Relationship between maximal incremental and high-intensity interval exercise performance in elite athletes.

This descriptive study aimed to explore the physiological factors that determine tolerance to exertion during high-intensity interval effort. Forty-seven young women (15-28 years old) were enrolled: 23 athletes from Taiwan national or national reserve teams and 24 moderately active females. Each participant underwent a maximal incremental INC (modified Bruce protocol) cardiopulmonary exercise test on the first day and high-intensity interval testing (HIIT) on the second day, both performed on a treadmill. The HIIT protocol involved alternation between 1-min effort at 120% of the maximal speed, at the same slope reached at the end of the INC, and 1-min rest until volitional exhaustion. Gas exchange, heart rate (HR), and muscle oxygenation at the right vastus lateralis, measured by near-infrared spectroscopy, were continuously recorded. The number of repetitions completed (Rlim) by each participant was considered the HIIT tolerance index. The results showed a large difference in the Rlim (range, 2.6-12.0 repetitions) among the participants. Stepwise linear regression revealed that the variance in the Rlim within the cohort was related to the recovery rates of oxygen consumption ([Formula: see text]), HR at the second minute after INC, and muscle tissue saturation index at exhaustion (R = 0.644). In addition, age was linearly correlated with Rlim (adjusted R = -0.518, p < 0.0001). In conclusion, the recovery rates for [Formula: see text] and HR after the incremental test, and muscle saturation index at exhaustion, were the major physiological factors related to HIIT performance. These findings provide insights into the role of the recovery phase after maximal INC exercise testing. Future research investigating a combination of INC and HIIT testing to determine training-induced performance improvement is warranted.

Rhythmic Neck Muscle Spasms and Upper Limb Muscle Myoclonic Jerks as an Unusual Initial Presentation of Posttraumatic Cervicothoracic Syringomyelia: A Case Report.

Posttraumatic syringomyelia with an initial presentation of involuntary movement is rare. We describe a 25-year-old patient who sustained complete traumatic spinal cord injury at the thoracic level and presented with rhythmic neck muscle spasms and upper limb muscle myoclonic jerks 1 month after trauma. Magnetic resonance imaging revealed syrinx formation between C3 and T1. Lumbar-peritoneal shunt and decompression were performed. The symptoms completely disappeared after surgery. This report highlights that rhythmic neck muscle spasms and upper limb muscle myoclonic jerks can be the initial and only manifestations of syringomyelia. LEVEL OF EVIDENCE: V.

The influence of platelet rich plasma on synovial fluid volumes, protein concentrations, and severity of pain in patients with knee osteoarthritis.

Knee pain is commonly seen in orthopedic and rehabilitation outpatient clinical settings. Patients with knee osteoarthritis (OA) are often complicated with joint soreness, swelling, weakness, and pain. These complaints are often caused by the excessive amount of synovial fluid (SF) accumulated in the bursae around the knee joint. This study was aimed to evaluate the effectiveness of platelet rich plasma (PRP) in treating patients with minor to moderate knee osteoarthritis (OA) combined with supra-patellar bursitis using a proteomic approach and clinical evaluation tool. In this study, 24 elderly patients with minor to moderate knee OA combined with supra-patellar bursitis were recruited. Musculoskeletal ultrasound was used for accurate needle placement for the aspiration of SF followed by subsequent PRP injections. Three monthly PRP injections were performed to the affected knees for a total of 3months. Approximately after the 2nd PRP injection, significant decreases in SF total protein concentrations, volumes, and Lequesne index values were observed. SF proteins associated with chelation and anti-aging physiological functions such as matrilin, transthyretin, and complement 5 increased at least 2-fold in concentrations. Proteins associated with inflammation, such as apolipoprotein A-I, haptoglobin, immunoglobulin kappa chain, transferrin, and matrix metalloproteinase decreased at least 2-fold in concentrations. Therefore, at least two monthly PRP injections may be beneficial for treating patients with minor to moderate knee OA combined with supra-patellar bursitis.

Suppression of atrial fibrillation following successful ablation of atrioventricular nodal reentrant tachycardia: a case report.

Inducible atrioventricular nodal reentrant tachycardia was demonstrated by electrophysiological studies in a 55-year-old female who suffered from intermittent palpitation, in which paroxysmal atrial fibrillation (AF) was consistently documented by electrocardiogram recordings. After ablation of the slow pathway, the atrioventricular nodal reentrant tachycardia and AF were not inducible. During 2 years of follow-up, there were no recurrences of AF in terms of symptoms or findings from Holter electrocardiograms. We suggest that the AF was triggered by the atrioventricular nodal reentrant tachycardia and the successful ablation of atrioventricular nodal reentrant tachycardia was associated with freedom arising from ablation of AF.

Drug targeting of HIV-1 RNA.DNA hybrid structures: thermodynamics of recognition and impact on reverse transcriptase-mediated ribonuclease H activity and viral replication.

RNA degradation via the ribonuclease H (RNase H) activity of human immunodeficiency virus type I (HIV-1) reverse transcriptase (RT) is a critical component of the reverse transcription process. In this connection, mutations of RT that inactivate RNase H activity result in noninfectious virus particles. Thus, interfering with the RNase H activity of RT represents a potential vehicle for the inhibition of HIV-1 replication. Here, we demonstrate an approach for inhibiting the RNase H activity of HIV-1 RT by targeting its RNA.DNA hybrid substrates. Specifically, we show that the binding of the 4,5-disubstituted 2-deoxystreptamine aminoglycosides, neomycin, paromomycin, and ribostamycin, to two different chimeric RNA-DNA duplexes, which mimic two distinct intermediates in the reverse transcription process, inhibits specific RT-mediated RNase H cleavage, with this inhibition being competitive in nature. UV melting and isothermal titration calorimetry studies reveal a correlation between the relative binding affinities of the three drugs for each of the chimeric RNA-DNA host duplexes and the relative extents to which the drugs inhibit RT-mediated RNase H cleavage of the duplexes. Significantly, this correlation also extends to the relative efficacies with which the drugs inhibit HIV-1 replication. In the aggregate, our results highlight a potential strategy for AIDS chemotherapy that should not be compromised by the unusual genetic diversity of HIV-1.