Subacute Low Back Pain in Active Duty

Torso extension muscle strength is measured with a modified version of the U of Michigan strength test system (Workability Systems, West Chester, Ohio) and a Chattanooga-Baseline® Hand Dynamometer - Digital LCD Gauge - ER™ 300 lb capacity (DJO Global, Chattanooga, Vista, CA USA). To measure trunk extension, the participant stands with their lower anterior abdomen against the padded board. The belt is placed around the posterior back and under the arms. Participants pull against the belt as forcefully as possible. Participants perform two maximal efforts maintaining each voluntary isometric exertion for 5 seconds, separated by 30-second rest; the highest value of the two trials will be accepted.

Time frame: 0, 3, 6, and 9 weeks

Torso flexion muscle strength is measured with a modified version of the U of Michigan strength test system (Workability Systems, West Chester, Ohio) and a Chattanooga-Baseline® Hand Dynamometer - Digital LCD Gauge - ER™ 300 lb capacity (DJO Global, Chattanooga, Vista, CA USA). For trunk flexion, the participant stands in the apparatus, buttocks against the padded board, the superior edge level with the iliac crest. A canvas belt is around the chest and under the arms horizontal to the force-measuring dynamometer on the apparatus frame. Participants pull against the belt as forcefully as possible. Participants perform two maximal efforts maintaining each voluntary isometric exertion for 5 seconds, separated by 30-second rest; the highest value of the two trials will be accepted.

Time frame: 0, 3, 6, and 9 weeks

The Visual Analog Scale (VAS) of pain will be used to assess pain at rest and after activity. (Revill et al., 1976) Participants will complete this scale following the push-ups, sit-ups, 6-minute walk and the lumbar trunk muscle test. This VAS pain subscale is a 10-cm horizontal line index with descriptive anchors at each end. At the far left (0.0 cm) is no pain and at the far right (10 cm) is worst possible pain. The participant is instructed to place a vertical line at some point between the anchors to describe their level of pain.

Time frame: 0, 3, 6, 9 Weeks

The Center for Epidemiologic Studies Depression (CES-D) scale is a self-report questionnaire that contains 20 items. Participants were asked to rate how often over the past week they experienced symptoms associated with depression. Scores range from 0-60 with high scores denoting greater depressive symptoms. CES-D scores were recorded at baseline (0 weeks) and subsequent visits. If the baseline score was greater than 23 the participants were not randomized.

Time frame: 0, 3, 6, 9 Weeks

The Short Form Health Survey Version 2.0 (SF-12v2) Health Survey will be used to determine each participant's overall impact of bodily pain on normal work. The SF12v2 has a question that asks participants to assess the impact of pain on normal work during the previous 4 weeks using options ranging from Not at all to Extremely. Responses are translated to numerical scores ranging from 0 to 100. Higher scores indicate less impact of bodily pain.

Time frame: 0, 3, 6, 9 Weeks

The 2-minute push-up test evaluates upper body endurance and strength as well as the stabilizing torso muscles of the abdomen and back. Starting in a prone position, the participant is positioned with their hands on the ground (shoulder width apart), toes in contact with the floor, spine parallel to the floor, elbows and hips in extension. The body moves as a single rigid unit and is lowered to the ground until elbows are at 90° angle. The body is then returned to the starting position by pushing the arms up to full extension. A push-up is counted if the elbows were brought to flexion of 90° or greater and then return to full extension, while keeping the body elevated on the toes. The number of push-ups performed in 2-minutes is recorded.

Time frame: 0, 3, 6, 9 Weeks

The 2-minute sit-up test measures trunk flexion and abdominal endurance. Starting in a supine position, the knee joints are flexed at a 90° angle, with fingers behind the head, soles of the feet and shoulder blades in contact with the floor. With the command to begin, the upper body is raised forward by flexing the abdominal muscles and then lowered. A sit-up is counted if the hands are behind the head, bringing the base of the spine to a vertical position and then returning the shoulder blades to the floor. The number of repetitions performed in 2 minutes is recorded.

Time frame: 0, 3, 6, 9 Weeks

The 6-Minute Walk Test (6-MWT) measures the distance a participant walks at a fast pace over a 6-minute period. Participants will walk as quickly as you can with the opportunity to stop and rest if required. This test measures functional capacity of walking. Healthy adults are expected to walk between 400 and 700 meters \[1300-2300 feet\] on the 6-minute walk test (Enright, 2003). Outcomes are reported in feet walked.

Time frame: 0, 3, 6, 9 Weeks

Physical activity will be measured using the Fitbit Charge 2 (San Francisco, CA). The Charge 2 is a wrist-worn three-axis accelerometer that measures steps walked, distance traveled, energy expenditure and floors climbed. The unique feature of this device is a wireless function that automatically uploads data to designated mobile phone devices or computers. Physical Activity is reported as average Kcal expended during a seven day period.

Time frame: 0, 3, 6, 9 Weeks