The purpose of this study to make comparison about back squat biomechanics among professional powerlifters by using many types of equipment during the lift and not just specific only an equipment. The intensity of the lift of eleven athletes also been manipulated with the use of the equipment. The lifters had been performed back squat by using few equipment such as by using the belt only (Raw), belt with elastic band that attached to the bar (Band), and by proper competition attire that consist of belt, knee wraps and squat suit (Equipped). There are different among the equipment used such as from the angle of the back, total hip moment and total knee moment as the increased of intensity.
There are many strength exercises for lower body that can be applied to gain strength such as squat and deadlift. But the most common exercise been applied by professional athletes or recreational trainers is squat. Obviously for powerlifters, besides bench press and deadlift, squat is the main exercise to strengthen lower body parts and mimics to nature of sport. In order to increase the support and avoid injurie, external equipment been used during position of squat in powerlifting. International Powerlifting Federation (IPF) stated that belt, knee wrap and single-ply powerlifting suit might be used by the powerlifters as it can help improve the performance of powerlifters by generate the power on extensor muscles so it can produce more force during the lift. By use of the suit, it can help improve hip flexion and increase power of hip extensor muscles. Blatnik and co-workers (2012) found that peak power during 90% of 1RM lift was 15% higher using a suit. By this study it shows that suit relatively can increase the power of powerlifters. As for the knee wraps, it helps with knee extension when the knee stretch in deep position. Lake (2012) stated that vertical impulse is 10% higher with the use of knee wraps. When compared to the lifters technique, the equipment did not accurately might help the lift as the joint and the technique might be changed between the lifters. Elastic band had been used in training as the used of equipment take most of time and can cause uncomfortable and study by Rhea (2009) and Anderson (2008) had showed the benefits using resistance band during training.
Based on the previous study, the use of resistance band during training is better compared to other equipment because it can support lifters lower extremity by support the joints during movement. Besides the stimulation of lower extremity muscle will divides equally on vary of motion compared to Raw squat. In order to understand the relationship between loads and squatting technique, it is necessary to discover joint moment distribution between knee and hip joint. Bryanton and co-workers (2012) investigated how joint moments changed in loads up to 90% of 1RM among female recreational lifters and found a relative increase in internal hip extensor moments. But it is not known at high intensities these result valid or not especially on powerlifters. Then the purpose of the study is to compare between joint kinetics and kinematics in three different situations when performing deep barbell squats. The conditions as stated above are, belt only (Raw), belt with elastic band (Band) and using the full equipment such as belt, knee wraps and squat suit (Equipped).
In order to know the relationship between joint kinetics and kinematics, 11 Norwegian powerlifters that in top ranked which divided 10 male and 1 female been invited which are professional powerlifters from junior and senior categories. The study had been informed and approved by The Regional Ethics Committee. Before the participants perform the exercise, they were given 43 markers to mark on based on anatomical position and then proceed with warm-up and static calibration. The lifters followed standardized progression which is average of 7 sets prior to 1RM up to their Raw 1RM. Between warm up sets and maximum attempts, five minutes were given for rest period. During the squat performance, it will judge by a certified IPF judge by following IPF rules based on IPF Rules Book, 2011. The data of biomechanical only is collected for last three attempts which reach 90%, 95% and 100% of 1RM. Next procedure is elastic band will be attached to the bar and attached to the rack above on both sides which use two types of elastic band, purple and green. The difference of the elastic band which is purple weight 0.58 kg is for lifters that lift below than 160 kg in Raw 1RM. While the green band weight 0.78 kg is for lifters that lift above 160 kg. Standardized progression also been followed with four series up to elastic band 1RM (Band 1RM) but only 1RM lift was recorded. Lastly by using all the competition equipment and performed 80%, 85% and 90% of estimated 1RM and last lift only recorded.
Eight 300 Hz infrared cameras been used to calculate the biomechanics of lifters by recorded the movement of 43 markers that given earlier that been put on anatomical position. For ground reaction force and centre of pressure recorded by force platforms at 1500 Hz. The calculation of hip and knee joint were used inverse dynamics using recursive Newton Euler equations of motions. For back angle defined as sagittal plane angle of the torso relative to vertical axis. For statistical analyses are the assess the effect of load on few variables such as back angle, hip and knee moment, and hip knee moment ratio. There few technical problems occurred during the test on each category which decreases the number of participants. For Band 1RM, three subjects were excluded and equipped condition six participants been excluded. During the increased of load, there also increase of back angle, total hip moment, velocity and as well concentric phase duration. The final result showed that as the increase of intensity, biomechanics at bottom position remained same. Knee moments also did not change when intensity increase because participants used their full potential in knee extensor at submaximal lifts. Between three conditions, Raw 1RM and Band 1RM showed similar biomechanics but without greater hip moments and lower thigh angle. On equipped condition, it difference on substantial loading and kinematic compared to Raw. For lifters with suit, might be tend to reduce posture and change in minimum velocity location and might cause increase spinal compression compared to two other condition.
As the conclusion, greater loading during Raw lifts with high intensities increased hip moments and greater trunk lean. Biomechanics for Band and Raw quite similar but the difference can be seen on hip moments. The best condition is on Equipped as it shows added support for hip and knee extensors as well with the adductor. It also shows the different on trunk angle between Equipped and Raw condition which is the trunk angle is less upright in Equipped. Finally for my recommendation, the study should more focus on Equipped as during real time situation the lifters obviously will used belt, knee wraps and suit compared to resistance band only. The study should more precise on biomechanics during before, during and after the lifters put the weight down. Besides the performance can be increase, the serious injuries can be avoided since this kind of sports use many crucial parts of body such as back that include spinal that may lead to serious injuries if affected. The study also should more accurate on biomechanics and risk used on specific equipment as this study include many equipment such as elastic band, knee wrap and single-ply powerlifting suit.