women’s world records indicated significantly higher results in the SQ (p < 0.001; ES = 1.22) and BP (p < 0.001; ES = 1.99) for the EQ compared to RAW division. The main finding of the study was that supportive gear increases maximal load lifted during powerlifting competition.
... Variation in lifting technique leads to muscle fatigue at varying rates forcing a worker to compensate for the weakness by altering their body position while performing lifting tasks [7]. Proper body positioning is critical for the optimal activation of muscles during the lifting process and will affect the amount of muscle fatigue associated with the movement [8][9]. ...
... The ROM findings correspond with powerlifters having less flexibility in the muscle groups that contribute meaningfully to competition lifts. The gluteus maximus and quadriceps muscles are prime movers of the squat (3) and deadlift (6). These muscles produce hip extension and knee extension, respectively, and powerlifters had decreased hip and knee flexion (4). ...
Article
Spence, A-J, Helms, ER, and McGuigan, MR. Range of motion is not reduced in national-level New Zealand female powerlifters. J Strength Cond Res XX(X): 000-000, 2021-Some research suggests male powerlifters have less range of motion (ROM) in several directions about the shoulder and hip compared with sedentary men. In addition, those differences may be more pronounced in groups with higher strength levels and more years of experience. However, there is no information on ROM in female powerlifters. The purpose of this study was to evaluate single-joint ROM in competitive female powerlifters and determine whether single-joint ROM would be an effective predictor of strength in this population. Twelve female powerlifters and 12 female recreationally trained age-matched controls attended one testing session. Subjects reported their years of training experience, frequency, and average duration of training sessions. Active ROM measurements were collected at the shoulder, hip, and knee, using goniometry. There was no significant difference (p > 0.05) between groups for age, height, body mass, training experience, and training frequency. Powerlifters reported significantly greater (p ≤ 0.05) training durations than recreationally trained women. Powerlifters had significantly greater shoulder horizontal abduction on the right side (p = 0.022, g = 0.97), but no other ranges were significantly different between groups, and no ranges were significantly related to strength. Powerlifting does not seem to affect shoulder, hip, or knee ROM differently than recreational resistance training in women. Single-joint ROM was not an effective predictor of strength in female powerlifters.
... The literature review contained different areas to be covered. Starting off the project with suitable descriptions for the exercise in focus (the deadlift) [6,7] and additional sources to identify common mistakes and posture variations [4,8] further review led to more insight into the dynamics of different exercise variations and the expectable outcomes [3,9]. Also information regarding the analysis had to be reviewed regarding the biomechanical process of the exercise [10] and last but not least the information needed to operate and assess the usability of the 3DSSPP software used in the project [11]. ...
Article
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This study features an analysis of the influences and effects of varying forms of execution while performing resistance training exercises from an ergonomic viewpoint using the University of Michigan's 3D Statistic Strength Prediction Program (3DSSPP). The exemplary use case chosen is the performance of Deadlifts (DL), one of the main full body training exercises in resistance training. The purpose of this study is to show the potential ergonomic problem of lower back impact of the exercise when executed with inaccurate form using the 3DSSPP to exemplary assess the usability of this form of software analysis for the specific area of exercises in resistance training. Based on the findings from the analysis and the results, it can be concluded that according to the software a possible indicator for poor technique especially during phase 1 to 3 is the lower strength requirements on torso and hips in these postures when rounding the back, explaining why people tend to make these mistakes.
... Halter şu anda olimpik statülü bu sporlardan sadece bir tanesidir. Bu spor branşlarında kaldırılabilecek ağır yükler ve yarışma esnasında icra etmeleri gereken ortak pozisyon ve duruşlar (kesme ve sıkıştırma) sırasında büyük oranda kuvvet meydana gelmektedir (7,10,11,12) . Bu nedenle, kamu, spor, tıb veya bilimsel kuruluşlarca bu tür aktivitelerin doğası gereği tehlikeli olduğu ve ayrıca uzun yıl-1 ...
Chapter
GİRİŞ Ağırlık antrenmanları, dünyanın birçok yerinde farklı kesimden insanlar tarafından tercih edilen popüler bir spor haline gelmiştir. Bazı insanlar ağırlık antrenmanlarını sağlık ve fitness rutinlerinin sadece bir parçası olarak kullanırken, bazıları ise; halter, powerlifting ve vücut geliştirme gibi rekabete dayalı, kazanma amacı güderek performansı geliştirmek için yapmaktadır. Günümüzde halter sporcularının silkme ve koparma tekniğinde tek tekrar maksimal yükü kaldırabilmesi beklenmektedir. Bu teknikler; halterin zemin tepki kuvvetiyle beraber, tek yönlü hareket (alt ekstremiteden üst ektremiteye) ve kuvvet iletiminin patlayıcı bir şekilde kaldırılmasını gerektirdiğinden, yüksek seviyede güç çıktısı oluşmaktadır. Powerlifting sporunda halter sporunda olduğu gibi, tek tekrar maksimal bir ağırlık kaldırılmaya çalışılır. Bununla birlikte Strongman (Güçlü Adam) ya-rışmaları; tır çekme, araba taşıma, kaya kaldırma, lastik çevirme gibi farklı etkinlikler barındırmaktadır. Bu etkinliklerden bazıları tek tekrar maksimal ağırlığı en hızlı ve en kısa sürede kaldırmayı gerektirmektedir. Vücut geliştirmede ise, diğer ağırlık sporlarından farklı olarak; yarışma sırasında kaldırılan ağırlığa değil, sporcunun fiziksel görünümü değerlendirilir. Ayrıca yarışmacıların özellikle kas kütlesi, kas yoğunluğu ve kas grupları arasında meydana gelen asimetri dikkate alınarak değerlendirilir . Halter, powerlifting ve vücut geliştirme gibi ağır yüklerin kaldırıldığı spor branşlarında, yıl içerisinde gerçekleştirilen farklı vücut ağırlığına sahip erkek ve kadın sporcuların katılabileceği yarışmalar düzenlen-mektedir. Halter şu anda olimpik statülü bu sporlardan sadece bir tanesidir. Bu spor branşlarında kaldırılabilecek ağır yükler ve yarışma esnasında icra etmeleri gereken ortak pozisyon ve duruşlar (kesme ve sıkıştırma) sırasında büyük oranda kuvvet meydana gelmektedir. Bu nedenle, kamu, spor, tıb veya bilimsel kuruluşlarca bu tür aktivitelerin doğası gereği tehlikeli olduğu ve ayrıca uzun yıl-1
... The starting position for the deadlift was with the player squatting, arms straight and downward, and an alternating hand grip on a bar placed in front of the lifter's feet. The bar had to be lifted in a continuous motion, until the player was standing with his knees locked and his shoulders pushed back (Escamilla et al., 2000). ...
Article
Introduction Recurrent ankle sprains are common in soccer players, characterized by restricted range of motion, pain, and decreased proprioception, strength, and postural control. The objective was to evaluate the effectiveness of a fascial therapy and strength training program, combined with kinesiotaping, in improving ankle range of motion, pain, strength and stability in footballers with recurrent sprains. Method A simple blind randomized clinical trial was conducted on soccer players. Thirty-six federated footballers were recruited and randomized to the two study groups. The experimental group received an intervention using myofascial techniques applied to the subastragaline joint, eccentric training with an isoinertial device and neuromuscular taping. The control group was administered an intervention using myofascial techniques on the subastragaline joint and eccentric training with an isoinertial device. The results were recorded for all players at baseline, after 4 weeks of intervention, and at the end of the 4-week follow-up period. Results Subsequent to intervention and follow-up, we found statistically significant improvements in the experimental group in ankle mobility, strength and stability. The control group exhibited improvements in all study variables. No differences in the improvement of variables were found based on the allocation of athletes to one group or another. Conclusion The combination of fascial therapy and eccentric strength training with an isoinertial device improves ankle mobility, strength and stability in footballers with recurrent ankle sprains. The use of taping techniques failed to provide a greater improvement of the study variables when combined with manual therapy and strength techniques.
