The deadlift is a widely used strength and conditioning exercise of many athletes, i.e., in track and field (1–3). Electromyography studies have shown that a variety of muscles in both, the lower and upper body are involved. Among these, the erector spinae (ES) and semitendinosus muscles exhibit the highest activations (4). Coaches rely on the deadlift not only because of the contribution of many large muscle groups, but also because of their simultaneous activation (5). The neuromotor control of the entire kinematic chain and the management of significant musculoskeletal loads require a great deal of coordinative effort. As a consequence, the frequent use of deadlifts can lead to multiple systematic adaptations (5).

Because altered posture, lumbopelvic kinematics, and movement patterns are often seen in low back pain patients, resistance training is typically recommended to improve functional status (6, 7). Strengthening the posterior chain, in conjunction with general exercise, has been demonstrated to significantly improve pain and disability status (7, 8). In this regard, exercises that recruit multiple muscles of the posterior chain, such as the deadlift, seem to be most effective (8).

Panjabi (9) presented a model of the spinal stabilization system, which consists of three subsystems. Vertebrae with their disks and their ligaments, muscles and tendons attached to the spine, and the neural system. The thoracolumbar fascia (TLF) and other components have been considered only as passive surrounding tissues, if at all (10, 11). However, recent studies suggest that the TLF may have a much greater influence on the maintenance of spinal stability and likewise paraspinal muscle activity. Using magnetic resonance imaging-based finite element analysis, Bojairami et al. (12) demonstrated that the TLF alone contributes 75% to spinal static stability.

Some studies suggest that the ability of the TLF to deform (in terms of stretching and relaxing) and slide on the epimysium of the erector spinae is a critical feature that distinguishes healthy individuals from low back pain patients (13–15). This group of patients has 13.8% less shear strain (13) and 28% less TLF deformability (15) than healthy controls.

The aim of this study was to investigate TLF deformation (TLFD) in athletes and non-athletes with and without acute low back pain (aLBP). Based on a previous study, we hypothesized that untrained aLBP patients (UaLBP) would have a lower TLFD than untrained healthy participants (UH) or track and field athletes [TF; Hypothesis 1; (13)]. It was further hypothesized that a lower TLFD would correlate with a lower deadlift velocity (VEL) (Hypothesis 2). However, because of the different groups, it was assumed that these examinations would also be influenced by the different muscle training status of athletes and non-athletes and probably by different movement patterns (e.g., pain avoidance in aLBP patients). Therefore, the analysis had to control for these group differences. It was thought that muscle training status, different movement patterns, or VEL would influence TLFD during deadlift in the groups and, therefore, the adjusted TLFD would differ from the unadjusted TLFD (Hypothesis 3).

We performed a case–control study with UaLBP patient cases and two control groups (athletes and pain-free adults). The study protocol was prospectively registered with the German Clinical Trials Register (DRKS00027074). The study, which adhered to the STROBE Statement, was reviewed, and approved by the ethical committee of the Diploma Hochschule, Germany (Nr.1014/2021). It was conducted in accordance with the declaration of Helsinki and all participants provided written informed consent.

The anthropometric data and baseline characteristics are shown in Table 1. As per the a priori sample size calculation, n = 48 participants (16 TF, 16 UH, 16 UaLBP) took part in the study (Figure 2). No adverse events or drop-outs were recorded.

The one-way ANCOVA revealed significant differences regarding TLFD during TET between groups [F(2, 44) = 11.7; p < 0.01; partial η² = 0.35; Hypothesis 1]. There was no univariate effect of the covariate age [F(1, 44) = 2.0, p = 0.17, η² = 0.04]. Tukey’s HSD showed significant differences between UaLBP and UH (24%; p < 0.01) and UaLBP and TF (35%; p < 0.01), but not between UH and TF (11%; p = 0.22). Descriptive statistics are shown in Figure 3A and Table 2A.

There were strong negative correlations between TFLD and VEL during deadlift for UaLBP [r_s(14) = −0.81, p < 0.01], UH [r_s(14) = −0.88, p < 0.01], and TF [r_s(14) = −0.89, p < 0.01]. The partial correlations were also strong for UaLBP [r_{s (14)} = −0.65, p = 0.04], UH [r_{s (14)} = −0.68, p = 0.03], and TF [r_{s (14)} = −0.89, p < 0.01] (Hypothesis 2).

