Article

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

August 2000
Medicine and Science in Sports and Exercise 32(7):1265-75

DOI:10.1097/00005768-200007000-00013

Source
PubMed

Authors:

Glenn S Fleisig

American Sports Medicine Institute

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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.

A Biomechanical Comparison Between Conventional, Sumo, and Hex-Bar Deadlifts Among Resistance Trained Women

Article

Dec 2024
J STRENGTH COND RES

Gundersen, AH, van den Tillaar, R, Falch, HN, Fredriksen, AB, and Larsen, S. A biomechanical comparison between conventional, sumo, and hex-bar deadlifts among resistance trained women. J Strength Cond Res XX(X): 000–000, 2024—The deadlift is a multijoint exercise frequently used to strengthen the lower extremities and spinal erectors. Despite variations, such as the conventional, sumo, and hex-bar deadlifts, little is known about how these techniques affect the concentric phase of maximal deadlifts among strength trained women. Therefore, this study used statistical parametric mapping to compare kinematics, net joint moments (NJMs), and surface electromyography amplitude between these deadlift variations during the last repetition of a 3 repetition maximum (3RM) in strength trained women. Eleven women (body mass: 67.64 6 7.27 kg, height: 161.91 6 3.05 cm, age: 23.18 6 3.46 years) performed 3RM deadlifts in conventional, sumo, and hex-bar deadlifts, lifting 103.18 6 18.47, 101.54 6 15.01, and 99.70 6 15.94 kg, respectively. The main findings showed that deadlifting with conventional and sumo techniques resulted in larger hip NJMs near the lockout. Conversely, deadlifting with the hex-bar technique resulted in greater barbell velocity, knee NJMs, and increased hip and knee flexion angles. Therefore, when training maximal 3RM deadlifts, we suggest that hex-bar deadlifts may be beneficial for targeting knee extensors and enhancing barbell velocity among strength trained women. Conversely, sumo and conventional deadlifts may be more effective for targeting the hip extensors near the lockout during the last repetition of 3RM deadlifts.

Differences between conventional and sumo variants of deadlifting: Kinematic, kinetic and electromiographic study

Article

Full-text available

Jan 2021

Deadlift is a measure of the overall strength of the whole body and it is one of the three exercises in the powerlifting competition. There are conventional and sumo variant of deadlift. The aim of this study was to determine the differences between the two lifting techniques from the aspect of kinematics, kinetics and electromyography. Nine physically active men, average age 29.1 ± 3.3 years, body height 181.0 ± 1.0 cm, body weight 82.3 ± 13.3 kg and body massindex 25.0 ± 3.8 kg/m2 were recruited forthisstudy. Each subject lifted weight close to his own body weight with three repetitions, in three series, for each of the techniques. The speed of one lift was 3 seconds for each of the phases (concentric and eccentric). The angles and amplitudes for the following figurative points were monitored: trunk in relation to the horizontal plane (angle), center of the hip joint and center of the knee joint in the "liftoff" (LO - position in which the weight separates from the ground) and "knee passing" (KP - position in which the weight passes in front of the knee position), i.e. in the liftoff-knee passing (LO-KP), knee passing-lift completion (KP-LC; LC - final, i.e. completely upright body position) and liftoff-lift completion (LOLC) phase. The mechanical work was monitored as a one of the kinetic variables. Electromyographic activity was monitored for the following muscles: m. vastus medialis, m. vastus lateralis, m. rectus femoris, m. gluteus Maximus, m. erector spinae (L3-L4), m. semimembranosus and m. biceps femoris caput longum. The monitored electromyographic variablewasthe average normalized amount of muscle activation in relation to maximal voluntary contraction, for all 18 individual deadlift repetitions (3 series × 3 repetitions × 2 techniques). One-way analysis of variance with repeated measurements (for the amount of muscle activation and performed mechanical work) and two-way analysis of variance with repeated measurements (for angles and amplitudes) were used for statistical data processing. Significant differences were found between techniques in the initial angular positions in all monitored joints (p<0.05), except for the angle in the knee joint where the trend was observed (p=0.0996), as well as in the transit position for the trunk angle relative to the horizontal plane and angle at the hip joint (p<0.05). There was a statistically significant difference between techniques in amplitudes in the hip joint during KP-LC phase (p<0.05) and total amplitude (p<0.05), as well as in the knee joint during LO-KP phase (p<0.05) and total amplitude in the form of a trend (p=0.0996). The performed mechanical work is significantly higher when lifting the load with the conventional deadlift technique (DLcon) (p<0.05). Activation of medial and lateral heads of m. quadriceps femoris is significantly higher (p<0.05) when lifting with sumo deadlift technique (DLsu). It was noticed that activation of postural muscle groups (m. erector spinae, m. gluteus maximum, m. semitendinosus and m. biceps femoris caput longum) is higher when lifting the load with DLcon, but not significantly (p>0.05).

