Acclimatization to intermittent hypoxia (IH) improves exercise performance by enhancing oxygen delivery and utilization, but the effect of IH on hemodynamic control remains unclear. This study investigates how two intensities of IH influence hemodynamic control to develop an IH regimen that improves aerobic fitness and minimizes risk of peripheral vascular disorder. Thirty healthy sedentary men were randomly divided into severe (SIH) and moderate (MIH) IH and control (C) groups. The subjects were exposed to 12% (SIH), 15% (MIH), or 21% (C) O2 for 1 h/day, 5 days/week for 4 weeks in a normobaric hypoxia chamber. The results demonstrate that (1) improved pulmonary ventilation and oxygen uptake by SIH and MIH; (2) SIH elevated blood pressure during exercise and increased plasma malondialdehyde and nitric oxide (NO) metabolite levels, accompanied by reduced hyperaemic arterial response, venous compliance, endothelium-dependent vasodilatation, and decreased plasma total antioxidant and vitamin E levels; (3) while such effects were not seen following MIH; and (4) there were no significant differences in endothelium-independent vasodilatation during all experimental periods among the three groups. We conclude that both SIH and MIH regimens improve pulmonary ventilation. However, SIH but not MIH decreases anti-oxidative capacity and increases lipid peroxidation in circulation, leading to suppression of vascular endothelial function, causing impairment of vascular haemodynamics.

Despite enhancing cardiopulmonary and muscular fitness, the effect of hypoxic exercise training (HE) on hemorheological regulation remains unclear. This study investigates how HE modulates erythrocyte rheological properties and further explores the underlying mechanisms in the hemorheological alterations. Twenty-four sedentary males were randomly divided into hypoxic (HE; n = 12) and normoxic (NE; n = 12) exercise training groups. The subjects were trained on 60% of maximum work rate under 15% (HE) or 21% (NE) O(2) condition for 30 min daily, 5 days weekly for 5 wk. The results demonstrated that HE 1) downregulated CD47 and CD147 expressions on erythrocytes, 2) decreased actin and spectrin contents in erythrocytes, 3) reduced erythrocyte deformability under shear flow, and 4) diminished erythrocyte volume changed by hypotonic stress. Treatment of erythrocytes with H(2)O(2) that mimicked in vivo prooxidative status resulted in the cell shrinkage, rigidity, and phosphatidylserine exposure, whereas HE enhanced the eryptotic responses to H(2)O(2). However, HE decreased the degrees of clotrimazole to blunt ionomycin-induced shrinkage, rigidity, and cytoskeleton breakdown of erythrocytes, referred to as Gardos effects. Reduced erythrocyte deformability by H(2)O(2) was inversely related to the erythrocyte Gardos effect on the rheological function. Conversely, NE intervention did not significantly change resting and exercise erythrocyte rheological properties. Therefore, we conclude that HE rather than NE reduces erythrocyte deformability and volume regulation, accompanied by an increase in the eryptotic response to oxidative stress. Simultaneously, this intervention depresses Gardos channel-modulated erythrocyte rheological functions. Results of this study provide further insight into erythrocyte senescence induced by HE.

INTRODUCTION Athletic trainers often work for elongated and irregular hours or days, and need to react in emergency situations. These professionals are at risk for work-related musculoskeletal disorders (WMSDs). This study investigated the WMSDs experienced by athletic trainers (ATs), plus related personal and occupational factors. METHODS A customized questionnaire with subject's demographic and WMSDs information was constructed and administered in all accessible ATs in Taiwan. In addition to descriptive analysis of demographics and WMSDs, the relationship between personal/occupational-related factors and WMSD symptoms were also evaluated. Results A total of 146 effective questionnaires were returned. The results indicated that a 48.5% prevalence rate of athletic trainers in Taiwan, and these disorders are mainly located in low back (42%), finger (38%) and shoulder (26%) regions. Logistic regression revealed that average work hour (odds ratio (OR) = 1.834, 95% confidence interval (CI): 1.066-3.156) and continue education participation (OR = 0.346, 95% CI: 0.140-0.854) were the most significant predictors for WMSDs occurrence. Performing taping was the most significant predictor for the low back (OR = 28.274, 95% CI: 2.568-311.423) and finger (OR = 19.535, 95% CI:2.273-167.912) symptoms; while performing providing first aid (OR = 12.128, 95% CI:3.881-37.899) was the most significant predictor for the shoulder's. Conclusion This study revealed that athletic trainers in Taiwan area suffered from high rate of WMSDs, and the relationship between WMSDs and specific job features were reported. Preventive and therapeutic modifications of the work environment to decrease the occurrence of WMSDs are in need for athletic trainers and other similar professions. Further research examining safe patient handling ergonomics, proper equipment in the context of athletic training and professional development strategies must be pursued.

No abstract

No abstract