... Both marker-based and marker-less 2D video motion capture rely on a line of sight of the participant throughout the movement and as such see similar occlusion limitations to 3D OMC [9]. Parallax error caused by the participant performing the movement at a nonperpendicular angle (out of plane) to the camera and perspective error caused by the participant moving toward or away from the camera are additional sources of error when using 2D video motion capture [11,12]. ...
Article
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Inertial-based motion capture (IMC) has been suggested to overcome many of the limitations of traditional motion capture systems. The validity of IMC is, however, suggested to be dependent on the methodologies used to process the raw data collected by the inertial device. The aim of this technical summary is to provide researchers and developers with a starting point from which to further develop the current IMC data processing methodologies used to estimate human spatiotemporal and kinematic measures. The main workflow pertaining to the estimation of spatiotemporal and kinematic measures was presented, and a general overview of previous methodologies used for each stage of data processing was provided. For the estimation of spatiotemporal measures, which includes stride length, stride rate, and stance/swing duration, measurement thresholding and zero-velocity update approaches were discussed as the most common methodologies used to estimate such measures. The methodologies used for the estimation of joint kinematics were found to be broad, with the combination of Kalman filtering or complimentary filtering and various sensor to segment alignment techniques including anatomical alignment, static calibration, and functional calibration methods identified as being most common. The effect of soft tissue artefacts, device placement, biomechanical modelling methods, and ferromagnetic interference within the environment, on the accuracy and validity of IMC, was also discussed. Where a range of methods have previously been used to estimate human spatiotemporal and kinematic measures, further development is required to reduce estimation errors, improve the validity of spatiotemporal and kinematic estimations, and standardize data processing practices. It is anticipated that this technical summary will reduce the time researchers and developers require to establish the fundamental methodological components of IMC prior to commencing further development of IMC methodologies, thus increasing the rate of development and utilisation of IMC. 1. Introduction Motion capture systems have been used extensively in biomechanics research to capture spatiotemporal measures of stride length, stride rate, contact time, and swing time and angular kinematic measures of joint angles. Such measures are commonly used in disease/condition diagnosis, injury prevention, and sport performance analysis [1–7]. The most common technologies used to collect human spatiotemporal and kinematic measures are three-dimensional (3D) optical, two-dimensional (2D) video, and electromagnetic based systems [8]. When motion capture data is collected in conjunction with data from force platforms, angular kinetics may also be modelled. Three-dimensional optical motion capture (OMC) systems are often considered to be the gold standard method of motion capture; however, these systems are expensive and typically confined to a small capture volume within a laboratory environment [9, 10]. For a full body motion analysis, researchers are required to place up to 50 markers at anatomically specific locations, and a line of sight to each marker must be maintained by at least two cameras for each data frame throughout the movement [9]. Maintaining a line of sight to each marker throughout the movement is a major challenge when using 3D OMC as markers often become displaced and/or occluded when implements (such as boxes for manual handling assessments and bats, balls, or barbells for sporting assessments) are included in the movement analysis [9]. The displacement and/or occlusion of markers results in loss of data, increased measurement error, increased tracking time, and sometimes the inability to analyse a captured movement. Two-dimensional (2D) video motion capture is a more affordable alternative to 3D OMC, requiring one or more video cameras with sufficient frame rate and video processing software such as the freely available software Kinovea (http://Kinovea.org, France) or Tracker (Open Source Physics). A number of drawbacks exist for 2D video motion capture. Multiple video cameras may be required for a full motional analysis. For example, for a running gait motion analysis, cameras may be required with views of the frontal and sagittal plane to capture joint varus/vulgus rotation and joint flexion/extension, stride length, stance duration, and swing duration, respectively. The high frame rate required to ensure accuracy when capturing fast movements (particularly sporting movements) result in large file sizes and extensive processing time. Both marker-based and marker-less 2D video motion capture rely on a line of sight of the participant throughout the movement and as such see similar occlusion limitations to 3D OMC [9]. Parallax error caused by the participant performing the movement at a nonperpendicular angle (out of plane) to the camera and perspective error caused by the participant moving toward or away from the camera are additional sources of error when using 2D video motion capture [11, 12]. Electromagnetic motion capture requires the participant to wear a specially designed suit of electromagnetic receiver sensors which receive electromagnetic waves from a base station transmitter located within the vicinity of where the movement is to be performed [8]. The receiver/transmitter network allows the position and orientation of the body to which the receiver sensors are attached to be determined within space [8]. Electromagnetic motion capture systems do not rely on line of sight measurements and thus do not encounter the problems of marker displacement and/or occlusion when implements are included in the motion analysis [8]. Low sampling rates currently make electromagnetic motion capture systems unsuitable for fast movements [8]. Motion capture often takes place at laboratory, clinical, or sporting facilities where equipment in the environment emit electromagnetic disturbance. Electromagnetic motion capture systems are susceptible to electromagnetic interference from the surrounding environment, causing potentially large errors in orientation estimations [8]. While each of these traditional motion capture methodologies have their own advantages and disadvantages, no single method is appropriate for all applications. Recent developments in inertial measurement unit (IMU) and magnetic, angular rate, and gravity (MARG) sensor technologies have resulted in researchers proposing the use of such devices to overcome many of the limitations of traditional motion capture systems, particularly when data needs to be collected outside of a laboratory. Inertial devices have been used for human motion capture in the areas of athlete external load monitoring [13–15], activity classification [16–20], and spatiotemporal and kinematic analysis [4–6, 21]. The methodology of external load monitoring using inertial devices uses the raw output data of the IMU/MARG device (often accelerations) and thresholding techniques to determine the amount of exposure an athlete may have to various magnitudes of acceleration (external load) over the course of a training session, game/competition, or other relevant period of time such as a week, month, or year [15]. Such data is typically used to provide some insight into athlete performance, training adaptation, fatigue, and risk of injury [15]. Activity classification is used to identify movement patterns such as walking, running, stair ascent/descent, and lying in various positions over an extended period of time (hours or days). Machine learning techniques such as K-nearest neighbour, decision trees, support vector machine, logistic regression, and discriminant analysis are often used to classify these common activities of everyday living [17, 22]. Activity classification can provide clinicians with valuable information about the decline in health or independence of elderly living at home, the activity levels of persons living with conditions or diseases, or the detection of falls or accidents [20]. Inertial-based human spatiotemporal and kinematic analysis requires complex sensor fusion and pose estimation methodologies to process raw MARG data. Numerous studies have demonstrated good agreement when comparing spatiotemporal and kinematic measures derived from IMU and MARG based motion capture systems with gold standard 3D OMC systems in clinical, ergonomic, and sporting applications [4, 23–27]. Similar to traditional motion capture methods, researchers have suggested the accuracy of IMU and MARG based motion capture to be dependent on the algorithms and methodologies used to process the raw data captured by the device [28, 29]. Previous research and reviews have primarily focussed on either the overall validity of inertial-based motion capture (IMC) (excluding methodology considerations) [4, 8, 30, 31], sensor fusion methodologies [32, 33], or position and orientation estimation (pose) methodologies [34–38], making it difficult and time consuming for researchers and developers to piece together all essential methodological components. Two reviews have attempted to summarise the methodological components of IMC; however, these reviews have limited detail around critical considerations such as sensor fusion, pose estimation, soft tissue artifacts (STA), sensor placement, biomechanical modelling, and magnetic calibration, which should be made when developing an IMC solution [39, 40]. The following technical summary is aimed at providing background and reference on all methodological components which must be considered when implementing an IMC solution for a given application (Figure 1). Such a summary will reduce the time spent by researchers and developers establishing the fundamental methodological components of IMC prior to further developing current techniques and enhancing the rate of development and utilisation of IMC.
