Multimedia applications over the Internet, such as IPTV and video on demand (VOD), have become fast growing applications in recent years. Such applications have stringent QoS constraints in terms of bandwidth, delay and packet loss. As a consequence, broadband access networks play an important role for multimedia applications. There are two emerging technologies offering both high bandwidth and QoS support, Ethernet Passive Optical Network (EPON) and Worldwide Interoperability for Microwave Access (WiMAX). By integrating these two technologies, EPON-WiMAX integrated network can: (1) provide broadband access, (2) support mobile users, and (3) decrease network planning cost and operating cost. Thus, EPON-WiMAX integrated network is an ideal choice for multimedia applications with ubiquitous access. In the EPON-WiMAX integrated network, ONU-BSs send the data received from the OLT to their subscribe stations (SSs) with QoS guarantee. However, some ONU-BSs could become hot-spots due to dynamics of mobility and bandwidth requirement of SSs. When an ONU-BS becomes overloaded, the QoS requirements would not be guaranteed and therefore the overall performance would be significantly decreased. In this study, a load balancing mechanism based on cell breathing was proposed for the hybrid EPON-WiMAX network. In the proposed approach, the load balancing problem was formulated into a linear programming problem. Our goal is to find the best power adjustment that maximizes system throughput. We present a Heaviest Load First Algorithm (HLFA) to obtain the optimal solution. We demonstrate the performance of our approach via extensive simulations. The simulation results show that the HLFA can provide the best solution to achieve load balancing and enhance the system throughput even though the system has multiple overloaded ONU-BSs.