Muscle activation and rating of perceived exertion of typically developing children during DRY and aquatic treadmill walking

An Aquatic Treadmill Alters Lower Limb Walking Dynamics in Typically Developing Children and Children with Cerebral Palsy

This block-randomized crossover study investigated how a speed-modulated aquatic treadmill (AT) impacts the walking biomechanics of pediatric gait. Eight cerebral palsy (CP) and fifteen typically developing (TD) children walked at normal, slow, and fast treadmill speeds in AT and dry treadmill (DT) conditions. The joint angles of participants were calculated from inertial measurement units to derive sample entropy (SE) measures that quantified the regularity or complexity of motion. A hierarchical statistical model revealed that the CP group had lower SE values for the hip, knee, and ankle joints in the AT and at slower than faster treadmill speeds. Only the SE values of the knee and ankle joints were impacted for the TD group. The lower SE values suggest improved regularity for participants at slower speeds and in the AT environment. This study highlights the potential of AT to improve the walking biomechanics of children with CP in acute exposure, but further work is needed to investigate the AT condition as a gait rehabilitation environment.

Overground, conventional treadmill, and aquatic treadmill walking joint kinematics differ in typically developing children and adolescents

Gait training is a common rehabilitation tool using repeated gait cycles to promote motor learning and improve overall walking ability (Booth et al., 2018; Kim & Lee, 2016;Novy et al., 2013). The purpose of this study was to quantify differences in peak and time-to-peak ankle plantarflexion, knee flexion, and hip flexion in typically developing children (7 males, 8 females, age 11.3 ± 4.1 years, 1.46 ± 0.18 m, and 44.2 ± 16.8 kg) during overground, conventional treadmill, and aquatic treadmill walking at three walking speeds (slow, normal, and fast). We hypothesized that increasing walking speeds and different walking environments would affect peak and time-to-peak kinematics of the lower limb. Faster speeds significantly increased peak kinematics, with peak plantarflexion increasing from 19.6⁰ during the slow speed condition to 25.7⁰ during the fast speed condition (p < 0.01). The overground environment had the highest peak knee flexion (67.4⁰), a 24.7⁰ increase compared to conventional treadmill and a 34.2⁰ increase compared to the aquatic treadmill (p < 0.01). Time-to-peak kinematics for peak ankle plantarflexion occurred 7.8 % and 9.9 % earlier in the gait cycle when compared to overground (p < 0.01) and conventional treadmill (p < 0.01). Faster speeds also resulted in earlier time-to-peak kinematics compared to slow speeds for ankle plantarflexion (p < 0.01) and hip flexion (p < 0.01). Findings of this study suggest that walking speed and environment significantly influence lower limb kinematics in typically developing children. Therefore, researchers should consider environmental factors when designing and evaluating gait training interventions.

Differences in lower limb co-contraction calculations vary clinical interpretation of aquatic treadmill walking in typically developing and children with cerebral palsy

Objective

The purposes of this study were to (1) investigate muscle co-contraction during aquatic (Wet) and conventional (Dry) treadmill walking at various speeds in typically developing (TD) and children with cerebral palsy (CP) and (2) explore how the clinical interpretation of co-contraction, using co-contraction indices (CCI), may vary depending on the method employed.

Methods

Fifteen TD children (30 limbs, 7 M | 8F, 11.3 ± 4.1 yrs., 1.46 ± 0.18 m, 44.2 ± 16.8 kg) and 10 children with CP (20 limbs, 6 M | 4F, 13.1 ± 3.5 yrs., 1.54 ± 0.18 m, 53.2 ± 26.2 kg, 7 GMFCS I and 3 II) participated in this study. Muscle activity of the tibialis anterior (TA), rectus femoris (RF), medial gastrocnemius (MG), and semitendinosus (ST) was recorded during three 3-min walking trials on a Dry treadmill followed by a Wet treadmill. Muscle co-contraction was calculated using three common CCI calculation methods for the RF/ST and TA/MG muscle pairings. Separate linear mixed-effects models examined the influence of population (TD vs. CP), walking speed (Slow, Normal, Fast), and treadmill environment (Dry vs. Wet) on CCI for each equation and muscle pairing.

Results

CCIUnnithan and CCIRudolph demonstrated that aquatic treadmill walking reduced muscle co-contraction in TD (p < 0.001) and CP (p < 0.012) populations for the RF/ST muscle pairing. Additionally, CCIUnnithan and CCIRudolph showed significant differences between speeds in both environments (p < 0.001) except for the Slow-Normal comparison in the aquatic treadmill (p > 0.423). All methods had a significant CCI reduction in the TA/MG muscle pairing for both populations. For the RF/ST muscle pairing, CCIF&W showed that only TD children had lower muscle co-contraction in the aquatic treadmill (p = 0.023). CCIF&W also showed no speed effect for the muscle pairings.

Conclusion

This study shows the potential of aquatic treadmill walking to reduce muscle co-contraction; however, caution is recommended as clinical implications can vary due to the computation method. Future studies should aim to report values from multiple methods to account for the variability within methods and validation of results.

The Rating of Perceived Exertion-Pediatric (RPE-P) Scale: Preliminary Validation

Physical activity is critical to functional rehabilitation for youth with chronic pain, which may be especially true for those with co-occurring obesity. To facilitate the development of physical activity interventions for youth with chronic pain, the newly developed "Rating of Perceived Exertion-Pediatric" scale was modeled after the widely used pain numeric rating scale-11. This study is an initial evaluation of the scale in a sample of adolescents (n = 157, 13-17 years, 51% female) with four subgroups: (1) healthy controls (healthy weight/no pain); (2) chronic pain/healthy weight; (3) obese (no pain); (4) chronic pain/obese. Participants rated perceived exertion using the new scale and the Borg 6-20 Scale of Perceived Exertion while holding a three-minute yoga pose (Warrior II). In the whole sample, the Perceived Exertion-Pediatric scale showed good concurrent (p < 0.001), convergent (all ps < 0.05), discriminant (p = 0.431), and known-groups validity (all ps < 0.05). The chronic pain subgroup also showed good concurrent (p < 0.001), mixed convergent (ps < 0.001 to 0.315), and good discriminant validity (p = 0.607). Limitations include the restricted age range, lack of diversity, and lack of test-retest reliability. The RPE-P shows promise as an assessment tool for perceived exertion in adolescents with and without chronic pain.