It's time to HIIT the gym...
The study was designed so that participants (Ages 18-30 and 65-80) were divided into groups with some doing High-Intensity Interval Cardio Training (HIIT), some doing resistance training and some doing Metabolic Resistance Training (MRT) over a 12 week period. Regardless of the modality of their exercise, all participants saw improvements in lean body mass and insulin sensitivity. However, only the HIIT and MRT exercisers showed improved aerobic capacity, an improvement in mitochondrial function for skeletal muscles (69% improvement for the older exercisers), and improved muscle protein synthesis and muscle protein content. Further, the study authors noted that the MRT exercisers also increased their muscular strength and the older participants had a 21% improvement in oxygen consumption. The resistance only exercisers saw none of those benefits.