Enhancing motor performance through brief skin cooling: exploring the role of enhanced sympathetic tone and muscle spindle sensitivity.

BACKGROUND: Although brief skin cooling (BSC) is widely used in sports medicine and rehabilitation for its positive effects on motor performance, the mechanism underlying this motor facilitation effect remains unclear. OBJECTIVES: To explore the hypothesis that BSC enhances muscle force generation, with cold-induced sympathetic activation leading to heightened muscle spindle sensitivity, thereby contributing to this effect. METHODS: The study involved two experiments. Experiment 1 included 14 healthy volunteers. Participants submerged their hand in ice water for 3 min. Sympathetic activity was measured via heart rate (HR), muscle force generation was assessed through plantar flexor strength during maximum voluntary contraction (MVC), and cortical contribution to force generation via the volitional wave (V-wave) with and without the cold pressor test (CPT). Experiment-2 involved 11 healthy volunteers and focused on muscle spindle sensitivity and Ia synapse efficacy, assessed using soleus T-reflex and H-reflex recordings before, during, and after CPT. RESULTS: Experiment 1 showed significant increases in HR (7.8%), MVC force (14.1%), and V-wave amplitude (93.4%) during CPT compared to pre-CPT values (p = 0.001, p = 0.03, and p = 0.001, respectively). In Experiment-2, hand skin temperature significantly decreased during CPT and remained lower than pre-CPT after 15 min (p < 0.001). While H-reflex and background EMG amplitudes remained unchanged, T-reflex amplitude (113.7%) increased significantly during CPT and returned to pre-CPT values immediately afterward (p < 0.001). A strong correlation was also observed between HR and T-reflex amplitude (r = 0.916, p = 0.001). CONCLUSION: BSC enhances muscle spindle sensitivity via the sympathetic nervous system, promoting more significant muscle force generation. The method used in this study can be safely applied in clinical practice.

Different doses of hyaluronic acid injections in patients with knee osteoarthritis: A multicenter, randomized, prospective, single-blind, clinical study.

BACKGROUND: Many formulations and dosing regimens are available for hyaluronic acid (HA). OBJECTIVE: To compare different doses of linear, high-molecular weight (HMW) HA injections among patients with knee osteoarthritis (OA). METHODS: Hundred patients were included in this randomized, single-blinded trial and randomly divided into three HA injection groups. The first group received five weekly 20 mg HA injections, the second group received three weekly 32 mg HA injections, and the third group received a single 48 mg HA injection. Patients were evaluated at baseline, 1, 3, and 6 months after the last injection for pain, stiffness, and function using the visual analog scale (VAS) and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) questionnaire. Quality of life, patient's global assessment, and Timed Up and Go (TUG) test scores were also evaluated. RESULTS: There was significant improvement in the WOMAC, VAS-pain, quality of life, patient's global assessment, and TUG test mean scores at all follow-up time points (p< 0.001). However, the groups showed no significant differences in WOMAC, VAS-activity pain, and patient global scores at any follow-up point. CONCLUSION: Intra-articular injections of different doses of linear HMW HA can improve pain, stiffness, function, and quality of life in patients suffering from knee OA over a six-month period.

The Effects of Neuromuscular Electrical Stimulation on Swallowing Functions in Post-stroke Dysphagia: A Randomized Controlled Trial.

The study aimed to evaluate the effects of traditional dysphagia therapy (TDT) and neuromuscular electrical stimulation (NMES) combined with TDT on functionality of oral intake, dysphagia symptom severity, swallowing- and voice-related quality of life, leakage, penetration-aspiration, and residue levels in patients with post-stroke dysphagia (PSD). Thirty-four patients with PSD were included in our prospective, randomized, controlled, and single-blind study. The patients were divided into two groups: (1) TDT only (control group, n = 17) and (2) TDT with NMES (experimental group, n = 17). TDT was applied to both groups for three consecutive weeks, 5 days a week, 45 min a day. Sensory NMES was applied to the experimental group for 45 min per session. Patients were evaluated by the functional oral intake scale (FOIS), the eating assessment tool (EAT-10), the swallowing quality of life questionnaire (SWAL-QOL), and the voice-related quality of life questionnaire (VRQOL) at baseline, immediately post-intervention, and at the 3rd month post-intervention. Fiberoptic endoscopic evaluation of swallowing (FEES) with liquid and semi-solid food was performed pre- and post-intervention. A significant post-intervention improvement was observed on all scales in both groups, and these improvements were maintained 3 months post-intervention. Leakage and penetration-aspiration levels with semi-solid food declined only in the experimental group. In conclusion, TDT is a non-invasive and inexpensive method that leads to improvement in many swallowing-related features in stroke patients; however, NMES as an adjunct therapy is costly but can provide additional benefits for improving features, such as penetration-aspiration and residue levels.

Acute effects of Red Bull energy drink on ventricular repolarization in healthy young volunteers: a prospective study.

OBJECTIVE: Energy drinks (EDs) are widely consumed products of the beverage industry and are often chosen by teenagers and young adults. Several adverse cardiovascular events and malignant cardiac arrhythmias following consumption of EDs have been reported in the literature. Several studies have suggested that the interval from the peak to the end of the electrocardiographic T wave (Tp-e) may correspond to the dispersion of repolarization and that an increased Tp-e interval and Tp-e/QT ratio are associated with malignant ventricular arrhythmias. This study investigated the acute effects of Red Bull ED on ventricular repolarization as assessed by the Tp-e interval and Tp-e/QT ratio. METHODS: A prospective, open-label study design was used. After an 8-h fast, 50 young, healthy subjects consumed 355 mL of Red Bull ED. The Tp-e interval, Tp-e/QTc ratio, and several other electrocardiographic parameters were measured at baseline and 2 h after ingestion of Red Bull ED. RESULTS: No significant changes in the Tp-e interval or Tp-e/QTc ratio were observed with Red Bull ED consumption. Red Bull ED consumption led to increases in both systolic and diastolic blood pressures, which were associated with an increased heart rate. CONCLUSION: Although ingestion of Red Bull ED increases the heart rate and diastolic and systolic blood pressures, it does not cause alterations in ventricular repolarization as assessed by the Tp-e interval and Tp-e/QTc ratio.