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

Abstract

Health authorities worldwide recommend 2-3 days per week of resistance training (RT) performed ∼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 (∼24 h between sessions) or NC (∼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 × 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 × 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.

Keywords: bone mineral density; erythrocytes; fat loss; hematology; muscle mass; muscle strength; recovery period; resistance training.

FIGURE 1

Experimental design. Participants were randomly assigned to either three consecutive (C) or non-consecutive (NC) days of resistance training (RT) per week for 12 weeks, and completed the same procedures except for the recovery period between RT sessions of each week. Blood samples were collected at weeks 1 and 12 of the RT as indicated. DXA, dual-energy X-ray absorptiometry; 10RM, 10-repetition maximum; UT, untrained; T, trained.

FIGURE 2

Ten-repetition maximum and body composition in untrained (UT) and trained (T) states for consecutive (C, ) and non-consecutive (NC, ) groups for: leg press with right leg (A), latissimus pulldown (B), leg curl with right leg (C), shoulder press (D), leg extension with right leg (E), body mass (F), lean mass (G), fat mass (H), fat percentage (I), arm fat mass (J), trunk fat mass (K), leg fat mass (L), bone mineral content (M), and bone mineral density (N). Values are means with 95% confidence interval. For (F–L), means are calculated from predicted values after adjustment for covariates. No significant training × group interaction for all parameters (p = 0.075–0.974). ^∗Significant difference between UT and T states (p < 0.001). ^#Significant group difference between C and NC (p = 0.025).

FIGURE 3

Plasma volume and red blood cell (RBC) parameters before resistance training (RT) at first session (Pre), and 0 and 24 h post-3rd RT session in untrained (UT, solid lines) and trained (T, dotted lines) states for consecutive (C, blue squares) and non-consecutive (NC, red circles) groups: plasma volume (A), RBC count (B), RBC count corrected for plasma volume changes (C), hematocrit (D), hemoglobin (E), mean corpuscular volume (F), mean corpuscular hemoglobin (G), mean corpuscular hemoglobin concentration (H), and RBC distribution width (I). Values are means with 95% confidence interval. No significant interaction for all parameters (p= 0.076–0.994) except corrected RBC count (^∗significant time × training interaction, p = 0.001; details in text). Significant main effect of time for all parameters (p < 0.001–0.003). Different letters indicate significant difference from other time points (p < 0.001–0.040). Comparison between UT and T states indicates significant difference between them (p = 0.001–0.041). ^#Significant group difference between C and NC (p = 0.006–0.030).