Investigating the supporting mechanisms of changes in neuropsychological function after stairclimbing in adults

Overview Participants will come into a psychology lab at Otago University for three visits. Postgraduate students will be supervising and running each experiment. With the assistance of a research assistant who is trained in all relevant methods and procedures. Each session separated by 1 week. The sessions will last approximately (1 ½ hours). During two of the three visits, stair climbing (15 mins) will precede brain recordings (set up approx. 45 mins) collected during cognitive testing (10 mins). Testing will occur at the same time of day on all occasions, and the order of the visits will be randomized and counterbalanced across participants. The two stair climbing sessions will be identical except for the duration of stair climbing. Participants will receive course credits to encourage them to attend all three sessions. Stair climbing On two of the three visits, stair climbing will precede neuropsychological testing, entailing 3 x ascending and descending one flight of stairs. The protocol involves multiple phases: warm-up (2 min; moderate-paced climb up and down 18 stairs at a self-selected pace, followed by brisk walking on flat ground), [stair climbing (1 min), recovery (1 min) x either 2 or 5 repetitions], stair climbing (1 min), cool down (3 min). The recovery and cool down phases involve walking down stairs and on flat ground at a self-selected pace. Number of stairs climbed and heart rate will be recorded. One visit will entail the 3 x 1 min stair climbing protocol, and the other visit will entail 6 x 1 min stair climbing. Participants will be asked be self-report their perceived level of exertion using the Borg RPE scale. A 15-grade scale for of perceived exertion rated from, i.e., no exertion at all to maximal exertion. Instructions: “Climb up and down the stairs one step at a time for 1 min, ascending vigorously and descending as desired. Vigorous means relatively intense, but not all-out”. All aspects of the two stair climbing protocols will be identical except for the number of intense stair climbing intervals (3 or 6). Neuropsychological Testing Participants will perform a battery of neuropsychological tests ( assessing cognition and mood). Throughout testing, haemoglobin concentrations and electrical activity will be recorded concurrently. The cognitive tests involve viewing a display on a computer monitor and then pressing a button. The displays show simple shapes that are not in any way stressful, offensive, or unpleasant. The responses involve indicating the location or identity of a target stimulus. Each response and response latency will be recorded. Button presses will be made on a two-button response box. No visual or audio recordings are involved, and all recordings are completely non-invasive. The cognitive tests are not difficult or stressful and participants will be encouraged to rest as often as they please. Hemoglobin concentrations and electrical activity measures Concentrations of oxygenated and deoxygenated haemoglobin will be measured continuously using near-infrared spectroscopy (NIRS). This method assesses cerebral oxygenation changes. The NIRS technique is based on the relative transparency of human tissue to near-infrared light and on the oxygenation-dependent light absorption changes caused by the chromophores oxyhemoglobin [O2Hb] and deoxyhemoglobin [HHb]. It is completely non-invasive and painless. In the current experiment six pairs of transmitter-receiver optodes of the NIRS device will be attached to participants’ scalp according to the international 10/20 standard system. The distance between transmitter and receiver of each pair was three centimetres. The twelve optodes formed ten channels in total; two on bilateral frontal areas and eight on bilateral motor regions. Concurrently with NIRS, the electrical activity of the brain will be recorded using electroencephalogram (EEG). EEG refers to recordings from multiple electrodes placed over the scalp, to record underlying electrical activity from the brain over a period of time (commonly referred to as brain waves). The EEG technique measures ionic current-voltage fluctuations which result from within the neurons of the brain. EEG is completely non-invasive and painless.