Kinetics in lumbosacral and lower-limb joints of sprinters during barbell hip thrust compared to deadlift and back squat

Article

Full-text available

Jul 2021
PLOS ONE

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.

Footwear Affects Conventional and Sumo Deadlift Performance

Article

Full-text available

Feb 2021

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.

Kinematic Differences Between the Front and Back Squat and Conventional and Sumo Deadlift

Article

Full-text available

Sep 2019

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.

The Comparison of Velocity between Front Squat, Back Squat, Sumo and Conventional Deadlift: 219 Board #57 May 29 11:00 AM - 12:30 PM

Article

Full-text available

Jun 2019

35. Powerlifting

Chapter

Jan 2018

Sean Maloney

An electromyographic and kinetic comparison of conventional and Romanian deadlifts

Article

Full-text available

Aug 2018
J EXERC SCI FIT

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.

Anthropometrical Determinants of Deadlift Variant Performance

Article

Aug 2019
J SPORT SCI MED

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.

Determinants of Deadlift Variant Performance

Article

Full-text available

Sep 2019
J SPORT SCI MED

Incidence and characteristics of acute and overuse injuries in elite powerlifters

Article

Full-text available

Mar 2019

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.

Hip and Knee Kinetics During a Back Squat and Deadlift

Article

Oct 2018

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.

Examining isotonic and isometric exercises for post-activation performance enhancement in kickboxers upper limb strength and power

Article

Full-text available

Jan 2025

Maximizing muscular performance to improve upper limb strength and power can be advantageous in preparing kickboxers for training and competition. The objective of this study was to evaluate the influence of isometric and isotonic upper limb post-activation performance enhancement (PAPE) strategies on the maximal strength of young men kickboxers’ upper limbs, assessed through handgrip strength (HG) and the chest medicine ball throw test (CMBT). Fifty-three amateur men kickboxers, aged between 16 and 23, participated voluntarily in this regional-level study. Over two weeks, participants were randomly exposed to three conditions: isometric, isotonic, and control (no warm-up) conditions. Each condition was repeated twice during this timeframe, resulting in six data collection sessions. After each condition, participants underwent assessments for HG strength and CMBT performance. Repeated measures ANOVA revealed significant differences between conditions in HG (p < 0.001; ES = 0.740). Post-hoc analysis revealed that the isometric condition showed significantly better scores compared to both the isotonic condition (p < 0.001) and the control condition (p < 0.001). Significant differences were found in CMBT (p < 0.001; ES = 0.355). Post-hoc analysis revealed that the isometric (p < 0.001) and isotonic conditions (p < 0.001) displayed significantly superior outcomes in contrast to control. In conclusion, isometric exercise significantly improved maximal HG strength and muscular power in the CMBT, showing a potential effective strategy for implementing PAPE for kickboxers.