... Where the value of p<0.05 to all variables search which shows statistically significant differences between pre and post-measurement for posttest. This development is due to the impact of the training plan applied to the lifters and is consistent with what (Andrew, 2001;Ebada, 2008;Ebada, 2011b;Ebada & Abdel Hadi, 2018;Escamilla et al., 2000) that high-intensity weight training programs improve the strength of muscle groups working in the three lifts. In addition to following the training principles such as adjustment, increase load and resistance near the maximum and maximum and the gradual resistance that affects the increase in strength and performance for powerlifters. ...
... The upward phase of the back squat can be split into three regions: (1) acceleration, when vertical bar velocity is increasing from at-depth to peak positive velocity; (2) sticking, vertical velocity decreases to a local minima; and (3) strength and deceleration, culminating in the greatest peak velocity followed by completion to standing upright (Escamilla et al. [21]; Appendix Fig. 6). While the sticking region is frequently assumed to be the area where success/failure occurs, there is no consensus on what the sticking region is other than the most difficult region of the barbell lift [6,22,23]. ...
Article
Previous literature suggests the sticking region, the transition period between an early peak concentric velocity to a local minimum, in barbell movements may be the reason for failing repeated submaximal and maximal squats. This study determined the effects of load on lower extremity biomechanics during back squats. Twenty participants performed the NSCA's one-repetition maximum (1RM) testing protocol, testing to supramaximum loads (failure). After completing the protocol and a 10-minute rest, 80% 1RM squats were performed. Statistical parametric mapping was used to determine vertical velocity, acceleration, ankle, knee, and hip sagittal and frontal plane biomechanics differences between 1RM, submaximum, and supramaximum squats (105% 1RM). Vertical acceleration was a better discriminative measure than velocity, exibiting differences across all conditions. Supramaximum squats emphasized knee moments, whereas 1RM emphasized hip moments during acceleration. Submaximum squats had reduced hip and knee moments compared to supramaximum squats, but similar knee moments to 1RM squats. Across all conditions, knee loads mirrored accelerations and a prominent knee (acceleration) to hip (sticking) transition existed. These results indicate that 1) submaximum squats performed at increased velocities can provide similar moments at the ankle and knee, but not hip, as maximal loads and 2) significant emphasis on hip strength is necessary for heavy back squats.
... The starting position for the deadlift was with the player squatting, arms straight and downward, and an alternating hand grip on a bar placed in front of the lifter's feet. The bar had to be lifted in a continuous motion, until the player was standing with his knees locked and his shoulders pushed back [29]. ...
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Background. Recurrent ankle sprains are common in soccer players, characterized by restricted range of motion, pain, and decreased proprioception, strength, and postural control. Methods. In this randomized controlled trial over 4 weeks, 36 recreationally active male football players randomly to experimental group (myofascial release applied to the subastragaline joint, eccentric training with an isoinertial device and neuromuscular taping) or control group (same intervention without neuromuscular taping). Outcomes measures were range of motion, strength, stability and perceived pain in the ankle joint. The within-subject effect and group interaction were obtained by means of a repeated measures ANOVA. Results. We found significant differences in range of motion in dorsiflexion (p < 0.001; η²p = 0.31) and plantar flexion (p < 0.01; η²p = 0.23). We also found differences depending on the moment in the strength in dorsiflexion (p = 0.001; η²p = 0.19) and plantar flexion (p < 0.001; η²p = 0.29) and in the intra-subject effect in the variables perceived pain (p = 0.03; η²p = 0.11) and the mean anteroposterior and mid-lateral velocity with eyes open (p < 0.001; η²p = 0.25). No significant changes in group interaction were found in any of the variables (p > 0.05). Conclusion. The combination of fascial therapy and eccentric strength training with an isoinertial device improves ankle mobility, strength and stability in footballers with recurrent ankle sprains. The use of taping techniques failed to provide a greater improvement of the study variables when combined with manual therapy and strength techniques. Trial Registration Number: www.clinicaltrials.gov (id: NCT04257916; Date of registration: 2nd, April, 2020).
... A conventional deadlift is a compound movement combining concentric, isometric, and eccentric contractions to lift an anteriorly displaced weight from the ground to upright stance. The deadlift is an essential compound movement utilized for resistance training, rehabilitation, and powerlifting (Escamilla et al., 2000). The deadlift activates and builds musculature of the posterior chain and core (Hamlyn et al., 2007)-including but not limited to the transverse abdominis, rectus abdominis, erector spinae, latissimus dorsi, trapezius, gluteus maximus, and hamstrings-contributing to athletic performance, strength, and rehabilitation for low-intensity low back pain (Berglund et al., 2015;Thompson et al., 2015). ...
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This study investigated weight distribution between the lower limbs using a symmetry index (SI) score of the vertical ground reaction forces (GRF) and measures of postural stability in high load/low repetition (termed "heavy") and low load/high repetition (termed "light") deadlifting. Ten participants performed two deadlift protocols with equal cumulative external load. These protocols were designed to represent standard high load/low repetition and low load/high repetition workouts; order was random and separated by 7 days. An effect of lifting condition (p = 0.023) and set number (p = 0.011) was observed such that lifts in the heavy condition were less symmetrical than those in the light condition and lifts became more symmetrical as set number increased. There was no effect of lift number on symmetry of force production (p = 0.127). Additional analysis revealed that center of pressure (COP) path length was greater during heavy lifts (p = 0.002) however COP range was unaffected suggesting controlled point of force application within the same boundaries regardless of lifting condition. As asymmetries have been previously associated with increased injury risk, greater training emphasis on the symmetrical performance of sub-maximal deadlifts should be considered to try to minimize the development of asymmetries.
... shows the comparison of force F based on approximative equation (3) and exact equation(4). The two lines are indistinguishable, which shows that the contribution of a z (L) is negligible in this case. ...
... , 이러한 동작 들은 모두 조정경기력과 높은 상관관계가 보고되었다 [13,14]. [11,12,19]. 또한, 단관절 운동은 다관절 운동에 비해 근력향상에는 큰 차이가 없는 것으 로 알려지고 있다 [20,21,22]. ...
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OBJECTIVES The purpose of this study was to analyze the relationship between isokinetic leg strength and maximum Isometric Med-Thigh Pull Test(IMTP) and maximum height of Counter Movement Jump (CMJ) in Korean national rowers.METHODS Each eight male and female athletes were participated in the study. Isometric IMTP, CMJ, and isokinetic trunk, hip, and knee strength were measured to analyze the relationship between the IMTP, CMJ and isokinetic strength. The correlation between variables was analyzed by the step-wise method of multiple regression analysis after analyzing the correlation between dependent and independent variables.RESULTS Knee, Hip and trunk isokinetic flexion and extension strength showed high correlation with maximum IMTP with the all participants. Knee extension and trunk flexion isokinetic strength showed higher correlation with IMTP. Knee extension isokinetic strength showed high correlation with CMJ.CONCLUSIONS For strengthening exercise of National rowers, ipsilateral strength balance and agonistantagonist strength balance of leg and trunk should be considered to improve performance efficiently.
... Thus it takes a longer time to complete the repetition. Shoulder-width stance also helps the lifters by having a smaller distance of center of gravity thus, increase the stability during the lifting phase [17,18]. The result of the present study that showed smaller number of repetitions done by the participants also aligned with the previous study which is due to the increasing of knee angle as the squat performed with narrow stance [19]. ...
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This study was conducted to determine the effect of different stance-width; i) narrow, ii) shoulder and iii) wide, on muscle activation and performance during Romanian deadlift (RDL) exercise. Thirty recreationally resistance trained men aged of 19-23 years old (22.20±1.13) were involved in this study. The participants need to perform RDL with 80% of their 1RM in three sessions with three difference stances in randomized order. To measure the muscle activation level during performing the exercise, the electromyogram (EMG) marker was placed on vastus lateralis, biceps femoris, gluteus maximus and multifidus muscles. The number of repetitions completed during each sets was recorded as indicator for performance. The mean EMG value during concentric and eccentric movement along with the number of repetitions completed were analysed using one way repeated measure analysis of variances (ANOVA). The result showed no significant differences were found on EMG reading of vastus lateralis and bicep femoris during eccentric and concentric phase of RDL when three different stances were used. However, when wide stances were used, a significant difference was observed on gluteus maximus whilst significant differences on multifidus were obviously seen when narrow stance were used. Higher number of repetition completed was significantly found when wide and shoulder width stances were used compared to narrow stance. The results of this study revealed the importance to choose correct stance width (depending on training objective) while performing RDL due to its effects on the muscle activation and performance.
