The Effects of Whey Protein Supplements on Markers of Exercise-induced Muscle Damage in Resistance-trained Individuals

Eccentric exercise can result in exercise induced muscle damage (EIMD), which can cause an abundance of ultrastructural muscular disruption and pro-inflammatory and pro-oxidant activity in the body, leading to an impairment of muscular force production and range of motion, along with elevated pain sensitivity, increased swelling, and arterial stiffness. Pasture-raised dairy products, obtained from strictly grass-fed cows, have been shown to possess more anti-inflammatory-, antioxidant-, and antihypertensive-like biochemicals compared with conventional products (i.e., with a different nutrient composition from a diet rich in grains versus grasses). However, human research trials on these products, such as whey protein concentrate (WPC), are neglected. This study addresses this gap, with a double-blind, randomized, placebo-controlled trial that compares the effect of conventional WPC versus WPC supplementation reported to be derived from pasture-raised cows on vascular function and indirect markers of muscle damage and inflammation in response to eccentric EIMD in healthy, young, resistance-trained women and men. Thirty resistance-trained individuals will complete an intense EIMD bout consisting of eccentric barbell back squats and then will be assessed 24, 48, and 72 hours post-EIMD for muscle soreness, range of motion, maximal isometric voluntary contraction, peripheral fatigue via magnetic stimulation, countermovement jump, barbell back squat velocity, and vascular function (i.e., arterial stiffness via carotid femoral pulse wave velocity). Subjects will be grouped into a conventional WPC, pasture-raised WPC, and placebo supplementation group and consume their respective supplementation thrice daily immediately post-EIMD until the study's completion.

Inclusion criteria

• Men and women 18-40 years old
• ≥3 months uninterrupted training of ≥3 days/week of resistance training
• Self-reported to be healthy

Exclusion criteria

• Not within defined age range
• History of allergy to dairy products
• History of experiencing pain while exercising in the lower extremities (i.e., hips/knees)
• Current use of anti-inflammatory/anti-pain medication (i.e., nonsteroidal anti-inflammatory drugs (NSAIDs) such as Tylenol, Advil, or Aleve
• Are pregnant or could possibly be pregnant by self-report
• People who answer 'yes' to any of the pre-participation screening questions on the PAR-Q questionnaire.