January 2022; Vol. 11, No. 1: Pages 7-11
Mechanisms mediating increased endurance following high- and low-load training with and without blood flow restriction
Matthew A. Chatlaong, J. Grant Mouser, John P. Bentley, Samuel L. Buckner, Kevin T. Mattocks, Scott J. Dankel, Jeremy P. Loenneke, & Matthew B. JesseeAbstract
Objectives: To determine if different mechanisms, i.e., changes in one-repetition maximum (1RM) strength (Δ1RM) or vascular conductance (ΔVC), mediate changes in endurance (ΔEND) following training with 70% 1RM (70/0), 15% 1RM (15/0), and 15% 1RM with blood flow restriction using 40% (15/40) or 80% (15/80) arterial occlusion pressure. Design: Secondary analysis of data from a previous training intervention study. Method: Previously, 39 participants trained 2x/week for 8 weeks (4 sets of knee extensions to momentary failure) with 2 of the 4 aforementioned conditions (randomized, 1 per leg). VC, 1RM, and END were tested pre/post-training. A two-wave multiple-mediator model (adjusted for baseline values of 1RM, VC, and END) was constructed to evaluate direct and indirect effects of training on ΔEND (relative to other conditions) with Δ1RM and ΔVC as mediators. Results presented as coefficients (95%CI). Results: The model accounted for 35.2% (p<.001) of the variance in ΔEND. Relative direct effects on ΔEND did not differ across conditions (all p>.231). There was an effect of Δ1RM on ΔEND [0.5 (0.0,0.9) repetitions] and evidence that Δ1RM mediated the effect on ΔEND for 70/0 compared to other conditions [vs. 15/0=1.4 (0.1,2.9); 15/40=1.4 (0.1,2.7); 15/80=1.1 (0.1,2.3) repetitions]. There was no evidence of a relationship between ΔVC and ΔEND [0.02 (-0.10,0.13) repetitions] nor of relative indirect effects through ΔVC when comparing conditions. Conclusions: Differences in Δ1RM translate to increased endurance in the 70/0 condition compared to other conditions, however, changes in ΔVC did not appear to mediate increased endurance across the conditions.
Received October 6, 2021; accepted January 10, 2022