... The loads for the hip and knee joints comprise 80-90%, whereas the ankle contributes 0-20%, of the total lower extremity moment to lift the system mass during the upward (concentric) portion of back squats (Escamilla, 2001;Flanagan et al., 2015;Flanagan and Salem, 2008;Fry et al., 2003;Hirata and Duarte, 2007;Lorenzetti et al., 2012). Previous research has delineated the concentric (upward) portion of the back squat into three distinct regions: Acceleration, when vertical bar velocity is increasing from zero to peak positive, Sticking/Failure Region, vertical velocity decreases to a local minima, and finally the Strength and Deceleration Region which ends when the person is fully standing erect (Escamilla et al., 2000). The ''Sticking Region" has garnered a great deal of attention, as research aims to understand how the body overcomes the external resistance (Bryanton et al., 2012;Kubo et al., 2018), leading to a success instead of failure Arandjelović , 2017, 2016;van den Tillaar, 2015;van den Tillaar et al., 2014). ...
Article
The back squat is a complex movement with significant demands on the lower extremities and trunk to raise an external load. The back squat is simultaneously an open and closed kinetic chain movement that requires coordination of the entire body for successful completion of the lift. Therefore, this study aimed to examine coordination of the thigh and shank, trunk and thigh, and the hip and knee during the concentric phase of maximum, supra-maximum (at 105% max), and sub-maximum (at 80% max) back squats. Fourteen resistance trained adults participated in this study. Maximum back squat loads were determined using a previously determined progressive load protocol. Motion capture of the trunk and lower extremities and ground reaction force data were recorded during all squats. Angle-angle plots and modified vector coding were performed to analyze segment and joint coupling angles and knee-hip moments. Overall, the concentric phase of back squats depict a transition from early knee dominance to hip dominance as the system ascends. Interestingly, all squats presented with coupling of thigh-rising and trunk-falling. Based on the angle-angle plots and the modified vector coding results, the prolonged coupling of trunk falling and thigh rising likely resulted in too large of a moment arm for the external load for the participants to overcome during Supramax conditions.
Article
OCCUPATIONAL APPLICATIONSHeavy deadlifting is used as a screening tool or training protocol for recruitment and retention in physically-demanding occupations, especially in the military. Spinal loads experienced during heavy deadlifts, particularly shearing forces, are well above recommended thresholds for lumbar spine injury in occupational settings. Although members of the noted occupation likely have stronger musculoskeletal systems compared to the general population, experiencing shearing forces that are 2 to 4 times larger than the threshold of injury, particularly under repetitive deadlift, may transform a screening tool or training protocol to an occupationally-harmful physical activity.
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Abstract Background: Biomechanical screening assessments are used to provide useful information about an athlete's movement proficiency. Clinically, movement proficiency is typically evaluated visually. This may result in low levels of agreement, leading to difficulties ensuring consistent athlete assessment. Objective: The objective was to determine levels of agreement within and between physical therapists. and students enrolled on a physical therapy course when visually evaluating athletes’ movement proficiency during biomechanical screening assessments. Design: This was an observational study. Methods: Twenty-seven physical therapists and 20 physical therapist students assessed 100 video recordings of athletes performing 4 lower-limb biomechanical screening assessments: squat, lunge, single leg squat (SLS) and deadlift. Analysis was completed on conditioned and unconditioned data. In the conditioned data, technique deviations were induced purposefully by the athletes. In the unconditioned data, deviations occurred naturally due to increased weight or movement complexity. In order to determine levels of agreement in the assessments, participants were required to classify the athletes’ movement as acceptable or aberrant. Each participant assessed the same video recordings on two separate occasions at least 30 days apart. Agreement levels were determined using Cohen and Fleiss Kappa. Results: Kappa scores at an interrater level ranged from 0.18 to 0.53 and intrarater agreement ranged from 0.38 to 0.62. Levels of agreement were higher in the conditioned data compared to the unconditioned data. Overall, the lunge and squat produced higher levels of agreement than the deadlift and SLS. Students and physical therapists demonstrated similar levels of agreement. Limitations: Screening assessments were evaluated through the use of video analysis. Conclusions: Greater efforts are needed to ensure standardization of movement analysis.
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Beck, M, Varner, W, LeVault, L, Boring, J, and Fahs, CA. Decline in unintentional lifting velocity is both load and exercise specific. J Strength Cond Res XX(X): 000-000, 2020-When monitoring the mean concentric velocity (MCV) for velocity-based resistance training, often a threshold in the decline in the MCV is used to regulate the number of repetitions performed. However, it is not clear if the decline in the MCV is affected by the type of exercise or the relative load used. Therefore, the purpose of this study was to compare the decline in the MCV between the overhead press (OHP) and deadlift (DL) during sets to fatigue at different loads. Thirty individuals (23 ± 3 years) with current training experience with both the OHP and DL completed a 1 repetition maximum (1RM) protocol for the OHP and DL. Subjects then returned to the laboratory on 2 separate occasions and completed 1 set of the OHP and DL to volitional fatigue at either 70 or 90% of their 1RM in a randomized order. The open barbell system measured the MCV of all repetitions. The absolute and relative (%) decline in the MCV was calculated for each condition and compared between loads (70 vs. 90% 1RM) and between lifts (OHP vs. DL). An alpha level of 0.05 was used at the criterion for statistical significance. The absolute decline in the MCV was greatest for the 70% OHP condition (0.36 ± 0.12 m·s) followed by 90% OHP (0.19 ± 0.10 m·s), 70% DL (0.16 ± 0.08 m·s), and 90% DL (0.09 ± 0.06 m·s); all were significantly different from one another (p < 0.05) except for 70% DL vs. 90% OHP (p = 0.441). There was a greater relative decline in the MCV for the OHP compared with the DL (50.1 ± 11.8% vs. 28.5 ± 11.8%; p < 0.001) and for 70% 1RM compared with 90% 1RM (44.5 ± 12.0% vs. 34.1 ± 12.0%; p < 0.001). These data suggest the decline in the MCV is both exercise and load specific. Applying a uniform velocity decline threshold for velocity-based training may reduce training volume to different extents depending on the exercise and relative load used.
Conference Paper
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The strength and conditioning and rehabilitation sectors use the deadlift as an integral part of their programming (Escamilla et al., 2000). Furthermore, what shoes to wear while deadlifting is a regular topic of weightlifting equipment forums. Strength and conditioning researchers and a range of industry practitioners suggest that weightlifting shoes, non-compressive soled shoes such as ConverseTM ‘Chuck Taylors’ or unshod (socks only or barefoot) conditions are essential in providing a stable platform and effective force transfer from the ground to the bar (Cressey, 2008). In contrast it is claimed that soft soled shoes produce instability and indirect ground reaction force (GRF) transmission, thus compromising lifting performance.
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As the sport of strongman is becoming increasingly popular, and such exercises are being commonly used by strength and conditioning coaches for a wide range of athletic groups, a greater understanding of the biomechanics of strongman exercises is warranted. To improve the quality of research, this systematic review summarised the research methodology used in biomechanical studies of strongman exercises and identified potential improvements to current approaches. A search of 5 databases found 10 articles adherent to the pre-defined inclusion criteria. The studies assessed 8 strongman exercises and included male participants of relatively similar body mass but varying training backgrounds. Due to the complexity of strongman exercises and the challenges in collecting advanced biomechanical data in the field, most studies used simplified measurement/analysis methods (e.g., 2D motion capture). Future strongman biomechanical studies should: assess under/un-researched strongman exercises; include a greater number of experienced and female strongman athletes; utilise more advanced (e.g., 3D motion capture and/or inertial sensor) technology so to provide a broader range and greater quality of data. Such approaches will provide strength and conditioning coaches, strongman coaches and athletes with a greater understanding of strongman exercises, thereby further improving exercise prescription, athlete performance and minimising risk of injury.
