Effect of blackcurrant consumption on physical fitness, bioenergetics and natural immunity during high intensity training; involvement of mitochondrial adaptation?

Study design- The study is divided into 2 stages, the first stage will establish a high intensity training (HIT) protocol together with appropriate biological measurements (listed below). The second stage will apply the HIT protocol to assess the additional fitness & health benefits of a consuming a blackcurrant extract prior to each HIT session. Stage 1. This first stage of the study will establish a HIT protocol that will identify adaptive changes in fitness and health (focus on mitochondrial bioenergenesis and natural immunity). These changes will be assessed by physical, subjective and blood biochemical parameters. Study participants - Participants will be assessed for their suitability by assessing their ability to do a short-cycle (5 km) with breathing apparatus on a stationary Wingate bike and a habitual Baecke questionnaire. During the trial, participants will be asked to complete on-line health and diet diaries each week (monitored by the trial co-ordinator) and asked to omit foods and dietary supplements that are high in antioxidants for the duration of the study (a list will given to all participants) . Fitness assessments – (i) VO2 max. A stationary Wingate cycle ergometer will be used to assess participant’s VO2 max. This will require the participant to cycle at incrementally wattage until volitional fatigue. The rate of CO2 increase, heart rate and respiratory exchange ratio (ratio of CO2 exhaled vs. O2 inhaled) will also be measured. In addition, blood lactate will be measured immediately post exercise. (ii) 15K stationary cycle ergometer time-trial. Participants will initally be asked to donate blood (see listof tests below) and complete physiological (e.g. heart rate, O2/CO2 exchange, thigh /tenderness measurements) and subjective (VAS fatigue/pain) assessments. Subjects will then be asked to perform a 15K timed trial on a stationary Wingate bike as quickly as possible. The completion time plus heart rate, work output, O2/CO2 exchange will be assessed. Immediately post cycle, physiological and subjective evaluations will be repeated. The physiological parameters will then be continuously monitored over the first 10 mins of exercise recovery, followed by a final measurement taken 20 mins post exercise. Additional blood samples will be taken immediately post exercise and after 20 mins recovery. Blood collected during this fitness assessment will be analyzed for blood glucose & lactate, insulin, inflammatory markers (C-reactive protein, IL-6, IL-10) levels, as well as oxidative and antioxidant parameters. In addition, blood leukocyte and platelet mitochondria function (e.g. respirometry, pro- & anti-oxidant capacity, fragility) will be assessed. HIT protocol - This will be performed over a 2-week period using a stationary Wingate cycle ergometer. The HIT protocol consists of a total of 6 HIT sessions over a 2-week period; 3 sessions every week. Participants will complete a 5 min warm-up cycle at 50W immediately prior to each HIT. The HIT protocol will consist of a repeated bout of 30 sec all-out cycling on a Wingate ergometer set at a resistance corresponding to 4.0% of the subject's body mass. Each bout will be separated by 1 min active recovery (light cycle at 30W). Incremental training will be implemented by increasing the number of repetitions from 6 repeats during first 2 sessions, to eight repeats during sessions 3 and 4 and then ten repeats during sessions 5 and 6. Within each HIT session, we aim to assess (i) leg swelling (thigh diameter & tenderness and (ii) VAS (fatigue, pain/soreness) and RPE evaluation. Stage 2: The fitness assessment, HIT and biological parameters established in stage 1 will be applied. The trial is designed as a double-blind cross-over involving two 2-week HIT blocks sandwiched between the two fitness assessments (VO2max and a 15K cycle ergometer time-trial) at the beginning and end of each 2-week HIT block. The dietary intervention will be taken prior to each of the HIT session (see above for details) Dietary Intervention - Participants will consume 3.2mg/Kg (anthocyanin equivalent) of a commercially-available anthocyanin-rich 30% blackcurrant extract (Just-The-Berries, NZ) OR a placebo (equivalent sugar and vitamin C present in the blackcurrant extract). Following a 2-week wash-out period, trial subjects will then cross-over the dietary interventions. The blackcurrant extract contains only blackcurrant and consists of 89% anthocyanin and 11% non-anthocyanin polyphenols). The blackcurrant extract will given to participants within opague gelatin capsules. Furthermore, neither the trial subjects nor the trial co-ordinator will know the order or the treatment being given in each arm of the study.