The Time-Course of Voluntary and Electrically Evoked Muscle Performance During and After Stretch-Shortening Exercise is Different

The aim of the study was to establish the dynamics of maximal voluntary contraction force (MVCF), height of drop jump (DJ) and electrically evoked quadriceps muscle force at different stimulation frequencies during and after 100 DJs (stretch-shortening exercise, SSE). Healthy untrained men (n = 11; age = 21.8 ± 1.7 years) participated in the study. DJs were performed with 30 s intervals between jumps from the height of 0.5 m with counter-movement to 90 degrees angle in the knee and immediate maximal rebound. The force of the quadriceps muscle, evoked by electrical stimulation at 1 Hz (Pt), 20 Hz (P20) and 100 Hz (P100) frequencies (electrically evoked performance, EEP), MVCF and height of DJ (voluntary evoked performance, VEP) were established during SSE (after 10, 50, 100 DJ) as well as at 1, 4, 8, 24, 48 and 72 h after SSE. Time-course of P20 and P100 during and after SSE was time (ANOVA: p < 0.001) and frequency dependent (ANOVA: p < 0.001) The Pt, P20 and P100 decreased significantly (p < 0.01) more than MVCF and H of DJ during SSE. At the beginning of SSE (during 1-10 DJs) P20 and P100 decreased significantly (p < 0.001) more than during 11-50 and 51-100 DJs. There was a significant (p < 0.05) increase in Pt, P20 and P100 from 8 h to 48 h, whereas height of DJ and MVCF significantly decreased at that time. In conclusion, the differences in time course of VEP and EEP are most evident at beginning of SSE, where VEP does not change as EEP decreases, and within 8-48 hours after SSE, where VEP decreases as EEP increases.

Key points

• There was no change in voluntary muscle performance while electrically evoked performance decreased significantly during first 10 drop jumps.
• There was a significant increase in electrically evoked muscle performance from 8 h to 48 h after 100 drop jumps, whereas voluntary contraction force, decreased significantly.
• The secondary decrease in the height of drop jump as well as in maximal voluntary contraction force correlated significantly with muscle soreness within 24-48 h after exercise.

Key words: Drop jump, muscle damage, electrical stimulation, low frequency fatigue     

Rituximab or Cyclophosphamide in the Treatment of Membranous Nephropathy: The RI-CYCLO Randomized Trial

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Effectiveness of recommendations to prevent reactivation of latent tuberculosis infection in patients treated with tumor necrosis factor antagonists

OBJECTIVE: To investigate the impact of official recommendations regarding the management of latent tuberculosis (TB) infection on the rate of active TB in patients receiving treatment with tumor necrosis factor (TNF) antagonists. METHODS: Data on active TB rates and on screening and treatment of latent TB infection were extracted from the BIOBADASER (Spanish Society of Rheumatology Database on Biologic Products), a registry of patients with rheumatic conditions treated with TNF antagonists. The rates of active TB among the BIOBADASER patients were compared with those in the background Spanish population, and BIOBADASER patients with rheumatoid arthritis (RA) were compared with a cohort of RA patients from the EMECAR (Morbidity and Clinical Expression of Rheumatoid Arthritis) study who were not treated with TNF antagonists and were followed up for 5 years. RESULTS: Active TB developed in 34 patients, of whom 32 started taking TNF antagonists prior to the official recommendations on latent TB infection (pre-OR) and 2 began treatment after the recommendations were issued (post-OR). All cases of TB occurred during treatment with infliximab, and 28 of these patients had RA. Pre-OR, the active TB rate in BIOBADASER patients was 20.9-fold higher than in the background Spanish population, while RA patients in the BIOBADASER had rates 22.6- and 6.2-fold higher than the background and EMECAR populations, respectively. Post-OR, 324 patients with a tuberculin skin test result > or =5 mm and/or chest radiograph findings suggestive of past TB were treated for 9 months with isoniazid (INH). Post-OR, active TB rates among the BIOBADASER patients decreased by 78% (incidence risk ratio [IRR] 0.22, 95% confidence interval [95% CI] 0.03-0.88; P = 0.008), while among RA patients in the BIOBADASER, the rate dropped by 83% and reached the EMECAR rate (IRR 1.0, 95% CI 0.02-8.2). There were no INH treatment-related hospitalizations or deaths. CONCLUSION: Strategies to treat latent TB infection that are tailored to the at-risk population can effectively and safely lessen the likelihood of active TB in patients treated with TNF antagonists.     

The journey of the non-radiographic axial spondyloarthritis patient: the perspective of professionals and patients

Clinical Rheumatology - Explore the perspective of patients and professionals regarding non-radiographic axial spondyloarthritis (nr-axSpA) and to define the patient’s journey from diagnosis...