Effects of Graded Protein Intake on Body Composition in Older Adults

Effects of Graded Protein Intake and Resistance Training on Body Composition in Older Adults

This clinical trial is intended to evaluate the effects of protein intake graded to resistance training volume over a 10-week period on macroscopic skeletal muscle adaptations and body composition. Briefly, all participants will complete a progressive resistance training protocol for 10 weeks, with one group consuming a constant amount of total daily protein (RDA of 0.8g/kg/day) to serve as an active comparator. The alternative group will consume total daily protein and protein supplement in a graded manner designed to increase as overall training volume increases. Protein intake and resistance training protocols are described in full elsewhere. The investigators hypothesize that the graded protein intake group will see larger benefits to skeletal muscle function, size, and body composition than the active comparator.

It is well established that aging induces a loss of skeletal muscle across a lifespan. The two primary considerations in attenuating this loss of skeletal muscle are nutritional intake, specifically protein consumption, and physical activity levels, specifically resistance training. Both of these factors have been shown to improve skeletal muscle adaptation outcomes in older adults. One primary consideration in the skeletal muscle loss in older adults is the concept of anabolic resistance, suggesting that older adults require a greater amount of protein consumption to elicit similar rates of muscle protein synthesis as compared to their younger counterparts. From this study, the investigators hope to reveal the effect between protein intake graded to resistance training vs constant protein intake at the recommended daily allowance in conjunction with the same resistance training protocol on body composition. The purpose of this study is to examine the skeletal muscle adaptations that occur in older adults consuming protein graded to resistance training volume as compared to older adults who consume protein at a constant level while resistance training (RT). Our hypotheses are:

1. Protein intake graded to RT volume will enhance skeletal muscle adaptation in older adults to a greater degree than those consuming protein at a constant rate, as measured via lean soft tissue mass assessed by dual energy x-ray absorptiometry (DXA)
2. Older adults consuming protein graded to RT volume will enhance strength to a greater degree than those consuming protein at a constant rate, as measured via isokinetic dynamometry and 3 repetition maximums of select exercises.
3. Older adults consuming protein graded to RT volume will see a greater change in muscle tissue thickness compared to those consuming protein at a constant rate, as measured via muscular ultrasound.

Community dwelling older adults (>55 years; men and women) who have not adhered to a progressive RT program in the last 3 months will be recruited for participation in this pilot study (n=20). All women recruited will be post-menopausal. In an initial telephone screening, participants will be assessed for eligibility criteria, and it will also be determined whether they are willing to be randomized into either of the two groups. The requirements of each intervention group will be explained in detail. Participants will be assessed for willingness to make necessary alterations to their diet, willingness to adhere to RT protocol, and willingness to consume the necessary amount of protein supplement. Once participants are recruited, they will be subsequently randomized using a web based program (https://www.randomlists.com/team-generator) wherein group assignments will be placed in numbered envelopes and opened by an independent researcher. This will be used to randomize participants to one of the two experimental groups. This randomization and assignment will be completely random, and not stratified to any subset of variables. All groups will complete the same resistance training protocol. Overall study design, resistance training protocol, detailed nutritional protocols are outlined in the tables submitted in supporting documents. Briefly, all participants will be assigned a 10-week RT protocol, adhering to the 2009 Position Stand from the American College of Sports Medicine, based on their baseline tested 3 repetition maximums. Participants in the graded protein intake group will be provided a certain amount of Whey Protein (WP) supplement to consume post-training session on training days, and between meals on non-training days. The control group will not receive WP supplement, whereas the intervention group will receive 25 g of WP supplement per day beginning at week 1 and will progress to 75g of WP supplement/day by week 10 of the intervention. This supplementation will assist overall protein intake, as the control group will consume a constant 0.8g/kg/day throughout the course of the study and the intervention group will consume 0.8 g/kg/day at week 1 and progress to 2.2 g/kg/day at week 10. For example, an 80 kg individual will consume a total of 176 g of protein/day at week 10, with 75 g of this protein coming from supplementation, and the additional 76g coming from dietary intake throughout the day. Should prescribed supplementation exceed the 2.2 g/kg/day threshold, adjustments will be made in protocol to accommodate proper protein intake. The investigators expect no adverse effects on renal and liver function as a result of increased protein intake based on the findings of a recent meta analysis by Devries et al. (2018). Additionally, participants will consume a ~500 kcal surplus per day to ensure adequate energy for protein accretion and recovery.

Covid-19 Protocol:

Investigators, study staff, and participants alike share responsibility for the health and safety of each other in an exercise/testing space. Maintaining a consistent six feet of distance; wearing face coverings that cover our mouths and noses; limiting our gathering sizes; and isolating or quarantining when ill or exposed to someone with the virus are Wake Forest University directives and policies investigators, study staff, and participants all must follow. Participants are encouraged to visit Our Way Forward to stay informed about the latest guidance and stay up to date regarding public health policy. The study team will follow guidelines set forth by public health officials.

Specifically, in this study, investigators, staff, and participants will mitigate the risks of virus transfer and take care of our community by abiding by the following safety directives:

• maintain six feet of distance at all times when feasible.
• wear a face covering for the entirety of time indoors and out. This face covering should cover your mouth and your nose, and adhere to our University face covering policy (no face shields without masks; no neck gaiters; no bandanas; and no masks, including N95, with a one-way valve).
• stay out of sessions when sick or after being exposed to someone who is sick.

In this study, any participant who does not follow these requirements will be asked to follow the safety directives.

Participants will be offered a mask should they not have one.

If participants do not comply, they will be asked to leave the study space out of an abundance of caution in regard to other participants and study staff.

Inclusion Criteria:

• >55 years of age
• Able to provide transportation to resistance training sessions and data collection days
• Able to read and write in English
• Have not adhered to a progressive resistance training program in the past three months
• Able to ambulate without assistance
• Willingness to provide informed consent and participate in the intervention
• Do not have a comorbidity that could be exacerbated by study protocol, such as severe cardiovascular disease, type I or type II diabetes, renal failure, liver disorders, or thyroid disease OR can provide explicit written consent from a primary care physician indicating that they can participate in this study.

Exclusion Criteria:

• Currently consuming an agent known to be confounding to skeletal muscle adaptation, such supplements that include, but are not limited to creatine monohydrate, growth hormone, or testosterone replacement therapy
• Currently undergoing cancer treatment
• Used whey protein supplements within the past three months
• Pre-menopausal status for women