PURPOSE: To investigate the potential of blocking the angiotensin II type I receptor (AT1R) on the hypertrophy response of elderly human skeletal muscle to four months of heavy resistance exercise training.
METHODS: 58 healthy elderly men (+65 years) were randomized into three groups, consuming either AT1R blocker (losartan, 100mg/day) or placebo for 4 months. Two groups performed resistance training (RT) and were treated with either losartan or placebo and one group did not train but was treated with losartan. Quadriceps muscle biopsies, MR scans and strength tests were performed at baseline and after 8 and 16 weeks. Biopsies were sectioned for immunohistochemistry to determine the number of satellite cells, capillaries, fibre type distribution and fibre area. Gene expression levels of myostatin, connective tissue and myogenic signalling pathways were determined by real time RT-PCR.
RESULTS: Four months of heavy resistance training lead in both training groups to expected improvements in quadriceps (∼3-4%) and vastus lateralis (∼5-6%) cross sectional area, type II fibre area (∼10-18%), as well as dynamic (∼13%) and isometric (∼19%) quadriceps peak force, but with absolutely no effect of losartan on these outcomes. Further, no changes were seen in satellite cell number with training and most gene targets failed to show any changes induced by training or losartan treatment.
CONCLUSION: There does not appear to be any effect of AT1R blocking in elderly men during four months of resistance training. Therefore, we do not find any support for using AT1R blockers for promoting muscle adaptation to training in humans.