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Biomechanical Analysis of the Deadlift

First published elitefts.com 2003

Introduction:

The deadlif t can be considered as one of the best tests of overall body strength (Groves, 2000). It is a multijoint movement that in simple terms involves picking up a barbell f rom the f loor and standing to the erectposit ion. The movement includes the recruitment of the muscles of the hip, lower back, upper back, quadriceps,hamstrings and abdominals. If used correctly, it can be an excellent exercise to use in the development ofstrength, speed and power. During this analysis, the objective was to compare and contrast the biomechanicalef f iciency of two types of deadlif t styles and determine which type should be used f or certain body types.Method:

Procedure:

The participant was given instructions on both conventional and semi round back deadlif t techniques. Thevideo recording equipment was set up at ninety degrees to the demonstration at a distance of approximatelyf ive metres away. This was to ensure parallax and perspective errors were each accounted f or. Recordingswere then made f or a series of conventional and rounded back deadlif ts. Multiple repetit ions were perf ormed ineach style at approximately 80 percent of the lif ters one repetit ion maximum. One repetit ion f rom each stylewas then analysed.

Participants:

The participant f or this study was one elite level power lif ter who has been competing at national level f or twoyears.

Apparatus:

The equipment used was a Sony digital handicam 120x zoom video camera set up on a tripod to record theobservations. A weights belt was used f or back support, as well as an Olympic style barbell in conjunction withweight plates. All observations were conducted at Apollo Fitness Centre.

Literature review:

In competit ive powerlif t ing, the deadlif t is the third lif t in order f ollowing the squat and bench press. It of tencomes down to perf ormance in the deadlif t to decide the dif f erence between winning and losing a competit ion.There is a saying in powerlif t ing circles that the competit ion does not start until the bar hits the f loor, meaningthat a strong deadlif t will of ten lead to a good competit ion result.Much of the research that involves the deadlif t has looked at sumo and conventional styles. Sumo style isused with a wider stance in which the lif ter grips the bar with the arms placed on the inside of the legs.Conventional style deadlif t ing involves f oot placement at approximately shoulder width apart and gripping the

bar on the outside of the legs (McGuigan & Wilson, 1996).Both techniques have been used ef f ectively in elite power lif t ing competit ion. Conventional style places a largeemphasis on the use of the erector spinae muscles because in this posit ion the trunk is normally f lexedf orward. Sumo style is perf ormed with a more erect and upright back alignment that allows f or greaterrecruitment of the hip muscles to perf orm the lif t (Piper & Waller, 2001).The sumo lif t is considered to be the more biomechanical ef f icient lif t of the both techniques (McGuigan &Wilson, 1996). It is suggested that bar travel is minimized with a shorter stroke and aids the ability to recruit agreater number of muscle f ibres f rom the posterior chain. Studies have indicated that sumo style deadlif t ingcan reduce bar travel by nineteen percent (McGuigan & Wilson, 1996).Studies by McGuigan & Wilson (1996) have indicated that in elite competit ive powerlif t ing the majority of worldrecords are held by lif ters using the conventional style. Sumo style deadlif t ing has not produced as many worldrecords but has perf ormed greater lif ts in terms of relative body weight. This gives rise to the suggestion thatconventional style deadlif t ing may be suited to lif ters of larger body mass with longer arm length and sumosuited to those of smaller body mass.The conventional style involves the use of the erector spinae, trapezius, quadriceps and hamstring muscles(Stone & O’Bryant, 1987). Further analysis of the conventional deadlif t indicates that the gluteal, latissimusdorsi, teres minor subscapularis, inf raspinatus, supraspinatus and biceps brachii all assist with the lif t to somedegree (Farley, 1995).The kinesiology of the conventional style involves setting up with the f eet spaced shoulder width apart.Common practise is to use an alternating grip which involves one hand pronated and the other hand supinatedto assist with grip strength. Common practise to set up f or the init ial pull involves aligning the shins close tothe bar (Farley, 1995).Keeping the load as close to the body as possible should assist with increasing the mechanical advantage f orgreater f orce production (Stone & O’Bryant, 1987). In contrast to this, some literature has suggested thatkeeping the load too close to the body may cause excessive drag and f riction against the body that maydecrease the ef f iciency of the lif t. Correct starting posit ion indicated by many texts suggests that the pelvicgirdle is in line with or slightly below the knees. The back should remain f lat and at an angle of f orty f ivedegrees to the f loor.Additional support f or this method put f orth by Daniels (2003) indicates keeping the back f lat and placing thehips below the half squat posit ion. This posit ion is said to put the init ial load of the pull on to the quadricepsmuscles without placing undue stress on the lumbar region of the spine (Groves, 2000).

