ECSS Paris 2023: OP-AP27
INTRODUCTION: Dynamic stretching (DS) is a widely recognized warm-up practice that induces acute adaptations in muscle performance, potentially through acute neural and/or mechanical changes [1]. However, the magnitude of acute neuromuscular changes during DS may vary with movement velocity and volume [2]. Therefore, this study aimed to investigate how DS volume and movement velocity affect homosynaptic depression and spinal reflex activity. METHODS: Eight young men (22 ± 5.24 years) performed four experimental sessions in random order: 1) Control Session; 2) DS with high volume and moderate velocity (7 sets of 10 repetitions at 60 beeps per minute - bpm; DS-HM); 3) DS with moderate volume and moderate velocity (4 sets of 10 repetitions at 60 bpm; DS-MM); 4) DS with moderate volume and high velocity (4 sets of 10 repetitions at 90 bpm; DS-MH). The protocols were conducted on the plantar flexors of the right ankle, with participants lying on the isokinetic machine with the knee fully extended. The rest intervals between the sets were 30 seconds. The homosynaptic depression and spinal reflex activity were assessed using tibial nerve stimulation associated with paired Hoffman reflex ratio (Hcon/Href), and maximal Hoffman reflex normalized to maximal Mwave (Hmax/Mmax) of the soleus muscle before (PRE), immediately after (POST), and 10 minutes (P10) after each protocol. RESULTS: The Generalized Mixed Model showed no significant main effect of condition (p = 0.106), but significant main effects of time (p = 0.005) and a time × condition interaction (p = 0.042) for homosynaptic depression. Tukey post hoc analysis indicated that the Hcon/Href ratio was significantly reduced immediately after the protocol only in the DS-HM condition (p = 0.007). However, this reduction was transient, with values returning to baseline 10 minutes after the DS protocol (p > 0.05). For the spinal reflex, the Generalized Mixed Model revealed no significant main effect of time (p = 0.157) but significant main effects of condition (p = 0.001) and a time × condition interaction (p = 0.001). Tukey post hoc analysis demonstrated a significant reduction in the Hmax/Mmax ratio at the P10 time point compared with PRE (p = 0.001) and POST (p = 0.001) in the DS-MM condition. CONCLUSION: A high volume of dynamic stretching reduces homosynaptic depression. Additionally, moderate movement velocity may attenuate spinal reflex activity, but only when performed with a moderate stretching volume. Collectively, these findings indicate that both stretching volume and movement velocity interact to modulate spinal excitability during dynamic stretching.
Read CV Denis VieiraECSS Paris 2023: OP-AP27
INTRODUCTION: Delayed-onset muscle soreness (DOMS) is a complex subacute pain syndrome involving interrelated muscular, fascial, and neural dysfunctions. While conventional recovery modalities often target single physiological pathways, the multi-level pathophysiology of DOMS suggests the need for multi-target interventions. Whole-body vibration (WBV) modulates neuromuscular function via neural inhibition, whereas tissue flossing (TF) uniquely targets fascial mechanics and local microcirculation. Despite their individual benefits, the potential synergistic effect of integrating these two distinct mechanical stimuli immediately post-exercise remains unexplored. This study investigated whether a combined TF and WBV protocol provides superior clinical outcomes in alleviating pain and accelerating functional recovery compared to isolated applications. METHODS: Forty-eight healthy, untrained males (age: 20.6 +/- 2.0 y; BMI: 22.5 +/- 1.7 kg/m2) were randomized into four groups (n=12 each): Control (CON), Tissue Flossing (TF), Whole-Body Vibration (WBV), and Combined (TF+WBV). DOMS was induced via 10 sets of 12 maximal isokinetic eccentric contractions (60 deg/s) of the dominant quadriceps. Interventions were applied immediately post-exercise: TF utilized thigh compression (150 mmHg) with active squats; WBV involved squats on a vibration platform (50 Hz, 3 mm amplitude); TF+WBV performed simultaneous vibration and flossing; CON rested. Clinical assessments included Visual Analogue Scale (VAS), Pressure Pain Threshold (PPT), passive knee Range of Motion (PROM), and Peak Torque (PT). Serum Creatine Kinase (CK) and Lactate Dehydrogenase (LDH) were analyzed to assess structural and metabolic stress. Measurements were taken at baseline, 0h, 24h, 48h, and 72h. RESULTS: A significant group x time interaction was observed for VAS (p < 0.05). The TF+WBV group showed superior pain relief, with significantly lower VAS scores compared to CON and TF at 0h, and sustained lower levels than CON through 72h. Regarding mechanical hyperalgesia, PPT was significantly higher in WBV and TF+WBV groups than CON immediately post-intervention (p < 0.05), with all interventions showing benefits over CON at 24-72h. While serum CK elevation and PT recovery showed no significant group differences, LDH levels were significantly suppressed in the TF and TF+WBV groups compared to CON at 72h (p < 0.05), suggesting reduced late-stage metabolic stress. CONCLUSION: The integration of Tissue Flossing and Whole-Body Vibration represents an effective multimodal rehabilitation strategy for managing DOMS. This combination provides synergistic benefits in alleviating pain and mechanical hyperalgesia, potentially mediated by enhanced metabolic clearance (suppressed LDH) and neural modulation. While it does not accelerate primary structural repair (CK), this strategy is highly recommended for acute symptom management in clinical and sports settings to facilitate earlier return to activity.
Read CV LU YAOECSS Paris 2023: OP-AP27