Stefan Schmid1, Michèle Stauffer2, Judit Jäger3, Renate List4, Silvio Lorenzetti5. 1. Bern University of Applied Sciences, Department of Health Professions, Bern, Switzerland; ETH Zurich, Institute for Biomechanics, Zurich, Switzerland. Electronic address: stefanschmid79@gmail.com. 2. Bern University of Applied Sciences, Department of Health Professions, Bern, Switzerland; Fios - Praxis für Physio- und Ergotherapie, Herzogenbuchsee, Switzerland. 3. ETH Zurich, Institute for Biomechanics, Zurich, Switzerland. 4. ETH Zurich, Institute for Biomechanics, Zurich, Switzerland; Human Performance Lab, Schulthess Clinic, Zurich, Switzerland. 5. ETH Zurich, Institute for Biomechanics, Zurich, Switzerland; Swiss Federal Institute of Sport Magglingen SFISM, Magglingen, Switzerland.
Abstract
BACKGROUND: Regular infant carrying might be a contributing factor for the development and progression of low back and pelvic girdle pain in mothers after childbirth. However, the neuromechanical adaptations of the spine due to different sling-based carrying techniques are not sufficiently well understood in order to provide evidence-based carrying recommendations. RESEARCH QUESTION: What are the immediate effects of different sling-based infant carrying techniques on trunk neuromechanics? METHODS: Using a Vicon motion capture and a wireless surface electromyography system, three-dimensional pelvis and spinal kinematics as well as activation patterns of eight trunk muscles were derived from fifteen healthy young women during upright standing and level walking without carrying a load and while carrying a 6 kg-dummy with a sling in front and on either side. Data were analyzed using Statistical Parametric Mapping, allowing group comparisons of discrete parameters (standing) as well as continuous data (walking). To distinguish between clinically relevant and clinically not relevant kinematic findings, statistically significant differences were only considered in case of ≥5°. RESULTS: Compared to unloaded walking, carrying the dummy in front was mainly associated with increased lumbar lordosis (standing: (Δ8.8°, p = 0.006; walking: (Δ ≥ 8.2°, 1-100% of gait cycle [%GC], p < 0.001). When carrying the dummy on the preferred side, increased thoracic kyphosis (standing: ≥6.4°, p ≤ 0.003; walking: Δ ≥ 5.6°, 1-100%GC, p < 0.001) and axial rotation towards the ipsilateral side (standing: Δ5.3°, p = 0.003; walking: Δ ≥ 5.0°, 46-58%GC, p = 0.002) were observed. All three conditions entailed increased paraspinal muscle activity during walking, although only unilaterally in side carrying (lumbar, preferred condition: Δ ≥ 13.2%maxMVIC, 49-57%GC, p < 0.001; thoracic, non-preferred condition: Δ ≥ 5.3%maxMVIC, 47-58%GC, p < 0.001). SIGNIFICANCE: Carrying an infant alternating on both sides using a sling could be advantageous for preventing musculoskeletal pain resulting from excessive lumbar hyperextension and paraspinal muscle hyperactivation in women after childbirth.
BACKGROUND: Regular infant carrying might be a contributing factor for the development and progression of low back and pelvic girdle pain in mothers after childbirth. However, the neuromechanical adaptations of the spine due to different sling-based carrying techniques are not sufficiently well understood in order to provide evidence-based carrying recommendations. RESEARCH QUESTION: What are the immediate effects of different sling-based infant carrying techniques on trunk neuromechanics? METHODS: Using a Vicon motion capture and a wireless surface electromyography system, three-dimensional pelvis and spinal kinematics as well as activation patterns of eight trunk muscles were derived from fifteen healthy young women during upright standing and level walking without carrying a load and while carrying a 6 kg-dummy with a sling in front and on either side. Data were analyzed using Statistical Parametric Mapping, allowing group comparisons of discrete parameters (standing) as well as continuous data (walking). To distinguish between clinically relevant and clinically not relevant kinematic findings, statistically significant differences were only considered in case of ≥5°. RESULTS: Compared to unloaded walking, carrying the dummy in front was mainly associated with increased lumbar lordosis (standing: (Δ8.8°, p = 0.006; walking: (Δ ≥ 8.2°, 1-100% of gait cycle [%GC], p < 0.001). When carrying the dummy on the preferred side, increased thoracic kyphosis (standing: ≥6.4°, p ≤ 0.003; walking: Δ ≥ 5.6°, 1-100%GC, p < 0.001) and axial rotation towards the ipsilateral side (standing: Δ5.3°, p = 0.003; walking: Δ ≥ 5.0°, 46-58%GC, p = 0.002) were observed. All three conditions entailed increased paraspinal muscle activity during walking, although only unilaterally in side carrying (lumbar, preferred condition: Δ ≥ 13.2%maxMVIC, 49-57%GC, p < 0.001; thoracic, non-preferred condition: Δ ≥ 5.3%maxMVIC, 47-58%GC, p < 0.001). SIGNIFICANCE: Carrying an infant alternating on both sides using a sling could be advantageous for preventing musculoskeletal pain resulting from excessive lumbar hyperextension and paraspinal muscle hyperactivation in women after childbirth.