Muscle Function After Childbirth

Summary

This study will evaluate lower extremity and trunk neuromuscular control in 78 nulligravid and postpartum women. Participants will attend two experimental sessions, approximately 1 week apart, to assess neuromuscular function. Physical activity levels will also be assessed.

Conditions

• Postpartum
• Muscle Fatigue
• Force Steadiness
• Nulligravid
• Muscle Weakness

Interventions

DIAGNOSTIC_TEST

Active Straight Leg Raise Test

The ASLR test is a well-established clinical test that assesses stability of the lumbar spine/pelvis, posterior pelvic pain severity, and ability to activate the abdominal muscles. It is performed in supine. Participants are instructed to raise one leg, with the knee straight, to a heel height of 20 cm. The leg is held at the top for 5 seconds, then slowly lowered to the ground. The participant is asked to report perceived difficulty to raise the leg on a 0 to 5 scale (0=not at all difficult; 5=unable to lift leg) and pain on a 0 to 10 scale (0=no pain; 10=worst possible pain). If difficulty or pain are rated at a 1 or higher, the test is repeated with the researcher providing external compression of the pelvis. If perceived difficulty or reported pain are lower with compression, the test is considered positive for lumbopelvic instability. The test is then repeated on the opposite limb.

OTHER

Active Straight Leg Raise Fatigue Task

The protocol is similar to the ASLR test, except that the participant is instructed to maintain the elevated leg off the ground for as long as possible. A biofeedback air cuff will be placed under the participant's lumbopelvic region to assess movement of the spine/pelvis. The cuff will be inflated to 40 mm Hg, and the participant instructed to keep the needle as close to 40 mm Hg as possible throughout the test; no information will be provided on how to affect cuff pressure, but visual feedback of cuff pressure will be provided throughout the task. Ratings of perceived exertion (RPE) and pain will be obtained from participants every 30-60 seconds. Task failure will be defined as a heel height ≤10 cm or a change in cuff pressure ≥20 mm Hg. Both limbs will be tested, but in different sessions. The order of limb testing (dominant vs non-dominant) will be randomized and counter-balanced. Limb dominance will be self-reported.

OTHER

Lower Extremity Strength Testing

A straight leg raise maximal voluntary contraction (MVC) of each lower extremity an MVC of the hip extensors of the grounded limb will be performed in supine before and within 2 minutes of completing the ASLR fatigue task. The straight leg raise MVC will be performed with a custom-made load cell instrumented strength testing device, which consists of a rigid platform on which the participant will lie. At the foot of the device is a tower that houses 2 load cells connected to a lightly padded push plate. The hip extension MVC will be performed on a force plate. Before the ASLR fatigue task, a minimum of 3 MVC trials will be performed for each muscle group, with a minimum of 1 minute rest between trials; the highest peak force will be considered the MVC. Only 1 MVC trial per muscle group will be performed following the ASLR Fatigue Task.

DIAGNOSTIC_TEST

Ultrasound imaging of abdominal wall

Real time ultrasound will be used to assess inter-recti distance above and below the umbilicus. Participants will be assessed with B Mode images in supine at rest, in supine while lifting their head, and in supine while performing a straight leg raise. The Principle Investigator has training and experience in musculoskeletal ultrasound.

Sponsors & Collaborators

• Carroll University

  lead OTHER

Principal Investigators

• Rita Deering, PT, DPT, PhD · Carroll University

Study Design

Allocation

NON_RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

20 Years

Max Age

35 Years

Sex

FEMALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2022-09-20

Primary Completion

2026-12-31

Completion

2027-07-31

Countries

• United States

Study Locations