Effect of a Cranberry Extract on Muscle Oxygenation and Mitochondrial Health in University Students

Each participant will be involved in the study for a period of 5 weeks, during which they will commit to 3 visits:

The first visit (on week 1) will be to obtain baseline measurements. During the second visit (on week 2), acute effects of the cranberry extract will be evaluated by giving a single high dose to the participants 1 hour before the trial events. The third visit (on week 5) will be to evaluate the chronic effects of the cranberry extract after 4 weeks of daily consumption. We will use the following instruments to gather data:

• Questionnaires (height, weight, dietary patterns, to determine training level, past injuries, single or multisport athlete etc.)
• Continuous wavelength NIRS will be used to measure oxygen levels in the quadriceps using portable Moxy monitors. For this test the subjects will be wearing the portable and convenient oxygen monitors taped firmly on the appropriate muscles. NIRS is a non-invasive method and measures the level of oxygenation in the muscle tissues by sending near-infrared light through the skin, which travels through the muscle fibers and is then recovered and returned to the surface of the skin and into the back of the sensor. As light moves through the skin layers (skin, fat and muscle), it scatters, and it identifies the oxygenated and the deoxygenated blood cells due to their colors. The blood cells identified are hemoglobin and myoglobin cells.

For the actual test, the quadriceps will be activated using electrical twitch stimulation at either 4 or 6Hz for 30 s at a current level that produce vigorous but submaximal contractions. During the contraction, the NIRS will be used in combination with short duration ischemic cuff periods (200 mmHg) applied by a Hokanson rapid cuff inflator. By repeating 5 second occlusion followed by 5 second deflation 6 times, at the same time as we activate the muscle, we will be able to determine muscle metabolism (mitochondrial oxygen consumption) by using the rate constant of the recovery from high to low metabolic rate.

• Skinfold measurement of the placement area for the Moxy oxygen monitors to determine if the light can penetrate subcutaneous tissues (has to be <15mm)