STANDARD WEIGHTBEARING SQUAT

DB METHOD SQUAT

Head looking forward and straight arm forward help maintain a straight and flat spine during the descent and ascent of the squat.

Head looking forward and straight arm forward help maintain a straight and flat spine during the descent and ascent of the squat.

No grip handles require the need to rely on erector spinae and abdominal muscles to stabilize the trunk and shift in trunk balancing motions. If the erector spine and abdominal muscles are weak then the trunk would be unstable during the descent and ascent which could result in musculoskeletal damage and pain.

The Straight arm forward position holding on to grip handles provides stability, support and balance for the trunk during the descent and ascent, and guards against any unexpected and sudden body motions.

Anterior pelvic tilt during the descent decreases the mechanical hip flexion moment and shifts the line of action of the gluteus maximus so that the gluteus maximus and hamstring are contracting concentrically. As the descent continues and these muscles shorten, they lose force (length-tension) and the advantaged of eccentric muscle contraction. At full squat, concentric contraction forces of these muscles are reduced, and the muscles have lost their spring reaction effect. These muscles remain concentrically action throughout descent and ascent. An anterior pelvic tilt also flexes the lumbar spine which closes down the intervertebral foramen the surrounds the spinal nerve.

Posterior pelvic tilt passively produces hip flexion and requires the gluteus maximus to contract eccentrically to control hip flexion throughout the descent and benefit from eccentric muscle training. At full squat, a reversal to an anterior pelvic tilt results in the gluteus maximus and hamstrings recoiling their passive elastic component and forcefully contracting concentrically as per the length -tension relationship, making the transition from descent to ascent efficient and energy conserving.

With the knee anterior to ankle and foot contact area, a mechanical dorsiflexion moment occurs at the ankle. In this position, the GFR lies anterior to the ankle, producing a mechanical dorsiflexion moment, and posterior to the knee producing a mechanical flexion knee moment. The dorsiflexion ankle moment places the ankle in a closed packet position which permits very little motion in the frontal or transverse planes and damage ankle ligaments if an unexpected movement occurs. The mechanical knee flexion movement minimizes action from the hamstrings during the descent.

Heel contact position on foot base plate places the GRF posterior to ankle joint, anterior to the knee at the start of the descending squat and posterior to the knee at 90˚ position and at full squat. The GRF anterior to the knee helps holds the knee in extension early in the descent allowing the quadriceps to stretch their elastic components before eccentrically contracting to control knee flexion. Late in the ascent, the GRF produced extension moment helps the quadriceps to extend the knee in full extension when the quads at a low mechanical advantage.

The anterior position of the flexed knee relative to the ankle and the resulting dorsiflexion moment at the ankle, placed the gastrocnemius on slack during most of the descent. Because of this slackened position, gastrocnemius activity is minimal for knee extension and ankle plantarflexion. At the start of the ascent, this position places the gastrocnemius in a poor and ineffective condition for actively producing forces to plantarflex the ankle, extend the knee and stabilize rotation of the femoral condyles. By mid ascent, the increase in knee extension will stretch the passive elastic components of the gastrocnemius so concentric contraction can

Heel contact places the GRF posterior to the ankle hold the ankle in a plantarflexed moment and knee in flexion requiring little concentric activity of the gastrocnemius and soleus during descent. At the start of the ascent, the gastrocnemius begins to stretch as the knee extends and the ankle is held by the GRF by the mechanical plantarflexion moment. This action stretches the elastic components of the gastrocnemius allowing it to effectively and rapidly produce concentric contraction during the ascent.