Relative safety of 4 weeks of blood flow‐restricted resistance exercise in young, healthy adults

This study evaluated the effect of 4 weeks of low‐load resistance exercise with blood flow restriction (BFRE) on increasing strength in comparison with high‐load resistance exercise (HLE), and assessed changes in blood, vascular and neural function. Healthy adults performed leg extension BFRE or HLE 3 days/week at 30% and 80% of strength, respectively. During BFRE, a cuff on the upper leg was inflated to 30% above systolic blood pressure. Strength, pulse‐wave velocity (PWV), ankle‐brachial index (ABI), prothrombin time (PT) and nerve conduction (NC) were measured before and after training. Markers of coagulation (fibrinogen and D‐dimer), fibrinolysis [tissue plasminogen activator (tPA)] and inflammation [high sensitivity C‐reactive protein (hsCRP)] were measured in response to the first and last exercise bouts. Strength increased 8% with BFRE and 13% with HLE ( P <0.01). No changes in PWV, ABI, PT or NC were observed following training for either group ( P >0.05). tPA antigen increased 30–40% immediately following acute bouts of BFRE and HLE ( P =0.01). No changes were observed in fibrinogen, D‐dimer or hsCRP ( P >0.05). These findings indicate that both protocols increase the strength without altering nerve or vascular function, and that a single bout of both protocols increases fibrinolytic activity without altering selected markers of coagulation or inflammation in healthy individuals.