Skeletal Muscle Protein Synthesis: Traditional and Cluster Sets
Condition: Resistance Exercise
Study type: Interventional

Summary: 
      Traditionally, when performing resistance exercise, repetitions are performed in a continuous
      manner resulting in a decrease in velocity, and thus power output. "Cluster" set is an
      alternative to counter the reduction in velocity and power output. Cluster sets incorporate a
      brief rest (15-30 seconds) between individual repetitions (inter-repetition rest) or group of
      repetitions (intra-set rest) within a set of resistive exercise. In contrast to traditional
      set configurations, which result in an almost linear decrease in force, velocity, and power
      -cluster sets maintain and/or attenuate the loss in power, primarily due to higher
      velocities.

      The purpose of this research is to compare the muscle protein synthesis response to acute
      bouts of cluster and traditional set configurations. Investigators will assess muscle protein
      synthesis rates before and after acute resistance exercise in 14 resistance-trained males and
      females (Age: 20-35; back squat 1.5 x body weight; 3 years of resistance training
      experience). The volunteers are required to be removed (at least six weeks) from all
      ergogenic levels of nutritional supplements that have previously been shown to affect protein
      synthesis. Blood and muscle biopsies will be collected as a part of testing. Further,
      subjects will be required to perform moderate-to-high intensity resistance exercise.
    

Detailed description: 
      The present study will be testing the effect of rest configuration on muscle protein
      synthesis. The protocols selected by the researchers were cluster set and traditional set,
      details will be explained further.

      Prior to participation, procedures of the study and the associated risks will be explained to
      participants prior to enrolling them in the study. Subjects who are interested in
      participating will be asked to read and sign an informed consent form. If they chose to do
      so, they will then fill out a medical history questionnaire. Those meeting entry criteria, as
      identified in the section on Inclusion and Exclusion Criteria, will have their height and
      weight recorded and blood pressure assessed through use of a blood pressure cuff, followed by
      determination of body composition by dual x-ray absorptiometry (DXA). DXA is a procedure used
      to provide researchers with information about body composition using two low dose x-rays.
      Briefly, participants will be asked to remove all metal objects. They will then be asked to
      lie on the DXA table where they will be positioned by a trained technician for accurate
      measurement. The total time of the body composition scan lasts approximately 6-10 minutes
      depending on the size of the participant. Following determination of body composition,
      participants will be asked to perform the back squat exercise after demonstration by trained
      personnel for familiarization with the exercise protocol. The total time associated with
      consent, body composition assessment, and initial familiarization is approximately 1 to 1.5
      hours.

      Each participant will be asked to participate in 2 experimental infusion trials, each
      separated by ≥7 days (Figure 2). The trials will differ in the specific resistance exercise
      bout performed (CLU or TRD conditions). A standardized evening meal will be provided the
      night before each experimental infusion. Participants will receive this meal on the 1RM
      testing day with instructions on when to consume it. Participants will be asked to refrain
      from any vigorous activities outside of daily living for 72 hours prior to each infusion
      trial. This will prevent a potential confounding of recently performed exercise on rates of
      muscle protein synthesis. In addition, subjects will be asked to record their food intake for
      3 d before the start of each test day in a food diary that will be provided during the
      screening.

      Subject Activity: On the days of the test, the subject is asked to arrive to Freer Hall by
      public transport or car in the morning at 8.00 am without eating breakfast (i.e., in the
      fasting state). After arrival, they will rest on a bed for the majority of the test day (8 -
      9.5 h in total). They will perform multiple sets of the back squat exercise with a moderate
      load (70-75% 1RM) at approximately 10.00 am to 11.00 am each test day. Hereafter, they are
      asked to rest on a bed again for the remainder of the test day. They will have free access to
      a restroom, and will be able to work on their laptop, read a book, or watch DVDs during the
      test day with the exception of during the muscle biopsy procedures.

      The resistance training protocols: Participants will perform a dynamic warm-up lasting
      approximately 5-10 minutes. Following the warm-up, participants will perform two sets of the
      back squat exercise using a barbell and weight plates with a load equivalent to 40-60% 1RM,
      as determined through the previous 1RM testing. After 1-2 minutes' rest, participants will
      perform the back squat using either traditional (4 sets of 10 repetitions with 120 seconds
      rest) or cluster (4 sets of two clusters of 5 repetitions with 30 seconds between clusters
      [intra-set rest] and 90 seconds between sets [inter-set rest]) set configurations with a load
      equivalent to

      ~70-75% 1RM.Participants will perform both protocols separated by at least 7 days
      (randomized), thus two trials will be performed. Participants will be asked to perform each
      repetition as explosively as possible. All testing will be performed on force plate with
      linear position transducers connected to the bar for determination of force, velocity, and
      power during the performance of the experiment.
    

Intervention name(s): Back-squat exercise
Intervention type(s): Other
Intervention description(s): Participants begin with a 5 min dynamic warm-up. Then, they will perform two sets of five repetitions at 40-60% of predetermined 1-repetition maximum (1-RM). The clustered bout will be 4 sets of 2 clusters of 5 repetitions with a 30-second intra-set rest between clusters, and 90-second inter-set rest at a load 70% of 1-RM. The traditional bout will be 4 sets of 10 repetitions with a 120-second inter-set rest at a load 70% of 1-RM.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Basic Science