The age-related loss of skeletal muscle mass (i.e. sarcopenia)and muscle performance (i.e. strength and power), decreases functionality and the ability to perform activities of daily living. Therefore, lifestyle interventions which may improve aging muscle health are important (i.e. resistance training and creatine supplementation). High-velocity resistance training (HVRT) has been shown to increase muscle mass and muscle performance in aging adults. Creatine (CR), a compound naturally found in red meat and seafood, has also been shown to increase muscle mass and muscle performance in aging adults. No study has examined the combined effects of HVRT and CR supplementation in aging adults. This study may determine whether this lifestyle intervention is effective to combat sarcopenia.

Purpose and hypothesis: The purpose of this thesis is to compare the effects of HVRT and CR supplementation to HVRT and placebo in healthy aging males. It is hypothesized that HVRT and CR supplementation will increase muscle mass, strength, power and tasks of functionality compared to HVRT and placebo.

Participants: An a priori power analysis (G*Power v. 3.1.5.1) indicated that 34 participants are required. This is based on a moderate effect size (Cohen's d = 0.25), an alpha level of .05, a ß-value of 0.8 for a repeated measures, within-between analysis of variance (ANOVA) design. Males (≥ 50 years) who are not engaged in resistance training for ≥ 6 weeks prior to the start of the study will be recruited. Participants will be informed of the risks and purposes of the study before written consent is obtained. The study will be approved by the Research Ethics Board at the University of Regina.

Methods and Research Design: The study will be a double-blind, repeated measures design. Participants will be randomized on a 1:1 basis to one of two groups: HVRT and CR or HVRT and placebo. The CR dosage will be 0.1g/kg/day as this dosage is effective for increasing muscle mass in aging males without resulting in adverse effects. On training days, participants will consume their supplement immediately after each training session mixed in water, juice or milk as post-exercise CR ingestion enhances its uptake into muscle and promotes increased muscle mass.

High-velocity Resistance Training Program: Participants will perform 3 sets of repetitions at 80% baseline 1-repetition maximum (1-RM) for the leg press, leg extension, leg curl, chest press, biceps curl, and triceps extension 2 times per week, for 8 weeks. Participants will perform the concentric phase of each muscle contraction as quickly as possible and will take 2 seconds to perform the eccentric phase.

Primary Dependent Variables

1. Muscle thickness: Muscle thickness will be assessed by B-mode ultrasound (LOGIQ e, GE Medical Systems) on knee flexors, knee extensors, elbow flexors, and elbow extensors in the Aging Muscle and Bone Health Laboratory, University of Regina.
2. Muscle strength: Leg press and chest press strength will be assessed using a 1-RM testing procedure in the Aging Muscle and Bone Health Laboratory, University of Regina.
3. Muscle power: Torque (Nm) and power (watts) will be measured for the knee flexors and extensors using an isokinetic dynamometer (Biodex System 3, Biodex Medical Systems Inc.).
4. Functionality tests: Dynamic balance will be measured as the time taken to perform backwards tandem walking over a distance of 6m on a 10cm-wide board that is raised about 4cm off the ground. Walking speed will be assessed by the time needed to walk an 80 m course.

Statistical Analyses: A 2 (group: CR vs. placebo) x 2 (time: pre- vs. post-training) repeated measures ANOVA will be used to determine differences between groups over time for the dependent variables. A one-factor ANOVA will be used to assess baseline characteristics and total training volume between groups. Significance will be set at an alpha level of 0.05 and all results will be expressed as means ± standard deviation. The magnitude of the difference between significant means will be determined by eta squared (η2). Statistical analyses will be performed using IBM SPSS Statistics, v. 24.

Inclusion Criteria:

• Males (≥ 50 years) who are not engaged in supervised resistance training for ≥ 6 weeks prior to the start of the study will be recruited to participate.

Exclusion Criteria:

• Participants will be excluded if they have taken medications that affect muscle biology or creatine monohydrate ≤ 12 weeks prior to the start of the study
• If they have a history of fragility fractures; diseases that are known to affect muscle biology (i.e. corticoids)
• If they suffer from severe osteoarthritis
• If they are currently participating in moderate-vigorous resistance training (≥ 3 times per week)
• If they are vegetarian
• If they are planning to travel during the study period for greater than 2 weeks duration at a time.
• Participants with kidney or liver abnormalities will be excluded.

The response to creatine supplementation is inconsistent between males and females. Females may not experience the same gains in muscle mass and strength following creatine supplementation and resistance training compared to males. Although speculative, females may have higher initial intramuscular creatine stores than males which make them less responsive to supplementation. Furthermore, creatine appears to have no effect on muscle protein kinetics in females. Therefore, for the purpose of this study, only healthy aging males will be recruited.

A research assistant who is not involved in the study in any other way will be responsible for randomization.