Plyometric Exercise-induced Mechano-morphological Changes of Plantar Flexor Muscle-tendon Unit in Cerebral Palsy

Plyometric Exercise-induced Mechano-morphological Changes of Plantar Flexor Muscle-tendon Unit in Cerebral Palsy

Plyometric Exercise-induced Mechanical and Morphological Changes in Plantar Flexors' Muscle-tendon Unit in Children With Unilateral Cerebral Palsy: A Randomized Controlled Trial

This study was designed to investigate the effect of three months of plyometric exercise training on the mechanical and morphological properties of the plantar flexor muscle-tendon unit in children with unilateral cerebral palsy (UCP). Thirty-eight children with UCP were randomly allocated to the plyometric exercise group (n = 19, underwent a plyometric training program) or the Control group (n =19, received usual physical rehabilitation alone). Both groups were assessed for the plantar flexors' morphological and mechanical properties before and after treatment.

Thirty-eight children with CP participated in the study. They were recruited from King Khalid Hospital and Physical Therapy Center of College of Applied Medical Sciences at Prince Sattam bin Abdulaziz University, Al-Kharj, Saudi Arabia. Their age ranged between 10 and 16 years, were functioning at levels I or II according to the Gross Motor Function Classification System, and had spasticity level 1 or 1+ per the Modified Ashworth Scale. Children were excluded if they had nonreducible structural deformities, received neurolytic agents such as BOTOX or Phenol injections in the past six months, underwent neuromuscular or orthopedic surgery in the last 12 months, or if they had cardiopulmonary problems preventing them from performing high-intense exercise training. Outcome measures Plantar Flexors' Morphological Properties: length of gastrocnemius muscle-tendon unit, gastrocnemius muscle belly, and achilles, in addition to fascicle length, pennation angle, and gastrocnemius muscle thickness were assessed using a standard high-resolution ultrasound imaging system. Plantar Flexors' Mechanical Properties: Passive range of motion of the ankle joint and maximum isometric voluntary contraction were assessed using an isokinetic dynamometer. The plyometric exercise group received a 12-week plyometric training program. Each session lasted 45 minutes and was repeated two times a week. The training was conducted in conformity with the National Strength and Conditioning Association guidelines and American Academy of Pediatrics safety standards. The plyometric exercise program consisted of ten unilateral and bilateral lower limb plyometrics in the form of hopping/bounding/jumping activities. The Iplyometric workout was proceeded by a 5-minute warm-up and ended up with a 5-minute cool-down. The control group received their usual physical rehabilitation program for 45 minutes, twice/week for 12 consecutive weeks. The program comprised advanced balance training, and gait training exercises, postural and flexibility exercises, strength training exercises.

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

The plyometric exercise group received a 12-week plyometric training program. Each session lasted 45 minutes and was repeated two times a week. The training was conducted in conformity with the National Strength and Conditioning Association guidelines and American Academy of Pediatrics safety standards. The plyometric exercise program consisted of ten unilateral and bilateral lower limb plyometrics in the form of hopping/bounding/jumping activities. The Iplyometric workout was proceeded by a 5-minute warm-up and ended up with a 5-minute cool-down

The control group received their usual physical rehabilitation program for 45 minutes, twice/week for 12 consecutive weeks. The program comprised advanced balance training, and gait training exercises, postural and flexibility exercises, strength training exercises.

The distance from the medial femoral epicondyle to the insertion of the Achilles tendon on the calcaneus. The gastrocnemius muscle-tendon length normalized to the lower limb length (%) was recorded.

The distance from the gastrocnemius muscle-tendon junction to its insertion. The achilles tendon length normalized to the lower limb length (%) was recorded.

Distance between the medial femoral epicondyle and its muscle-tendon junction. The gastrocnemius muscle belly length normalized to the lower limb length (%) was recorded.

The passive ankle dorsi and plantar flexion angle (degrees) were measured by moving the ankle into maximum dorsiflexion and plantarflexion through the isokinetic dynamometry.

The isometric maximum voluntary contraction was determined as the maximum rate of force (Nm) that participants were able to develop during an isometric contraction of the plantar flexors with the ankle in a neutral position (90 degrees) and the knee in a full extension.

The difference (mm) between the calculated length changes of the muscle-tendon unit and the muscle-length changes recorded by the ultrasound.

The achilles tendon stiffness (N/m) was calculated through linear regression of the absolute tendon force and related changes in tendon length.

The achilles tendon strain (%) was calculated as the tendon elongation divided by the initial tendon length

The achilles tendon stress was calculated as the tendon elongation divided by the initial tendon length and expressed in (N/mm2).

Young's modulus (N/mm2) was calculated as the ratio of achilles tendon tensile stress to tensile strain

Inclusion Criteria: Hemiparetic cerebral palsy Age between 10 to 16 years Spasticity level 1 or 1+ according to the Modified Ashworth Scale Gross motor function level I or II according to the Gross Motor Function Classification System Exclusion Criteria: Structural deformities Musculoskeletal or neural surgery in the last year BOTOX injection in the last 6 months. Cardiopulmonary disorders limit the ability to engage in explosive exercise training Perceptual and behavioral disorders.