Comparable muscle fatigue responses across different low-load blood flow restriction protocols among women

Low-load blood flow restricted (LLBFR) resistance exercise has been demonstrated to accelerate acute muscle fatigue, but these responses may be dependent upon the protocol used. The purpose of this investigation was to examine fatigue characteristics following acute LLBFR resistance exercise with a 75-repetition (75-rep; 1 × 30, 3 × 15), 3 sets to failure (3×), and 1 set to failure (1×) protocols.

Sixteen women randomly performed 75-rep, 3× , and 1× LLBFR protocols consisting of unilateral, submaximal (30% of maximal voluntary isometric contraction; [MVIC]), isokinetic (90°·s^-1), leg extension muscle actions. Separate two-way, 3 (Condition [75-rep, 3× , 1×]) × 2 (Time [Pretest, Posttest]), repeated-measure ANOVA models were used to examine MVIC, peak twitch torque (PTT), surface electromyography amplitude (sEMG AMP), voluntary activation (VA), and V_wave/M_wave ratio.

There were no significant (p = 0.516-0.984) interactions for any of the fatigue characteristics. Collapsed across Conditions however, MVIC torque (21.1%), PTT (11.0%), sEMG AMP (1.9%), and VA (4.6%) decreased across Time (p < 0.001-0.011). There was no change in V_wave /M_wave ratio (p = 0.639-0.822).

Despite differences in set and repetition schemes, all three LLBFR protocols induced comparable decreases in MVIC torque, PTT, sEMG AMP, and VA. The current results highlight the potential efficacy of a single set of LLBFR performed to volitional failure to provoke fatigue responses comparable to multiple set protocols.