Plasma concentration of high-mobility group box 1 (HMGB1) after 100 drop to vertical jumps and after a 1200-km bicycle race

Repetitive Bouts of Exhaustive Exercise Induces a Systemic Inflammatory Response and Multi-Organ Damage in Rats

Multiple organ dysfunction syndrome can follow severe infection or injury, but its relationship to exercise is not well understood. Previous studies have observed that prolonged strenuous exercise can lead to transiently increased level and/or activity of markers for systemic inflammatory response and multiple organ damage. However, few studies have analyzed the pathogenesis of the inflammatory response and subsequent multi-organ injury in exhaustive exercise conditions. In this study, we established a rat model of repetitive bouts of exhaustive running (RBER) and investigated its effects on multiple organ damage. Rats were subjected to RBER in either uphill or downhill running modes daily for a period of 7 days. Morphologically, RBER causes tissue structural destruction and infiltration of inflammatory cells in the skeletal muscles and many visceral organs. RBER also causes sustained quantitative changes in leukocytes, erythrocytes, and platelets, and changes in the concentration of blood inflammatory factors. These inflammatory alterations are accompanied by increases in serum enzyme levels/activities which serve as functional markers of organ damage. In general, RBER in the downhill mode seemed to cause more damage evaluated by the above-mentioned measures than that produced in the uphill mode. A period of rest could recover some degree of damage, especially for organs such as the heart and kidneys with strong compensatory capacities. Together, our data suggest that, as a result of multi-organ interactions, RBER could cause a sustained inflammatory response for at least 24 h, resulting in tissue lesion and ultimately multiple organ dysfunction.

Exercise alarms the immune system: A HMGB1 perspective

The "danger" model of immunology states that the immune system detects and responds to danger by releasing endogenous molecules called alarmins. Strenuous exercise perturbs physiological homeostasis, increasing circulating alarmins to drive the inflammatory response. We describe a working concept of exercise-induced High Mobility Group Box (HMGB)1, a prototypical alarmin, in modulating immune responses and adaptations.

Performance and physiological analysis of 500 km non-stop cycling: a case study

Ultra-endurance sports have gained popularity over the last years. In this case, a well-trained cyclist completed 503.5 km non-stop (33.3 km.h^-1). Speed and power output were reduced during the trial, being the reduction of power attributable to changes in pedal velocity rather than pedal forces. Heart rate (HR) showed an initial cardiovascular drift and progressively decreased independently of power. A decreased HR variability, a marked inflammatory response, signs of muscle damage and alterations of the haematological profile were observed after the trial. These adverse physiological effects were still present 24-48 h after exercise. A reduction in handgrip maximal voluntary contraction was observed immediately after the trial and 24 h later despite these muscles being minimally active during exercise. These findings show the high levels of stress to which the organism is subjected during ultra-endurance exercise even in the case of a trained cyclist.