8. Resistance training and bone health

As if spending most of 2022 releasing my e-book wasn't enough, I decided to finally tackle my Biomechanics studies via the London College of Canada. Because, who wants to take a break, right?

This was something I've wanted to do since 2019 and then it became even more attractive in 2020 when during the lock down I started taking several online assessments on biomechanics and the musculoskeletal system and successfully passing all of them. 

So a few weeks after Conjugate Iron was released, I managed to take some of the profits and invest on an online Biomechanics course which I'm currently in the middle of.

And before this introduction deviates towards an endless brag instead of the actual subject of this article, I want to thank those who supported me and move onto talking about the amazing abilities our bones possess. 

Let's begin. I'm not going to expand on the bone itself as much since the article needs to stay around the resistance training realm. Also, the more you dive into the study of the human body the less you realize that you know. At least in my case.

WHAT IS BONE 

Bone is mineralized connective and dynamic tissue (it can regenerate and remodel, up to a certain extent) that adapts to load alterations. It allows the body to move via the musculoskeletal system by providing attachment points for the muscles. It also supports and protects some of our organs. It is made of collagen which helps provide a soft structure and calcium phosphate which helps make the bone strong and flexible as well as adjust to the stress that it is given through more difficult activities such as sports or manual labor etc. 

Bone provides storage for minerals like calcium and phosphorus (around 80% of phosphorus is stored in bones and teeth) as well as electrolytes like potassium which can be found in a small percentage since most of it can be found in the muscles. It also contains red and yellow marrow. 

Red bone marrow contains blood stem cells which can turn into white and red blood cells as well as platelets which prevent bleeding by clotting the area. 

Yellow bone marrow contains mesenchymal stem cells that store fat and can turn into bone, muscle or cartilage cells. It also contains adipocytes to a very high percentage which also store fat. 

Bone is consisted of 4 different cells: 

1.OSTEOBLASTS 

Deriving from osteoprogenitor cells, osteoblasts exist on the surface of the bone and help with the initial creation as well as remodeling depending on activity as mentioned above. They help synthesize and release collagen which mineralizes and then becomes the bone matrix as well as regulate calcium and phosphate ion numbers in order to keep the balance in its development. 

2. OSTEOCLASTS 

Multi-nucleated cells that break down bone. They originate from the white blood cells that exist in the red bone marrow. They are the cells that initiate remodeling by dissolving the mineral and breaking down bone matrix. This process is called bone resorption. 

They also moderate bone loss during pathologic conditions. 

3. OSTEOCYTES 

Taking up nearly 95% of cells in the bone tissue, Osteocytes are the longest living bone cell. They take shape and develop after the Osteoblasts have submerged in the mineral bone matrix. Shaped like a tree with branches, Osteocytes are essentially the osteoblasts that have secreted Collagen which then calcifies, encasing them in the organic bone matrix. 

They act as mechano-sensors and have a large part in the functional adaptation by registering the amount of strain on the bone. Them registering deformation inside the bone along with bone lining cells which detect strain on the surface of the bone, make up for a very powerful and accurate system in terms of bone adaptation and remodeling. 

*Osteblasts and Osteclasts take up around 5% of the bone cells. 

4. BONE LINING CELLS 

They were considered to be pre-osteblasts but later studies have shown that they are osteoblasts that did not differentiate to osteocytes or go through apoptosis which is the cells programmed time of collapse/death.

Residing on the surface of bone, these cells are flat, long and slender. 

They remove non-mineralized collagen and prepare the bone for remodeling. After completion they apply a thin layer of collagen over the surface of the bone. 

BONE ADAPTATION (Wolff's Law) 

Wolff's Law was developed by the German anatomist/surgeon Julius Wolff (1836-1902)

"Bone in a healthy person or animal will adapt to the loads it is placed under. If loading on a particular bone increases, the bone will remodel itself over time to become stronger to resist that sort of loading. The external cortical portion of the bone becomes thicker as a result." 

The converse is true as well: if the loading on a bone decreases, the bone will become weaker due to turnover, it is less metabolically costly to maintain and there is no stimulus for continued remodeling that is required to maintain bone mass."

According to Dr Wolff, both the bone density and the organization of bone trabeculae correlate with the magnitude and direction of compressive and tensile stresses of loading (Julius Wolff 1892). 

INACTIVITY AND BONE LOSS 

Regular resistance training will help develop dense bones which in turn will ensure that the skeleton will stay strong avoiding fractures due to conditions such as osteoporosis. 