Progressive and Asymmetrical Deadlift Loads Captured by Wearable Motion Tape Sensors

Article

Full-text available

Dec 2024
SENSORS-BASEL

Weight training is widely adopted and highly effective for enhancing both muscular strength and endurance. A popular weightlifting exercise is the deadlift, which targets multiple muscle groups including the lower back, glutes, and hamstrings. However, incorrect technique (i.e., poor form) can slow training progress, result in asymmetrical muscle development, and cause serious injuries. The objective of this study was to validate that a self-adhesive, elastic fabric, wearable, skin-strain sensor called Motion Tape (MT) could monitor a person’s posture while performing deadlift exercises. Two pairs of Motion Tape were attached on the front and back sides of the pelvis at each posterior superior iliac spine to record muscle engagement during deadlift exercises. The results of this preliminary study confirmed that the MT identified asymmetry in muscle engagement during deadlifting repetitions. In addition, the sensors could quantify the different levels of effort exerted according to the deadlift weight load.

Comparison of EMG Activity in Hip-and Knee- Dominant Kettlebell Swing

Thesis

Jun 2022

Abd Muin

Abstract Purpose: The purpose of this study was to determine the muscle activation of Erector Spinae (ES), Gluteus Maximus (GM), Biceps Femoris (BF), and Vastus Lateralis (VL) during the hip and knee-dominant Kettlebell swing exercise. To the best of our knowledge, this was the first study investigating muscle activation during the Kettlebell hip-dominant and knee-dominant Kettlebell swing exercise. Methods: Nine volunteers participated in the present study (age 20.7 ± 0.9 years, body mass 58.6 ± 3.9 kg, height 170.3 ± 3.3 cm) with a resistant training experience of 3.9 ± 1.1 yrs, performed 10-repetition in the hip-dominant and knee-dominant swing kettlebell exercises. The electrical muscle activity of four right muscles (ES, GM, BF, and VL) was recorded using a surface Trigno Wireless EMG System (Delsys Inc, USA), and processed using software EMG Works Acquisition 4.0.5 (Delsys Inc. Boston, MA USA) for integrated EMG to calculate the raw data. The muscle activity was normalized to a maximal voluntary isometric contraction (MVIC) specific for each muscle. Results: Paired-sample T-test showed that there were no significant differences in muscle activation during the two different styles of the kettlebell swing (p>0.05). The data analyses collected were with presented mean ± standard deviation showed with values muscles EMG %MVIC activation patterns showed off the ES (hip-dominant < knee-dominant), GM (hip-dominant > knee-dominant), BF (hip-dominant < knee-dominant), and VL (hip-dominant > knee-dominant) across the 2 styles of kettlebell swing exercises. Conclusion: In conclusion, the activation of the four muscles varies within both kettlebells with different dominant swings. However, results showed that there was no statistical significance. Therefore, these findings suggest that there is no advantage to performing one style of swing over the other in kettlebell swing exercises during training. The present findings provide practical information regarding the muscle-specific demands of kettlebell exercises which may provide valuable insight for athletes, fitness enthusiasts, and exercise practitioners who implement variations styles of kettlebell training programs. Keywords: Kettlebell; Electromyography; Muscles activation; hip-dominant; knee-dominant

Analyzing Deadlift Form with Bio-mechanical Linkage Data

Preprint

Full-text available

Oct 2024

Self-knowledge from resistance training

Article

Full-text available

Jul 2024

Giovanni Rolla

The problem of self-knowledge has been thoroughly discussed in the context of traditional epistemology. In parallel to that traditional approach, Ecological-Enactive Cognition (EEC) has emerged in the last 30 years as a genuine contender in the cognitive sciences. According to EEC, the unity of analysis of cognitive processes is the dynamics between brain, body and environment. In this paper, I advance an EEC approach to self-knowledge, which immediately suggests that knowing oneself is a matter of knowing what one’s body can do. I then turn to resistance training, particularly weightlifting, and argue that it offers a paradigmatic case of self-knowledge in EEC’s terms. I contend that periodically reaching the point of mechanical failure provides an important insight into self-knowledge. Thus, resistance training allows the trainee to achieve knowledge of themselves in a fundamentally practical manner—and doing so is transformative of the kind of actions they are capable of.

