No abstract

To test the hypothesis that severe hypoxia during low-resistance/high-repetition strength training promotes muscle hypertrophy, 19 untrained males were assigned randomly to 4 weeks of low-resistance/high-repetition knee extension exercise in either normoxia or in normobaric hypoxia ( FiO(2) 0.12) with recovery in normoxia. Before and after the training period, isokinetic strength tests were performed, muscle cross-sectional area (MCSA) measured (magnetic resonance imaging) and muscle biopsies taken. The significant increase in strength endurance capacity observed in both training groups was not matched by changes in MCSA, fibre type distribution or fibre cross-sectional area. RT-PCR revealed considerable inter-individual variations with no significant differences in the mRNA levels of hypoxia markers, glycolytic enzymes and myosin heavy chain isoforms. We found significant correlations, in the hypoxia group only, for those hypoxia marker and glycolytic enzyme mRNAs that have previously been linked to hypoxia-specific muscle adaptations. This is interpreted as a small, otherwise undetectable adaptation to the hypoxia training condition. In terms of strength parameters, there were, however, no indications that low-resistance/high-repetition training in severe hypoxia is superior to equivalent normoxic training.

This study analyzed the interaction between the anterior cruciate ligament (ACL) and the intercondylar notch roof (INR) in hyperextension of the knee using magnetic resonance cinematography. Cinematographic image series of 15 knees were investigated. Two independent observers identified the image that displayed the beginning of contact between the ACL and the INR. They determined knee extension on this image and on the image that displayed maximum hyperextension of the knee. Correlations between a variable representing impingement and the inclination angle of the INR, the anterior laxity of the knee, and full hyperextension were examined. Theoretical, impingement-free tibial tunnel positions for the knees were calculated as a percentage of the anteroposterior tibial width. All ACLs of the knees in this study made contact with the INR. The average extension angle at the beginning of impingement was -6.3 +/- 3.8 degrees. There were significant correlations between impingement and maximum manual displacement as measured with the arthrometer (r = 0.77; P < 0.001), maximum hyperextension (r = 0. 67; P = 0.007), and notch roof angle (r = -0.73; P = 0.002). There were biomechanically acceptable tunnel positions for all knees but one. Hyperextension is physiologically associated with impingement of the ACL. In uninjured knees there was a correlation between ACL impingement and hyperextension, inclination of the INR, and maximum manual displacement of the tibia. Impingement free tibial tunnel positioning is possible in most knees without notchplasty.

These results indicate a shift towards a more type II dominated gene expression pattern in the vasti laterales muscles of the CON/ECC-OVERLOAD group in response to training. We suggest that the increased eccentric load in the CON/ECC-OVERLOAD training leads to distinct adaptations towards a stronger, faster muscle.

In view of its good efficacy and the lower cost of treatment, endoscopic ligation plus propranolol may be recommended as initial procedure for prevention of recurrent variceal hemorrhage, whereas TIPS seems to be the preferable procedure in patients with recurrent bleeding after adequate endoscopic and pharmacological treatment.