A new crop of founders from ByteDance, DJI, Tencent, Amazon Lab126, Smartisan and other major tech companies is pushing AI hardware into narrow sports-training niches, from skiing and golf to tennis and basketball. The report centers on startups such as Heygo, BirdieSense, PomBot, LUMISTAR, MossCode, BleeqUp and XbotGo, and tracks their products, funding rounds and go-to-market strategies over the past two years. The common thread is not general fitness tracking. These companies are trying to answer a harder question: whether a movement is correct, where it breaks down, and how to turn that judgment into usable feedback. In skiing, Heygo uses two IMU sensors clipped to ski boots and a model trained on million-level skiing data to infer ski posture. In golf, BirdieSense uses a monocular camera and on-device 3D pose analysis. In tennis and table tennis, robot trainers are replacing repetitive ball-feeding sessions, a use case that is easier for users to pay for immediately. The article also points to a second branch of the market focused on recording sports activity rather than judging technique, including AI watches, sports glasses and auto-tracking cameras. Across both branches, falling edge-compute costs, large-model-based natural-language feedback and crowdfunding-led overseas distribution are helping the category gain momentum, even though no single blockbuster financing has yet defined the sector.