Intermittent Voluntary Isometric Contractions Effects on Performance Enhancement and Sticking Region Kinematics in the Bench Press

Article

Full-text available

Apr 2023
J HUM KINET

During the last years, post-activation performance enhancement (PAPE) has gained notorious popularity due to the capacity to improve the acute rate of force development (RFD) using different strategies with different muscle contraction regimes as conditioning stimuli. The aim of the present study was to analyse the role of a maximal isometric post-activation performance enhancement (PAPE) protocol in performance and its effects on the kinematics of the sticking region. Twenty-one trained participants (age 26.4 ± 5.4 years) underwent two experimental sessions: an experimental session consisting of a single set and a single repetition of the bench press at the 93% of 1RM (which is considered a traditional conditioning activity to induce PAPE) (TRAD) and an isometric experimental session (ISO) consisting of 15 maximal voluntary isometric contractions in the sticking region of the medium grip bench press lasting 1 s with a 1 s rest interval between contractions. Both TRAD and ISO experimental conditions improved performance from post0 to post4, post8, post12 and post16, but only the ISO condition improved performance from the start of the lift to the start of the sticking region from pre to post (p < 0.001), and only the ISO condition improved maximum (p = 0.005) and minimum (p = 0.025) peak velocities. The results of this study suggest that short duration maximal voluntary isometric contractions improve the velocity of the lift prior to the initiation of the sticking region, which ultimately improves the impulse and facilitates the lift.

Influence of the base of support widths on postural control and feet loading symmetry during squat – preliminary study

Article

Jan 2022
Acta Bioeng Biomech

Purpose: The symmetry of feet loading and adequate postural control are crucial aspects of proper squat performance. The study aimed to evaluate the effect of various stance widths during squat on postural control and symmetry of feet loading. Methods: Thirty healthy individuals participated in this study. Each participant performed one type of squat with a narrow stance (NS), hip stance (HS) and wide stance (WS). Results: A significantly higher value of CoP path length, the velocity of sways and Area95 were obtained for the WS squat compared to NS and HS. In addition, the wide feet setting significantly affected not only the feet loading symmetry but also the strategy (high LyE), the amount of irregularities (high SampEn) and the CoP time-series roughness complexity (high FD). It has been shown that as the base of support grew, the asymmetry index grew. Conclusions: The wide squat is less stable, requiring more complex postural control behavior and more flexibility. Performing this squat significantly shifts the pressure to the dominant limb.

Effects of the ankle angle on the electromyographic activity of the trunk and lower extremities during isometric squat exercises

Article

Full-text available

May 2022

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.

Low Back Biomechanics during Repetitive Deadlifts: A Narrative Review

Article

Full-text available

Dec 2021

OCCUPATIONAL APPLICATIONS Heavy 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.

Training the Industrial Athlete: Targeted Exercises to Reduce Occupational Injury Risks

Article

Jan 2021

Range of Motion Is Not Reduced in National-Level New Zealand Female Powerlifters

Article

Jul 2021

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.

Computer-Aided Ergonomics: A Case Study for the Analysis of Resistance Training Exercises

Article

Full-text available

Dec 2020

Erman Çakıt

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.

Bölüm AĞIRLIK ANTRENMANI YARALANMALARININ EPİDEMİYOLOJİSİ: HALTER, POWERLIFTING VE VÜCUT GELİŞTİRME

Chapter

Apr 2020

Erhan Kara

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

Fascial therapy, strength exercises and taping in soccer players with recurrent ankle sprains: A randomized controlled trial

Article

Apr 2021

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.

Inertial-Based Human Motion Capture: A Technical Summary of Current Processing Methodologies for Spatiotemporal and Kinematic Measures

Article

Full-text available

Mar 2021

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.

INVESTIGATION OF THE EFFECT OF THE 5-MONTH SPECIAL MULTI-COMPONENT TRAINING PROGRAM ON THE PERFORMANCES OF A BLIND POWERLIFTER

Article

Feb 2021

Khaled Ebada

Effects of External Load on Sagittal and Frontal Plane Lower Extremity Biomechanics During Back Squats

Article

Jan 2021

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.

Improvement of Mobility, Strength, Stability and Pain in Soccer Players with Recurrent Ankle Sprains Through Myofascial Release, Strength Exercises and Taping: A Randomized Controlled Trial.

