SummaryStudy aim: The aim of this study to determine whether creatine ethyl ester (CEE) supplementation combined with resistance training (RT) is effective for improving hormonal changes, body composition and muscle strength in underweight non-athlete men.Materials and methods: Sixteen underweight non-athlete men participated in this double-blind study and were randomly assigned to one of two groups: RT with placebo (RT + PL, n = 8) and RT with CEE supplementation (RT + CEE, n = 8). The participants performed 6 weeks of RT (60–80% 1RM) combined with CEE or PL. 48 hours before and after the training period, muscle strength (1RM for leg press and bench press), body composition (percentage of body fat, circumference measurements of the arm and thigh), serum levels of testosterone, cortisol, and growth hormone (GH) of the participant were measurements.Results: Significant increases were observed for weight, muscle strength and muscle mass, serum levels of testosterone and GH between pre and post-test in the RT + CEE group (p < 0.05). In addition, cortisol level was significantly decreased in the post-test in the RT+CEE group. The decrease in fat percent was greater in the RT + PL group than in the RT + CEE group (%change = –6.78 vs. –0.76, respectively). Weight and leg strength changes in the RT + CEE group were significant compared to the RT + PL group (p < 0.001, p = 0.05, p = 0.001; respectively). However, in other variables, despite the increase of GH and testosterone levels and lower levels of cortisol in the RT + CEE group, no significant differences were observed between the two groups (p < 0.05).Conclusion: It seems that the consumption of CEE combined with RT can have significant effects on body weight and leg strength in underweight non-athlete men. This supplement may provide a potential nutritional intervention to promote body weight in underweight men.

A rest–pause (RP) technique involves performing one or more repetitions at high resistance to failure, followed by a short rest before performing one or more repetitions. These techniques can affect neuromuscular conditions and fatigue by changing the rest time between repetitions. This study compared the effect of 12 weeks of RP and traditional resistance training (TRT) on myokines (myostatin (MSTN), follistatin (FLST) and insulin-like growth factor-1 (IGF-1)) and functional adaptations. The study recruited 29 men between the ages of 20 and 30 who had performed resistance training for at least 6 to 12 months. Participants were randomly divided into three groups: RP, TRT, and control; resistance training was performed 3 days per week for 12 weeks. The training methods of the two groups were largely similar. The results showed that RP increased IGF-1 and FLST/MSTN more than the TRT group (% change = 19.04, % change = 37.71), and only the RP and TRT groups had significant changes in the FLST/MSTN ratio compared to the control group (p < 0.001 and p = 0.02, respectively). In addition, FLST levels increased and MSTN decreased in the RP and TRT groups, but the rate of change in FLST was significant in the RP and TRT groups compared to the control group (p = 0.002 and p = 0.001, respectively). Leg press and bench press strength, and arm and thigh muscular cross-sectional area (MCSA) increased more in the RP group than in the others, and the percentage of body fat (PBF) decreased significantly. The change between strength and MCSA was significant (p ≤ 0.05), and the PBF change in RP and TRT compared to the control (ES RP group = 0.43; ES TRT group = 0.55; control group ES = 0.09) was significant (p = 0.005, p = 0.01; respectively). Based on the results, the RP training technique significantly affects strength and muscle hypertrophy more than the TRT method, which can be included in the training system to increase strength and hypertrophy.