Strength and hypertrophy responses to constant and decreasing rest intervals in trained men using creatine supplementation

Abstract

BackgroundThe purpose of the current study was to compare strength and hypertrophy responses to resistance training programs that instituted constant rest intervals (CI) and decreasing rest intervals (DI) between sets over the course of eight weeks by trained men who supplemented with creatine monohydrate (CR).MethodsTwenty-two recreationally trained men were randomly assigned to a CI group (n = 11; 22.3 ± 1 years; 77.7 ± 5.4 kg; 180 ± 2.2 cm) or a DI group (n = 11; 22 ± 2.5 years; 75.8 ± 4.9 kg; 178.8 ± 3.4 cm). Subjects in both groups supplemented with CR; the only difference between groups was the rest interval instituted between sets; the CI group used 2 minutes rest intervals between sets and exercises for the entire 8-weeks of training, while the DI group started with a 2 minute rest interval the first two weeks; after which the rest interval between sets was decreased 15 seconds per week (i.e. 2 minutes decreasing to 30 seconds between sets). Pre- and post-intervention maximal strength for the free weight back squat and bench press exercises and isokinetic peak torque were assessed for the knee extensors and flexors. Additionally, muscle cross-sectional area (CSA) of the right thigh and upper arm was measured using magnetic resonance imaging.ResultsBoth groups demonstrated significant increases in back squat and bench press maximal strength, knee extensor and flexor isokinetic peak torque, and upper arm and right thigh CSA from pre- to post-training (p ≤ 0.0001); however, there were no significant differences between groups for any of these variables. The total volume for the bench press and back squat were significantly greater for CI group versus the DI group.ConclusionsWe report that the combination of CR supplementation and resistance training can increase muscular strength, isokinetic peak torque, and muscle CSA, irrespective of the rest interval length between sets. Because the volume of training was greater for the CI group versus the DI group, yet strength gains were similar, the creatine supplementation appeared to bolster adaptations for the DI group, even in the presence of significantly less volume. However, further research is needed with the inclusion of a control group not receiving supplementation combined and resistance training with decreasing rest intervals to further elucidate such hypotheses.

The effects of pre versus post workout supplementation of creatine monohydrate on body composition and strength

“…In elite male handball players, creatine supplementation for 32 days resulted in an increase in 1-RM bench press (8.30 vs. 5.29 kg; creatine versus control) [33]. These and other investigations indeed show that creatine supplementation in general has a significant anabolic and performance-enhancing effect [34,35] which is in agreement with the current investigation. Mechanistically, creatine supplementation has been shown to increase muscle fiber size, enhance myosin heavy chain protein synthesis, activate satellite cells as well as increase the concentrations of intramuscular ATP and PCr [6,7,12,36,37].…”

Effects of Five Weeks of Resistance Training and Relatively-Dosed Creatine Monohydrate Supplementation on Body Composition and Muscle Strength, and Whole-Body Creatine Metabolism in Resistance-Trained Males

“…Statistical analysis revealed a moderate effect size for the increase in leg press 1-RM in the CR group (d = 0.51). This suggests additional participants might have provided adequate statistical power to reveal a significantly greater strength gain in the CR group, which is in agreement with previous research (Earnest et al, 1995;Souza-Junior et al, 2011;Rawson and Volek, 2003). The participants were instructed to maintain their normal mixed diets for the duration of the study, and there were no significant differences between-or within-groups throughout the course of the study for daily total caloric intake (Table 3).…”

Performance Enhancing Diets and the PRISE Protocol to Optimize Athletic Performance

“…In male recreational bodybuilders, 4 weeks of creatine supplementation at 5 g·d −1 , combined with resistance training, led to increases in lean body mass and 1 repetition maximum (RM) bench press with indication of greater benefit from postexercise versus preexercise supplementation [ 55 ]. The second trial also focused on recreationally trained men but included a creatine loading phase and lasted for 8 weeks [ 56 ]. Furthermore, for one of the groups, the rest interval between resistance exercises was progressively decreased by 15 seconds each week, which resulted in a lower training volume [ 56 ].…”

“…The second trial also focused on recreationally trained men but included a creatine loading phase and lasted for 8 weeks [ 56 ]. Furthermore, for one of the groups, the rest interval between resistance exercises was progressively decreased by 15 seconds each week, which resulted in a lower training volume [ 56 ]. Despite the reduced training volume, increases in muscle cross sectional area for the upper arm and thigh, as well as 1 RM for the squat and bench press, were not different between groups, suggesting that creatine supplementation can be used to increase training efficiency [ 56 ].…”

“…Furthermore, for one of the groups, the rest interval between resistance exercises was progressively decreased by 15 seconds each week, which resulted in a lower training volume [ 56 ]. Despite the reduced training volume, increases in muscle cross sectional area for the upper arm and thigh, as well as 1 RM for the squat and bench press, were not different between groups, suggesting that creatine supplementation can be used to increase training efficiency [ 56 ]. Other recent trials have shown creatine to reduce postexercise levels of inflammation [ 57 ] and muscle damage [ 58 ], suggesting it may facilitate recovery.…”