Preprint

Full-text available

Dec 2020

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).

The influence of compressive gear on maximal load lifted in competitive powerlifting

Article

Full-text available

Dec 2020

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.

High Load With Lower Repetitions vs. Low Load With Higher Repetitions: The Impact on Asymmetry in Weight Distribution During Deadlifting

Article

Full-text available

Sep 2020

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.

Physics of powerlifting: bar force profile during deadlift using video analysis and accelerometers

Article

Sep 2020

The Relationship between Isokinetic Trunk, Leg Strength and Isometric Mid-Thigh Pull Test, Counter Movement Jump in National Rowing Athletes

Article

Full-text available

Jul 2020

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.

The effects of stance width on muscle activation and performance during Romanian deadlift exercise

Article

Full-text available

Apr 2020

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.

Modified Vector Coding Analysis of Trunk and Lower Extremity Kinematics during Maximum and Sub-maximum Back Squats

Article

May 2020
J BIOMECH

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.

Music-based biofeedback for sports applications

Thesis

Jan 2019

Valerio Lorenzoni

The sonic instructor: A music-based biofeedback system for improving weightlifting technique

Article

Full-text available

Aug 2019
PLOS ONE

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.

Determining Interrater and Intrarater Levels of Agreement in Students and Clinicians When Visually Evaluating Movement Proficiency During Screening Assessments

Article

Jan 2019

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.

The Impact of Weight-Bearing Lower Limb Exercises on Balance and Gait in Patients Undergoing Total Knee Arthroplasty: Pre-experimental Study

Article

Full-text available

Aug 2024

The development of an automated assessment system for resistance training movement

Article

Mar 2024
SPORT BIOMECH

Kinetics comparison between conventional and Romanian deadlift among recreationally active men

Conference Paper

Jan 2023

The comparison of electromyographic activation between conventional deadlift and Romanian deadlift among trained men

Conference Paper

Jan 2023

The Effect of Lifting Straps on Deadlift Performance in Females

Article

Oct 2023

Trahey, KM, Lapp, EM, Talipan, TN, Guydan, TJ, Krupka, AJ, and Ellis, CE. The effect of lifting straps on deadlift performance in females. J Strength Cond Res 37(10): 1924–1928, 2023—Using lifting straps (LS) while deadlifting may increase the total number of repetitions performed and barbell velocity, and preserve grip strength; however, research in this area has only been conducted on men. This study investigated the effects of lifting straps on the total number of repetitions, mean and peak barbell velocity, and grip strength during the deadlift exercise in women. Ten women (20.1 ± 1.1 years; 165.4 ± 5.6 cm, 68.9 ± 10.3 kg) with 3.2 ± 2.1 years of resistance training experience participated in the study. After completing a 1-repetition maximum (1RM) test without LS, subjects completed 2 protocols: performing 3 sets of as many repetitions as possible of 80% 1RM with lifting straps (WS) and without lifting straps (NS). During both protocols, mean and peak barbell velocity were measured during each set, and grip strength was recorded before deadlifting and after each set. Repeated-measures analysis of variance were used to examine differences in the variables of interest, with an alpha level of 0.05 used to establish statistical significance. The WS condition allowed participants to perform significantly more reps while resulting in no statistically significant differences in mean or peak barbell velocity. The magnitude of grip strength loss was significantly lower during the WS condition. Results indicate that using LS while deadlifting allows women to perform more repetitions with greater preserved grip strength without negatively affecting barbell velocity. Thus, LS appear beneficial for deadlift performance in women and should be considered during resistance training involving the deadlift exercise.

SUMOylation and DeSUMOylation: Prospective therapeutic targets in cancer

Article

Sep 2023
LIFE SCI

How accurate are visual assessments by physical therapists of lumbo-pelvic movements during the squat and deadlift?

Article

Jun 2021
PHYS THER SPORT

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.

Decline in Unintentional Lifting Velocity Is Both Load and Exercise Specific

Article

Jul 2020
J STRENGTH COND RES

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.

