Effects of Increased Greek Yogurt Consumption in Youth and Young Adult Athletes

Inflammation Clinical Trial

Official title:

Effects of Increased Greek Yogurt Consumption on Circulating Markers of Bone Metabolism and Inflammation in Youth and Young Adult Athletes

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT05922462
• Other study ID #: REB 22-303
• Status: Recruiting
• Phase: N/A
• Start date: September 1, 2023
• Est. completion date: April 30, 2026

Study information

• Verified date: October 2023
• Source: Brock University
• Contact: Panagiota Klentrou, PhD
• Phone: 9056885550
• Email: nklentrou[@]brocku.ca
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

Physical activity and dairy consumption during growth and development are each known to improve peak bone mass in young adults. Peak bone mass, the maximum amount of bone a person will have in their lifetime, is typically reached in the early 20's in females and late 20's in males. However, evidence suggests that young people do not consume enough dairy to maximize their bone mass. The resulting effect in peak bone mass can be troublesome, particularly for athletes, such as volleyball players. This study aims to determine whether increased dairy consumption combined with training can have an additive effect on the physiology of young competitive athletes. Specifically, we will examine whether Greek yogurt consumption will lead to beneficial changes in bone metabolism and inflammation, in adolescent and young adult, male and female athletes, similar to those observed with whey protein supplementation. Many athletes choose exclusively protein supplementation and miss out on other nutrients vital for healthy growth and development. By examining the benefits of Greek yogurt across different athlete age groups and sexes, this work will help reshape the attitudes, beliefs, and behaviours surrounding diet of young athletes.

Description:

Purpose: This study will investigate the effect of chronic high-impact exercise training and GY consumption on bone metabolism and inflammation compared with isonitrogenous/isocaloric whey protein (WP) supplementation (a common practice by athletes) in youth and young adult athletes.

Participants: A total of 40 varsity athletes (aged 17-22 years; 20 males, 20 females) will be recruited in year one, and 40 club athletes (aged 15-16 years; 20 males, 20 females) will be recruited in year two. Participants will be recruited from the varsity teams at Brock and club teams in the Niagara area (one male and one female team from each age group). All participants (and the parents/guardians of club athletes) will provide written informed consent in order to be included in the study. Potential participants will complete an online health screening questionnaire to document general health and individual and family health history. It will also be used to record information on medication use and for female participants to report menstrual history and status, as well as the use and type of oral contraceptives (brand and hormone). Athletes will be excluded from the study if they are injured and unable to participate in practices, have an allergy to dairy foods/dairy protein or have been diagnosed with lactose intolerance.

Athletes from each team will be randomly assigned to either the GY intervention group or the WP comparison group. Thus, eight treatment groups (n = 10 athletes per group):

• GY x Female Varsity

• GY x Male Varsity

• GY x Female Club

• GY x Male Club

• WP x Female Varsity

• WP x Male Varsity

• WP x Female Club

• WP x Male Club

Study Design and Procedures: The study will follow a randomized controlled parallel design over a two-year period. At the beginning of their training season, varsity (year one) and club athletes (year two) will be invited to participate in this 24-week study, consisting of an 8-week control condition (September to November) and a 16-week intervention condition (November to March).

Control Condition: During the 8-week control condition, participants will be instructed to follow their typical, habitual diet and training protocols. Seven-day food records will be completed by participants and assessed by a registered dietitian (RD) using the Keenoa online food tracker application in order to determine baseline dairy, calcium, and protein, intake levels in their habitual diets during the competitive season.

Intervention Condition: During the 16-week intervention condition, participants will be randomly assigned to either the GY or WP group. To monitor adherence, all participants will be asked to log their daily GY or WP intake.

Participants in the GY group will be instructed by the RD to consume 2 servings/day of 175 g commercially available GY (0% MF, flavoured, 130 calories, 17 g protein, 225 g calcium; e.g., OIKOS High Protein GY) for a total of 16 weeks. This serving amount has been used in the investigators' previous study in adolescent female soccer players, but slightly lower than in recreationally active adult males. For their convenience, the athletes will be provided with appropriate scoops to measure out 175 g of GY per serving of the larger 650 g commercially available, pre-packaged containers. Although it is recommended to consume the two servings morning and night, to increase ecological validity and strengthen the feasibility of the intervention, the timing of the servings will be flexible to facilitate the training and competition routines. For the same reasons, the athletes will be able to choose the flavour of their GY.

