Effects of Consecutive Versus Non-consecutive Days of Resistance Training on Strength, Body Composition, and Red Blood Cells

Health authorities worldwide recommend 2-3 days per week of resistance training (RT) performed similar to 48-72 h apart. However, the influence of recovery period between RT sessions on muscle strength, body composition, and red blood cells (RBCs) are unclear. Aim: Examine the effects of three consecutive (C) or non-consecutive (NC) days of RT per week for 12 weeks on strength, body composition, and RBCs. Methods: Thirty young, healthy and recreationally active males were randomly assigned to 3 C (similar to 24 h between sessions) or NC (similar to 48-72 h between sessions) days of RT per week for 12 weeks. Both groups performed three sets of 10 repetitions at 10 repetition maximum (RM) of leg press, latissimus pulldown, leg curl, shoulder press, and leg extension for each session. Ten RM and body composition were assessed pre- and post-RT. RBC parameters were measured on the first session before RT, and 0 and 24 h post -3rd session in untrained (week 1) and trained (week 12) states. Results: No training x group interaction was found for all strength and body composition parameters (p = 0.075-0.974). Training increased strength for all exercises, bone mineral density, and total body mass via increased lean and bone mass (p 0.001). There was no interaction (p = 0.076-0.994) and RT induced temporal changes in all RBC parameters (p < 0.001-0.003) except RBC corrected for plasma volume changes (time x training interaction; p = 0.001). Training increased hematocrit and lowered mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration (p = 0.001-0.041) but did not alter uncorrected RBC, hemoglobin, mean corpuscular volume and RBC distribution width (p = 0.178-0.797). Conclusion: Both C and NC RT induced similar improvements in strength and body composition, and changes in RBC parameters.