The Relationship Between Acute Exercise-Induced Changes in Extramuscular Connective Tissue Thickness and Delayed Onset Muscle Soreness in Healthy Participants: A Randomized Controlled Crossover Trial

Pain quality patterns in delayed onset muscle soreness of the lower back suggest sensitization of fascia rather than muscle afferents: a secondary analysis study

Delayed onset muscle soreness (DOMS) of the lower back is considered a surrogate for acute low back pain (aLBP) in experimental studies. Of note, it is often unquestioningly assumed to be muscle pain. To date, there has not been a study analyzing lumbar DOMS in terms of its pain origin, which was the aim of this study. Sixteen healthy individuals (L-DOMS) were enrolled for the present study and matched to participants from a previous study (n = 16, L-PAIN) who had undergone selective electrical stimulation of the thoracolumbar fascia and the multifidus muscle. DOMS was induced in the lower back of the L-DOMS group using eccentric trunk extensions performed until exhaustion. On subsequent days, pain on palpation (100-mm analogue scale), pressure pain threshold (PPT), and the Pain Sensation Scale (SES) were used to examine the sensory characteristics of DOMS. Pain on palpation showed a significant increase 24 and 48 h after eccentric training, whereas PPT was not affected (p > 0.05). Factor analysis of L-DOMS and L-PAIN sensory descriptors (SES) yielded a stable three-factor solution distinguishing superficial thermal ("heat pain ") from superficial mechanical pain ("sharp pain") and "deep pain." "Heat pain " and "deep pain" in L-DOMS were almost identical to sensory descriptors from electrical stimulation of fascial tissue (L-PAIN, all p > 0.679) but significantly different from muscle pain (all p < 0.029). The differences in sensory description patterns as well as in PPT and self-reported DOMS for palpation pain scores suggest that DOMS has a fascial rather than a muscular origin.

MRI T2 mapping and shear wave elastography for identifying main pain generator in delayed-onset muscle soreness: muscle or fascia?

INTRODUCTION

The main generator of delayed onset muscle soreness (DOMS) is still unknown. This study aimed to clarify the main generator of DOMS.

METHODS

Twelve participants performed eccentric exercise (EE) on lower legs. MRI and ultrasound were used to assess changes of calf muscle and deep fascia before and after EE. These results were then compared to the muscle pain level.

RESULTS

Compared to baseline, muscle pain peaked at 24-48 h after EE (downstairs 22.25 ± 6.196, 57.917 ± 9.298, F = 291.168, p < 0.01; resting 5.833 ± 1.899, 5.083 ± 2.429, F = 51.678, p < 0.01). Shear wave speed (SWE) of the deep fascia and T2 values of the gastrocnemius muscle and deep fascia all increased and peaked at 48 h after EE (1.960 ± 0.130, F = 22.293; 50.237 ± 2.963, F = 73.172; 66.328 ± 2.968, F = 231.719, respectively, p < 0.01). These measurements were positively correlated with DOMS (downstairs: r = 0.46, 0.76, 0.87, respectively, p < 0.001; resting: r = 0.42, 0.70, 0.77, respectively, p < 0.001). There was a significant positive correlation between SWE and T2 values of deep fascia (r = 0.54, p < 0.01).

CONCLUSION

DOMS is a common result of muscle and fascia injuries. Deep fascia edema and stiffness play a crucial role in DOMS, which can be effectively evaluated MR-T2 and SWE.

CRITICAL RELEVANCE STATEMENT

Delayed-onset muscle soreness is a common result of muscle and deep fascia injuries, in which the edema and stiffness of the deep fascia play a crucial role. Both MRI and shear wave elastography can be effectively used to evaluate soft tissue injuries.

KEY POINTS

• The deep fascia is the major pain generator of delayed-onset muscle soreness. • There is a significant correlation between fascia injury and delayed-onset muscle soreness. • MRI and shear wave elastography are preferred methods for assessing fascia injuries.

A new perspective on tissue gliding dysfunction bordered by deep fascia as an indicator of delayed onset muscle soreness: A case report

INTRODUCTION

The deep fascia, especially its thickness and stiffness, plays an important role in the mechanism of delayed onset muscle soreness (DOMS). Here, we present a patient with DOMS associated with a tissue gliding dysfunction bordered by the deep fascia.

CASE PRESENTATION

A 25-year-old woman developed DOMS of the left upper arm. We confirmed the tissue gliding dysfunction during manual skin traction by ultrasound imaging and treated with acupuncture aimed at stimulating the deep fascia. Tissue gliding between subcutaneous and muscle tissues bordered by the deep fascia was analyzed qualitatively and quantitatively, i.e., phases and distance of displacement. At the initial examination, the tissue gliding phases were in the same direction synchronously and the distance of displacement was 0.66mm. After the DOMS symptoms improved with direct acupuncture to the deep fascia, the phases changed independently in opposite directions and their displacement was 7.04mm.

CONCLUSIONS

In this patient, tissue gliding played an important role in the symptoms of DOMS. This case report focusing on tissue gliding provides a new perspective on understanding the pathogenesis of DOMS.

Effects of Maximal Eccentric Trunk Extensor Exercise on Lumbar Extramuscular Connective Tissue: A Matched-Pairs Ultrasound Study

Recently, it has been shown that the extramuscular connective tissue (ECT) is likely involved in delayed onset muscle soreness (DOMS). Therefore, the aim of the present study was to investigate the effects of maximal trunk extension eccentric exercise (EE) on ECT thickness, self-reported DOMS, ECT stiffness, skin temperature, and possible correlations between these outcomes. Healthy adults (n = 16, 29.34 ± 9.87 years) performed fatiguing EE of the trunk. A group of highly active individuals (TR, n = 8, > 14 h of sport per week) was compared with a group of less active individuals (UTR, n = 8, < 2 h of sport per week). Ultrasound measurements of ECT thickness, stiffness with MyotonPro and IndentoPro, skin temperature with infrared thermography, and pain on palpation (100 mm visual analog scale, VAS) as a surrogate for DOMS were recorded before (t0), immediately (t1), 24 h (t24), and 48 h (t48) after EE. ECT thickness increased after EE from t0 to t24 (5.96 mm to 7.10 mm, p = 0.007) and from t0 to t48 (5.96 mm to 7.21 mm, p < 0.001). VAS also increased from t0 to t24 (15.6 mm to 23.8 mm, p < 0.001) and from t0 to t48 (15.6 mm to 22.8 mm, p < 0.001). Skin temperature increased from t1 to t24 (31.6° Celsius to 32.7° Celsius, p = 0.032) and t1 to t48 (31.6° Celsius to 32.9° Celsius, p = 0.003), while stiffness remained unchanged (p > 0.05). Correlation analysis revealed no linear relationship between the outcomes within the 48-hour measurement period. The results may confirm previous findings of possible ECT involvement in the genesis of DOMS in the extremities also for the paraspinal ECT of trunk extensors. Subsequent work should focus on possible interventions targeting the ECT to prevent or reduce DOMS after strenuous muscle EE.