Participants in the WP group will follow a similar consumption schedule but will be instructed by the RD to consume two servings/day of 2/3 of a scoop of commercially available WP powder (flavoured, ~29 g, 120 calories, 19 g protein, 112.5 g calcium; e.g., PURE Whey Protein, Walmart) for a total of 16 weeks. The WP scoop will be dissolved in water (e.g., 1 g of WP isolate to 10 mL of water, as recommended by the manufacturer). This protein dose is similar to the previous dose in young swimmers and comparable to other studies in adults. Athletes will be provided with appropriately marked scoops (corresponding to 2/3 of the manufacturer scoop) to measure their single servings.

For the duration of both the GY and WP intervention condition (16 weeks), participants will be asked to maintain their habitual intakes (as per what they were doing in the control condition). That is, they will not be asked to stop any other protein supplementation they may have been taking during the control condition. The GY/WP servings during the intervention condition will be added to their habitual diet. Participants will be asked to track their daily dietary intake several times during the study (weeks 0, 8, 16, and 24), including all food, liquids, and supplements, using the Keenoa online food tracker application. Despite the added energy intake from the GY/WP, we do not expect any (significant) weight gain with the added ~300 calories per day due to the athletes' high energy expenditures.

Blood Samples: All participants will be instructed not to consume any food or liquids (except water, as needed) 8 hours prior to the time of their blood draw, not to exercise for 12 hours prior to the blood draw, and not to make any changes to their normal routines. A total of 10 mL of blood will be collected from an antecubital vein by a certified phlebotomist or registered nurse using a standard venipuncture technique at four timepoints: weeks 0, 8,16, and 24. All blood samples will be centrifuged at 1,405 x g at 4°C for 10 min. Serum and plasma will be aliquoted into pre-labeled Eppendorf tubes and stored at -80°C until analysis. The serum concentrations of markers and regulators of bone remodelling (osteocalcin, P1NP, CTX, OPG, sclerostin, RANKL, PTH), and the plasma concentrations of inflammatory cytokines (IL6, IL10, TNFα), sex hormones (estrogen, testosterone) and growth factors (IGF-1) will be measured in duplicate using commercially available ELISA kits.

Bone Properties: Transaxial quantitative ultrasound (QUS; Sunlight Omnisense™ 7000S, Sunlight Medical, Israel) will be used at weeks 0, 8, 16, and 24 to assess bone strength by measuring the speed of sound (SOS; m/s) along the bone at the distal 1/3 of the radius and at the mid-tibia of the dominant limbs, as previously described. The strength of bone is determined by the shortest time elapsed between the transmission and reception of the signal transmitted, with faster transmissions reflecting stronger bone. QUS can be used for the assessment of bone strength and is particularly suited for studies in healthy populations as it is portable, relatively inexpensive, and non-invasive (no radiation exposure). Because QUS measures the SOS along the bone it is not affected by bone size, thus allowing for comparisons between participants of different sizes. QUS has been previously used by the principal investigator and others to demonstrate the effect of exercise training or physical activity on various bones and in different age groups, including children.

Body Composition: Body mass (kg) and body composition will be measured using bioelectrical impedance analysis (BIA; InBody520 bioelectrical impedance analysis system following standard procedures.

Dietary Assessment: Participants' dietary intake, including energy intake, as well as macronutrient, micronutrient, vitamin, and supplement intakes will be recorded at weeks 0, 8, 16, and 24 using the Keenoa food application. Using the same application, participants will be asked to log their daily GY or WP intake in order to monitor adherence. In addition, participants' knowledge of nutrition will be assessed at the beginning (week 0) and completion of the study (week 24) using the self-reported 97-item GeSNK. The GeSNK encompasses 64 items assessing general and sport-specific nutrition knowledge, with the aim of exploring knowledge regarding macro- and micronutrients in various food choices, and awareness of diet-health associations, knowledge of fluid replacement, supplement intake, and food choices in regard to sport recovery meals. The GeSNK will be completed online along with the medical screening questions used to screen for inclusion criteria.

Training Volume and Physical Activity: Training logs will be collected from participants and coaches every week throughout the study. In addition, leisure-time physical activity will be assessed using the GSLTPAQ modified for the purpose of this study. The GSLTPAQ evaluates leisure-time physical activity using indicators of the intensity of exertion as light, moderate, vigorous, or very vigorous. Weekly physical activity metabolic equivalents are estimated based on the number of 15 min blocks at each intensity level multiplied by assumed energy consumption values. The GSLTPAQ is a standardized tool that has been demonstrated to be valid and reliable in children, adolescents, and adults.

