Urine proteomics as a non-invasive approach to monitor exertional rhabdomyolysis during military training

Exertional rhabdomyolysis (ERM), a condition often associated with strenuous exercise, a common practice in the military activities, can be defined as the process of injury and rupture of muscle cell membranes, with leakage of its components into the blood stream. Creatine kinase (CK) has been extensively used for ERM diagnosis, albeit several studies reported the discrepancy between CK levels and clinical signs or symptoms. In this study, we analyzed the biochemical profile of the blood, and the urinary proteome of ten marine soldiers in a special training course. The samples were collected in two periods, M1 and M2, which correspond to the lowest and highest CK levels during training, respectively. Quantitative urinary proteome profile of M1 and M2 was determined showing changes with highest significance in immune system and cell adhesion-related pathways after strenuous physical exercise. Changes in the abundance of several proteins was observed in individuals carrying genetic polymorphisms related to greater risk for muscle damage. Remarkably, we identified a panel of proteins (CTSH, PIK3IP1, DEFB1, ITGB1, BCAN, and TNFRSF10C) that present high correlation with three classical blood biochemical markers of ERM and AGT MET235Thr and ACE I/D polymorphisms. These proteins represent potential urine markers of muscle damage due to intense physical conditions such as military training activities.

Sarcoplasmic Reticulum from Horse Gluteal Muscle Is Poised for Enhanced Calcium Transport

We have analyzed the enzymatic activity of the sarcoplasmic reticulum (SR) Ca2+-transporting ATPase (SERCA) from the horse gluteal muscle. Horses are bred for peak athletic performance yet exhibit a high incidence of exertional rhabdomyolysis, with elevated levels of cytosolic Ca2+ proposed as a correlative linkage. We recently reported an improved protocol for isolating SR vesicles from horse muscle; these horse SR vesicles contain an abundant level of SERCA and only trace-levels of sarcolipin (SLN), the inhibitory peptide subunit of SERCA in mammalian fast-twitch skeletal muscle. Here, we report that the in vitro Ca2+ transport rate of horse SR vesicles is 2.3 ± 0.7-fold greater than rabbit SR vesicles, which express close to equimolar levels of SERCA and SLN. This suggests that horse myofibers exhibit an enhanced SR Ca2+ transport rate and increased luminal Ca2+ stores in vivo. Using the densitometry of Coomassie-stained SDS-PAGE gels, we determined that horse SR vesicles express an abundant level of the luminal SR Ca2+ storage protein calsequestrin (CASQ), with a CASQ-to-SERCA ratio about double that in rabbit SR vesicles. Thus, we propose that SR Ca2+ cycling in horse myofibers is enhanced by a reduced SLN inhibition of SERCA and by an abundant expression of CASQ. Together, these results suggest that horse muscle contractility and susceptibility to exertional rhabdomyolysis are promoted by enhanced SR Ca2+ uptake and luminal Ca2+ storage.

Clinical Characteristics and Outcomes of Exertional Rhabdomyolysis after Indoor Spinning: A Systematic Review

ObjectivesMore patients are being diagnosed with exertional rhabdomyolysis secondary to indoor spinning. We conducted a systematic review to characterize the clinical characteristics of this new clinical entity.MethodsWe conducted a thorough literature search on PubMed, Embase, Web of Science, Scopus and The Cumulative Index to Nursing and Allied Health Literature (CINAHL). Articles published from inception till 23rd June 2021 were considered for inclusion. A two-stage article selection process was performed. Articles that reported clinical characteristics and outcomes for patients with SIER were included. Quality assessment was performed using the Joanna Briggs Institute checklists.ResultsThere was a total of 22 articles and 97 patients with SIER. Most patients were healthy females who had attended their first spinning session. The average time to clinical presentation was 3.1 ± 1.5 days. The most common presenting symptoms were myalgia, dark urine and muscle weakness involving the thigh. Seven patients (7.2%) developed acute kidney injury, and two patients (2.1%) required temporary inpatient haemodialysis. Four patients (4.1%) developed thigh compartment syndrome and required fasciotomies. There were no long-term sequelae or mortality observed. The average length of stay was 5.6 ± 2.9 days.ConclusionsHealthcare professionals must have a high index of suspicion of SIER if any patient presents with myalgia, dark urine or weakness after a recent episode of indoor spinning. Fitness centre owners, spinning instructors and participants should also be better educated about the clinical characteristics and manifestations of SIER.

Clinical characteristics of spinning-induced rhabdomyolysis and other causes of rhabdomyolysis: a comparative study

Introduction Spinning is an indoor stationary cycling programme that can cause severe rhabdomyolysis. We compared the clinical characteristics of spinning-induced exertional rhabdomyolysis (SER) with other exertional rhabdomyolysis (ER) and non-exertional rhabdomyolysis (NER). Methods This was a retrospective observational study of adult patients presenting with rhabdomyolysis to an emergency department from August 2018 to August 2019. Patients were classified as SER, ER or NER based on chart review. We compared patient demographics, serum creatine kinase (CK), transaminase and creatinine levels, admission rates, duration of hospitalisation and treatment prescribed. Results: 62 patients were analysed. SER patients were predominantly female (77% vs. 24% vs. 26%, p < 0.01), Chinese (100% vs. 47% vs. 79%, p < 0.01) and younger (mean age 27.7 vs. 34.6 vs. 59.4 years, p < 0.01) than those with ER and NER. The SER group had the highest CK level (20,000 vs. 10,465 vs. 6,007 U/L, p < 0.01) but the lowest mean serum creatinine level (53.5 vs. 80.9 vs. 143.5 μmol/L, p < 0.01) compared to the ER and NER groups. Admission rates were the highest in SER patients (100% vs. 57% vs. 90%, p < 0.01). SER mean inpatient length of stay was longer than ER but shorter than NER patients (4.3 vs. 1.9 vs. 6.0 days, p = 0.02). Conclusion: SER is a unique form of rhabdomyolysis. Predominantly seen in young, healthy women, it often presents with extremely high CK levels. However, the prognosis is good and the rate of complication is low with fluid treatment.