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Discussion/ Conclusion:

Choosing a style of deadlif t ing can best be suited to a person’s individual body mechanics. Many variablescome into play that may af f ect the ef f iciency of the lif t. These f actors include torso, leg and arm length (Stone& O’Bryant, 1987).Movements are governed by physical laws. Understanding and applying biomechanical principles to deadlif t ingtechnique can result in the lif t being more energy ef f icient and allowing greater peak perf ormance. In contrast ,poor body mechanics become less ef f icient and may cause injury (Stone & O’Bryant, 1987).Mechanical work can be described as f orce exerted on an object over a distance it is dislaced (Sif f , 2000). Foref f icient use of f orce, the displacement should be along the same line and in opposite direction to theresisting f orce of the load (Stone & O’Bryant, 1987). This gives additional support to keeping the bar close tothe body while deadlif t ing which will assist with a more ef f icient movement and less wasted ef f ort. This may bedue to the reduced moment arm of f ornce.In contrast to much of the research put f orth, I suggest a dif f erent starting posit ion to the conventionaldeadlif t that may assist those lif ters who tend to be of taller stature with longer arm length. Both sumo andconventional styles have been studied extensively but minimal research has been done in what I call a semiround back style which may contra- indicate some previous research with regards to lumbar spine loading.The semi round back style involves a similar init ial set up to the conventional style but the hip girdle is set at ahigher start posit ion f or the init ial pull. This posit ion would be almost a quarter squat posit ion with the upper

back kept f lat and at a ten degree lean to the f loor, as opposed to f orty f ive degrees lean suggested in manytexts.Previous research has suggested that a person maybe more biomechanical ef f icient in the quarter squatposit ion than in the half squat posit ion. Studies have indicated that greater loads can be used in the partialquarter squat movement than the half squat (Sif f , 2000).The semi round method also allows f or the bar to travel in a straight line. The shortest distance between twopoints is a straight line, theref ore this can decrease the distance of travel. The conventional method causesthe lif ters lower limbs to shif t f orward in the starting posit ion. This will cause the bar to travel in a ‘S’ typemotion with the load moving away f rom the body and then moving back towards the body once the load hascleared the knees.This gives rise to the idea of trying to turn the deadlif t into the quarter squat motion but the load being of f thef loor. For this to occur, the lif ter must have an extremely strong upper and lower back. The higher startingposition can reduce the displacement of the load and theref ore in turn reduce the amount of work perf ormed.Studies by Horn (1988) suggest that electromyographic activity in the spinal erector muscles were twice asactive in conventional lif ters when compared with sumo technique. Cholewicki et al (1991) studied the lumbarspine load of both sumo and conventional technique. No signif icant dif f erence was f ound in disc compressionf orce at L4/L5 regions using both techniques. There were signif icantly greater L4/L5 moments and load shearf orces in the conventional technique. This may suggest that the greater f orward lean of round back techniquemay f urther increase L4/L5 moments and shear f orces indicating that much caution must be taken whenconsidering this method f or athletes as f or the increased risk of injury to the lower back region.This type of lif t ing conf licts with much of the research that suggests correct deadlif t f orm. In the absence ofprevious research, experiential evidence has indicated that using the semi round back method has resulted inthree athletes breaking world deadlif t records in WPC and WDFPL f ederations. Other competit ion resultsinclude a f urther f ive lif ters who have broken Victorian state and Australian national records. This may be dueto reduced bar displacement and theref ore reducing the amount of work perf ormed. This technique has onlyworked f or taller type lif ters, which may be more biomechanical ef f icient f or those with longer type levers.Much assistance work must be employed to strengthen the abdominal, spinal erector, hamstring, gluteal andupper back muscles f or this method to be ef f ective. Care and patience must be exercised if considering usingthe round back method as a pref erred style.Further research in this area is needed to investigate dif f erential leverages and the muscles responsible f oref f ective motion. When considering various techniques, individual body leverages need to be taken intoaccount along with the assessment of the individuals muscle strengths and weaknesses. Caution should beused bef ore considering this technique due to the increased risk of injury. If employed correctly, the semi roundback method may lead to greater competit ion totals f or the powerlif ter.

References

Cholewicki, J., McGill, S. and Norman, R. (1991). Lumbar Spine Loads During the Lif t ing of Extremely HeavyWeights. Medical Science Journal of Sports Exercise. Vol 23, pp1179- 1186.Daniels, D. (2003). Deadlif t 101, Part1. Powerlif t ing USA. Vol 26. No.8.Groves, B. (2000). Powerlif t ing: Technique and Training f or Athletic Muscular Development. Champaign: HumanKinetics.Farley,K. (1995). Analysis if the Conventional Deadlif t. Strength and Conditioning Journal. Vol 15, No. 2, pp 55-58.McGuigan, R.M. & Wilson, B.D. (1996). Biomechanical Analysis of the Deadlif t. Journal of Strength andConditioning Research. 10(4), 250-255.Piper, T.J. & Waller, M.A. (2001). Variations of the Deadlif t. Strength and Conditioning Journal. Vol 23, No. 3, pp

66-73.Stone, M. & O’Bryant, H. (1987). Weight Training: A Scientif ic Approach. (2nd ed.). Edina: Burgess International.