From the Literature.

New research in healthy volunteers indicates that high-intensity interval training stimulates muscle cells to boost production of mitochondrial proteins and delay the aging process at the molecular level. The Cell Metabolism findings are encouraging because with age, the energy-generating capacity of cells’ mitochondria slowly decreases. To examine the molecular players involved in the benefits of exercise, investigators from the Mayo Clinic randomly assigned 36 men and 36 women from 2 age groups (18–30 years old and 65–80 years old) into 3 different exercise programs: highintensity interval biking, strength training with weights, and a combination of strength training and interval training. By performing thigh muscle biopsies and various laboratory tests, the team found that all programs enhanced insulin sensitivity and lean mass, but only high-intensity interval training and combined training improved aerobic capacity and skeletal muscle mitochondrial respiration. The younger and older volunteers in the interval training group experienced a 49% and 69% increase in mitochondrial respiration, respectively. The interval training was less effective at improving muscle strength, however. By comparing proteomic and RNA-sequencing data from people on different exercise programs, the researchers found evidence that exercise encourages cells to make more RNA copies of genes coding for mitochondrial proteins and proteins responsible for muscle growth. Highintensity training revealed a more robust increase in gene transcripts than other exercise modalities, and it also reversed many age-related differences in protein production and increased mitochondrial protein synthesis. Increases in certain mitochondrial and ribosomal proteins were greater relative to changes in RNA content, indicating an increase in the synthesis rate of proteins. This suggests that exercise adaptations are regulated to a greater extent at the posttranscriptional level. The investigators also found a lowering of posttranslational protein damage following exercise training that may improve the functional quality of proteins.