Bluetooth Low Energy (BLE) is a promising 2.4 GHz technology for Body Area Networks (BAN) in health care and lifestyle applications. However, the global increase of wireless devices using the crowded spectrum in the 2.4 GHz frequency band can create coexistence issues. This work studies the performance of BLE in environments with multiple BLE devices. An experimental setup consisting of 10 BLE nodes is used to measure BLE application throughput with different connection parameters and under different interference sources, such as other BLE devices and WiFi. The results quantify the decrease of the application throughput and the influence of BLE connection parameters in the experimental settings, as well as suggest parameter values suitable for densely deployed environments.