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.
Highlights
Health authorities worldwide, such as the American College of Sports Medicine (ACSM; Garber et al, 2011) and World Health Organization (World Health Organization, 2010), recommend that adults perform resistance training (RT) at least twice a week for health benefits
There was no interaction (p = 0.076–0.994) and RT induced temporal changes in all red blood cell (RBC) parameters (p < 0.001–0.003) except RBC corrected for plasma volume changes
The recommendation is to perform the RT sessions at least 48 h apart, i.e., on NC days (Garber et al, 2011). This recommendation stems from two acute studies by Haddad and Adams (2002) and Bickel et al (2005) which demonstrated that a recovery period of 48–72 h between RT sessions is needed to optimize the molecular responses favorable to gains in muscle size and strength based on two bouts of isometric contraction via electrical stimulation in rats (Haddad and Adams, 2002) and humans (Bickel et al, 2005)
Summary
Health authorities worldwide, such as the American College of Sports Medicine (ACSM; Garber et al, 2011) and World Health Organization (World Health Organization, 2010), recommend that adults perform RT at least twice a week for health benefits. Fat-free mass increased among all participants but changes in fat mass and quadriceps thickness were inconsistent Another subsequent study of five resistancetrained men showed that 21 C days of 1RM testing and maximal voluntary isometric contraction of the elbow flexors significantly improved the 1RM strength in both arms to a similar extent, and that the arm that performed three additional sets of elbow flexions daily significantly increased arm muscle thickness (Dankel et al, 2017). The authors only reported strength changes for two exercises and did not account for the other exercises that were performed
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