The Effect of Sorbet Containing Australian Native Plant Davidson Plum on muscle recovery in Long-distance Runners

The study is designed as a pilot double blind, randomised, placebo-controlled trial over the period of three weeks including baseline and a follow up at 24-, 48- and 72-hours following exercise protocol. At baseline, prior to the supplementation intervention, participants will complete a treadmill running protocol that includes submaximal and then maximal phases. The protocol consists of a 10-minute self-selected warm-up. The starting speed will be individualised to each participant’s current fitness level (determined by the most recent 5- or 10-km race time), with the speed increasing in four stages by 1 km·h-1. The aim of the submaximal phase of the test is to finish at, or just above, the lactate threshold pace, defined by a blood lactate concentration of ~4 mmol. Following a 5-minute recovery period, the participants complete a maximal incremental test to volitional exhaustion, where treadmill speed is increased by 0.5 km·h-1 every 30 seconds until the speed achieved at the end of the submaximal stage is reached. From this point forward, the treadmill speed remains unchanged, and the gradient increased by 0.5% every 30 seconds until volitional exhaustion. Participants will consume 170g of Strawberry sorbet containing 10% Davidson plum powder or Strawberry sorbet containing no Davidson plum for 10 days following baseline testing administered by the researcher (Dietitian). On day 7, participants will complete a high intensity running session on a treadmill involving 15-minute running at a speed equating to 60% VO2max, determined during the baseline incremental maximal exercise test, and 15-minute running at a speed equating to 75% of VO2max. The participants will be required to complete up to 8 × 1-minute intervals at a speed equating to 95% VO2 max, with 2 minutes of active recovery between each interval, or until volitional exhaustion Polyphenol intervention - In total, 170 g of Strawberry sorbet containing 10% Australian Freeze-dried Davidson Plum powder (Superfood Co) will be consumed twice daily (2 x 85g) at the pre-determined times (morning and evening) by participants. This equates to 1.5 scoops of sorbet. Dietary intake will be assessed using a 3-day food diary (2 weekdays and one weekend day) before consuming the functional food product (sorbet) and again at the end of the study during the last week of intervention.