Investigating the efficacy of supplementation with a proprietary dairy powder in supporting muscle recovery following exercise-induced muscle damage in healthy individuals

This is a double-blind, placebo controlled, parallel design intervention study that will allow us to evaluate whether long-term supplementation with dairy powder supplement promotes muscle recovery following eccentric exercise-induced muscle damage to the quadriceps. Prospective participants who have passed the study's inclusion/exclusion criteria will be asked to attend a familiarisation session (approximately 1 hr) where they will meet with the study’s principal investigator. During this session, the study’s trial coordinator (Research Associate, approx. 5 years experience in human studies) and principal investigator (Research Scientist, PhD) who will introduced them to the subjective visual analogue scale (VAS) and questionnaire for pain assessment that they will be asked to respond to during the trial days. Each participant’s quadriceps muscle function will be measured using a Biodex isokinetic dynamometer where they will be asked to perform three maximal concentric, eccentric and isometric contractions. Muscle function measures on quadriceps of both legs will be conducted. Participants will be also be familiarised to the bench stepping exercise that they will need to complete during the trial day. Participants will be required to step up (concentric) on a bench set at a height of 110% of their lower leg length then by step down (eccentric) from the bench with the contralateral leg at a speed of 15 cycles per minute for two minutes. During this exercise, participants will wear a weighted vest containing an additional mass corresponding to 15% of their bodyweight. Recruited participants will be evenly randomised into two treatment groups: (1) Dairy powder is a spray-dried buttermilk powder with a complex blend of lipids comprised of saturated (13%) and unsaturated (mono, poly and trans) fatty acids (5.2%), gangliosides (0.4%) and phospholipids (8%) or (2) Placebo powder. At the start of the study arm, the trial co-ordinator will then give participants sachets, with each sachet containing a dose of either the dairy powder supplement (5 g) or the placebo (4.8 g). Participants will be instructed to reconstitute the contents of a single sachet in 250 mL in water with a provided shaker provided to them once daily for four weeks. The trial coordinator will meet with each participant weekly to track their compliance. During the four-week intervention period, participants will be required to avoid consuming omega-3 supplements. The day after their four-week supplementation period, participants will arrive at the research facility to complete their exercise trial day. They will initially undergo quadriceps muscle function assessments as previously described followed by subjective pain assessments (questionnaire and VAS scale). Following the muscle function assessment, participants will be required to complete their customised bench stepping exercise that they were familiarised to for 30 minutes at a frequency of 15 cycles per minute. The leg assigned to undergo eccentric muscle damage exercise, will be evenly distributed between the left and right leg for the study cohort but individually randomly determined. Immediately after the exercise, assessments of quadriceps muscle function of both legs and subjective pain will be conducted. At 24, 48, 72 and 96 hours post exercise, participants will be required to return to the facility for muscle function and subjective pain assessments.