The Effects of Cold-water Immersion on Exercise Performance Recovery and Postprandial Plasma Aminoacidemia

In order to optimize sports performance, high-level athletes are required to manage conflicting training objectives, which often result in periods of high-volume training. These athletes need to perform heavy resistance training sessions to promote physiological adaptations, which consequently induce fatigue. Yet, they need to minimize fatigue to perform subsequent high-quality training sessions often within the same day. To support these training endeavours, a high-quality dietary regimen and adequate protein consumption is deemed to be an essential component of an athlete's recovery plan, as it has been shown to support muscle recovery and reduce muscle inflammation following exercise. Indeed, current sports nutrition recommendations advocate for the consumption of dietary protein and carbohydrate after exercise to promote tissue repair and replenish muscle energy stores (glycogen). Additionally, previous research has shown how water immersion therapies post-exercise may alleviate fatigue and restore performance. However, little is known about how different temperatures, as well as timing of cold-water immersion can support performance recovery in a population of athletes adhering to contemporary post-exercise nutrition recommendations. The objective of this project is to investigate the effects of timing of cold-water immersion relative to exercise on performance recovery within the same day, as well as to investigate whether cold water immersion augments blood amino acid concentrations after exercise and protein intake.

In the 48-hours prior to testing visits, participants will need to fill out a dietary log 2 days before the first visit and replicate their diet before the second and third visit. Participants will also be asked to adhere to the same exercise routine in order to replicate exercise behaviours for all testing days. Testing sessions will be separated by a minimum of seven days but not more than 30 days. The female participants with a regular menstrual cycle will only be tested during the follicular phase (from day one of menstruation and lasts fourteen days) to ensure a standardized hormone level. Each testing day will begin in the morning. Participants will arrive in the laboratory in an overnight fasted state and begin by ingesting a telematic pill and then consume a standardized carbohydrate rich breakfast drink. Afterwards, the athlete will complete the performance tests, which will include five counter-movement jumps, five drop jump, five squat jumps, one 5-second maximal voluntary isometric contraction (MVIC) of the knee-extensors, eight 1-second maximal voluntary isometric contractions (MVIC) of the knee extensors, five maximal isokinetic contractions at three different angular velocities (60, 180, and 240°/s). Then, they will perform the resistance training protocol, consisting of ten sets on the leg press at 65% 1RM. The 1st and 10th sets will be taken to failure. Sets 2 to 9 will be performed at 10 repetitions each. Between set 1 and set 2, they will perform 30 depth drops. The rest time between sets will be two minutes. Immediately post-training, participants will be asked to repeat the same performance tests. They will then be provided with a protein and carbohydrate drink (25 g of whey protein and 45 g of carbohydrate) that will be consumed within 5 minutes. During the experimental visit, 11 blood samples will be collected relative to the water immersion (T = -120, 0, 15, 30, 45, 60, 90, 120, 180, 240, and 300 min), and subsequently analysed for postprandial plasma amino acid concentration. The consumption of the beverage will be followed by an 10-minute mid-clavicular immersion in either CWI (10°C) that is immediate (CWI_0), delayed for 3-hours (CWI_3), or an immediate thermoneutral bath (35°C) (THERM). Following the final blood draw (T = 300 min), the performance tests will be performed one last time to evaluate recovery from the strength training. The participant will be asked to fill out the Short Recovery and Stress Scale (SRSS) that measures recovery and stress across emotional, mental, physical, and overall dimensions using eight items before each testing session. They will also be asked to fill out a visual analogue scale (VAS) regarding subjective appetite sensations at the same time as every blood sample. Furthermore, skin and core body temperatures will be monitored throughout the experiment. At the end of each of the experimental visits, the participants will receive an ad libitum pasta meal to measure energy intake. The participants will be instructed to eat until they are comfortably full within 30 minutes. The amount of food consumed will be recorded to calculate the energy intake of each participant. Participants will also need to complete a questionnaire the 24 and 48 hours after each testing session to assess their level of delayed onset muscle soreness. Following the final testing session, participants will be invited to complete a belief questionnaire, aimed at gauging their perceived effectiveness of the recovery conditions they were subjected to.

