Effects of Post-exercise Protein Supplementation in Young Athletes

Study Overview
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Brief Summary
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This randomised double blind, placebo-controlled study examined the effects of post-exercise consumption of whey protein (PRO) or carbohydrate (CHO) on performance recovery, muscle damage and inflammatory cytokine responses following a high intensity interval swim (HIIS) in 10-17-year old male and female swimmers.

Detailed Description
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Study Procedures: All tests and measurements were performed during three visits at the given swim teams training/practice facility. During Visit 1, participants were informed of all tests and procedures that will take place and were familiarised with all testing protocols. All anthropometric measurements were also performed during this meeting (see below). Visit one took   60-90 minutes. During visit 2, Participants arrived at the testing centre for 06:00h, provided a fasted venous blood sample (for biochemical markers - see below). Following the saliva and blood samples, a light breakfast ( 300-400 kcal, depending on body mass) (e.g. banana, apple, plain granola bar, water etc.) was provided. Following breakfast (approximately 45-60 min),all participants performed a standardised warm-up in the pool (1000m - short course) followed by 5min of rest and the subsequent performance test in the form of a maximal 200m-front-crawl. Following the maximal 200m performance test, participants underwent a maximal high intensity interval swim protocol (HIIS). The HIIS consisted of 15 high-intensity swimming repetitions (5x100m, 5x50m and 5x25m at maximal intensity) with a work-to-rest ratio of 1:1. Immediately following the HIIS participants exited the pool and provided a second blood sample (blood samples were collected pre-, 30min, 2, 6 and 24h post-HIIS). This was then followed by the first supplement drink  30-40. 1.5h after consuming the first supplement drink, participants returned to the pool to complete a second maximal 200m swim, followed by a blood test and received their second supplement drink. 1.5h following the supplement drink, a standardised vegetarian lunch was provided, 1.5h following lunch participant provided another blood sample and performed the final 200m swim of that day. Prior to departure participants were provided with a food record sheet to track all food consumption that evening and were instructed to return it to a study investigator the following day. During visit 3, Participants returned to the testing location at 06:00h, provided a fasted Blood and saliva samples, were given the same breakfast as they received on day 2 and were administered a muscle soreness questionnaire. Following breakfast (approximately 45-60 min),all participants performed the same standardised warm-up as they did in day 2 (1000m - short course) followed by 5min of rest and the subsequent performance test in the form of a maximal 200m-front-crawl. Groups and supplementation protocol - Participants matched into one of three groups: Protein (0.3g/kg - whey protein isolate), Carbohydrate (0.3g/kg - maltodextrin) or placebo control (flavoured water) (H2O), matched for age, sex and body mass. All groups consumed a total of two supplements, both the investigators and the participants themselves were blinded to the contents of the drink. All drinks were chocolate flavoured and served in black opaque protein shaker cups. For the protein and carbohydrate groups, each participant received an isoenergetic amount of supplement (2 x 0.3g/kg - whey protein isolate or maltodextrin) throughout the duration of the study at the given time-points outlined above. Biochemical measurements: Venous blood samples and a saliva sample will be collected on 5 separate occasions (pre-, 30min, 2, 6 and 24h post-HIIS). To control for circadian rhythm, the exercise session and related blood samples will be performed at the same time of day. Venous blood samples were collected from the antecubital fossa of each participant using a standard venipuncture technique. Endocrine response such as anabolic/hormonal markers, inflammatory markers (cytokines - IL-6, IL-10, TNF-α) and indicators of muscle fatigue/damage (CK) were examined.

Official Title
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Effects of Post-exercise Protein Supplementation on Performance Recovery, Muscle Damage, Inflammation and Bone Turnover in Adolescent Swimmers

Conditions
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Fatigue, Inflammation, Bone Resorption

Intervention / Treatment
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* Dietary Supplement: Experimental:Whey protein
* Dietary Supplement: Active Comparator: Isoenergetic control - Carbohydrate
* Other: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: competitive swimmers (swim competitively for a minimum of 2y) male or female 11-17y free from any medical conditions Exclusion Criteria: yes on medical screening questionnaire not classified as a competitive swimmer (swim competitively for <2y) outside the desired age range (<11 or >17)

Ages Eligible for Study
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Minimum Age: 11 Years
Maximum Age: 17 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Participants were divided into three groups: PRO (0.3g/kg - whey protein isolate), CHO (0.3g/kg - maltodextrin) or placebo control (H2O), matched for age, sex and body mass
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Whey protein<br>Whey protein isolate | Dietary Supplement: Experimental:Whey protein<br>* Each participant in the protein group received 2 protein drinks immediately following exercise. The supplement was given using a relative quantity of whey protein isolate (0.3g/kg) and was chocolate flavoured.<br>|
| Active Comparator: Isoenergetic control - Carbohydrate<br>Carbohydrate or maltodextrin | Dietary Supplement: Active Comparator: Isoenergetic control - Carbohydrate<br>* Each participant in the carbohydrate group received 2 drinks immediately following exercise. The supplement was given using a relative quantity of maltodextrin (0.3g/kg), non-caloric chocolate flavouring was added to mask the drinks contents.<br>|
| Placebo Comparator: Placebo control - Water<br>Water - chocolate flavoured | Other: Placebo<br>* Each participant in the water group received 2 drinks immediately following exercise. The water was provided in a similar volume using the same non-caloric chocolate flavouring as the other drinks.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Performance recovery | 200m front crawl time (s) measured in short course pool (25m) | 24 hours | 
| IL-6 (pg/ml) | Myokine | 24 hours | 
| IL-10 (pg/ml) | Anti-inflammatory cytokine | 24 hours | 
| TNF-alpha (pg/ml) | Pro-inflammatory cytokines | 24 hours | 
| Muscle damage | Creatine kinase activity (u/L) | 24 hours | 
| Bone formation marker | Procollagen type 1 intact N-terminal propeptide, PINP (ng/ml) | 24 hours | 
| Bone resorption marker | Carboxy-terminal collagen crosslinks, CTXI (ng/ml) | 24 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Bone turnover balance | Balance between bone formation and resorption calculated from the ratio of Median (PINP)/Median(CTXI) | 24 hours | 
| Rate of Bone turnover | Rate of bone formation and resorption calculated as √[MoMF(square) + MoMR(square) | 24 hours |