Core – The Whole Picture.

From that perfect looking Olympic snatch, to something as humdrum as mopping the floor, every movement involves the core. Whether you are a professional athlete, a crossfitter, a fitness enthusiast or someone with a desk job, all movements, no matter how simple or complex, rely on the use of core. 

What Makes The Core? 

Think of your core as the center of your body, and through this very center the force to perform all movements pasees to our extremities. 

Image 1 shows the core muscles: 

  • Rectus abdominis, or widely referred to as abs, at the front, 
  • The internal and external obliques, 
  • The erector spinae, 
  • Lumbar multifidus, and quadratus lumborum at the back, 
  • The diaphragm at the upper edge and
  • The pelvic floor, and the iliac psoas at the bottom.

Until a few moments ago, you thought it was all about those washboard abs! Your core is far more complex, and training to build a strong and functional one requires more than performing crunches and leg raises. 

Great, now you know what makes the core. 

Why Build A Strong and Efficient Core? Let’s Find Out.  

There are a plethora of reasons behind world-class athletes, strength and conditioning professionals, and physical therapists around the world talking so much about the importance of building a strong core. Ever wondered why? Here are a few reasons :

  • Postural Control and Postural Balance: Our movement involves constant balance and unbalance. Imagine you want to jump, and while your legs push off, your trunk is falling down towards the ground – the constant battle with gravity. In scientific terms, it is the ability of your body’s postural system (musculoskeletal, vestibular, somatosensory and visual) to maintain the center of mass within the limits of stability. 

This complex skill of postural balance and control is what allows you to sit upright in your office chair, get in and out of it, and drive your car. Building a strong core allows us to perform simple and complex tasks with good coordination, and provides our body with stability. 

  • Low Back Pain  (LBP):  More than 60% of people around the world develop chronic low back pain. Literary evidence suggests performing systematic all-round core strengthening helps in prevention and treatment of LBP. 
  • Stability: Core strengthening improves stability and control of the lumbar spine and pelvis, thereby allowing for efficient execution of athletic skills, as well as activities of daily living such as bending to pick up an object and tying of shoelaces. 
  • Healthy Ageing:  Ageing is associated with reduced muscle capacity,  loss of functionality in performing activities of daily living (ADL), poor gait, and increased risk of falls and fractures. Performing core strengthening improves functional abilities in performing ADLs, reduces tremors and the risk of falls by improving postural control and stability. 
  • Dysmenorrhoea: A common gynecologic disorder, refers to painful menstruation. Pain can reduce the quality of life and can become irritating to live with. Performing planned core strengthening exercises improves blood flow to the musculature around the pelvis, and improves the metabolism of the uterus, which reduces the intensity of pain and duration of dysmenorrhoea.

Guidelines On How To Build A Strong and Functional Core.  

You want a strong core? Make sure you train the flexion (forward bending or rounding of the spinal column; ), extension (backward bending of the spine), lateral flexion (bending sideways), and rotational strength (ability to rotate the torso) of your core. 

  • Free Weight exercises, such as the squat, bench press, clean and jerk, snatch, and deadlift are excellent to develop a rock-solid core, as they work on all the muscles of the core. Adding destabilizing bars, using resistance bands to suspend weights from the bars further loads the erector spinae. 
  • Unilateral exercises such as skater squats, unilateral dumbbell shoulder press, chest press, and rear foot elevated split squats are great for building external obliques as they challenge the rotational strength of the core. 
  • Hollow rocks, sit-ups, hanging leg and knee raises target the rectus abdominis, internal and external obliques. 
  • Instability in performing exercises such as stir-the-pot is great to work on external obliques..
  • Front plank with and without hip extension on the floor, and on stability ball targets internal obliques, multifidus, and erector spinae. 
  • Exercises such as Pallof press train anti-rotation strength by targeting transverse abdominis, and isometrically contracting rectus abdominis. 
  • Glute bridges are great for developing strong erector spinae and the gluteal muscles. 
  • Prone trunk and hip extensions are great for strengthening the lumbar multifidus. 
  • Performing side planks and Copenhagen planks with and without suspension systems for transverse abdominis, and the adductors of the hip. 
  • Unloaded and loaded birddog are excellent to build transverse abdominis, primary trunk stabilizer, and anti-rotation strength. 

Investing 15-20 minutes daily in strengthening the core will make sure you keep it strong, have the ability to perform daily tasks efficiently, and keep health problems such as low back pain, at bay. 

Author details:

Shikhar Suman Bassi

Exercise physiologist and strength Coach. 

M.Sc. Sport and Health Sciences

University Of Exeter, 

Exeter, United Kingdom. 

