Trunk Muscle Activity during Drop Jump Performance in Adolescent Athletes with Back Pain

Abstract

In the context of back pain, great emphasis has been placed on the importance of trunk stability, especially in situations requiring compensation of repetitive, intense loading induced during high-performance activities, e.g., jumping or landing. This study aims to evaluate trunk muscle activity during drop jump in adolescent athletes with back pain (BP) compared to athletes without back pain (NBP). Eleven adolescent athletes suffering back pain (BP: m/f: n = 4/7; 15.9 ± 1.3 y; 176 ± 11 cm; 68 ± 11 kg; 12.4 ± 10.5 h/we training) and 11 matched athletes without back pain (NBP: m/f: n = 4/7; 15.5 ± 1.3 y; 174 ± 7 cm; 67 ± 8 kg; 14.9 ± 9.5 h/we training) were evaluated. Subjects conducted 3 drop jumps onto a force plate (ground reaction force). Bilateral 12-lead SEMG (surface Electromyography) was applied to assess trunk muscle activity. Ground contact time [ms], maximum vertical jump force [N], jump time [ms] and the jump performance index [m/s] were calculated for drop jumps. SEMG amplitudes (RMS: root mean square [%]) for all 12 single muscles were normalized to MIVC (maximum isometric voluntary contraction) and analyzed in 4 time windows (100 ms pre- and 200 ms post-initial ground contact, 100 ms pre- and 200 ms post-landing) as outcome variables. In addition, muscles were grouped and analyzed in ventral and dorsal muscles, as well as straight and transverse trunk muscles. Drop jump ground reaction force variables did not differ between NBP and BP (p > 0.05). Mm obliquus externus and internus abdominis presented higher SEMG amplitudes (1.3–1.9-fold) for BP (p < 0.05). Mm rectus abdominis, erector spinae thoracic/lumbar and latissimus dorsi did not differ (p > 0.05). The muscle group analysis over the whole jumping cycle showed statistically significantly higher SEMG amplitudes for BP in the ventral (p = 0.031) and transverse muscles (p = 0.020) compared to NBP. Higher activity of transverse, but not straight, trunk muscles might indicate a specific compensation strategy to support trunk stability in athletes with back pain during drop jumps. Therefore, exercises favoring the transverse trunk muscles could be recommended for back pain treatment.

Performance in dynamic movement tasks and occurrence of low back pain in youth floorball and basketball players

“…According to our findings, there was no association between LBP incidence and peak vGRF or vGRF side-to-side asymmetry, measured in VDJ landing. In a cross-sectional investigation, Müller et al were also unable to find a difference in vGRFs of youth athletes with and without LBP [48]. Future studies should investigate if loading rate is associated with LBP, because it has been shown to be a stronger risk factor for lower extremity injuries than peak GRF [49].…”

Commentary: Trunk Muscle Activity during Drop Jump Performance in Adolescent Athletes with Back Pain

“…The results of Mueller et al ( 2017 ) suggest an altered neuromuscular activation pattern (increased trunk muscle activity during drop landing) in adolescent athletes with BP. Their study recruited 11 adolescent athletes with BP and 11 controls into a cross-sectional study.…”

“…Statistical issues aside, it is problematic when a cross-sectional study design (which can offer nothing more than association) is used to imply both causality and treatment recommendations for BP. In the presence of only cross-sectional data and an absence of key known confounding variables, the conclusion “ For prevention and therapy, specific sensorimotor exercises addressing the transverse trunk muscles with e.g., 3-dimensional loading situations might be beneficial” (Mueller et al, 2017 ) is speculative. While cross-sectional data are useful in identifying associations, inferences regarding causality should not be made from these study designs (Stovitz et al, 2017 ).…”

“…Thus, it contributes to a substantial existing body of research that has consistently shown that pain is associated with increased trunk muscle activity (Arendt-Nielsen et al, 1996 ; Graven-Nielsen et al, 1997 ; Hodges et al, 2009 ; Wong et al, 2016 ). However, Mueller et al ( 2017 ) posit that the observed increased trunk muscle activity may be a maladaptive strategy that needs correction without considering that such phenomena may occur as a consequence of an interplay of multidimensional factors, recently reported to be related to BP experience in adolescents (Smith et al, 2017 ).…”

“…Rather, factors which predict BP at a young age are considered to be multi-dimensional and include gender, negative BP beliefs and poor mental health (O'Sullivan et al, 2017 ; Smith et al, 2017 ). Mueller et al ( 2017 ) have focused on a single physical factor (trunk muscle activation patterns) drawing inferences regarding BP prevention and treatment. This article prompts consideration of three essential aspects regarding research design and interpretation of findings: Interpreting results from cross-sectional designs Interpreting pain-related differences in motor behavior Translating and conveying scientific results to the end-user (patients, healthcare professionals and policy makers).…”