Statistical Analysis: The data analysis with all ages combined using age and/or training volume as covariates will be performed leading to at least one additional publication and presentation. Prior to analysis, all variables will be tested for normality by visual inspection of histograms and z-scores (± 3) and by assessing the skewness and kurtosis (± 3). For dependent variables that are normally distributed, a series of two-way repeated measures analysis of variances with sex or age/training volume as covariates (RM-ANCOVAs) will be used to examine changes over time with main effects and interactions for the intervention conditions (GY vs WP) and time (0, 8, 16, and 24 weeks) on body composition and biochemical markers. In the event of a significant interaction or a main effect for time, posthoc pairwise comparisons will be performed with Bonferroni adjustment for multiple comparisons. If the assumption of sphericity is violated, the Greenhouse Geisser correction factor will be used. Dependent variables that may not be normally distributed will be log-transformed before the analysis. The significance level will be set at p <0.05.

Sample Size: Using G*Power analysis for an RM-ANCOVA (2 intervention groups, 4 timepoints, sex as covariate), we calculated that a total sample size of n = 36 (i.e., 18 per intervention group) would be required to detect a medium effect of partial η2 = 0.06 with a power of (1-β) = 0.90, and a probability level of p = 0.05. Thus, the proposed total of 40 participants (40 varsity and 40 club athletes) is more than adequate to detect significant effects and interactions, while allowing for a 20% attrition rate.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 40
• Est. completion date: April 30, 2026
• Est. primary completion date: June 30, 2025
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 15 Years to 22 Years

Eligibility

Inclusion Criteria:

• Competitive youth or varsity athletes

Exclusion Criteria:

• Presence of injury

• Inability to participate in practices

• Allergy to dairy foods/dairy protein or

• Diagnosis with lactose intolerance

Related Conditions & MeSH terms

• Bone Diseases, Developmental
• Bone Growth Abnormal
• Inflammation

Intervention

Dietary Supplement:
• Greek yogurt
For 16 weeks, athletes will consume 2 servings/day of 175 g GY (0% MF, flavoured, 130 calories, 17 g protein, 225 g calcium; e.g., OIKOS High Protein GY)
• Whey protein
For 16 weeks, athletes will consume 2 servings/day of 2/3 of a scoop of commercially available WP powder (flavoured, ~29 g, 120 calories, 19 g protein, 112.5 g calcium; e.g., PURE Whey Protein, Walmart)

Locations

Country	Name	City	State
Canada	Brock University	St. Catharines	Ontario

Sponsors (2)

