Additional Information on Strength Training and Bone Health

Q:

The Fitness First staff has commented that strength training improves bone mass/density.  Please explain.

A:

To start, the primary purpose of bones is to provide a structural frame for the body, to work with muscle, ligaments, tendons, and joints to provide movement, to protect vital organs, and to produce blood cells and calcium for the entire body.

Bones are a dynamic tissue that are continuously being broken down and restructured in a process called remodeling.  During remodeling, bones cells called osteoclasts break down and absorb existing bone and other bone cells called osteoblasts deposit new bone.  Peak bone mass is generally reached between the ages of 25 and 30.  Bone mass starts to diminish around the age of 40.

Due to the critical nature of bone, maximizing peak bone mass, maintaining bone mass, and minimizing bone loss during aging are important.  One of the best ways to achieve these goals is through strength training.  Strength training increases the physical stresses on bone. These stresses activate the osteoblasts to deposit new bone in the stressed area.

Similar to muscle, bones respond to progressive overloads.  Progressive overloading means safely and systematically applying higher levels of stress to the bone.  Properly applying the overload leads to greater increases in bone mass or minimizes bone loss due to aging.

The following websites were used in answering the question:

https://www.unm.edu/~lkravitz/Article%20folder/bonemass.html

 https://www.google.com/amp/s/www.livestrong.com/amp/article/133645-how-does-exercise-increase-bone-density/

Strength Training and Bone Health

            There has always been a cloud of hesitancy around strength training. Now, some may feel that it is meant only for athletes who must compete at a high, physical level. However, there were times when even athletes were told to stay away from the activity, until the added strength and stability resistance training provides was fully understood and appreciated. And can’t we all benefit form a little more strength and stability? So, in truth, strength training can (and should) be viewed as a method to benefit all, regardless of the individual’s activity level, age, or gender. One large benefit of strength training that every person should find of interest is the ability to strengthen our bones, the first layer of foundation for our body.

            Sherk et al. found that those who strength train have a significantly higher bone mineral density than those who do not (2010).  Those with a higher bone mineral density have stronger bones, and thus a sturdier foundation.  The International Osteoporosis Foundation (2017) report that, in the US, over 45 million people suffer from osteoporosis. For those 50 years or older, one’s risk for having either osteoporosis or low bone mineral density is 55%.  Luckily, strength training has shown to have benefits in all age ranges, and that elderly individuals can benefit just as much as their younger counterparts.  Warren et al. concluded a study that middle aged women who progressively strength trained had a significantly higher bone mineral density within the femoral neck- a common location for hip fractures- than those who did not (2008).The strength of our hip and low back become extremely important as we age to reduce our risk of injuries. To further support that any age group can benefit from strength training, Taunton et al. conducted a study using participants age 75-80 to show the positive effects of strength training on bone mineral density. Specifically, the study showed that strength training significantly improved bone mass in the lumbar spine of the low back (2002). This is extremely relevant as the World Health Organization has stated that 60-70% of the population will experience low back pain, with an increased risk above age 55. Clearly, strength training has no limits on what age range it can help.

            Studies have also followed the bone mineral density in those who are trying to lose weight and have been placed on a lower calorie diet. Beavers et al. compared the effects of resistance training to aerobic exercise on bone mineral density in a population trying to lose fat mass.  It was determined that strength training significantly preserved more bone strength than aerobic exercise. This is very important because many people feel that when trying to lose weight, cardio is the answer. However, strength training offers many important benefits as well.

            There are many benefits that can be acquired when one begins strength training. One large benefit is the ability to increase one’s bone strength. While this can be advantageous at any age, it especially becomes important as we progress later in life when our bones become weaker. While it is important to try to strengthen one’s bones as early as possible in life, plenty of research supports that beginning a strength training program at any age can have a significant and positive effect on bone mineral density. It is time to view strength training as a tool for all, because we all deserve the benefits.

References

Sherk, V.D., Bemben, M.G., & Bemben, D. A. (2010). Comparisons of bone mineral density and bone quality in adult rock climbers, resistance- trained men, and untrained men. Journal Of Strength & Conditioning Research (Lippincott Williams & Wilkins), 24(9), 2468-2474.

Beavers, K. M., Beavers, D. R., Martin, S. B., Marsh, A. R., Lyles, M. F., Lenchik, L., & ... Marsh, A. P. (2017). Change in Bone Mineral Density During Weight Loss with Resistance Versus Aerobic Exercise Training in Older Adults. Journals Of Gerontology Series A: Biological Sciences & Medical Sciences, 72(11), 1582-1585. doi:10.1093/gerona/glx048

Taunton, J., Donnelly, M., Rhodes, E., Elliott, J., Martin, A., & Hetyei, J. (2002). Weight training in elderly women: the effects of progressive resistance training on body composition, muscular strength, bone mineral density, functional ability and psychosocial attitudes of women 75-80 years. New Zealand Journal Of Sports Medicine, 30(4), 106-113.

