This study was designed to assess the effect of a 12-week aqua-plyometric (AquaPlyo) training on muscle strength, bone health, and physical ability in children with juvenile idiopathic arthritis (JIA). Forty-eight patients with JIA were randomly allocated to the AquaPlyo group (n = 24, received an aquatic-based plyometric training program, twice/week, over 12 weeks) or the control group (n = 24, received standard exercise program). Both groups were assessed for muscle strength, bone health, and physical ability pre and post-treatment.

Forty-eight patients with JIA were recruited from the pediatric rheumatology clinics of three large referral hospitals in Riyadh, Saudi Arabia. The study included patients who had a confirmed diagnosis of Polyarticular JIA (according to the criteria set forth by the International League of Associations for Rheumatology), aged 12-18 years, identified being stable cases, and did not participate in a regular exercise program (in the past six months). Patients who had fixed deformities, a history of joint surgery, or whose radiological investigations revealed erosive changes of bone, ankylosing, or fractures were excluded.

Outcome measures

1. Muscle strength: The peak concentric torque of the right and left quadriceps muscle was measured through an Isokinetic Dynamometer.
2. Bone health: Areal bone mineral density, volumetric bone density, and bone mineral content of the lumbar spine and neck of femur were measured through Dual-Energy X-ray Absorptiometry (DEXA) scanning.
3. Physical ability: The physical performance was assessed using the 6-minute walk test.

The AquaPlyo group received a 12-week AquaPlyo training, 45 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 AquaPlyo program consisted of ten unilateral and bilateral lower limb plyometrics in the form of hopping/bounding/jumping activities conducted in a water medium. The AquaPlyo training included a warm-up for 10 minutes and a cool-down for 5 minutes. The control group received the standard exercise program, 45 minutes per session, two times a week for 12 consecutive weeks. The program consisted of flexibility exercise, strength training, weight-bearing, proprioceptive training, and free treadmill walking or cycle ergometry.

Inclusion Criteria:

• Confirmed diagnosis of JIA
• Polyarticular onset of JIA with bilateral involvement of the knee joint
• Age between 12 and 18 years
• Stable conditions (i.e., receive stable doses of medications in the past three months)
• Not participating in a regular exercise program in the past six months

Exclusion Criteria:

• Fixed deformities
• History of joint surgery
• Ankylosing or fractures
• Bone destruction (erosive changes of the knee joint)
• Cardiopulmonary comorbidities
• Recommendation against engaging in potentially explosive physical activities by the attending Rheumatologist.

This was a single-blind protocol. The researcher who collected the data was blind to the allocation of treatment