An almond, dried grape and dried cranberry (AGC) mix for improving endurance exercise performance in athletes

Half of the participants will consume a mix almonds grapes and cranberries (daily intake of 75 grams of whole, raw, unsalted almonds, 25 grams of sultanas (dried grapes), 25 grams of dried cranberries), which are high in antioxidants, nitrates and arginine, while the other half of the participants will consume an amount of muesli bars that is of an equivalent energy intake. Both participant groups will consume their respective foods (almonds, sultanas and cranberries OR muesli bars) for 4 weeks. All foods will be provided to participants for free and participants may consume the foods in any portion size they desire (i.e. a single sitting or spread across the day) and their compliance will be assessed using a daily checklist, as well as any uneaten test foods being returned at testing visits. Both groups will complete a five-week training program of standardised exercise training performed on participants own bikes that will be fitted with a stationary bike trainer, which essentially allows a road bike to function like an exercise bike in a gym. These training sessions will occur in participants' own homes and they will be required to exercise within specific, individualised heart rate zones (they will be provided and familiarised with heart monitors) for a prescribed duration. Participants will not be supervised during their training, but they will need to record their heart rate during training sessions and will also need to report the sessional rating of perceived exertion (RPE), which assesses how much effort was required for each session. During light training and tapering training, training compliance will be assessed by training impulse (which is a function of average heart rate and duration of exercise sessions) as recorded heart rate data can be analysed in Polar Pro Trainer 5 software. Due to the fatigue-induced changes in the function of the autonomic nervous system (including cardiovascular function), participants may have difficulty attaining the prescribed heart rate zones. Thus, during heavy training compliance will instead be determined by the function of sessional RPE and duration. This training is split into three phases: a six-day period of light training, a 13-day period of heavy training, and a 13-day taper/recovery period. The initial six-days of light training will involve cycling for approximately 45 min per day, at a low/medium intensity, such that it will allow participants to recover from any pre-study training prior to the baseline assessments. Baseline testing is performed the day after completion of light training and then the dietary intervention (almonds, sultanas dried cranberries or control) begins and continues until the end of the study (i.e. for 4 weeks). The day after baseline testing, participants complete 13 days of heavy training that is intended to induce substantial fatigue from which they will not recover by the testing session at the end of these 13 days (i.e. it is expected to reduce endurance performance). The heavy training program involves a strenuous, interval-style training schedule which requires participants to cycle for 124 min per day. Testing is again performed the day after completion of heavy training, with the 13-day tapering training phase then beginning the subsequent day. The taper training will involve cycling for approximately 50 min per day, at a medium intensity and includes 3 rest days. This will allow participants to recover from and adapt to the stimulus that was provided by the two weeks of heavy training, and is expected to increase performance to above baseline levels. The rationale for this type of training program is to investigate whether almonds, sultanas and cranberries can reduce the impairment in exercise performance due to heavy physical training and/or induce a greater improvement in performance by the end of training, with both outcomes being advantageous for athletes.