Written By: Coach Matt Quinn
(*Editors Note: This is a great piece that Coach Matt wrote in response to a discussion he had with a colleague, who is a healthcare professional. Note that many of these same arguments hold true when referring to any type of pulling movement that begins from below the hips, such as Cleans, Snatches, RDLs, and all types of pulls.)
Helen returns home from a routine trip to the grocery store with several bags. She decides to take the two heaviest bags into the house first. As she approaches her front door, she sets the bags down, retrieves her keys, and unlocks her front door. Helen then thinks about the safest way in which she can lift the bags off the ground. She first tightens her core and sets her back in tight extension. She then hinges at her hips, and lowers herself through slight knee flexion to bend over and grasp the bags. From here, Helen maintains the angle between her torso and hips, drives her feet into the ground and stands with fully extended knees and hips. Helen has just completed a safe, and successful deadlift.
One of the greatest risk factors for functional limitations and disabilities in middle-aged to older adults is muscular weakness (Volakis et al, 2015). Thus, a muscular strengthening component should be incorporated into fitness programs for individuals in this age range (“Why Strength Training”, 2010). Specifically, fitness instructors should aim to strengthen functional movement patterns that produce transferability into activities of daily living. Functional movements patterns are based on the way our bodies are designed to move, and they mimic the biomechanical demands life places upon us. Functional movements are multi-planar, multi joint, core to extremity movements. So, is the deadlift a functional movement? As we saw in the anecdote above, the deadlift presents itself in real life situations, but does it fit the other criteria? The answer is yes.
The deadlift requires motion or stability in all three planes. The first, and perhaps most obvious, is the sagittal plane. We move through the sagittal plane as we lift the bar up off the ground. The second plane of motion is the frontal plane, which represents side-to-side motion. As we lift the bar off the ground, we must stabilize the bar in a manner that allows both sides of the bar to be elevated off the floor simultaneously. A lack of stability in this plane would result in a lopsided bar as it is lifted. Finally, the deadlift also requires stability in the transverse plane. Stability in the transverse plane resists rotational movement of the bar (Robertson, 2012). If an individual were unstable in the transverse plan, they would twist or rotate as they lifted the bar.
The primary joints used for force production during the deadlift are the hips, knees and ankles. The deadlift requires activation in the ankle plantar flexors and knee extensors, but demands the most significant amount of activation from the hip extensors and knee flexors (Escamilla, 2000). To better understand movement at these joints, we will re-visit Helen’s task of lifting her grocery bags, starting from the ground and moving up.
Ankle plantar flexion is achieved primarily through activation of the gastrocnemius and soleus muscle groups. Plantar flexion is loosely defined as downward movement of the foot. A good example of plantar flexion is the “push off” motion of our foot during walking (Neptune, 2001). Although her feet would remain in contact with the ground, Helen would be using her plantar flexors to push into the ground and help initiate movement of the bar.
Knee flexion is achieved through activation of the muscles of the hamstring. Although her starting position is achieved mainly through hip flexion, slight knee flexion is required in order for Helen to position herself correctly. Ideally, the proper amount of knee flexion would place her shins perpendicular to the floor. This degree of knee flexion must be maintained as the bags are lifted until hip extension has been initiated.
The quadriceps muscles assist the gluteus maximus and hamstring in producing hip extension in addition to acting as the primary knee extensors (Frigo et al., 2010). As Helen lifts the bags off the floor, the contraction of her quadriceps would oppose the actions of the gluteus maximus and hamstring, thus stabilizing her knee position in slight flexion. With a fixed knee position, her gluteus maxmimus and hamstring can produce maximal hip extension once the bags have reached knee level. As she extends her hips and no longer requires knee flexion, the contraction of her quadriceps extends, or straightens, her knees from their previously flexed position.
Core to Extremity
Lifting any object off the floor, particularly a heavy one, requires both movement and stability of our core, depending upon which plane of movement we consider. When discussing core to extremity movement, it is important to understand that our body’s core is comprised of many muscle groups that work in conjunction to move or stabilize the core. While some core muscles may be acting to move the core in the sagittal plane, others will be activated in order to stabilize our torso in the frontal and transverse planes. Multiple layers of abdominal, oblique, spinal, and hip musculature work in conjunction to move and stabilize the core (Di Jensen, 2013) (Conneely, 2006). Movement with a stable core is imperative so that we ensure structural safety through efficient production and transfer of force from the core to our extremities (Bliss, 2005).
The deadlift is the epitome of a core to extremity movement, requiring significant activation of primary core muscles (Hamlyn, 2007). We use the core musculature to stabilize the spine while simultaneously moving the trunk towards the ground in order to reach the object. From this position, our stable core allows for transfer and production of force through our ankles, knees, hips, back, and arms as we safely elevate the object from the floor.
The deadlift often criticized as a dangerous exercise that simply leads to injury, when in fact it is a basic human movement. While it is possible to injure yourself without proper instruction, the deadlift is a functional movement that our anatomy is built to execute. The deadlift is one of the most effective ways to train not only the posterior chain and core, but it also aids in the development of the assisting muscle groups, like the quadriceps. These muscle groups are of critical importance to everyone, whether it is an elite athlete looking to improve performance, or a father wishing to be able to safely lift his son off the ground. For these reasons, the deadlift should be an integral part of most, if not all physical activity regimens in order to best prepare individuals for the demands placed upon them by their activities of daily living.
Bliss, L., & Teeple, P. (2005). Core stability: The centerpiece of any training program. Current Sports Medicine Reports, 4(3), 179.
Conneely, M., O’Sullivan, K., & Edmondston, S. (2007). Dissection of gluteus maximus and medius with respect to their suggested roles in pelvic and hip stability: Implications for rehabilitation?. Physical Therapy in Sport, 7(4), 176.
Di Jensen, E. (2013). What are the core muscles of the body?. Retrieved 5/10, 2015, from http://www.livestrong.com/article/98988-core-muscles-body/
Escamilla, R., Fransisco, A., Fleisig, G., Barrentine, S., Welch, C., Kayes, A., et al. (2000). A three-dimensional biomechanical analysis of sumo and conventional style deadlifts. Medicine and Science in Sports and Exercise, 32(7), 1265–1275.
Frigo, C., Pavan, E., & Brunner, R. (2010). A dynamic model of quadriceps and hamstrings function.. Gait and Posture, 31(1), 100.
Hamlyn, N., Behm, D., & Young, W. (2007). Trunk muscle activation during dynamic weight-training exercises and isometric instability activities. . Journal of Strength and Conditioning Research, 21(4), 1108.
Neptune, R., Kautz, S., & Zajac, F. (2001). Contributions of the individual ankle plantar flexors to support, forward progression and swing initiation during walking. Journal of Biomechanics,34(11), 1387.
Robertson, M. (2012). Saggital plane first. Retrieved 5/11, 2015, from http://robertsontrainingsystems.com/blog/sagittal-plane-first/
Volaklis, K. A., Halle, M., & Meisinger, C. Muscular strength as a strong predictor of mortality: A narrative review. European Journal of Internal Medicine, (0)
Why strength training?. (2011). Retrieved 5/10, 2015, from http://www.cdc.gov/physicalactivity/growingstronger/why/