Each volunteer performed these exercise twice , following either an intravenous injection of phosphocreatine ( PCr ) or a placebo of an isotonic NaCl solution .
each volunteer performed these exercise twice , following either an intravenous injection of phosphocreatine ( pcr ) or a placebo of an isotonic nacl solution .
O O O O O O O O O O O O O B-other_organic_compound O B-other_organic_compound O O O O O O B-inorganic I-inorganic I-inorganic O