The Effect of Spinal Manipulation on Hip Extension Strength and Jump Height

The purpose of this study is to study the effects of lumbar manipulation on hip extension strength and jump height in healthy subjects.

Procedures to be followed: First, the subject will be asked to complete a medical history form. Then they will be instructed on the procedure for strength and jump testing. Next, range of motion of the low back will be measured. Then hip strength will be measured using a digital handheld measurement tool. The subject will then be asked to jump as high as they can on a floor mat. The subject will then receive a sealed envelope indicating the intervention they will to receive, either the manipulation or a fake manipulation. Instructions will be provided, and the subject will be positioned on a treatment table to receive the intervention. At this point, they will either receive the manipulation or fake manipulation on the right and left side. An immediate re-test of hip strength will be taken, and the subject will again jump as high as they can on a floor mat. Follow-up measures of these tests will be completed again 20 minutes after the intervention is given.

The participant will complete a medical history form and undergo a brief active range of motion screen of the lumbar spine. The participant will complete a hip strength test utilizing the microFET 2 Manual Muscle Tester Hand Held Dynamometer. The participant will then jump as high as they can on the Just Jump System. A sealed envelope indicating the intervention to be received will be given to the participant. An investigator blinded to the pre and post-measures will open the envelope indicating the intervention to be performed. The participant will be blinded to which intervention group they are categorized to. The participant will be positioned on a high-low treatment table to receive the assigned intervention, either intervention 1 (thrust mobilization) or 2 (sham mobilization). The participant will either receive the thrust-mobilization or sham mobilization up to 2 times on the left and right side. An immediate re-test of hip strength will be conducted followed by performing the same three jumps. Follow-up measures at 20 minutes post-intervention will be performed.

Intervention for the Thrust-mobilization Group The intervention group will receive passive spinal rotational grade V mobilization, based on Maitland's approach. The intervention will be performed with the subject in right sidelying and left sidelying. The operator's palpating hand is placed over the L2-3 intervertebral space, and the other hand bends both legs of the participant up to the range at which the L2-3 midposition is found. The participant is then asked to straighten the lower leg and hook the upper leg over it with the upper leg's knee positioned over the side of the plinth. While the lower component is kept still, the participant's trunk is rotated until the hip starts to lift off from the plinth. The bottom hand and uppermost hand rest under a pillow and the chest wall, respectively. With the starting position settled, the operator stands behind the participant, takes up the slack within the spine and then provides a grade V mobilization while stabilizing the uppermost shoulder.

Intervention for the Sham Group Subjects are positioned in right sidelying. The experimenter holds both knees with one arm while placing their opposite hand on the participant's lumbar spine. The experimenter performs 1 min of ﬂexion and extension PROM without reaching physiological end range in either direction of movement. This is repeated with the subject in left sidelying.

Double Blind: The subjects will not know what intervention they are receiving - same generic script is provided. One Investigator is performing all pre and post-tests without knowledge of intervention, the other investigator is opening the envelope and providing the intervention behind a screen without knowledge of test results. This investigator will record the subjects assigned # and which intervention they received. Investigators will record data on spreadsheet separately.

Eligibility Criteria:
Inclusion Criteria:

* Between the ages of 18 and 30
* able to read and write in English and clearly understand the informed consent.

Exclusion Criteria:

* currently have low back pain
* pregnant or may be pregnant
* previously diagnosed with spondylolisthesis, a herniated disc, or have signs and symptoms of nerve root compression
* history of spine surgery
* history of cancer, compression fracture, osteoporosis, osteopenia, or a history of systemic, connective tissue, or neurological disease,
* pain with the pre-manipulative hold
* positive findings on medical history form, or physical exam,
* presence of anxiety during the procedure