Lead Sponsor	Collaborator
Brock University	York University

Country where clinical trial is conducted

Canada, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Osteocalcin	Morning, fasted, resting serum levels of the bone remodelling marker osteocalcin (ng/ml)	Baseline (week 0)
Primary	Osteocalcin	Morning, fasted, resting serum levels of the bone remodelling marker osteocalcin (ng/ml)	End of control period and pre-intervention (week 8)
Primary	Osteocalcin	Morning, fasted, resting serum levels of the bone remodelling marker osteocalcin (ng/ml)	Middle of intervention period (week 16)
Primary	Osteocalcin	Morning, fasted, resting serum levels of the bone remodelling marker osteocalcin (ng/ml)	Completion of intervention period (week 24)
Primary	Amino-terminal propeptide of type I collagen (P1NP)	Morning, fasted, resting serum levels of bone formation marker P1NP (pg/ml)	Baseline (week 0)
Primary	Amino-terminal propeptide of type I collagen (P1NP)	Morning, fasted, resting serum levels of bone formation marker P1NP (pg/ml)	End of control period and pre-intervention (week 8)
Primary	Amino-terminal propeptide of type I collagen (P1NP)	Morning, fasted, resting serum levels of bone formation marker P1NP (pg/ml)	Middle of intervention period (week 16)
Primary	Amino-terminal propeptide of type I collagen (P1NP)	Morning, fasted, resting serum levels of bone formation marker P1NP (pg/ml)	Completion of intervention period (week 24)
Primary	Osteoprotegerin (OPG)	Morning, fasted, resting serum levels of bone formation regulator OPG (pg/ml)	Baseline (week 0)
Primary	Osteoprotegerin (OPG)	Morning, fasted, resting serum levels of bone formation regulator OPG (pg/ml)	End of control period and pre-intervention (week 8)
Primary	Osteoprotegerin (OPG)	Morning, fasted, resting serum levels of bone formation regulator OPG (pg/ml)	Middle of intervention period (week 16)
Primary	Osteoprotegerin (OPG)	Morning, fasted, resting serum levels of bone formation regulator OPG (pg/ml)	Completion of intervention period (week 24)
Primary	C-telopeptides of type I collagen (CTX)	Morning, fasted, resting serum levels of bone resorption marker CTX (ng/ml)	Baseline (week 0)
Primary	C-telopeptides of type I collagen (CTX)	Morning, fasted, resting serum levels of bone resorption marker CTX (ng/ml)	End of control period and pre-intervention (week 8)
Primary	C-telopeptides of type I collagen (CTX)	Morning, fasted, resting serum levels of bone resorption marker CTX (ng/ml)	Middle of intervention period (week 16)
Primary	C-telopeptides of type I collagen (CTX)	Morning, fasted, resting serum levels of bone resorption marker CTX (ng/ml)	Completion of intervention period (week 24)
Primary	Sclerostin	Morning, fasted, resting serum levels of bone resorption regulator sclerostin (pg/ml)	Baseline (week 0)
Primary	Sclerostin	Morning, fasted, resting serum levels of bone resorption regulator sclerostin (pg/ml)	End of control period and pre-intervention (week 8)
Primary	Sclerostin	Morning, fasted, resting serum levels of bone resorption regulator sclerostin (pg/ml)	Middle of intervention period (week 16)
Primary	Sclerostin	Morning, fasted, resting serum levels of bone resorption regulator sclerostin (pg/ml)	Completion of intervention period (week 24)
Primary	Receptor activator of nuclear factor kappa-? ligand (RANKL)	Morning, fasted, resting serum levels of bone resorption regulator RANKL (pg/ml)	Baseline (week 0)
Primary	Receptor activator of nuclear factor kappa-? ligand (RANKL)	Morning, fasted, resting serum levels of bone resorption regulator RANKL (pg/ml)	End of control period and pre-intervention (week 8)
Primary	Receptor activator of nuclear factor kappa-? ligand (RANKL)	Morning, fasted, resting serum levels of bone resorption regulator RANKL (pg/ml)	Middle of intervention period (week 16)
Primary	Receptor activator of nuclear factor kappa-? ligand (RANKL)	Morning, fasted, resting serum levels of bone resorption regulator RANKL (pg/ml)	Completion of intervention period (week 24)
Primary	Parathyroid hormone (PTH)	Morning, fasted, resting serum levels of bone related hormone PTH (pmol/L)	Baseline (week 0)
Primary	Parathyroid hormone (PTH)	Morning, fasted, resting serum levels of bone related hormone PTH (pmol/L)	End of control period and pre-intervention (week 8)
Primary	Parathyroid hormone (PTH)	Morning, fasted, resting serum levels of bone related hormone PTH (pmol/L)	Middle of intervention period (week 16)
Primary	Parathyroid hormone (PTH)	Morning, fasted, resting serum levels of bone related hormone PTH (pmol/L)	Completion of intervention period (week 24)
Primary	Interleukin-6 (IL6)	Morning, fasted, resting plasma levels of the inflammatory cytokine IL6 (pg/ml)	Baseline (week 0)
Primary	Interleukin-6 (IL6)	Morning, fasted, resting plasma levels of the inflammatory cytokine IL6 (pg/ml)	End of control period and pre-intervention (week 8)