The ANCOVA for group comparisons of TLFD during deadlift revealed significant differences [F(2, 42) = 6.78; p < 0.01; partial η² = 0.24; Hypothesis 3]. There was a univariate effect of the covariates VEL [F(1, 42) = 18.2, p < 0.01, η² = 0.30] and EST [F(1, 42) = 10.0, p < 0.01, η² = 0.19] but no significant effect of DEV [F(1, 42) = 0.20, p = 0.66, η² = 0.005] or age [F(1, 42) = 0.42, p = 0.52, η² = 0.01]. Tukey’s HSD showed a significant difference between UH and TF (−20%; p < 0.01), but not between UaLBP and UH (10%; p = 0.09), and UaLBP and TF (−10%; p = 0.39). Descriptive statistics are shown in Figure 3B and Table 2B.

The basic mechanisms of force transmission from fascial tissue to skeletal muscle have been studied and convincing evidence of this has been found (24–26). However, the relative contributions of these mechanical interactions to training outcomes or remote exercise effects under in vivo conditions are often neglected in sports science as noted by a consensus paper, pointing to the urgency of research in this area. (27). The present study is novel in that it examined TLFD (measured with ultrasound) and deadlift velocity (measured with a three-axis gyroscope) during spinal movement in athletes and non-athletes.

One of the main findings of this study was a high TLFD in UH (−26%) and TF (−37%) in contrast to UaLBP (−3%) during the TET (Hypothesis 1). This confirms previous research in which the TLF was 28% less deformable in UaLBP than in healthy participants (15). In conjunction with the earlier finding of reduced shear strain between the fascial layers of the TLF in low back pain, this may be indicative of adhesions between the TLF and the epimysium of the ES (13). It has been suggested that impaired neuromuscular control and recruitment patterns due to low back pain lead to this observation (13). However, the results of our study tend to imply that TLFD could also be dependent on training status and activity and it becomes apparent that the understanding of these relationships needs to be extended in future studies.

To determine the presumed correlations between TLFD, and VEL without the influence of the epidemiological variables, EST and DEV, a partial correlation was performed which corrected the related calculations (Hypothesis 2). TLFD showed a strong correlation with VEL (p < 0.01), which was highest level [r_s(14) = 0.88] in TF. This was surprising because the EST, together with the pennation angle of the ES fibers, predicts the torque that the muscle can deliver by 68% (23). Therefore, it was hypothesized that the correlation corrected for EST would be less than the full correlation. However, finite model analysis suggests that the ES can only exert its full force with the support of TLF [by decreasing the intramuscular pressure and thereby reducing the stress; (12)], which could explain these results and the linear relationship between TLFD and VEL. Future studies focusing on the fascial system in both competitive sports and pathological changes in the myofascial system are therefore promising.

There was a significant difference between TF and UH in TFLD during the deadlift adjusting for EST, DEV, and VEL but no differences between UaLBP and the other groups (Hypothesis 3). The ANCOVA revealed a significant effect for VEL and EST (p < 0.01) but not for DEV (p = 0.66). The estimated marginal means of TF differed the most from the unadjusted mean (−11.9% versus −37.0%), suggesting that training status and velocity during the deadlift contributed significantly to TLFD during the exercise. TF had an about 20% thicker ES, achieving a 33–62% higher speed in the deadlift than UH or UaLBP. For UaLBP, the estimated marginal means showed exactly the opposite difference from the unadjusted means of TF (−21% versus −3.2%). The EST at baseline was almost the same in UaLBP and UH (30.1 mm versus 29.8 mm), which is consistent with a previous study that found no differences in deadlift force or electromyographic excitation between aLBP patients and healthy controls (8). A lower VEL is commonly observed in individuals with aLBP and has been associated with avoidance of potentially pain-causing movements (7). The UaLBP in this study achieved only 75% of the VEL of UH and 61% of TF. This could confirm this assumption. Despite an indication of reduced mean lumbar ROM in a meta-analysis by Laird et al. (7), the ANCOVA revealed no significant influence of DEV on TLFD during deadlift. However, the studies included in the analysis by Laird defined low back pain inconsistently. Therefore, it is possible that in the acute state, this reduced ROM is less significant.

The TLFD during a TET is lower in UaLBP compared to UH and TF who achieved the highest TLFD. TLFD and velocity performance during deadlift are strongly correlated. The training status, respectively, the force of ES and VEL that a participant can exert on the dumbbell during the deadlift, in addition to the group membership, determines the TLFD during the exercise. The results suggest that TLFD, in addition to training status, may be an important factor in weightlifting or spinal extension tasks.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by the Diploma University of Applied Science. The patients/participants provided their written informed consent to participate in this study.

AB, RR, TS, and RS designed the study. AB wrote the first draft of the manuscript. AB, JW, RR, TS, and RS co-wrote and reviewed the manuscript. AB and JW performed the statistical analysis. All authors read and approved the final manuscript.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.