Straight Leg Deadlifts

by Brent Brookbush MS, PES, CES, CSCS, ACSM H/FS

Do Not Lock the Knees (or nearly lock knees):

Locking the knees during a dead-lift has 3 potentially hazardous consequences. First, load on a locked knee increases stress on the posteriorly situated medial collateral ligaments, lateral collateral ligaments, the posterior cruciate ligaments, arcuate popliteal ligament, and the posterior oblique popliteal ligament. Overtime, the increase in force on these passive structures may lead to adaptive lengthening and instability of the knee.

Second, it would seem that a locked knee increases reliance on the deep longitudinal sub-system (sacrotuberous ligament, biceps femoris, peroneals). Reliance on this subsystem as a prime-mover reinforces a common compensatory pattern - synergistic dominance of the biceps femoris as a hip extensor over an inhibited glute complex. This is potentially hazardous to sacroiliac joint mechanics. When the biceps femoris is forced to act as a prime mover during eccentric control of hip flexion it increases tension on the sacrotuberous ligament and causes the sacrum to posterior tilt relative to the ilium. If this pattern is reinforced with exercise it could lead to SI joint dyskinesis, low-back and SI joint pain, inhibition of the glute complex and further reliance on the deep longitudinal subsystem. This could be viewed as a pathological positive feedback loop.

Last, the locked, or near locked knee increases the length and tonicity of the biceps femoris, reducing an individual’s ability to anteriorly tilt the pelvis on a fixed femur. If form is not carefully monitored, the individual may attempt to “steal” range of motion from the lumbar spine. The increase in lumbar flexion imparts additional force on lumbar extensors that are now placed in a lengthened position. The increase in force necessary for dynamic contractions in a lengthened position may be beyond the capacity of the lumbar extensors, especially during heavy lifts. This may set the stage for acute injury.

The primary extensor of the hip is the Gluteus Maximus not the Hamstrings.

Too often I hear dead-lifts referred to as “exercise for the hamstrings” - ignoring the fact that the gluteus maximus is the primary hip extensor under load. The gluteus maximus has the largest cross section of any muscle in the human body. Performance in hip dominant motion will improve if an individual can increase the activity and strength this musculature.

The “hip thrust” seems to be a particularly effective cue. To ensure proper loading of the hip extension musculature keep the knees slightly bent, and move the hips back as you descend. Thrust the hips forward, concentrating on a glute contraction when lifting the weight. The kinesiological analysis for hip extension is below:

See our deadlift progressions videos:

1. Deadlift
2. Single Leg Deadlift
3. SLTD with Scaption/PNF Carry Away
4. Deadlift with Anterior to Posterior Pull
5. SLTD and Progressions with Anterior to Posterior Pull

Deadlift

Single Leg Touchdown

Single Leg Touchdown with Scaption/PNF Carry Away

Deadlift with Anterior to Posterior Pull

Single Leg Touchdown and Progression with Anterior to Posterior Pull

&npsp;

Hip Extension

• Prime Mover: Gluteus maximus
• Synergists: Biceps femoris (long head), semitendinosus, semimembranosus, posterior head of adductor magnus
• Antagonists: Psoas, iliacus, tensor fascia latae, rectus femoris, anterior adductors especially pectineus, sartorius
• Neutralizers: Gluteus minimus and anterior fibers of gluteus medius neutralize external rotation force of gluteus maximus and deep rotators of hip (acting to stabilize the hip joint)
• Stabilizers: Deep rotators of hip
• Fixators: Intrinsic stabilization subsystem, rectus abdominis, obliques, quadratus lumborum, erector spinae

© Brent Brookbush 2012

Questions, comments, and criticisms are welcomed and encouraged –