Resistance Training, Detraining, and Retraining Study 2022 (TraDeRe2022)

Physiological Adaptations to Resistance Training, Detraining, and Retraining in Young Healthy Males and Females

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.

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: 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 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 to identify molecular and cellular biomarkers explaining responses to RT, detraining and retraining

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.

Participants (healthy untrained men and women, age 18-40) will conduct 10-week RT intervention and a 10-week DT period and the exact same 10-week RT intervention again. RT consists of two training sessions per week of total body workouts.

Participants (healthy untrained men and women, age 18-40) 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.

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.

Maximal muscle strength will be assessed via one repetition maximum (1RM) tests of both the leg press and barbell biceps curl exercises according to the NSCA's guidelines.

Change in muscular performance after 20-week continuous RT period and two 10-week RT periods separated by a 10-week DT period

Change in 1 repetition maximum and 10 repetition maximum tests in dynamic leg press and biceps curl exercises, maximal force in isometric knee extension test, and flight time in countermovement jump.

Vastus lateralis and biceps brachii muscle cross-sectional area (mm2) and thickness (mm) at the mid-limb will be assessed using a B-mode axial plane ultrasound (model SSD-α10, Aloka, Tokyo, Japan) with a 10 MHz linear-array probe (60 mm width) in extended-field-of-view mode (23 Hz sampling frequency).

Change in upper and lower limb muscle CSA after 20-week continuous RT period and two 10-week RT periods separated by a 10-week DT period

Vastus lateralis and biceps brachii muscle cross-sectional area (mm2) and thickness (mm) at the mid-limb will be assessed using a B-mode axial plane ultrasound (see above).

BIA (InBody 770, Biospace Co. Seoul, Korea) method will be utilized to estimate changes in lean mass (kg).

BIA (InBody 770, Biospace Co. Seoul, Korea) method will be utilized to estimate changes in fat mass (kg).

Change in muscle fiber cross-sectional area, fiber type, mitochondrial count, and capillary density will be determined by immunohistochemistry. Anaerobic enzymes and sarcoplasmic protein contents in myofibers will be measured by Western blotting and by SDS-PAGE.

A high-throughput serum Nuclear Magnetic Resonance (NMR) metabolomics platform will be used for the absolute quantification of serum lipids and metabolite profile. The NMR metabolome assay yields at least 220 different metabolites including amino acids, apolipoproteins, cholesterol, fatty acids, glycolysis related metabolites, and inflammation markers. Serum metabolomics will be quantified from acquired fasting blood samples by Nightingale (Finland) company, specializing in metabolomics quantification. Further, statistical analysis of provided data will be handled at Finnish Institute for Health and Welfare (THL, Finland). In addition, mass spectrometry based targeted/untargeted metabolomics analysis will be conducted from serum and/or muscle samples if funding for those analysis is available.

Inclusion Criteria: No regular resistance training history BMI within range 18.5-30 kg/m2 Participants must be 18-40 years old No history in systematic endurance-type training (> 2 endurance exercise sessions lasting > 30 minutes per week for the last six months) non-smoker not currently consuming any anti-inflammatory drug(s) Exclusion Criteria: history of medication that could affect exercise responses use of nutritional supplements aside from those that are protein- or carbohydrate-based (ex. creatine) or basic minerals, vitamins, or fish oil products any acute or chronic illness affecting cardiovascular, respiratory, musculoskeletal and/or endocrine function any other condition that may limit the ability to perform resistance training and testing (ex. uncontrolled hypertension, diabetes, arthritic conditions, neuromuscular complications)