Resistance Training, Detraining, and Retraining Study 2022
Condition: Exercise Training; Skeletal Muscle; Skeletal Muscle Atrophy
MeSH terms: Muscular Atrophy
Study type: Interventional

Summary: 
      The research project is aiming to examine the muscular adaptations to resistance training
      (RT), detraining (DT) and repeated RT (i.e. retraining). The research project will also
      examine differences in muscular adaptations between 20 weeks of continuous RT and 20 weeks of
      intermittent RT including a 10-week DT period in the middle of the training intervention.
      This is randomized controlled trial in which the research participants will be randomized
      into discontinuous and continuous groups (both n=~20). Both will be doing a 2-3-week
      familiarization and control period at the start. Then in the former there will be an initial
      strength training period (10-wks), a DT period (10-wks), and a second strength training
      (retraining) period (10-wks). The second group includes a 10-wk non-training control period
      (10-wks) followed by a RT period (20-wks). Participants will be young, healthy men and women
      (age 18-35, which 50% are females) with no systematic RT experience during the last 6 months.
      Measurements will be completed before and after each study period. Body composition will be
      measured via bioelectrical impedance analysis (BIA) and 3D body scans. Dynamic leg press and
      elbow flexion one repetition-maximum (1RM) will be used to test maximal strength. Anaerobic
      performance and strength endurance will be tested in elbow flexion and dynamic leg press
      using RM tests. Vastus lateralis (VL) and biceps brachii muscle cross-sectional area (CSA)
      will be assessed via ultrasound. Muscle biopsies of the VL muscle will be obtained to assess
      changes in muscle fiber morphology and factors regulating and associated with the
      hypertrophic processes and metabolism. Blood samples will be collected to analyze changes in
      metabolism and physiology. A rating of perceived exertion (RPE) during training will be
      collected after every exercise to ensure proper training intensity. Finally, nutrition and
      habitual physical activity will be assessed with 4-day diet diaries and physical activity
      questionnaires before the intervention and during each 10-week period.
    

Detailed description: 
      It is well known that RT increases skeletal muscle size and strength. However, there seems to
      be a difference in increases in muscle size (termed hypertrophy) and strength in upper and
      lower limb musculature in untrained population after RT. Moreover, there is large
      inter-individual variation in the adaptations gained through RT. Also at the moment, the
      responses to de- and retraining are not well known, and new research designs for
      investigating possible muscle memory are needed. Muscle mass and strength, once achieved with
      RT, can be obtained faster with subsequent retraining if the initial adaptations were lost
      due to inactivity. RT causes many molecular and cellular changes in myofibers that aid in
      hypertrophic processes, yet their adaptations to DT and contribution to muscle memory are
      still marginally researched. It is, therefore, essential to widen our knowledge about the
      permanence of physiological adaptations in skeletal muscle to periods of DT and repeated
      exposure to RT.

      The primary objectives to achieve by this project are:

        1. to determine the magnitude of 10-week RT period on upper and lower limb maximal dynamic
           strength and muscle size compared to the non-training control group

        2. to determine whether the responses to 20-week continuous RT differs in adaptations in
           maximal strength and muscle hypertrophy from two 10-week RT periods separated by a
           10-week detraining period

        3. to identify molecular and cellular biomarkers explaining responses to RT, detraining and
           retraining
    

Intervention name(s): Resistance training, detraining, retraining
Intervention type(s): Other
Intervention description(s): Participants (healthy untrained men and women, age 18-40) start with a 3-week familiarization and baseline measurement period. After that, they are randomized to two intervention groups, where other group will conduct 10-week RT intervention and a 10-week DT period and again the exact same 10-week RT intervention again whereas the other group start with a 10-week non-training period and then continues with a 20-week RT intervention. RT consists of two training sessions per week of total body workouts. Same measurements are conducted for both groups with the same time intervals.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Participants (healthy untrained men and women, age 18-40) start with a 3-week familiarization and baseline measurement period. After that, they are randomized to two intervention groups, where other group will conduct 10-week RT intervention and a 10-week DT period and again the exact same 10-week RT intervention again whereas the other group start with a 10-week non-training period and then continues with a 20-week RT intervention. RT consists of two training sessions per week of total body workouts. Same measurements are conducted for both groups with the same time intervals.
Masking: Double (Investigator, Outcomes Assessor)
Primary purpose: Basic Science