Which tool is NOT typically associated with strength training essentials?

The choice of yoga blocks as the answer highlights their primary association with flexibility, balance, and support in yoga practices rather than strength training. Yoga blocks are commonly used to help individuals modify poses and enhance their alignment, making them more relevant to practices focused on stretching and mobility rather than the specific goals of strength training, such as building muscle power or endurance.

In contrast, retention collars are crucial for ensuring that weights remain securely in place on barbells, spotters or partners play a pivotal role in ensuring safety during heavy lifts and maximizing the effectiveness of workouts, and weight belts provide additional support for the lower back during heavy lifting. Thus, yoga blocks stand out as not being directly tied to strength training essentials.