We all know that it’s important to allow mechanical fitness (bones, connective tissues) to be built before pouring on the mileage otherwise you face major injury risks (ie stress fractures). I was wondering if anyone knows of a study on how much hard-surface running and at what progression results in ideal preparation. For example: at what volume of running is the mechanical fitness peaked? I know there will be a lot of anecdotal info out there. I’m looking for something more on the scientific side.
I was wondering if anyone knows of a study on how much hard-surface running and at what progression results in ideal preparation. For example: at what volume of running is the mechanical fitness peaked?
I don’t know if you’ll hit on any hard and fast ‘rule’ because there are a ton of variables.
Bone is living tissue. Osteoblasts build bone; osteoclasts destroy it. The interaction of the two is bone turnover, or “remodeling.” Every 10 years you have a brand-new skeleton.
Bone has a mechanical loading curve with an elastic range and then a plastic point, the plastic point being where it can no longer recover from mechanical stress and it cracks.
The short answer to your question, though a vague one, is "any weight bearing exercise up to the plastic point will increase bone “fitness” by which you really mean strength/density, I think we can use those interchangeably.
Exercise must be specific: if you want to build density in leg bones you need to stress leg bones (run, walk, etc). If you want to build spinal density you must axially load the spine.
Also notable is the fact that calcium - an electrolyte - is lost in sweat. This is less Ca for your bones to rebuild. Not a problem if you get enough Ca to eat… might be if you already have weakened bones.
Does that help? I truly don’t think there’s an answer to your question.
PM me if you need more info.
I don’t know of a specific study…but I do know:
Adding to whats already been said: Bone registers stress as a measure of force per unit area. To stimulate new bone formation, a minimal essential strain must be applied to the bone. For most people, this is 1/10 the force required to fracture said bone. If this stress is applied regularly, the diameter of the bone will increase, thus decreasing the overall force per unit area that the bone experiences during exercise. After adaptation occurs, the MES increases and the force that provided adaptation before will now be belong the adaptation threshold. This adaptation can be achieved a number of ways. Running for long extended periods of time can yield results, but they will come about slower as the overall force being applied at the time of impact isn’t that high. High impact exercises like sprints and box jumps, and things like squats add high pressure to the bone in a shorter period of time and will cause faster adaptation. The greater the load applied and the greater the force that is required to be supported by the skeletal structure, the greater adaptation aswell.
I just finished my first year of ‘official’ university training with my university team. Before that I trained sprints extensively doing many box jumps, squats, cleans etc and subjected my bones to a high level of stress. I did much more work in the weight room. That being said, I’ve never had a stress fracture, shin splint, or any real lower body injury save for one at the beginning of this season that was caused by my shoes being way too old to be running in. At the end of this season, several people had to miss workouts because of shin issues, and 2 people had to take time off because they have stress fractures. Maybe I’m just lucky, but I’d like to think that this prior training has given me bones which can withstand more stress for extended period. Hope this helps.
Running for long extended periods of time can yield results, but they will come about slower as the overall force being applied at the time of impact isn’t that high. High impact exercises like sprints and box jumps, and things like squats add high pressure to the bone in a shorter period of time and will cause faster adaptation. The greater the load applied and the greater the force that is required to be supported by the skeletal structure, the greater adaptation as well.
This prompts me to ask how ‘impact’ and ‘load’ relate. Let’s focus on what seems to be the number one risk area, the tibia. I would imagine the benefits to the tibia from muscular strength exercise would be limited and that progressively longer runs would be far superior. Would you agree? I realize that obviously, a combination of strength ex and long runs is the best option.