A New Direction to Athletic Performance: Understanding the Acute and Longitudinal Responses to Backward Running

Backward running (BR) is a form of locomotion that occurs in short bursts during many overground field and court sports. It has also traditionally been used in clinical settings as a method to rehabilitate lower body injuries. Comparisons between BR and forward running (FR) have led to the discovery that both may be generated by the same neural circuitry. Comparisons of the acute responses to FR reveal that BR is characterised by a smaller ratio of braking to propulsive forces, increased step frequency, decreased step length, increased muscle activity and reliance on isometric and concentric muscle actions. These biomechanical differences have been critical in informing recent scientific explorations which have discovered that BR can be used as a method for reducing injury and improving a variety of physical attributes deemed advantageous to sports performance. This includes improved lower body strength and power, decreased injury prevalence and improvements in change of direction performance following BR training. The current findings from research help improve our understanding of BR biomechanics and provide evidence which supports BR as a useful method to improve athlete performance. However, further acute and longitudinal research is needed to better understand the utility of BR in athletic performance programs

Prophylactic treatment with alkaline phosphatase in cardiac surgery induces endogenous alkaline phosphatase release.

Introduction: Laboratory and clinical data have implicated endotoxin as an important factor in the inflammatory response to cardiopulmonary bypass. We assessed the effects of the administration of bovine intestinal alkaline phosphatase (bIAP), an endotoxin detoxifier, on alkaline phosphatase levels in patients undergoing coronary artery bypass grafting. Methods: A total of 63 patients undergoing coronary artery bypass grafting were enrolled and prospectively randomized. Bovine intestinal alkaline phosphatase (n=32) or placebo (n=31) was administered as an intravenous bolus followed by continuous infusion for 36 hours. The primary endpoint was to evaluate alkaline phosphatase levels in both groups and to find out if administration of bIAP to patients undergoing CABG would lead to endogenous alkaline phosphatase release. Results: No significant adverse effects were identified in either group. In all the 32 patients of the bIAP-treated group, we found an initial rise of plasma alkaline phosphatase levels due to bolus administration (464.27±176.17 IU/L). A significant increase of plasma alkaline phosphatase at 4-6 hours postoperatively was observed (354.97±95.00 IU/L) as well. Using LHA inhibition, it was shown that this second peak was caused by the generation of Tissue Non Specific Alkaline Phosphatase (TNSALP-type alkaline phosphatase). Conclusions: Intravenous bolus administration plus 8 hours continuous infusion of alkaline phosphatase in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass results in endogenous alkaline phosphatase release. This endogenous alkaline phosphatase may play a role in the immune defense system

Hyperaggregating effect of hydroxyethyl starch components and University of Wisconsin solution on human red blood cells: a risk of impaired graft perfusion in organ procurement?

BACKGROUND: The standard preservation solution used during organ procurement and preservation of most organs is the University of Wisconsin (UW) solution. Despite its superiority over other cold storage solutions, the inclusion of hydroxyethyl starch (HES) as one of the components of the UW solution has been both advocated and denied. This study determined whether HES had any effect on red blood cell (RBC) aggregability and correlated aggregation parameters with HES molecular weight. METHODS: Human RBC aggregability and deformability were investigated in vitro, at 4 degrees C, with a laser-assisted optical rotation cell analyzer. The study of RBC aggregation in a binary HES-HES system gave an indication about the nature of HES-RBCs interactions. Bright field microscopy and atomic force microscopy were used to morphologically characterize the aggregates size and form. RESULTS: High molecular weight HES and UW solution had a potent hyperaggregating effect; low molecular weight HES had a hypoaggregating effect on RBC. RBC aggregates were of large size and their resistance to dissociation by flow-induced shear stress was high. CONCLUSION: The authors' in vitro experiments conclusively showed that the physiologic function of RBCs to form aggregates is significantly affected in the presence of HES. The use of high molecular weight HES in UW solution accounts for extended and accelerated aggregation of erythrocytes that may result in stasis of blood and incomplete washout of donor organs before transplantation

Pulsatile cardiopulmonary bypass and renal function in elderly patients undergoing aortic valve surgery

