Adaptations to Resistance training (Connective tissue)

     As we have progressed in this series, we have learned all about the Neural adaptations of resistance training and the muscular adaptations to resistance training. Now, we will discuss the connective tissue adaptations. Connective tissue refers to bones, tendons, ligaments and cartilage. For this article I'll focus more on the bone adaptation with the rest of the connective tissue adaptations to come in future posts.

    Before we deep dive the adaptations, we need to have a little background knowledge about bone structure. Bones are generally fall into two categories: Axial and Appendicular. Axial bones are found in the skull, Vertebrates, Ribs, and the sternum. Appendicular bones are found in the shoulder girdle, pelvis, and bones of the extremities. Within Axial and Appendicular bone structures lie Trabecular and Cortical bone. Trabecular are your spongy bones while your cortical bones are more solid and compact. Cortical bones surround the trabecular bones. Think of a turtle in how the outer shell is solid and compact while underneath is soft and spongy. Within the Trabecular bone structure encompass blood vessels bringing nutrients to the bone. Since the trabecular bones are less dense, they responded better to adaptive change then Axial bones. What are those adaptive changes?

    Glad you asked.

    When you lift weights, you create force on the bone structure that can either be bending, compressive or torsional. This process is called mechanical loading. As mechanical load takes place, and the bone bends the body responds through osteoblasts (protein collagen molecules). Through osteoblasts a new bone matrix is formed thus increasing the diameter of the bone. That diameter of the bone is called Bone Mineral Density (BMD). In order to have these adaptations a few things have to take place. For starters, the Minimal Essential Strain (MES) threshold must be met. The MES is typically 1/10 of the force to fracture the bone. As long as the force applied to the bone is above that ratio then your good. Meaning lifting those 10-pound dumbbells won't get you those bone adaptations that you are looking for. (Hence another reason to lift HEAVY while in the gym).

     In addition to meeting the MES specificity of loading, speed and direction of loading have to take place. Specificity of loading means that bones will adapt to areas that were under tension. Performing heavy deadlifts and squats will adapt the femur, not the clavicle. Speed applies to how fast the impact is. Slow, application of force.... think grinding through a heavy squat set is a different force then performing plyometrics. Those applications of varying force help expose the bone to different intensities. Direction of loading applies more so to exercise selection. Single-joint machine-based selection that isolates a single muscle group with the machine itself providing support instead of bone structure are not the best choice for bone adaptations to exist. Barbell/ Dumbbell Multi-joint exercises that apply force in multiple directions will elicit more of a response. 

    These adaptations will not take place overnight. Continued progressive overload that incorporates variation in training for at least six months will provide the stimuli necessary for connective tissue adaptations. One caveat, a younger adolescent crowd will have adaptations faster due to the younger nature of the bone.