The 45 degree hyper extension is definitely one of the machines we use most with clients, especially beginners. Its such a great tool for teaching people how to engage their hamstring and glutes without the lower back taking over.
You can see here Dyah is keeping a relaxed, slightly flexed spine. We usually coach the movement this way to keep the erector spinae muscles relaxed so that the glutes and hamstrings can do the work. What we are looking for is a good contraction of the glutes and hamstrings at the top of the movement without the lower back taking over. Done correctly, this piece of kit is absolutely amazing! #CNFITNESS