The Effect of Peak Force At Long and Short Muscle Lengths and the Impact on Muscle Growth and Strength

Summary

The goal of this clinical trial is to learn the effect of applying peak force/resistance to skeletal muscles during resistance exercise training in young and healthy adults. Participants will undergo two types of resistance training conditions that are randomly assigned to the left arm and leg and the right arm and leg. The LONG condition refers to Prime Fitness machines set to setting number '3' which applies peak force at a long muscle length. The SHORT condition refers to Prime Fitness machines set to setting number '2' which applies peak force at a short muscle length.

The main questions the trial aims to answer are:

1. Does applying peak force at a longer or shorter muscle length during resistance exercise training result in greater muscle growth?
2. Does applying peak force at a longer or shorter muscle length during resistance exercise training result in greater muscle growth?

We hypothesize that:

1. LONG will induce greater hypertrophy compared to SHORT conditions
2. LONG will result in greater increases in 1RM strength compared to SHORT
3. LONG and SHORT training will result in angle specific increases in isokinetic strength
4. Muscle oxygenation will decline to a greater degree during LONG compared to SHORT exercise and this will be maintained between weeks 1 and 12 of training

The investigators will compare the change in muscle volume and muscular strength between the LONG and SHORT training conditions, which each participant will have the left arm and leg as well as the right arm and leg randomly assigned to either exclusively LONG or SHORT conditions.

Participants will:

* Resistance train the left and right arm and leg with two separate conditions; LONG and SHORT for 12 weeks, with the first and last weeks dedicated to only strength testing (Isotonic and Isokinetic) and measuring muscle volume via magnetic resonance imaging (MRI)
* Visit the gym for resistance training 2 times per week
* Visit the UBC MRI Research Facility in weeks 1 and 12 for MRI of muscle volume

Conditions

• Muscle Hypertrophy
• Muscular Strength

Interventions

OTHER

LONG and SHORT Resistance Training

One side of the body will be randomly assigned to perform exercises in position 3 (LONG) with the other randomly assigned to position 2 (SHORT) of Prime Fitness horizontal shoulder adduction, horizontal shoulder abduction, shoulder abduction and hip extension. Each exercise will include 1 warm up set at 50% 1RM followed by 4-5 sets of 8-12 repetitions per limb. 2 minutes of rest between sets on the same side of body will be administered as the participant will alternate between the right and left limb. The left and right side limbs will alternate each session in which one starts each exercise, resulting in 10 training sessions each where the left and right limbs starts first on each exercise. All sets will be performed to momentary failure. A Dynamic Double Progression will be employed to ensure intensity is maintained.

OTHER

Maximal Isotonic Strength Testing (1RM)

Each limb will perform a 1RM strength test with each Prime Fitness machine training horizontal shoulder adduction, horizontal shoulder abduction, shoulder abduction and hip extension respectively. Each machine will be set to position 1 (maximal load in mid-range). Testing will occur in weeks 1 and 12 of the study with the non-dominant arm and leg tested before the dominant arm and leg in each exercise. Participants self-selects first warm up set with a weight that is performed between 6-10 repetitions on both limbs. Rest for 1 minute between limbs and subsequent set. A weight is then selected by research staff to perform 3 repetitions with based on previous set. Load is now increased until 1RM is achieved. Rest periods should remain at least 1 minute alternating between limbs, with 1RM being complete within 3-5 attempts. Participant will rest 2-5 minutes before starting testing on the next exercise. Repeat for all exercises. Use pre testing data to inform 1RM attempts for post testing.

OTHER

Isokinetic Strength Testing

Participants will engage in isokinetic strength testing on the isokinetic dynamometer (Biodex) in weeks 1 and 12 for each of the four movements: Horizontal shoulder adduction, horizontal shoulder abduction, shoulder abduction and hip extension. Participants will perform each movement unilaterally. Participants will start with the non-dominant arm and leg for each movement. Each movement will be tested through A maximal active range of motion. Participants will complete 10 sub-maximal repetitions to allow familiarization each movement. After a 2-minute rest, participants will complete 3 maximal concentric and eccentric repetitions with 30 seconds rest at 30 degrees per second before the Biodex is reset for the next movement.

OTHER

Muscle Oxygenation

During the first and last LONG and SHORT training session (visit 5 and visit 24), A near infrared spectroscopy sensor (NIRS device) (Trainred) will be affixed to the muscle belly of the deltoid during the lateral raise exercise to measure muscle oxygenation.

Sponsors & Collaborators

• University of British Columbia

  lead OTHER

Principal Investigators

• Dr. Cameron Mitchell · University of British Columbia, School of Kinesiology

Study Design

Allocation

NA

Purpose

OTHER

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

19 Years

Max Age

30 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2024-12-01

Primary Completion

2025-05-01

Completion

2025-05-30

Countries

• Canada

Study Locations