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Objectives To investigate the accuracy of visual assessments made by physical therapists of lumbo-pelvic movements during the squat and deadlift and how much movement is considered injurious. Design Quantitative Cross-sectional. Participants 14 powerlifters, 10 Olympic weightlifters and six physical therapists. Setting The lifters were recorded simultaneously by video and an inertial measurement unit (IMU) system while performing squats and deadlifts. The physical therapists assessed the videos and rated whether specific lumbo-pelvic movements were visible during the lifts and whether the movement amplitude was considered injurious. Main outcome measures The nominal visual assessments, if there was a movement and if it was considered injurious, were compared to the degrees of movement attained from the IMU system. Results During the squat, a posterior pelvic tilt of ≥34° was required to visually detect the movement. For other lumbo-pelvic movements, there was no significant difference in the amount of movement between those who were assessed as moving or not moving their lumbo-pelvic area, nor was there a difference in movement amplitude between those who were assessed as having an increased risk of injury or not. Conclusions Physical therapists did not consistently detect lumbo-pelvic movements during squats and deadlifts when performed by competitive lifters.
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Background: The sport of strongman is becoming increasingly popular, catering for females, lightweight, and Masters competitors, with strongman exercises also being used by strength and conditioning coaches for a range of athletic groups. Thus, a systematic review was conducted to examine researchers' current understanding of the biomechanics of strongman exercises, with a view to improve strongman athlete performance, provide biomechanical evidence supporting the transferability of strongman exercises to strength and conditioning/rehabilitation programs, and identify gaps in the current knowledge of the biomechanics of strongman exercises. Methods: A two-level search term strategy was used to search five databases for studies relevant to strongman exercises and biomechanics. Results: Eleven articles adherent to the inclusion criteria were returned from the search. The studies provided preliminary biomechanical analysis of various strongman exercises including the key biomechanical performance determinants of the farmer's walk, heavy sled pull, and tire flip. Higher performing athletes in the farmer's walk and heavy sled pull were characterized by a greater stride length and stride rate and reduced ground contact time, while higher performing athletes in the tire flip were characterized by a reduced second pull phase time when compared with lower performing athletes. Qualitative comparison of carrying/walking, pulling and static lifting strongman, traditional weight training exercises (TWTE), and common everyday activities (CEA), like loaded carriage and resisted sprinting, were discussed to further researchers' understanding of the determinants of various strongman exercises and their applications to strength and conditioning practice. A lack of basic quantitative biomechanical data of the yoke walk, unilateral load carriage, vehicle pull, atlas stone lift and tire flip, and biomechanical performance determinants of the log lift were identified. Conclusions: This review has demonstrated the likely applicability and benefit of current and future strongman exercise biomechanics research to strongman athletes and coaches, strength and conditioning coaches considering using strongman exercises in a training program, and tactical operators (e.g., military, army) and other manual labor occupations. Future research may provide a greater understanding of the biomechanical determinants of performance, potential training adaptations, and risks expected when performing and/or incorporating strongman exercises into strength and conditioning or injury rehabilitation programs.
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The performance of ten elite powerlifters were analyzed in a simulated competition environment using three-dimensional cinematography and surface electromyography while bench pressing approximately 80% of maximum, a maximal load, and an unsuccessful supramaximal attempt. The resultant moment arm (from the sagittal and transverse planes) of the weight about the shoulder axis decreased throughout the upward movement of the bar. The resultant moment arm of the weight about the elbow axis decreased throughout the initial portion of the ascent of the bar, recording a minimum value during the sticking region, and subsequently increased throughout the remainder of the ascent of the bar. The electromyograms produced by the prime mover muscles (sternal portion of pectoralis major, anterior deltoid, long head of triceps brachii) achieved maximal activation at the commencement of the ascent phase of the lift and maintained this level essentially unchanged throughout the upward movement of the bar. The sticking region, therefore, did not appear to be caused by an increase in the moment arm of the weight about the shoulder or elbow joints or by a minimization of muscular activity during this region. A possible mechanism which envisages the sticking region as a force-reduced transition phase between a strain energy-assisted acceleration phase and a mechanically advantageous maximum strength region is postulated.
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The purpose of this study was to examine the relationship between total estimated work, bar load and total oxygen consumption (TVO2) during the deadlift exercise. Forty-two observations of TVO2 during a wide range of deadlifting bouts were made on a heterogeneous sample of 10 males and 14 females. TVO2 was measured by standard open-circuit spirometry. An R of 0.912 for work and TVO2 indicated that total estimated work during deadlifting can be used to predict oxygen cost accurately. The calculated regression equation was TVO2 (litres of O2) = 2.63 + 0.80 work (kJ) with a S.E.E. of 1.50 litres O2. An R of 0.909 for bar load and TVO2 indicated essentially the same predictability using bar load as the independent variable. The calculated regression equation was TVO2 (litres O2) = 2.88 + 0.005 bar load (kg) with a S.E.E. of 1.5 litres O2. Care should be taken when converting oxygen cost to energy expenditure values using non-protein R equivalents, since underestimations are likely, due to the heavy glycolytic involvement.
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Three high-skilled powerlifters performed parallel squats with different burden weights. Using a sagittal plane biomechanical model, the moments of force about the bilateral axes of the lumbo-sacral, hip, knee, and ankle joints were determined. A local biomechanical model of the knee was used in order to calculate the knee joint forces induced. The greatest moments were found in the lumbo-sacral joint. The maximum hip moment was greater than that of the knee moment which was greater than the ankle moment. The knee moment had a flexing direction and reached its maximum at the deepest position of the squat, while the lumbo-sacral and hip moments were found to reach their maxima during the first half second of the ascent. One lift that caused a bilateral quadriceps tendon rupture was stimulated and was found to give a maximum knee flexing moment ranging between 335 Nm and 550 Nm. This moment induced a force in each quadriceps tendon of between 10.9 kN and 18.3 kN at the occasion of rupture.
