Jocelyn Wittstein on Instagram: "Box jumps are a great exercise to train your fast twitch muscle fibers which atrophy as we age. The drop jump down and a rebound after that provides impact that stimulate bone formation. This is a process called mechanotransduction. Maintaining strength, power, agility and bone density will help reduce fracture risk. The box you drop jump from does not need to be this high- even just an 8 inch drop creates significant ground reaction force. If new to plyometrics