Eligibility Criteria:
Inclusion Criteria

To be eligible to participate in this study, a participant must meet all the following criteria:

1. Healthy adult between 18 - 40 years (inclusive).
2. Individual with a BMI between \>18.5 and \<30 kg/m2 (inclusive).
3. Individual who is in good general health (no uncontrolled diseases or conditions).
4. individual with a history of regular resistance training ≥2 per week for the past six-months.
5. Individual who is currently competing at the varsity, provincial, national or international level in their respective sport.
6. Individual who is free from any musculoskeletal injuries and/or conditions that might affect their ability to perform resistance exercises or undergo cold-water immersion.
7. Individual who has maintained stable use of medication and/or supplements, stable dietary and lifestyle habits, and stable body weight (weight loss or gain \<3 kg), for the last three-months prior to screening.
8. Individual who agrees to maintain usual training habits between sessions.

Exclusion Criteria

1. Individual who is lactating, pregnant or planning to become pregnant during the study.
2. Females with irregular menstrual cycles (defined as outside 24-38 days cycle range, based on self-reports).
3. Individual who adheres to a diet (e.g., vegan diet) that restricts consumption of dairy products.
4. Has a known sensitivity, intolerability, or allergy to any of the study products or their excipients (i.e., lactose intolerant).
5. Weight loss or gain \> 3 kg in the 3 months prior to study visit 1.
6. Currently or planning to be on a weight loss regimen during the study.
7. Recent (within 2 weeks of screening visit) history of an episode of acute GI illness such as nausea/vomiting or diarrhea.
8. Have a history of irritable bowel disease (IBS), inflammatory bowel disease (IBD, including ulcerative colitis and Crohn's disease), functional constipation or diarrhea (defined by the Rome IV diagnostic criteria), celiac disease, malabsorption, gastroparesis, diverticulosis, gastric or duodenal ulcers, pancreatitis, or eating disorder; or have a history of intestinal surgery (excluding appendectomy or herniorrhaphy) or bariatric surgery.
9. Have an abnormality or obstruction of the gastrointestinal tract precluding swallowing (e.g., dysphagia) and/or digestion (e.g., history of bowel obstruction).
10. Participated in upper gastrointestinal endoscopy and/or colonoscopy or preparation within 3 months prior to screening visit.
11. Diagnosed with hypercholesterolemia or hypertriglyceridemia (i.e., elevated fasting low- density lipoprotein (LDL) (≥ 135 mg·dL-1; ≥ 3.5 mmol·L-1) or elevated triglycerides (≥ 150 mg·dL-1; ≥1.7 mmol·L-1).
12. Has a history of heart disease/cardiovascular disease, uncontrolled hypertension (≥ 140 systolic or ≥ 90 diastolic mmHg), kidney disease (dialysis or renal failure), hepatic impairment or disease.
13. Is Type I or Type II diabetic or pre-diabetic \[i.e., elevated fasting blood glucose levels (≥ 100 mg·dL-1; ≥ 5.6 mmol·L-1) and/or elevated hemoglobin A1c (≥ 6.0%)\].
14. Has a history of liver or gallbladder disease or stomach ulcers.
15. Has a positive medical history of unstable thyroid disease, previously diagnosed major affective disorder, psychiatric disorder that required hospitalization in the prior year, immune disorders and/or immunocompromised (e.g., HIV/AIDS).
16. Diagnosed with cancer (except localized skin cancer without metastases or in situ cervical cancer) within 5 years prior to the screening visit, or any clinically significant disease or disorder which, in the opinion of the investigator, may either put the potential participant at risk because of participation in the study, or influences the results or the potential participant's ability to participate in the study.
17. Major surgery in 3 months prior to screening or planned major surgery during the study.
18. History of alcohol or substance abuse (including cannabinoids) in the 12 months prior to screening (including having been hospitalized for such in an in-patient or out-patient intervention program).
19. Current or previous tobacco use within the last 6 months.
20. Self-report of blood donation totaling between 101 mL to 449 mL of blood within 30 days prior to screening or a blood donation of more than 450 mL within 56 days prior to baseline.
21. Self-report of donating plasma (e.g., plasmapheresis) within 14 days prior to screening.
22. Any other active or unstable medical conditions or use of medications/supplements/therapies that, in the opinion of the investigator, may adversely affect the participant's ability to complete the study or its measures or pose a significant risk to the participant.