ContraTRAIN - a Validation Study of Contralateral Training Protocols
Condition: Healthy
Study type: Interventional

Summary: 
      This study aims to validate the use of contralateral designs in studies of effects of
      resistance exercise. It will recruit healthy young (18-35 years) individuals, which will be
      allocated to 4 experimental groups. In two of the experimental groups, 3x10 or 6x10
      repetitions of heavy resistance exercise on one leg will be combined with no training of the
      other leg for 7 weeks. In the third group, 3x10 repetitions of heavy resistance exercise on
      one leg will be combined with 6x10 repetitions of heavy resistance exercise on the other leg
      for 7 weeks. In the fourth group, which serves as a control group, a period of no training
      (similar in length to the training period of groups 1-3; 7 weeks), before both legs will
      train 3x10 repetitions of heavy resistance exercise in an unilateral manner.
    

Detailed description: 
      Our understanding of how exercise affects muscular adaptations at the cellular and molecular
      level comes from the use of skeletal muscle biopsies. Such studies are met by several
      challenges, including its invasive nature, costs of muscle analyses, large inter-participant
      variability in response to exercise and a limited number of subjects (related to ethical
      concerns regarding exposing participants to biopsies). Consequently, studies often include
      small sample sizes, resulting in low statistical power. This poses a great challenge to the
      field of exercise physiology. While increasing sample size may not always be feasible,
      employing alternative designs may offer a way to increase the statistical power. An example
      of such a design is the so-called cross-over design, wherein participants serve as their own
      control thereby reducing the inter-participant variation. An interesting variant of the
      cross-over design is the unilateral or contralateral exercise model. In such designs, each of
      the participant's limbs (e.g. legs) are randomly allocated to perform different types of
      training/treatments in close temporal proximity. This design obliterates the need for a
      wash-out period and removes the potential effects of confounding factors such as diet,
      activity and sleep decreases. Thus, resources, time spent and variability can be reduced.
      However, validation of such studies is lacking.

      In an effort to validate a contralateral training design, the investigators will recruit
      young (18-35 years) healthy individuals to 4 groups performing unilateral progressive
      strength training; (1) one leg with no training and one leg with 3x10 maximal repetitions,
      (2) one leg with no training and one leg with 6x10 maximal repetitions, (3) one leg with 3x10
      maximal repetitions and one leg with 6x10 maximal repetitions and (4) a control group with an
      initial period of no training (similar in length to the training period of groups 1-3)
      followed by a period of 3x10 maximal repetitions on each leg. Leg training will consist of
      one-legged leg press and one-legged knee extensions. All groups, except the control group
      (during the no-training control period), will train the upper body by 3x10 maximal
      repetitions in bench press and lying rowing. Prior to the 7 week training intervention, all
      four groups will go through a 3-week period of familiarization to training and repeated
      testing (4 test time points for performance measures).

      This design allows us to investigate the benefits of a contralateral design compared to the
      more common two-group design, the intra-individual variation vs the inter-individual
      variation, the potential contralateral effect of training one leg on the physiology and
      functional abilities of the non-trained leg, and whether or not these perspective are
      affected by training volume. We will also investigate whether participant classification into
      low or high responders is universal across several measures of muscle mass and strength, and
      between different training volumes. Further, by measuring several hypertrophy-related
      outcomes (e.g. changes in ribosome volume, activation of satellite cells and transcriptional
      changes), the investigators will extend previous findings regarding the effects of training
      volume on these variables and their ability to predict training outcomes.
    

Intervention name(s): Strength training 3x10RM + no training; Strength training 6x10RM + no training; 3x10RM + 6x10RM
Intervention type(s): Other; Other; Other
Intervention description(s): Progressive unilateral strength training 3 times per week for 3 + 7 weeks. One leg exercises with 3 sets of 10 maximal repetitions, the other leg does not exercise.; Progressive unilateral strength training 3 times per week for 3 + 7 weeks. One leg exercises with 6 sets of 10 maximal repetitions, the other leg does not exercise.; Progressive unilateral strength training 3 times per week for 3 + 7 weeks. One leg exercises with 3 sets of 10 maximal repetitions, the other leg exercises with 6 sets of 10 maximal repetitions.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Basic Science
Keywords: Contralateral; Strength training; Muscle