The effect of sorbet containing the Australian native plant Davidson plum ( Davidsonia jerseyana ) on muscle recovery following a high-intensity interval training session in long-distance runners – A protocol for a double-blind parallel trial

Background Regular moderate exercise generates low levels of reactive oxygen species (ROS). However, excessive ROS production during exercise can harm the physiological functions of tissues, including skeletal muscle. This can lead to increased muscle soreness, impaired function and delayed recovery. Eccentric exercise induces mechanical muscle damage and triggers an acute inflammatory response. This response is characterised by fluid infiltration and recruitment of immune cells to clear damaged tissue, which also initiates the repair process. Dietary antioxidants were proposed to reduce oxidative stress and enhance recovery, while the potential of native Australian plants as functional recovery foods remains underexplored. Aim To determine whether 10 days of consumption of a strawberry sorbet containing Davidson plum (Davidsonia jerseyana ) powder enhances muscle recovery following a high-intensity interval training session in long-distance runners. The study is designed as a pilot double-blind, randomised, placebo-controlled trial over a period of 3 weeks. Methods Endurance-trained participants will complete a running session after consuming either the active sorbet or a placebo sorbet for 7 days (pre-loading). Muscle recovery will be assessed using a visual analogue scale, countermovement jumps on dual force plates and a sit-and-reach test. Capillary blood samples will be analysed for muscle damage (creatine kinase). Physiological parameters including heart rate variability, blood pressure and anthropometrics will be recorded. Baseline cardiorespiratory fitness will be determined using a V˙O 2 max test. Summary This trial aims to determine whether a sorbet containing bioactive compounds from an Australian native plant can enhance recovery following intense exercise.