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To overcome many of the complications after ACL reconstruction (prolonged knee stiffness, limitation of complete extension, delay in strength recovery, anterior knee pain), yet still maintain knee stability, we developed a rehabilitation protocol that emphasizes full knee extension on the first postoperative day and immediate weightbearing according to the patient's tolerance. Of 800 patients who underwent intraarticular ACL patellar tendon-bone graft reconstruction, performed by the same surgeon, the last 450 patients have followed the accelerated rehabilitation schedule as outlined in the protocol. A longer than 2 year followup is recorded for 73 of the patients in the accelerated rehabilitation group. On the 1st postoperative day, we encouraged these patients to walk with full weightbearing and full knee extension. By the 2nd postoperative week, the patients with a 100 degree range of motion participated in a guided exercise and strengthening program. By the 4th week, patients were permitted unlimited activities of daily living and were allowed to return to light sports activities as early as the 8th week if the Cybex strength scores of the involved extremity exceeded 70% of the scores of the noninvolved extremity and the patient had completed a sport-specific functional/agility program. The patient database was compiled from frequent clinical examinations, periodic knee questionnaires, and objective information, such as range of motion measurements, KT-1000 values, and Cybex strength scores. A series of graft biopsies obtained at various times have revealed no adverse histologic reaction.(ABSTRACT TRUNCATED AT 250 WORDS)
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To compare the effectiveness of 3 weight-training movements for the hamstrings, 11 weight-trained men performed 3 repetitions at 75% of 1 repetition maximum of the leg curl (LC), stiff-leg deadlift (SLDL), and back squat. Integrated electromyography (EMG) and peak EMG were analyzed in the biceps femoris and semitendinosus independantly during the concentric (CON) and eccentric (ECC) phase of each exercise. Results were as follows: CON-LC and CON-SLDL elicited the greatest integrated EMG activity, with no significant difference between exercises. The CON-squat showed approximately half as much integrated EMG activity as CON-LC and CON-SLDL. Highest peak EMG was found in the CON-LC and CON-SLDL, with no significant difference in these exercises. The CON-squat produced a peak EMG that was approximately 70% of LC and SLDL. We conclude that LC and SLDL involve the hamstrings to a similar degree; however, the back squat involves only about half as much hamstring integrated EMG activity as LC and SLDL. (C) 1999 National Strength and Conditioning Association
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The purpose of this study was to document the differences in kinematics between the Sumo and conventional style deadlift techniques as performed by competitive powerlifters. Videotapes of 19 conventional and 10 Sumo contestants at two regional New Zealand powerlifting championships were analyzed. It was found that the Sumo lifters maintained a more upright posture at liftoff compared to the conventional lifters. The distance required to lift the bar to completion was significantly reduced in the Sumo technique. No significant difference was found between the techniques as to where the sticking point (first decrease in vertical bar velocity) occurred. (C) 1996 National Strength and Conditioning Association
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This study evaluated the “direct linear transformation” method developed by Abdel-Aziz and Karara (1971) for use with high-speed cine techniques. Two high-speed cameras were used to film a series of points with known spatial coordinates. From knowledge of these “control” points, the parameters representing interior and exterior orientations were determined. The spatial coordinates of unknown points were then calculated. Position data were very accurate. The mean deviations of computed coordinates from the actual coordinates were .4 cm in the vertical direction (Z), .4 cm in the horizontal direction (X), and .5 cm in the horizontal direction (Y). Displacement-time data in the X, Y, and Z directions for the dynamic test were as expected. The calculated vertical accelerations of a ball during free flight were within 1% to 4% of the value of g (−9.8 m/sec2). It was concluded that the photogrammetric method is applicable to cinematographic techniques. Additionally, the flexibility of this technique appeared to be superior to any of the existing three-dimensional cinematographic methods.
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This study investigated the muscular torques and joint forces during the parallel squat as performed by weightlifters. (JD)
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The purpose of this study was to formulate a kinematic model of performance in the parallel squat, based on the movement characteristics of world class powerlifters, and to determine if the model could be utilized to assess technique differences between high and less-skilled subjects. Two trials were recorded via high-speed cinematography from a side view of twenty-four Ss during the 1974 U.S. Senior National A.A.U. Powerlifting Championships. Vertical and horizontal displacement patterns of three joint centers and the center of the bar were determined for the best trial of each S. These data were subsequently used to calculate desired linear and angular coordinates, velocities and accelerations for body segments and bar. Results indicated that although there was some variability in most kinematic parameters, vertical bar velocity was found to be very similar among competitors, even for Ss of different bodyweight. Consequently, the vertical velocity of the bar was selected as the parameter around which performance could be modeled in the parallel squat. A model was formulated by plotting the mean values in vertical bar velocity for all Ss scaled to a common time base. The resultant model was contrasted with vertical bar velocity data for less-skilled Ss to assess typical performance errors.
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The mechanical role of the lumbar posterior ligaments during lifting tasks remains controversial. This study was designed to assess the ligament and disc contribution in resisting trunk flexion moment during extremely heavy lifts performed by national class powerlifters. Direct measurements of lumbar vertebrae kinematics in sagittal plane were obtained from videofluoroscopy utilizing multiple digitizing, correction for optical distortions and digital filtering. Four experienced powerlifters executed three trials, resulting in about 72 mA s of total radiation exposure. In the first trial, joint angles were measured when subjects fully flexed their spines to a point where the passive tissues resisted the flexor moment creating myoelectric silence in the extensor musculature. Next, two conventional deadlift style lifts were executed with the barbell load ranging from 183.7 to 210.9 kg. Four vertebral corners were digitized at a sampling rate of 30 Hz. The relative intervertebral joint angles, distance between the ligament attachment points, shearing and compressive displacements were calculated from a rigid body motion approach. Analysis revealed that except for one trial of one subject, they accomplished their lifts with an amount of lumbar flexion between 1.5 and 13 degrees less than they demonstrated during full flexion. Resultant ligament lengths at the beginning of the lifts ranged from 56.1 to 99.8% of their lengths when the trunk was fully flexed. It was concluded that ligaments did not strain sufficiently to contribute substantial resistance to the trunk flexion moment, relegating this responsibility to the musculature.
Article
The reaction moments at the knee, hip, and L4/L5 joints, and the compressive and shearing forces on L4/L5 are documented in powerlifters competing in a national powerlifting championship. Analyses were made of 13 female and 44 male competitors. The joint moments and forces were estimated from a linked segment model (WATBAK) that incorporated functional low back extensor musculature with a moment arm of 6 cm and a line action that was oriented 5 degrees posteriorly to the L4/L5 compression axis. This oblique orientation of the extensor muscles reduced the anterior shearing load on the vertebral motion unit. Average compressive loads on L4/L5 were estimated up to 17,192 N while the highest average L4/L5 and hip moments were 988 and 1047 N.m, respectively. The sumo deadlift style resulted in a 10% reduction in the joint moment and 8% reduction in the load shear force at the L4/L5 level when compared with the conventional lifting style. Formulation of linear regression equations to predict the load lifted using reaction joint moments yielded substantial unexplained variability, though significant relationships were found. This analysis suggested that there is large variability in the pattern of loading joints among national class powerlifters.
Article
Biomechanical analysis of the two-dimensional models composed from roentgenographic pictures and electromyographic analysis of the shear force exerted on the tibia during standing on both legs were conducted in 21 young adult males. The simultaneous contraction of the quadriceps and hamstrings was observed in all electromyograms. Amplitude observed on electromyograms of the hamstrings increased as the trunk flexion angle increased. The calculated average values of shear force were negative at every knee flexion angle (negative value means posteriorly directed force). As the trunk flexion angle increased, posterior drawer force increased at knee flexion angles of 30 degrees and 60 degrees. The simultaneous contraction of the quadriceps and the hamstrings was considered to be the main factor that influenced these results. Standing on both legs with knee and trunk flexion was considered to be applicable in the early stages after anterior cruciate ligament reconstruction.
Article
Rehabilitation is recognised as a critical component in the treatment of the anterior cruciate ligament (ACL) injured athlete, and has been the subject of intense research over the past decade. As a result, sound scientific principles have been applied to this realm of sports medicine, and have improved the outcome of both surgical and nonsurgical treatment. Possibly the most intriguing of these principles is the use of the kinetic chain concept in exercise prescription following ACL reconstruction. The hip, knee, and ankle joints when taken together, comprise the lower extremity kinetic chain. Kinetic chain exercises like the squat recruit all 3 links in unison while exercises such as seated quadriceps extensions isolate one link of the chain. Biomechanical assessment with force diagrams reveals that ACL strain is reduced during kinetic chain exercise by virtue of the axial orientation of the applied load and muscular co-contraction. Additionally, kinetic chain exercise through recruitment of all hip, knee, and ankle extensors in synchrony takes advantage of specificity of training principles. More importantly, however, it is the only way to reproduce the concurrent shift of ‘antagonistic’ biarticular muscle groups that occurs during simultaneous hip, knee, and ankle extension. Incoordination of the concurrent shift fostered by exercising each muscle group in isolation may ultimately hamper complete recovery. Modifying present day leg press and isokinetic equipment will allow clinicians to make better use of kinetic chain exercise and allow safe isokinetic testing of the ACL reconstructed knee. Reconstruction of the ACL with a strong well placed graft to restore joint kinematics, followed by scientifically sound rehabilitation to improve dynamic control of tibial translation, will improve the outcome after ACL injury.