Warren, M., Petit, M. A., Hannan, P. J., & Schmitz, K. H. (2008). Strength Training Effects on Bone Mineral Content and Density in Premenopausal Women. Medicine & Science In Sports & Exercise, 40(7), 1282-1288.

International Osteoporosis Foundation (IOF). https://www.iofbonehealth.org/

Strength Training and Muscle Soreness

Muscle Soreness: What causes it? Does it correlate to muscle growth? And should you train when sore?

Muscle soreness is an uncomfortable experience we’ve all dealt with at some point. It is one of the outcomes of intense exercise, whether it is vigorous strength training, a tough day of speed work at the track, or a long day of yard work.  Intense exercise results in an accumulation of lactic acid in the muscles, which is a natural byproduct of muscle metabolism.  This build-up of lactic acid can irritate muscles, causing soreness and discomfort. Muscle soreness associated with exercise is known as Delayed Onset Muscle Soreness (DOMS).   However, lactic acid is not the sole contributor to DOMS. Interestingly, lactic acid is actually removed from muscle anywhere from a few hours to less than a day after a workout. This begs the question of why do we experience soreness days after a training session? This is due to swelling in the muscle compartment which results in an incursion of white blood cells known as prostaglandins (anti-inflammatory) that rush to the muscles to repair the microscopic damage following a vigorous training session. It is part of the normal process referred to as anabolism and is no cause for concern. This type of inflammation can accumulate for days after a workout, which explains why we may be sore three or four days after an intense training session.

 Is there a direct correlation between DOMS and muscle growth?  In other words, is soreness a prerequisite for growth? And if one isn’t sore days after a workout, does that mean muscle isn’t being built?

Dr. Richard Weil of OnHealth.com (2017) states that there has been no scientific evidence to support the idea that DOMS directly results in greater muscle size and strength. Individuals can become stronger without getting sore, but some just aren’t satisfied with their workout unless they’re sore afterward.  There may be some rationale for this thinking. In order for growth to occur, microscopic damage to muscle fibers must take place. Soreness is an indication of muscle damage and thus growth probably isn’t far behind. But to reiterate, there has been no scientific backing of the idea that DOMS is necessary for growth. Wayne Westcott, fitness research director and strength training consultant (1995), indicates that ultimately “there is a direct relationship between the exercise effort and the recovery period required for optimum muscle development. That is, a harder exercise session produces more muscle microtrauma and requires more recovery time for the tissue-building processes to be completed.” However, an intense, effective workout can still take place without the muscle soreness to follow.  Dr. Weil recommends that the most efficient, effective method for increasing muscle size and strength is to strength train with a resistance that can be controlled throughout the entire range of motion. He advises slow and controlled performance on the concentric and eccentric portions of the movement, emphasizing the importance of taking the muscle to complete fatigue. To do this, he encourages individuals to complete their set to momentary muscle failure, and then have their spotter assist with extra/forced repetitions, allowing the individual to control the resistance during the eccentric portion on their own for five to ten seconds. This technique is demanding, but extremely effective. 

 If soreness lingers into your next training session, should you still train?

Westcott (1995) found that strength training two to three times per week was optimal for muscle size and strength gains. These findings are supported with those from the University of Florida (Braith et al. 1989). Muscle recovery typically takes anywhere from 48-72 hours, hence the recommendation of two to three strength training sessions per week. Westcott also advocated that when training twice a week, spacing out those two sessions between Monday and Thursday, or Tuesday and Friday, was optimal.  If muscle soreness occurs, it will usually coincide with that period of muscular recovery, meaning that you shouldn’t be sore by the time of your next training session if they’re spaced out correctly. Weil (2017) advises to warm-up for 10-15 minutes with light aerobic exercise before beginning your training session. This may help reduce swelling and increase circulation to and from the muscle. Muscle groups may be worked again after two to three days rest, but it is recommended the exercises used should be varied and different from the previous training session.  Neal Pire, MA, CSCS, exercise physiologist and certified health coach at Castle Connolly Private Health Partners in New York City suggests that exercise can help reduce DOMS by increasing circulation to the sore muscles and enhancing mobility.

            Muscle soreness is a completely natural, but uncomfortable side-effect of exercise. As long as two to three days rest is allowed, an individual’s muscles should be recovered enough to train. Well-designed, intense strength training prescriptions account for this and allow for proper recovery before stimulating the muscular system again.  Mild soreness while training will cause no harm, and in fact, the training itself will provide relief to the sore region due to increased blood flow and circulation.

https://www.onhealth.com/content/1/muscle_soreness

http://www.healthy.net/Health/Article/Strength_Training_How_Many_Days_Per_Week/519/3

https://www.weightwatchers.com/us/article/working-out-if-youre-sore

Westcott, W. L. (1995). Strength Fitness: Physiological Principles and Training Techniques, Fourth Edition. Dubuque, Iowa: Wm. C. Brown and Benchmark.

Westcott, W. L. and Guy, J. A physical evolution. IDEA Today, 14 (9): 58-65.