What is the load or weight called when lifting weights?

Why does back get stiff while standing and or walking for long periods of time? Can my Chihuahua walk 2 miles my Chihuahua can walk to Miles is it harmful? What muscle group does back extension work? What is strain of the subscapularis muscle belly? A proper cool down routine does? What are some effective spine flexibility stretches to improve overall mobility and reduce stiffness? Why are my arms so skinny as a male? What would a good name be for a kickboxing fitness club? What do you have to do to become a physical theripist? How can I properly perform the assisted glute ham raise exercise to target my hamstrings and glutes effectively? Do skeletal muscles react quickly? When is a prime time for athletes to stretch to achieve long term improvements in their flexibility? What are the primary muscles worked by the pec deck machine? What are some Substances that allow athletes to exercise longer are called? What is a good workout routine for a 14 year old girl to do at home? What kind of effect does a push up bar have on the body? What is the proper technique for performing an abdominal crunch to effectively target and strengthen the core muscles? How do dumbbell weights work and how can they be effectively incorporated into a workout routine? How many times a day do you use the ab belt? Which muscle does the exercise "skull crushers" primarily target?