Delayed Effect of Blood-Flow-Restricted Resistance Training on Rapid Force Capacity

PURPOSE: The aim of the present study was to investigate the effect and time course of high-frequent low-load resistance training with blood-flow restriction (BFR) on rapid force capacity (i.e. rate of torque development (RTD)).

METHODS: Ten male subjects (22.8±2.3 years) performed four sets of knee extensor exercise (20%1RM) to concentric failure during concurrent BFR of the thigh (100mmHg), while eight work-matched controls (21.9±3.0 years) trained without BFR (CON). Twenty-three training sessions were performed within 19 days. Maximal slow and fast knee joint velocity muscle strength and rapid force capacity (e.g. RTD) as well as evoked twitch contractile parameters was assessed before (Pre) and 5 and 12 days after training (Post5, Post12). Muscle biopsies were obtained Pre, after 8 days (Mid8) and 3 and 10 days post training (Post3, Post10) to examine changes in myofiber area and expression of myocellular proteins known to be modified by cellular stress (CaMKII,Annexin-A6,SNO-CYS).

RESULTS: RTD remained unchanged following BFR training at Post5, while increasing 15-20% Post12 (P<0.01). Evoked muscle twitch parameters showed a general decline Post5 (P<0.01), while returning to baseline levels at Post12. All contractile parameters essentially remained unchanged in CON. Elevated CaMKII was observed with BFR training at Post3 (57%) and Post10 (71%) (P<0.05), while SNO-CYS increased in CON at Mid8 (P<0.05).

CONCLUSION: This study is the first to show that low-load resistance exercise performed with blood-flow restriction leads to marked increases in rapid force capacity (RTD). However, a general delayed adaptive response was observed for voluntary contractile parameters (including RTD) in parallel with a decline and subsequent recovery in evoked contractile properties, suggesting the delayed gain in rapid force capacity mainly have a peripheral origin.