Age, inactivity and sometimes lack of proper nutrition will lead towards bone loss (osteopenia) and later on to osteoporosis. We lose bone density at nearly 1% per year after we reach 40 years of age. 

Lack of activity will cause bone density to decrease and then it's literally open season for anything that might happen to us. From a minor slip or fall to a basic work injury/accident. So many different ways we can get hurt that could lead to bone fracture. And sadly the older we get, the lighter the injury can be and it will still have a large impact on our body. A very common injury we see in older people is a hip or shoulder/clavicle fracture due to a fall. 

The hip is especially dangerous since more than 50% of the people who suffer a broken hip never fully recover. We've all seen that person who went through such a serious injury and just wasn't the same since. Hips, spine, wrists are all points that can get damaged badly and will affect our life tremendously if they do so. 

Osteoporosis is a worldwide concern and it only gets worse, women are more susceptible to it due to a generally smaller frame and thinner bone structure and later in life  because of the rapid drop of estrogen after menopause. Estrogen has the ability to restrict osteoclast activity and therefore retain bone mineral density. Less estrogen, less mineral density retention. 

Same thing happens to men and the loss of testosterone which also affects bone density. After the age of 60, both sexes lose bone density at a very similar rate.

Men statistically will have the same amounts of bone loss as women nearly ten years later in life. In other words a man who is susceptible to develop osteoporosis will have the same amount of bone loss at 75 with a woman who is around 8-10 years younger. This is mainly due to bone/skeleton size differences. 

A BRIEF MENTION OF ARTHRITIS 

Exercising while suffering from arthritis can be highly beneficial. From extreme cases of severe lower body arthritis where people can only walk inside a pool and eventually are able to swim and move around more easily to people who literally can't close their fist due to the pain in their hands. 

Training will help the muscles stabilize the joints and improve (lengthen or shorten) range of motion and life quality. This will combat ligamentous laxicity which can occur when a person suffers from Rheumatoid Arthritis. It'll also help decrease joint inflammation (synovitis) which can gradually lead to articular bone erosion. 

It's a brief mention since arthritis appears in the joints and not in the bones per sé. But it does often happen because of the lack of cartilage which prevents the friction between two bones. There are so many parameters to consider that I might end up making a series of articles. Since two bones connect at the joint, it's relevant to have osteoarthritis included.

I'm not going to expand further on the various bone diseases and conditions I just thought I should write about osteopenia/osteoporosis which in so many cases is our fault just because of inactivity besides the obvious injury/fracture/disability etc. 

EXERCISE RECOMMENDATIONS AND THEIR BENEFITS 

Resistance training has profound benefits in regards of slowing down the bone loss process and becomes a must for longevity and health. Any activity that initiates stress on our bones will force them to remodel. Running, jogging and walking do have their benefits as well since the do add stress to the lower extremities and spine. At the same time compound movements like the squat, deadlift, overhead press, kettlebell swings and so many more will impact many more areas. 

And besides bone health, they will promote better balance and strength at ANY age. A bit unrelated yet related: I always say "if you can sit, you can box squat" and this another amazing exercise that everybody can utilize provided that they are can sit down and stand up again. You can find my article on the box squat and how it helped immensely with my  injuries in this website. 

Resistance exercise is highly beneficial for the elderly as well, or should I say ESPECIALLY for the elderly. Where do I begin? Stronger, healthier muscles. Increased bone mineral density. Increased tendon health. Helps with circulation. Helps regulate your blood sugar levels. Protects them from falls with increased balance and muscle stability. How many times have you heard of an older person slipping and tearing tendons or ligaments in their shoulder when they tried to break their fall? 

Even worse, slip and break a hip? Moderate to high intensity from 50% to 70% is ideal in terms of stressing the muscle, the muscle pulls on the bone and the remodeling process begins. Mix compound movements with isolation/accessory exercises. You can do your leg press, leg extensions and leg curls but it's great if you add some kind of squat in there as well. Any kind. Start with bodyweight squats or bodyweight box squats if you're somebody who's never trained. Do the same if you haven't exercised in a long time or if you've never exercised and you're older. 

Start by sitting on a high box, then gradually lower it. Below parallel is ideal as far as stretching the hamstrings and if you eventually get to a low box, you're golden. Always depending on your ability to move 100% and that should be discussed with your coach or physician if you're suffering from injury or disability. If your range of motion is limited, sit as low as it remains pain free and beneficial. 

Goblet squats or goblet box squats with a dumbbell or kettlebell are also highly therapeutic and valuable regardless if you're a competitive athlete or somebody who wants to improve their life quality in general. 