Article
The purpose of this study was to examine the effectiveness of weight-belts during the performance of the parallel squat exercise. Six subjects were filmed (40 fps) as they performed three trials at each of three belt conditions (NB, none; LB, light; HB, heavy) in random order and three load conditions (70, 80, 90% 1RM (one repetition maximum] in increasing order. The parameters examined were collected and interfaced to a computer via an analog-to-digital (A/D) converter: ground reaction forces, intra-abdominal pressure (IAP), and EMG for the rectus abdominus (RA), external oblique (EO), and erector spinae (ES) muscles. Most differences were observed during the 90% 1RM condition, and only they are presented in this paper. Maximum IAP values were always greater (P less than 0.05) for the weight-belt conditions (LB, 29.2; HB, 29.1 greater th an NB, 26,8 kPa). Similar results were observed for the mean IAP. The integrated EMG (iEMG) activity of the muscles and adjusted mean values for back compressive force and back muscle force followed a similar but opposite pattern, with NB being the greatest. ES mEMG/(L5/S1) values for HB (18.1%) were the least, followed by LB (20.01%) and NB (22.3%). Few differences were observed between belt types. These data suggest that a weight-belt can aid in supporting the trunk by increasing IAP.
Article
Intra-abdominal pressure (IAP) has been widely hypothesized to reduce potentially injurious compressive forces on spinal discs during lifting. To investigate the effects of a standard lifting belt on IAP and lifting mechanics, IAP and vertical ground reaction force (GRF) were monitored by computer using a catheter transducer and force platform while nine subjects aged 28.2 +/- 6.6 yr dead-lifted a barbell both with and without a lifting belt at 90% of maximum. Both IAP and GRF rose sharply from the time force was first exerted on the bar until shortly after it left the floor, after which GRF usually plateaued while IAP either plateaued or declined. IAP rose significantly (P less than 0.05) earlier with than without the belt. When the belt was worn, IAP rose significantly earlier than did GRF. Both with and without the belt, IAP ended its initial surge significantly earlier than did GRF. Variables significantly greater with than without a belt included peak IAP, area under the IAP vs time curve from start of initial IAP surge to lift-off, peak rate of IAP increase after the end of its initial surge, and average IAP from lift-off to life completion. In contrast, average rate of IAP increase during its initial surge was significantly lower with the belt. Correlations are presented which provide additional information about relationships among the variables. Results suggest that the use of a lifting belt increases IAP, which may reduce disc compressive force and improve lifting safety.
Article
In order to investigate intra-thoracic pressure (ITP) and intra-abdominal pressure (IAP) during lifting and jumping, 11 males were monitored as they performed the dead lift (DL), slide row (SR), leg press (LP), bench press (BP), and box lift (BL) at 50, 75 and 100% of each subject's four-repetition maxima, the vertical jump (VJ), drop jump (DJ) from 0.5 and 1.0 m heights, and Valsalva maneuver (VM). Measurements were made of peak pressure, time from pressure rise to switch-marked initiation of body movement, and time from the movement to peak pressure. The highest ITP and IAP occurred during VM (22.2 +/- 6.0 and 26.6 +/- 6.7 kPa, respectively) with one individual reaching 36.9 kPa (277 mm Hg) IAP. In ascending order of peak ITP during the highest resistance sets, the activities were SR, BP, VJ, DJ, DL, BL, LP, and VM, while the order for IAP was BP, VJ, DJ, BL, DL, LP, SR, and VM. Pressures significantly (P less than 0.05) increased with amount of weight lifted, rising before and peaking after the weight moved. IAP generally rose earlier and was of greater magnitude than ITP. For the jumps, pressure rose and diminished before the feet lost contact with the ground. Drop-jump height did not affect pressure. Correlation of pressure with weight lifted was fair to good for most activities.
Article
The load on the lumbar spine was calculated in eight power lifters when they executed an extremely heavy lift. The calculated load on L3 as well as the total load lifted during training in the last year were related to the bone mineral content (BMC) in the L3 as determined with dual photon absorptiometry. The loads on L3 in the lifters ranged between 18.8 and 36.4 kN. The BMC values were extremely high and closely correlated to the amount of weight lifted during training (r2 = 0.82). The study showed that intensive training will increase the BMC to an extent that the spine can tolerate extraordinary loads.
Article
The purpose of the study was to investigate the effects of load height on selected performance characteristics of a squat exercise. A lower center of mass bar was designed that allowed the integrity of the squat exercise to be maintained while possibly reducing the chances of injury. Five trials were performed with the center of mass of the bar was set at shoulder height (C1) and lowered 18% (C2) and 36% (C3) of the subject's height below the normal bar position using the inverted "U" bar. All trials were filmed as the subjects lifted on a force platform. A balloon catheter was inserted into the subject's recta to monitor intra-abdominal pressure (IAP). High correlations were found between IAP, joint moment, and force data. Many of the critical parameters occurred just after the lowest squat position. Significant differences (P less than 0.05) in trunk angle excursion and trunk angular velocity indicated a greater ease of hip extension for the center of mass bar conditions. No differences were observed between conditions for thigh and knee angles and joint moments indicating kinematic similarity for the lower extremity. IAP was always least for C2 and C3, while compression, shear, and back muscle forces did not differ. It was estimated that the greater IAP was responsible for relieving back muscle forces and compression by up to 15 and 21%, respectively, and increased stress with the weight at shoulder height stimulated a response for greater IAP to help alleviate the stresses on the spine.
Article
An analysis of errors arising from the Direct Linear Transformation (DLT) approach to three-dimensional reconstructions from two-dimensional images has been undertaken, the principal factor studied being the number and distribution of control points used in the calibration procedure. Significantly increased error was found to be associated with extrapolation to unknown points outside the control point distribution space. Differences in accuracy between two camera position set-ups and 11 vs 12 DLT parameter solutions were also examined.
Article
The purpose of this paper is to study the load-elonga tion characteristics of a Grade II sprain of the anterior cruciate ligament (ACL) at the time of local anesthesia arthroscopy. The data may be used to increase diag nostic and prognostic accuracy when evaluating Grade II ACL sprains and to structure properly a rehabilitation program following ACL injury. This report is based on the data from two in vivo strain gage studies of Grade II ACL sprains. Following instrumentation of the ligament, several events com mon to physical examination and rehabilitation pro grams were tested. The Lachman test produced greater elongation of the anteromedial fibers than did the anterior drawer or pivot shift test. A fairly high force of 80 pounds may be required by the examiner's hands to test satisfactorily the anteromedial fibers in the acutely injured large athlete. The proper order for a rehabilitation program should be crutch walking, cycling, walking, slow running, and faster running. Patients should be cautioned to run on a perfectly level surface. Cycling produced 7% as much elongation as an 80 pound Lachman test, and the one leg half squat 21 % as much. Quadriceps rehabilitation can be done more safely using these exercises. Quadriceps exercises by knee extension against a 20 pound weight boot in the range of full extension to 22° flexion created peak elongation of the anteromedial fibers ranging from 87 to 121% of that produced by an 80 pound Lachman test. We recommend that quadri ceps exercises and testing by knee extension through a full range of motion not be done during the first year following ACL injury or reconstruction. Quadriceps contraction against a 20 pound weight boot at 45° flexion produced 50% as much elongation as an 80 pound Lachman test. Beginning at 9 months post-ACL reconstruction, we do measure quadriceps strength isometrically with the knee flexed 45°.
Article
The purpose of the study was to evaluate selected parameters describing performance characteristics of a free-weight and isokinetic bench press. A secondary purpose was an attempt to clarify the technique requirements essential for a successful lift. Parameters describing the free-weight condition were generated from cinematographic data (150 fps) for five trials each at 90 and 75% of the subject's maximal performance (1RM). Isokinetic data were obtained from an instrumented Cybex Power Bench Press at two speeds corresponding to the average speeds for the free-weight conditions. Despite differences, accommodation appeared to occur for both methods when the lifts were performed maximally. A "sticking region" was defined as the portion of the free-weight activity when the subjects' force application was less than the weight of the bar. No significant difference (P less than 0.05) was observed between the 90% 1RM (26.02%) and 75% 1RM (26.94%) mean relative time values for these regions. For the Cybex device, the percentage of the activity which was isokinetic was longer for the slower speeds of rotation (0.47 rad X s-1 = 70%) and steadily decreased until the movement was only 50% isokinetic at 1.74 rad X s-1. The observed relationships between applied force-time data along with anatomical considerations suggest an ideal technique for the lift.
