Time Restricted Eating and Resistance Exercise Training: Effects on Muscle Fiber Hypertrophy

Time Restricted Eating (TRE) consists of scheduling mealtimes during a particular eating window throughout the day.TRE is known to maintain muscle mass, decrease fat mass, and improve body composition (Sandoval et al., 2021).The purpose of this study is to utilize a longitudinal muscle fiber size analysis method to determine the effects of TRE and resistance exercise training on skeletal muscle hypertrophy in a caloric surplus and increase knowledge in this area.Collaborators at California State University, Fullerton (CSU Fullerton) created a study that consisted of two groups: the TRE group, and the FED group.The FED group involved designated nutrition intake guidelines, which involved eating 4 meals distributed throughout the day and consuming 20 g of whey protein powder Pre and Post workout (Hamane, 2019).The TRE group consumed their meals within an eight hour eating window.In this study, 14 individuals (8 males; 6 females) were self-selected into either group once they met the inclusion criteria.Participants followed an eight week resistance exercise training program for four days a week.Each group was in a caloric surplus based on individual Basal Metabolic Rate (BMR), and protein and macronutrient consumption was similar across both the TRE and FED groups (Hamane, 2019).The Pre and Post vastus lateralis muscle biopsies, obtained from CSU Fullerton, were sent to San Francisco State University and stored in the freezer at -20℃ in 50% glycerol.An average of 10 fibers Pre and Post biopsies were isolated from each sample, stained with Alexa Fluor 568 and DAPI, and placed on a microscopic slide for imaging on the Zeiss LSM 710 confocal microscope.A longitudinal muscle fiber size method previously developed by the Muscle Physiology Lab was utilized to assess the participant's muscle fiber measurements using the Pre and Post muscle biopsies (Bagley & Galpin, 2015;Machek et al., 2021).A Repeated Measures ANOVA with combined data displayed muscle growth in both groups (15%).Muscle growth results entailed TRE (17%) and FED (13%).There was a notable difference in the muscle fiber increase found between males (3%) and females (32%) Post study for both groups.The noteworthy results suggest that both the TRE and FED resulted in stimulated muscle hypertrophy for most participants after eight weeks of resistance exercise training.Furthermore, results indicated that female participants can exhibit muscle hypertrophy at an increased rate when performing resistance exercise training combined with a caloric surplus diet.v