Trail running is a sport that consists of running and hiking over trails.  Trail running often takes place on mountainous terrains.  Many trails are in the open with very little shade to keep the body cool. Altrail Vest is a way to keep the athlete cool while also supplying drinking water.      

           Altrail Vest circulates cold water through a custom-designed vest with integrated heat exchange tubes. Cold water is loaded into a 3-liter reservoir attached to the vest's back and circulated by a pump powered by an onboard battery. The flow speed of the pump can be adjusted with high granularity to achieve fine cooling outputs. The pump flow rate is set by PD control that uses skin temperature sensors as feedback. The temperature of the water in the reservoir is monitored by a thermal resistor located in the reservoir. When the water in the reservoir rises above a preset temperature, the vest alerts the user that the cooling capacity is compromised by activating a vibrating motor and flashing a warning on the onboard LCD screen. During normal operation, the LCD screen displays the reservoir's water temperature and skin temperature. By default, the LCD backlight is off unless a button is pressed to conserve battery life.  There is a detachable drinking tube that can connect to the water supply to drink from.