Primary	Interleukin-6 (IL6)	Morning, fasted, resting plasma levels of the inflammatory cytokine IL6 (pg/ml)	Middle of intervention period (week 16)
Primary	Interleukin-6 (IL6)	Morning, fasted, resting plasma levels of the inflammatory cytokine IL6 (pg/ml)	Completion of intervention period (week 24)
Primary	Interleukin-10 (IL10)	Morning, fasted, resting plasma levels of the anti-inflammatory cytokine IL10 (pg/ml)	Baseline (week 0)
Primary	Interleukin-10 (IL10)	Morning, fasted, resting plasma levels of the anti-inflammatory cytokine IL10 (pg/ml)	End of control period and pre-intervention (week 8)
Primary	Interleukin-10 (IL10)	Morning, fasted, resting plasma levels of the anti-inflammatory cytokine IL10 (pg/ml)	Middle of intervention period (week 16)
Primary	Interleukin-10 (IL10)	Morning, fasted, resting plasma levels of the anti-inflammatory cytokine IL10 (pg/ml)	Completion of intervention period (week 24)
Primary	Tumour necrosis factor-alpha (TNFa)	Morning, fasted, resting plasma levels of the pro-inflammatory cytokine TNFa (pg/ml)	Baseline (week 0)
Primary	Tumour necrosis factor-alpha (TNFa)	Morning, fasted, resting plasma levels of the pro-inflammatory cytokine TNFa (pg/ml)	End of control period and pre-intervention (week 8)
Primary	Tumour necrosis factor-alpha (TNFa)	Morning, fasted, resting plasma levels of the pro-inflammatory cytokine TNFa (pg/ml)	Middle of intervention period (week 16)
Primary	Tumour necrosis factor-alpha (TNFa)	Morning, fasted, resting plasma levels of the pro-inflammatory cytokine TNFa (pg/ml)	Completion of intervention period (week 24)
Secondary	Insulin-like growth factor 1 (IGF1)	Morning, fasted, resting plasma levels of IGF1 (ng/ml)	Baseline (week 0)
Secondary	Insulin-like growth factor 1 (IGF1)	Morning, fasted, resting plasma levels of IGF1 (ng/ml)	End of control period and pre-intervention (week 8)
Secondary	Insulin-like growth factor 1 (IGF1)	Morning, fasted, resting plasma levels of IGF1 (ng/ml)	Middle of intervention period (week 16)
Secondary	Insulin-like growth factor 1 (IGF1)	Morning, fasted, resting plasma levels of IGF1 (ng/ml)	Completion of intervention period (week 24)
Secondary	Testosterone	Morning, fasted, resting plasma levels of testosterone (pg/ml) will be measured in male athletes	Baseline (week 0)
Secondary	Testosterone	Morning, fasted, resting plasma levels of testosterone (pg/ml) will be measured in male athletes	End of control period and pre-intervention (week 8)
Secondary	Testosterone	Morning, fasted, resting plasma levels of testosterone (pg/ml) will be measured in male athletes	Middle of intervention period (week 16)
Secondary	Testosterone	Morning, fasted, resting plasma levels of testosterone (pg/ml) will be measured in male athletes	Completion of intervention period (week 24)
Secondary	Estrogen	Morning, fasted, resting plasma levels of estrogen (pg/ml) will be measured in female athletes	Baseline (week 0)
Secondary	Estrogen	Morning, fasted, resting plasma levels of estrogen (pg/ml) will be measured in female athletes	End of control period and pre-intervention (week 8)
Secondary	Estrogen	Morning, fasted, resting plasma levels of estrogen (pg/ml) will be measured in female athletes	Middle of intervention period (week 16)
Secondary	Estrogen	Morning, fasted, resting plasma levels of estrogen (pg/ml) will be measured in female athletes	Completion of intervention period (week 24)
Secondary	Body mass	Body mass (kg) will be measured using Bioelectrical Impedance	Baseline (week 0)
Secondary	Body mass	Body mass (kg) will be measured using Bioelectrical Impedance	End of control period and pre-intervention (week 8)
Secondary	Body mass	Body mass (kg) will be measured using Bioelectrical Impedance	Middle of intervention period (week 16)
Secondary	Body mass	Body mass (kg) will be measured using Bioelectrical Impedance	Completion of intervention period (week 24)
Secondary	Fat mass	Fat mass (kg) will be measured using Bioelectrical Impedance	Baseline (week 0)
Secondary	Fat mass	Fat mass (kg) will be measured using Bioelectrical Impedance	End of control period and pre-intervention (week 8)
Secondary	Fat mass	Fat mass (kg) will be measured using Bioelectrical Impedance	Middle of intervention period (week 16)
Secondary	Fat mass	Fat mass (kg) will be measured using Bioelectrical Impedance	Completion of intervention period (week 24)
Secondary	Lean mass	Lean mass (kg) will be measured using Bioelectrical Impedance	Baseline (week 0)
Secondary	Lean mass	Lean mass (kg) will be measured using Bioelectrical Impedance	End of control period and pre-intervention (week 8)
Secondary	Lean mass	Lean mass (kg) will be measured using Bioelectrical Impedance	Middle of intervention period (week 16)
Secondary	Lean mass	Lean mass (kg) will be measured using Bioelectrical Impedance	Completion of intervention period (week 24)
