High-energy nutrition bars for cold-weather exercise

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

In a randomized, double-blind crossover design, physically active adults will consume isocaloric 350 kcal bars that differ by macronutrient composition (higher-carbohydrate: 50% CHO/30% fat/20% protein vs higher-fat: 30% CHO/50% fat/20% protein) before exercise in a 5°C climatic chamber. Baseline measures include height, weight, DXA body composition, and V̇O2peak, and participants complete practice sessions to standardize exercise familiarity. Diet and activity are controlled with a 24-hour lead-in diet, participants consume the assigned bar under cold conditions, rest for 60 minutes to induce physiological cold responses, then perform an aerobic time-trial while substrate oxidation and temperatures are monitored. The order of bar assignments is randomized and only a designated staff member is unblinded to treatment codes.

Why it matters

Who can join: the full rules

Inclusion Criteria: • Men and women aged 18 - 39 years (17 if active Military)

* Physically active (exercise minimum 2 days per week)
* Have supervisor approval (permanent party military and civilians at NSSC)
* Willing to refrain from alcohol, nicotine products and dietary supplement use while on study diets
* Females must have normal menstrual cycles between 26-32 days in duration; 5 menstrual cycles within the past 6 months; or using oral/hormonal contraceptive which contains low-dose estrogen/progesterone to maintain continuous levels throughout the 28-day cycle (i.e., no placebos)
* Only consume caffeine products while on study diets if provided by study staff
* Body mass index (BMI) between 18.5-30 kg/m2
* In good health as determined by OMSO (Office of Medical Support and Oversight)

Exclusion Criteria:

* Metabolic or cardiovascular abnormalities, gastrointestinal disorders (i.e., kidney disease, diabetes, cardiovascular disease, hypertension etc.) that is unsuitable for the study determined by OMSO
* Disease or medication (i.e., diabetes medications, statins, corticosteroids, etc) that affects macronutrient utilization and/or the ability to participate in strenuous exercise
* Allergies or intolerance to foods (including but not limited to lactose intolerance/milk allergy), vegetarian practices
* Present condition of alcoholism, anabolic steroids (testosterone, enanthate, undecanoate, etc), or other substance abuse issues
* Unwilling to stop use of nutritional/sports supplements (creatine, multivitamins, whey etc.) while enrolled in the study
* Sensitivity to medical adhesives resulting in significant skin irritation
* Acute or chronic musculoskeletal injury that compromises the ability to run and ruck march
* History of disease of the gastrointestinal tract including (but not limited to) diverticulosis, diverticulitis and inflammatory bowel disease, peptic ulcer disease, Crohn's disease, ulcerative colitis; or previous gastrointestinal surgery
* Difficulty swallowing large pills or unwilling to insert rectal temperature sensor
* Raynaud's syndrome.
* History of cold injuries of any severity (e.g., frostbite, trench foot, chilblains) that puts the volunteers at increased risk for an adverse effect
* Cold-induced bronchospasms/asthma
* Blood donation within 8 weeks of the study
* Unwillingness or inability to adhere to study exercise restrictions
* Scheduled MRI within 2 weeks after completing test in cold

Where it's running

• Usariem
  Natick, Massachusetts, United States Recruiting

Study contacts

• Study coordinator: USARIEM Recruitment
• Email: USARMY.USARIEM-MNDstudies@health.mil
• Phone: 508-206-2278

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.