 The benefits of resistance training are well documented and applicable to the whole population. People performing resistance training exercise, experience increases in fat loss, muscular strength, size and tone, and subsequent improvements in athletic performance, injury prevention and personal health. Unfortunately, the road to these benefits is not straightforward. Participants relying on self-observation make critical mistakes, which result in injury and a low rate of progress towards their goals. Personal trainers provide expert guidance and feedback to athletes to support their path to success. However, their high cost and lack of availability means that often people fall into the trap of bad practice. I'm looking at using technology solutions to allow people to avoid these gaps. This is my research, which takes place in the School of Health Sciences at UCD. My research basically is the development and evaluation of a biofeedback system for resistance training. This is to replace the role of a personal trainer and allow people training by themselves to achieve the same safety and optimal training results. I use sensors such as these shimmer devices, mobile phone technology, to develop biofeedback systems consisting of our visual and haptic feedback to the user. And through such a system, their training can be greatly improved, tracked and they can get more insight about their everyday training. Such insights come from the sensor signals and they include the velocity, acceleration and 3D position of body segments. The mobile device then gives a wide range of valuable feedback to the user, similar to that which a personal trainer would provide. While I carry out my data collection in the gym, I spend my everyday research here in the insight centre at UCD. Here I carry out signal processing and program development based on this, which end up being the biofeedback system for users. I'm hoping that my research done in this office can translate to real-world changes to the way people train in the gym.