Secondary	Body fat percentage	Body fat percentage (%) will be measured using Bioelectrical Impedance Analysis	Baseline (week 0)
Secondary	Body fat percentage	Body fat percentage (%) will be measured using Bioelectrical Impedance Analysis	End of control period and pre-intervention (week 8)
Secondary	Body fat percentage	Body fat percentage (%) will be measured using Bioelectrical Impedance Analysis	Middle of intervention period (week 16)
Secondary	Body fat percentage	Body fat percentage (%) will be measured using Bioelectrical Impedance Analysis	Completion of intervention period (week 24)
Secondary	Height	Height (cm) will be measured using a stadiometer	Baseline (week 0)
Secondary	Height	Height (cm) will be measured using a stadiometer	End of control period and pre-intervention (week 8)
Secondary	Height	Height (cm) will be measured using a stadiometer	Middle of intervention period (week 16)
Secondary	Height	Height (cm) will be measured using a stadiometer	Completion of intervention period (week 24)
Secondary	Bone Properties	Bone speed of sound (m/s) will be measured with transaxial quantitative ultrasound	Baseline (week 0)
Secondary	Bone Properties	Bone speed of sound (m/s) will be measured with transaxial quantitative ultrasound	End of control period and pre-intervention (week 8)
Secondary	Bone Properties	Bone speed of sound (m/s) will be measured with transaxial quantitative ultrasound	Middle of intervention period (week 16)
Secondary	Bone Properties	Bone speed of sound (m/s) will be measured with transaxial quantitative ultrasound	Completion of intervention period (week 24)
Secondary	Dietary intake (kcal/day)	Participants' dietary intake, including energy intake, as well as macronutrient, micronutrient, vitamin, and supplement intakes will be recorded using the Keenoa food application. Using the same application, participants will be asked to log their GY or WP intake in order to monitor adherence.	Baseline (week 0)
Secondary	Dietary intake (kcal/day)	Participants' dietary intake, including energy intake, as well as macronutrient, micronutrient, vitamin, and supplement intakes will be recorded using the Keenoa food application. Using the same application, participants will be asked to log their GY or WP intake in order to monitor adherence.	End of control period and pre-intervention (week 8)
Secondary	Dietary intake (kcal/day)	Participants' dietary intake, including energy intake, as well as macronutrient, micronutrient, vitamin, and supplement intakes will be recorded using the Keenoa food application. Using the same application, participants will be asked to log their GY or WP intake in order to monitor adherence.	Middle of intervention period (week 16)
Secondary	Dietary intake (kcal/day)	Participants' dietary intake, including energy intake, as well as macronutrient, micronutrient, vitamin, and supplement intakes will be recorded using the Keenoa food application. Using the same application, participants will be asked to log their GY or WP intake in order to monitor adherence.	Completion of intervention period (week 24)
Secondary	Energy expenditure (kcal/week)	Leisure-time physical activity will be assessed using the GSLTPAQ modified for the purpose of this study	Baseline (week 0)
Secondary	Energy expenditure (kcal/week)	Leisure-time physical activity will be assessed using the GSLTPAQ modified for the purpose of this study	End of control period and pre-intervention (week 8)
Secondary	Energy expenditure (kcal/week)	Leisure-time physical activity will be assessed using the GSLTPAQ modified for the purpose of this study	Middle of intervention period (week 16)
Secondary	Energy expenditure (kcal/week)	Leisure-time physical activity will be assessed using the GSLTPAQ modified for the purpose of this study	Completion of intervention period (week 24)
Secondary	Training volume (hours/week)	Training logs will be collected from participants and coaches	Baseline (week 0)
Secondary	Training volume (hours/week)	Training logs will be collected from participants and coaches	End of control period and pre-intervention (week 8)
Secondary	Training volume (hours/week)	Training logs will be collected from participants and coaches	Middle of intervention period (week 16)
Secondary	Training volume (hours/week)	Training logs will be collected from participants and coaches	Completion of intervention period (week 24)
Secondary	Nutrition knowledge	Participants' knowledge of nutrition will be assessed using the self-reported 97-item General and Sport-Specific Nutrition Knowledge Questionnaire (GeSNK)	Baseline (week 0)
Secondary	Nutrition knowledge	Participants' knowledge of nutrition will be assessed using the self-reported 97-item General and Sport-Specific Nutrition Knowledge Questionnaire (GeSNK)	Completion of intervention period (week 24)