Stretch-shortening Cycle Exercise: a Clinical Trial Investigating Its Role for Strength, Bone Mineral Density, and Functional Capacity in Children With Obstetric Brachial Plexus Injury

Fifty-six children with OBPI were recruited from the Physical Therapy Outpatient Clinic of Prince Sattam Bin Abdulaziz University and three referral hospitals in Riyadh provenience, Saudi Arabia. The study included children who had a confirmed diagnosis of upper arm type of OBPI, classified as level I or II per Narakas classification system, aged 10-16 years, had a functional level of grade III according to the Mallet scoring system, and were consuming a balanced diet. Children who had a history of corrective neuromotor or musculoskeletal surgery, shoulder dislocation/subluxation, calcium supplements, or cognitive issues were excluded.

Outcome measures

1. Muscle strength: The peak isometric muscle strength of the shoulder flexors, abductors, external rotators, elbow flexors, and extensors was measured using a hand-held dynamometer.
2. Bone mineral properties: Bone mineral density and bone mineral content of the humeral, radial, and ulnar shafts were measured through Dual-Energy X-ray Absorptiometry (DEXA) scanning.
3. Upper-extremity function: The functional performance was assessed using the brachial plexus outcome measure (BPOM) activity scale.

The SSC-Ex group received a 12-week therapist-led SSC-Ex training, for approximately 35 minutes per session, two times a week for 12 consecutive weeks, in conformity with the National Strength and Conditioning Association guidelines and American Academy of Pediatrics safety standards. The SSC-Ex program consisted of ten unilateral and bilateral upper extremity exercises in the form of push-ups and ball slams/throws/passes activities. The SSC-Ex program preceded with a warm-up for 5 minutes and ended with a cool-down for 5 minutes. The control group received the standard exercise program, 35 minutes per session, two times a week for 12 consecutive weeks. The program consisted of flexibility exercises, strength training, weight-bearing exercises, proprioceptive neuromuscular facilitation, manual guidance, and functional training.