Article
This study documented characteristics of the dead lift of teenage lifters. Films of 10 "skilled" and 11 "unskilled" contestants in a Michigan Teenage Powerlifting Championship provided data for analysis. Equations of motion, force, and moments were developed for a multisegment model of the lifters' movement in the sagittal plane and applied to the film data. Analysis was limited to 1) body segment orientations, 2) vertical bar accelerations, 3) vertical joint reaction forces, 4) segmental angular accelerations, 5) horizontal moment arms of the bar to selected joints, and 6) intersegmental resultant moments. Significant differences (P less than 0.05) in body segment orientation indicated a more upright posture at lift-off in the skilled group. Maximum vertical bar acceleration and angular acceleration of the trunk tended to occur near lift-off in the skilled lifters. The unskilled subjects demonstrated greater variability and magnitude in linear and angular acceleration parameters. In all lifters, maximum vertical force was experienced at the ankle joint. Within each subject, the hip joint experienced the greatest torque because of the relatively large horizontal moment arm of the bar (dominant mass in the system) to this joint. In all subjects, the magnitude of the mass lifted, and not the technique, was the primary determinant in the intersegmental resultant moment acting at the hip and the vertical force experienced at the ankle, knee, and hip joints.
Article
The purpose of this study was to quantify the amount of anterior tibial displacement occurring in anterior cruciate ligament-deficient knees during two types of rehabilitation exercises: 1) resisted knee extension, an open kinetic chain exercise; and 2) the parallel squat, a closed kinetic chain exercise. An electrogoniometer system was applied to the anterior cruciate ligament-deficient knee of 11 volunteers and to the uninvolved normal knee in 9 of these volunteers. Anterior tibial displacement and the knee flexion angle were measured during each exercise using matched quadriceps loads and during the Lachman test. The anterior cruciate ligament-deficient knee had significantly greater anterior tibial displacement during extension from 64 degrees to 10 degrees in the knee extension exercise as compared to the parallel squat exercise. In addition, the amount of displacement during the Lachman test was significantly less than in the knee extension exercise, but significantly more than in the parallel squat exercise. No significant differences were found between measurements in the normal knee. We concluded that the stress to the anterior cruciate ligament, as indicated by anterior tibial displacement, is minimized by using the parallel squat, a closed kinetic chain exercise, when compared to the relative anterior tibial displacement during knee extension exercise.
Article
The purpose of this study was to quantify the amount of anterior tibial displacement occurring in anterior cru ciate ligament-deficient knees during two types of re habilitation exercises: 1) resisted knee extension, an open kinetic chain exercise; and 2) the parallel squat, a closed kinetic chain exercise. An electrogoniometer system was applied to the anterior cruciate ligament- deficient knee of 11 volunteers and to the uninvolved normal knee in 9 of these volunteers. Anterior tibial displacement and the knee flexion angle were meas ured during each exercise using matched quadriceps loads and during the Lachman test. The anterior cru ciate ligament-deficient knee had significantly greater anterior tibial displacement during extension from 64° to 10° in the knee extension exercise as compared to the parallel squat exercise. In addition, the amount of displacement during the Lachman test was significantly less than in the knee extension exercise, but signifi cantly more than in the parallel squat exercise. No significant differences were found between measure ments in the normal knee. We concluded that the stress to the anterior cruciate ligament, as indicated by ante rior tibial displacement, is minimized by using the par allel squat, a closed kinetic chain exercise, when com pared to the relative anterior tibial displacement during knee extension exercise.
Article
A cadaveric model that incorporated quadriceps and hamstrings muscle loads was developed to simulate the squat exercise. The addition of hamstrings load affected knee kinematics in two ways. First, anterior tibial translation during flexion ("femoral roll-back") was significantly reduced ( P = 0.003) and second, internal tibial rotation during flexion was reduced ( P = 0.008). However, quadriceps force was unaffected by the ad dition of hamstrings load. Thus, it seems likely that hamstrings muscle activity that has been observed in vivo during a squat probably functions synergistically with the anterior cruciate ligament to provide anterior knee stability. After the ACL was sectioned, anterior tibial transla tion was significantly increased during the squat ( P = 0.04). The anterior cruciate ligament was then recon structed using a graft instrumented with a load cell. During passive motion, maximal graft tension was at full extension. During simulated squat exercise, the addition of hamstrings caused a significant decrease in graft load ( P = 0.006). During the squat, maximal graft tension was at full extension, and was equal to the graft tension at full passive extension. Thus, the squat exercise may be useful in the early stages of anterior cruciate ligament rehabilitation.
Article
The purpose of this study was to analyze forces at the tibiofemoral joint during open and closed-kinetic-chain exercises. Five healthy subjects performed maximum isometric contractions at 30, 60, and 90 degrees of knee flexion during open-kinetic-chain extension, open-kinetic-chain flexion, and closed-kinetic-chain exercises. Electromyographic activity of the quadriceps and hamstrings, as well as load and torque-cell data, were recorded. Tibiofemoral shear and compression forces were calculated with use of a two-dimensional biomechanical model. The results showed that, during the open-kinetic-chain extension exercise, maximum posterior shear forces (the resisting forces to anterior drawer) of 285 +/- 120 newtons (mean and standard deviation) occurred at 30 degrees of knee flexion and maximum anterior shear forces (the resisting forces to posterior drawer) of 1780 +/- 699 newtons occurred at 90 degrees of knee flexion. The closed-kinetic-chain exercise produced significantly less posterior shear force at all angles when compared with the open-kinetic-chain extension exercise. In addition, the closed-kinetic-chain exercise produced significantly less anterior shear force at all angles except 30 degrees when compared with the open-kinetic-chain flexion exercise (p < 0.05). Analysis of tibiofemoral compression forces and electromyographic recruitment patterns revealed that the closed-kinetic-chain exercise produced significantly greater compression forces and increased muscular co-contraction at the same angles at which the open-kinetic-chain exercises produced maximum shear forces and minimum muscular co-contraction.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
The purpose of this study was to analyze intersegmental forces at the tibiofemoral joint and muscle activity during three commonly prescribed closed kinetic chain exercises: the power squat, the front squat, and the lunge. Subjects with anterior cruciate ligament-intact knees performed repetitions of each of the three exercises using a 223-N (50-pound) barbell. The results showed that the mean tibiofemoral shear force was posterior (tibial force on femur) throughout the cycle of all three exercises. The magnitude of the posterior shear forces increased with knee flexion during the descent phase of each exercise. Joint compression forces remained constant throughout the descent and ascent phases of the power squat and the front squat. A net offset in extension for the moment about the knee was present for all three exercises. Increased quadriceps muscle activity and the decreased hamstring muscle activity are required to perform the lunge as compared with the power squat and the front squat. A posterior tibiofemoral shear force throughout the entire cycle of all three exercises in these subjects with anterior cruciate ligament-intact knees indicates that the potential loading on the injured or reconstructed anterior cruciate ligament is not significant. The magnitude of the posterior tibiofemoral shear force is not likely to be detrimental to the injured or reconstructed posterior cruciate ligament. These conclusions assume that the resultant anteroposterior shear force corresponds to the anterior and posterior cruciate ligament forces.
Positive moment arms are anterior to joint; negative moment arms are posterior to joint; positive moments are knee flexor and ankle plantar flexor moments
  • Lo
  • Kp
LO, liftoff; KP, knee passing; LC, lift completion. Positive moment arms are anterior to joint; negative moment arms are posterior to joint; positive moments are knee flexor and ankle plantar flexor moments;