To evaluate if pulsatile cardiopulmonary bypass (CPB) has any protective influence on renal function in elderly patients undergoing aortic valve replacement (AVR).Forty-six patients (≥75 years old) with aortic valve stenosis underwent AVR with either pulsatile perfusion (PP) or non-pulsatile perfusion (NP) during CPB. Haemodynamic efficacy of the blood pump during either type of perfusion was described in terms of the energy equivalent pressure and the surplus haemodynamic energy. Urine samples were collected before surgery, at sternum closure, and at 2 and 18 h of intensive care unit stay to detect acute kidney injury markers. Perioperative urine levels of N-acetyl-β-d-glucosaminidase (NAG), kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin (NGAL) were assessed together with plasma creatinine, creatinine clearance (CCr) and 24-h haemodynamic monitoring. Normally distributed continuous variables were described as mean ± standard deviation and non-normally distributed data were presented as the median [25th-75th percentiles].PP was characterized by a significantly higher amount of surplus haemodynamic energy transferred to the patients (P < 0.001), with lower mean systemic vascular resistance during CPB (P = 0.020) and during 18 h postoperatively (group-P = 0.018). No difference was found between pre- and postoperative CCr in the PP group (71 ± 23 vs 60 ± 35 ml/min, P = 0.27), while its statistically significant perioperative decrement was observed in the NP group (67 ± 24 vs 45 ± 15 ml/min, P < 0.001). The PP group showed significantly lower urinary levels of NAG at 18 h postoperatively (P = 0.008), and NGAL at sternum closure (P = 0.010), 2 h (P < 0.001) and 18 h (P = 0.015) postoperatively.Short-term PP in elderly patients showed higher safety for renal physiology than NP, resulting in better maintenance of glomerular filtration and lower renal tissue injury

Inhibition by dexamethasone of the reperfusion phenomena in cardiopulmonary bypass

A placebo-controlled double-blind study of patients undergoing cardiopulmonary bypass was conducted, comparing the effects of dexamethasone and a placebo on the activation of the plasmatic systems and blood cells and on the postoperative course after cardiopulmonary bypass. In the placebo group two patterns of blood activation could be distinguished. From the start of bypass, blood-material interaction caused an increase in complement C3a and elastase concentration. After release of the aortic cross-clamp, a statistically significant increase was observed in tumor necrosis factor, leukotriene B4, and tissue plasminogen activator activity (p < 0.01, p < 0.05, p < 0.05, respectively). Dexamethasone treatment was not able to inhibit complement activation and elastase release during cardiopulmonary bypass. However, dexamethasone treatment effectively inhibited the increase in tumor necrosis factor, leukotriene B4, and tissue plasminogen activator activity after release of the crossclamp (p < 0.01 compared with the placebo group). In the postoperative period the patients in the placebo group had hyperthermia and hypotension and required considerable intravenous fluid administration and cardiotonic treatment. The dexamethasone-treated patients, however, showed normothermia (p < 0.01), had significantly higher blood pressures (p < 0.01) without supportive treatment, and consequently were in the intensive care unit for a shorter period of time. We conclude that dexamethasone prevents the hemodynamic instability after cardiopulmonary bypass and thus improves the postoperative course by inhibition of the leukocyte and tissue plasminogen activator activity generated after release of the aortic crossclamp

Inhibition by dexamethasone of the reperfusion phenomena in cardiopulmonary bypass

A placebo-controlled double-blind study of patients undergoing cardiopulmonary bypass was conducted, comparing the effects of dexamethasone and a placebo on the activation of the plasmatic systems and blood cells and on the postoperative course after cardiopulmonary bypass. In the placebo group two patterns of blood activation could be distinguished. From the start of bypass, blood-material interaction caused an increase in complement C3a and elastase concentration. After release of the aortic cross-clamp, a statistically significant increase was observed in tumor necrosis factor, leukotriene B4, and tissue plasminogen activator activity (p < 0.01, p < 0.05, p < 0.05, respectively). Dexamethasone treatment was not able to inhibit complement activation and elastase release during cardiopulmonary bypass. However, dexamethasone treatment effectively inhibited the increase in tumor necrosis factor, leukotriene B4, and tissue plasminogen activator activity after release of the crossclamp (p < 0.01 compared with the placebo group). In the postoperative period the patients in the placebo group had hyperthermia and hypotension and required considerable intravenous fluid administration and cardiotonic treatment. The dexamethasone-treated patients, however, showed normothermia (p < 0.01), had significantly higher blood pressures (p < 0.01) without supportive treatment, and consequently were in the intensive care unit for a shorter period of time. We conclude that dexamethasone prevents the hemodynamic instability after cardiopulmonary bypass and thus improves the postoperative course by inhibition of the leukocyte and tissue plasminogen activator activity generated after release of the aortic crossclamp