Effects of Multimodal Intervention Program Among Elite Weightlifters with Knee Pain

Article

Feb 2020

The Biomechanics and Applications of Strongman Exercises: a Systematic Review

Article

Full-text available

Dec 2019

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.

A systematic review of the biomechanical research methods used in strongman studies

Article

May 2019

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.

A biomechanical analysis of the sticking region in the bench press

Article

Full-text available

Sep 1989

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.

Prediction of the oxygen cost of the deadlift exercise

Article

Full-text available

Sep 1994

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.

Intra-abdominal and intra-thoracic pressures during lifting and jumping

Article

Apr 1988

Joint load during the parallel squat in powerlifting and force analysis of in vivo bilateral quadriceps tendon rupture

Article

Jan 1986

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.

Space Requirements of the Seated Operator

Article

Jan 1955

Dempster WT

Accelerated Rehabilitation after Anterior Cruciate Ligament Reconstruction 1

Article

Aug 1990
AM J SPORT MED

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)

ACSM's Guidelines for Exercise Testing Prescription

Book

Jan 2014

American College of Sports Medicine

Electromyographic Activity of the Hamstrings During Performance of the Leg Curl, Stiff-Leg Deadlift, and Back Squat Movements

Article

May 1999

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

Biomechanical Analysis of the Deadlift

Article

Nov 1996

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

TEST & MEASUREMENT: Using Lift Repetitions to Predict Muscular Strength in Adolescent Males

Article

Dec 1993

Direct linear transformation method for three-dimensional cinematography

Article

Jun 1978

R Shapiro

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.

Kinetics of the parallel squat

Article

Jun 1978

This study investigated the muscular torques and joint forces during the parallel squat as performed by weightlifters. (JD)

A kinematic model of performance in the parallel squat by champion powerlifers

Article

Feb 1977
Med Sci Sports

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.

Lumbar posterior ligament involvement during extremely heavy lifts estimated from fluoroscopic measurements

Article

Feb 1992
J BIOMECH

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.

Lumbar spine loads during the lifting of extremely heavy weights

Article

Nov 1991

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.

Biomechanical analysis of rehabilitation in the standing position

Article

Dec 1991
AM J SPORT MED

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.

Kinetic Chain Exercise in Knee Rehabilitation

Article

Jul 1991

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.

The effectiveness of weight-belts during the squat exercise

Article

Mar 1990

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.

Effects of a belt on intra-abdominal pressure during weight lifting

Article

May 1989

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.

Intra-abdominal and intra-thoracic pressures during lifting and jumping

Article

May 1988

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.

The Loads on the Lumbar Spine During Extreme Weight Lifting

Article

Apr 1987

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.

Biomechanics of the squat exercise using a modified center of mass bar

Article

Sep 1986

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.

The accuracy of DLT extrapolation in three-dimensional film analysis

Article

Feb 1986
J BIOMECH

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.

An in vivo strain gage study of elongation of the anterior cruciate ligament

Article

Jan 1985
AM J SPORT MED

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°.

A comparison between free-weight and isokinetic bench pressing

Article

Jul 1985

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.

Kinematics and kinetics of the dead lift in adolescent power lifters

Article

Nov 1985

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.

Comparison of closed and open kinetic chain exercise in the anterior cruciate ligament-deficient knee

Article

Jan 1993
AM J SPORT MED

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.

Comparison of closed and open kinetic chain exercise in the anterior cruciate ligament-deficient knee

Article

Jul 1993
AM J SPORT MED

D M White

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.

Hamstrings - An anterior cruciate ligament protagonist. An in vitro study

Article

Mar 1993
AM J SPORT MED

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.

Comparison of Tibiofemoral Joint Forces during Open-Kinetic-Chain and Closed-Kinetic-Chain Exercises.

Article

May 1993

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)

Comparison of Intersegmental Tibiofemoral Joint Forces and Muscle Activity During Various Closed Kinetic Chain Exercises

Article

Dec 1996
AM J SPORT MED

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, 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;

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

Abstract

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