Low-load resistance training without blood flow restriction increases maximally supported mitochondrial respiratory capacity by 30% from baseline, whereas low-load resistance training with blood flow restriction does not increase maximally supported mitochondrial respiratory capacity from baseline.

When muscles are worked to fatigue with light weights and no blood flow restriction, the repeated contractions create physical stress and energy depletion inside the muscle cells. This triggers a molecular signal that tells the cell to build more energy-producing factories called mitochondria and make them better at using oxygen to generate energy. When blood flow is restricted, the muscle cells experience a different kind of stress that shifts their adaptation toward improving short-term endurance instead of building more energy capacity.