The Effects of Heavier- and Lighter-load Resistance Training on Arm and Leg Muscle Mass in Young Adult Women
Condition: Skeletal Muscle Hypertrophy
MeSH terms: Hypertrophy
Study type: Interventional

Summary: 
      When you perform weightlifting, your body makes new proteins within your muscle. These new
      proteins can increase the size of the fibers within your muscle to make your muscle larger, a
      process called hypertrophy. The common convention surrounding gains in muscle mass and
      strength are that higher-loads (i.e. heavier weights) used for fewer repetitions are better
      for increasing strength and lower-loads (i.e. lighter weights) used for higher repetitions
      are better for increasing muscle mass. However, recent research has found that when higher-
      and lower-loads are used when participants exercise until volitional fatigue (i.e. cannot
      perform another repetition), muscle mass and strength increases are similar regardless of
      using a higher- or lower-load. Many of these studies have examined this effect in males with
      fewer studies examining the effects of higher- and lower-load training in females when
      assessing changes in muscle mass, strength, and muscle endurance.

      Further, it has been shown that there is substantial individual variation in response to
      resistance exercise training where individuals can be broadly categorized as higher- or
      lower-responders to resistance exercise training. This study aims to explore how the muscle
      mass, strength, and muscle endurance of females are impacted by both higher- and lower-loads
      while also exploring how individuals may respond to the training interventions.
    

Detailed description: 
      The study will be a total of 12 weeks in total duration. Weeks 1 and 12 will include testing
      assessments of skeletal muscle mass, muscle strength, and muscle endurance. Weeks 2-11 will
      be comprised of the resistance training intervention wherein participants will train thrice
      weekly at the Chan Gunn Pavilion research laboratory at the University of British Columbia.

      Resistance training sessions will include unilateral knee extensions and unilateral dumbbell
      bicep preacher curls with each being performed for three sets. Limbs assigned to train with
      higher-loads will perform between 8-12 repetitions per set and limbs assigned to train with
      lower-loads will perform between 20-25 repetitions per set. Participants will rest 90 seconds
      between sets and 120 seconds between exercises. Each exercise will be performed in its
      entirety before moving on to the next.

      Participants will also be supplemented with whey protein which will be ingested twice daily
      during the resistance training phase.
    

Intervention name(s): Higher-load resistance training; Lower-load resistance training
Intervention type(s): Other; Other
Intervention description(s): This intervention will have one arm and one leg of each participant training with ~80% of their one repetition maximum; This intervention will have one arm and one leg of each participant training with ~30% of their one repetition maximum
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: A within participant design will be used wherein each participant will be assigned to both training conditions. One arm and one leg will train with higher-loads and one arm and one leg will train with lower-loads; limb allocation will be randomized.
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Skeletal Muscle; Hypertrophy; Strength; Muscle Endurance