Mix it up with seated machine exercises, you don't have to leave the gym crawling every time. Train smart and have a plan. The exercise rotation mentioned above applies to most of us. Intensity changes depending on demand and schedule and/or musculoskeletal injuries. 

THE SCIENCE 

Studies were done on male and female groups both above 50 years of age. Women were all post menopausal. None of the participants had done any sort of exercise in at least 2 years. The research lasted 6 months and both groups went through the same resistance training regiment. After figuring out their 1 rep max, they trained with moderate intensity between 40% and 60% and then switched to a higher intensity regiment of 70% for sets and reps. 

Moderate intensity:

They trained 3 times per week with seated machines and for about 75 minutes per session. Doing sets of 10+ reps and performed over 10 exercises in that session. 

The exercises that were chosen were for upper and lower body and switched from compounds like leg press, chest press, seated shoulder press to isolation exercises like bicep curls, tricep extensions, side lateral raises etc. 

The results:

This program largely increased bone mineral density of the greater trochanter for both sexes. It also increased lean muscle mass by nearly 3.5% for women and 2% for men. It also increased max force output for both sexes. 

High intensity:

They also trained three times per week for about 75 minutes per session. And performed more than 10 exercises in every session as well. The intensity was set at 70% of their individual 1 rep max. 

The difference is, they used free weights while primarily standing. The compound exercises that were chosen were the squat, deadlift, bench press, incline bench, shoulder press and some of the isolation choices were variations of the lat pull down and standing rows, leg curls, leg extensions, calf raises and hand grippers. 

The goal was 3 sets of 8 reps per exercise. This high intensity program was periodized, not repeated the next week and so forth like the moderate intensity training cycle. 

They split it into 2 cycles of 12 weeks each with one active recovery week in between were no resistance training was allowed, only fitness activities. This allowed them to recover from the 2 x 3 month high intensity periodization cycles. 

The results:

This program also increased bone mineral density for both sexes with the difference that men had a significant increase in their lumbar spine bone density as well. Lean muscle mass also increased with greater results this time for both sexes at above 8% for women and above 3% for men. 

Max force output also increased for both sexes. 

High intensity training promoted better bone formation than moderate intensity, particularly in elderly men. 

Interestingly enough, regardless of the program or level of intensity there were no significant changes in IGF-1 in either gender which leans towards the possibility that the increase in bone density was strictly caused by the physical stress and not an increase of the Insulin-like Growth Factor 1 also knows as Somatomedin C. 

IGF-1 is a hormone that along with PTH (parathyroid hormone) enhance the differentiation of osteoblasts to osteocytes and is a highly important constituent of the organic skeletal intercellular substance. 

It can increase longitudinal growth and the circumference of the periosteum as well as the mineral density of bones. 

Exercise reduces cortisol levels as well, which is a well known osteoblast inhibitor. Therefore it prevents bone healing and growth.

I hope that you found this article as interesting as I found it exciting to write. I spent dozens of hours and nearly 45 days trying to put it together as well as possible. At the same time making it accessible to everybody. Hope it wasn't too "technical" and I also hope that it carried the message clearly. We all need to exercise. 

That being said, not everybody is 100% healthy (trust me, I can relate) and if you are somebody with no experience, suffers from severe injuries or is just elderly that you consult a doctor/surgeon/physician/strength and conditioning coach before you embark on this neverending journey. Exercising at high intensity is difficult at every level regardless of your maximum potential, age, level of physical ability (injured or not) or how much you want it. Be smart. Be responsible. 

Find a program that fits your individual needs and TRAIN. 

Terry Eleftheriou for Conjugate Iron

December 2022

https://linktr.ee/terryconjugateiron

Article references

. London College of Canada course on Biomechanics 

. Basic Biomechanics of the Musculoskeletal System, Fourth Edition by Margareta Nordin, Victor H. Frankel

. Stem cells journal

. Harvard health publishing

. D.Nieman. (1998). The Exercise-Health Connection. Human Kinetics

. R.A. Robergs, and S.O. Roberts. (1997). Exercise Physiology: Exercise, Performance and Clinical Applications. Mosby.

. Epidemiology of osteoporosis and fragility fractures by the International Osteoporosis Foundation 

. Resistance training and bone mass 

Heidi M. Weingart, M.A. and Len Kravitz, Ph.D.

. PubMed Central - Gender Disparities in Osteoporosis by Khaled A. Alswat

. Maddalozzo, G.F., and Snow, C.M. 2000. High intensity resistance training: Effects on bone in older men and women. Calcified Tissue International, 66, 399-404.