In the last few years I have seen many companies develop linear encoder and accelerometry-based systems to measure power output during weightlifting exercises. This is mostly due to the fact that linear encoders and accelerometers are becoming relatively cheap and it is getting easier to write appropriate software routines to perform all measurements.
I have been using for one year the SmartCoach and I am very pleased with what i have seen so far. I have used it mainly for testing purposes and to analyse training sessions and testing sessions performed by strength and conditioning coaches around the country with the remote coaching modality.
The software is simple, easy to use and starts with a very good diary/scheduling system which allows the production of nice training schedules which can be sent to athletes and coaches.
Remote coaching is a great function as it allows a remote coach to write a session or check the content and execution not only in terms of sets/reps/external load but also in terms of power output per repetition.
It really works very well!
The software engineers have recently developed new routines to allow the users to perform strength testing and graphically present the Force/Velocity and Power/Velocity relationships to allow the determination of various parameters useful for strength training prescription.
I am pleased with this product and I recommend anyone interested in visiting the website to download the software for free!