References

  • Chuter, V., de Jonge, X., Thompson, B. and Callister, R., 2014. The efficacy of a supervised and a home-based core strengthening programme in adults with poor core stability: a three-arm randomised controlled trial. British Journal of Sports Medicine, 49(6), pp.395-399.
  • Hibbs, A., Thompson, K., French, D., Wrigley, A. and Spears, I., 2008. Optimizing Performance by Improving Core Stability and Core Strength. Sports Medicine, 38(12), pp.995-1008.
  • Human Kinetics. 2021. Build Your Core. [online] Available at: <https://us.humankinetics.com/blogs/excerpt/build-your-core> [Accessed 25 February 2021].
  • Martins, H., Lüdtke, D., César de Oliveira Araújo, J., Cidral-Filho, F., Inoue Salgado, A., Viseux, F. and Martins, D., 2019. Effects of core strengthening on balance in university judo athletes. Journal of Bodywork and Movement Therapies, 23(4), pp.758-765.
  • Martuscello, J., Nuzzo, J., Ashley, C., Campbell, B., Orriola, J. and Mayer, J., 2013. Systematic Review of Core Muscle Activity During Physical Fitness Exercises. Journal of Strength and Conditioning Research, 27(6), pp.1684-1698.
  • NADLER, S., MALANGA, G., BARTOLI, L., FEINBERG, J., PRYBICIEN, M. and DEPRINCE, M., 2002. Hip muscle imbalance and low back pain in athletes: influence of core strengthening. Medicine & Science in Sports & Exercise, 34(1), pp.9-16.
  • Oliva-Lozano, J. and Muyor, J., 2020. Core Muscle Activity during Physical Fitness Exercises: A Systematic Review. International Journal of Environmental Research and Public Health, 17(12), p.4306.
  • Publishing, H., 2021. Core conditioning — It’s not just about abs – Harvard Health. [online] Harvard Health. Available at: <https://www.health.harvard.edu/healthbeat/core-conditioning-its-not-just-about-abs> [Accessed 25 February 2021].
  • S Saleh, H. and E Mowafy, H., 2016. Stretching or Core Strengthening Exercises for Managing Primary Dysmenorrhea. Journal of Womens Health Care, 05(01).
  • Smith, B., Littlewood, C. and May, S., 2014. An update of stabilisation exercises for low back pain: a systematic review with meta-analysis. BMC Musculoskeletal Disorders, 15(1).
  • Willardson, J., 2007. Core Stability Training for Healthy Athletes: A Different Paradigm for Fitness Professionals. Strength and Conditioning Journal, 29(6), p.42.
  • Willson, J., Dougherty, C., Ireland, M. and Davis, I., 2005. Core Stability and Its Relationship to Lower Extremity Function and Injury. Journal of the American Academy of Orthopaedic Surgeons, 13(5), pp.316-325.

Fundamentals of Training

Training or performing physical exercise has numerous health and mental benefits and must be a part of your daily life. It helps you build strength, speed, power, endurance, improve skill, build confidence and ambition, and  improve self-esteem. It helps you gain knowledge about your body; how it performs, what are its physical and mental capacities, and how you could improve them. It also makes your body more resilient against injuries and illness. 

Principles of training

Training is the practical application of science of sport and health sciences to improve the quality of life, improve athletic performance, reduce the risk of injury, and assist in injury rehabilitation. For training to be effective in achieving its desired outcome, few key elements, such as training intensity, training volume, training load, specificity, progression and periodization need to be in perfect harmony. 

Let’s learn about some of the key principles of training and how you could apply them to your training to achieve your goals.

  1. Training Load or training intensity:  Exercise is a stressor that produces physical and mental responses in the body. It is this stress that helps us adapt to training. For training to be effective, and for optimal adaptation, this stress needs to be appropriately controlled. This is achieved by careful application of training load. It has two variables:
  • External load: This is determined by the organization, quality, and  quantity of exercise. For example: in resistance training external load is the amount of weight lifted. Total work done, distance covered, or velocity achieved are other examples of external load. 
  • Internal load: Specific external load creates a specific internal load in the body (termed as psychophysiological response). Heart rate, skin color, sweating, genetics, nutrition, lactate threshold, hydration, and sleep are some examples of internal load. 

Image showing training structure. 

  1. Training Volume: Training Volume and load are inversely proportional. Meaning, as the intensity (load) goes up, training volume goes down. In resistance training, number of sets and repetitions represent total volume of training. Whereas, the amount of weights lifted in training intensity. A good training program should strive to strike the right balance between training load and training volume. 
  1. Individuality: Every individual is different (anatomy, training age, genetics lifestyle), and training should be planned as per the individual differences. 
  1. Specificity: Simply put, if you want to improve your 100 mt sprint, you shouldn’t be training like a marathon runner. Specific training induces specific responses, meaning your training should mimic the demands and skill of your actual activity or sport. 
  2. Progressive Overload: In order to continue making progress, training demands placed on the systems of the body must be increased (overloaded) as they adapt and become capable of producing better performance (speed, strength, power and endurance). This is why training must always be progressive in nature, barring when the body is reaching the state of overreaching or overtraining. 

Application of principles of training

Now that you know about some of the core principles of training, let’s learn how to apply the principles of training intensity and training volume to your training. 

Volume is the number of sets and repetitions you perform. If you perform three sets of five repetitions, your total volume is fifteen repetitions. Volume and intensity are conversely proportional – as intensity goes up, volume reduces. It is humanly not possible to perform multiple sets or reps with one-rep-maximum load. 

It is common to prescribe training volume on the basis of one repetition-maximum (1-RM). Here is how you can find your one repetition-maximum of a particular exercise.  1-RM strength could be predicted using repetitions-to-fatigue with a submaximal weight. 

Beginners: 1-RM (kg) = 1.554  X 7 – to 10-RM weight (kg) – 5.181

Advanced: 1-RM (kg) = 1.172  X 7 – to 10-RM weight (kg) + 7.704

For example, estimate 1-RM bench press score for a trained individual whose 10-RM bench press is 70 kg as follows:

1-RM = 1.172 X 70 KG + 7.704 = 89.7 kg. 

Image showing the relation between intensity and volume of training.

Ratings of perceived exertion: Another widely used and reliable tool for prescribing exercise intensity is Borg’s Ratings of perceived exertion (RPE). Developed by Gunnar Borg, the scale allows the user to rate how easy or how hord the exercise is, providing an indication of exercise intensity. 

The scale goes from 1 – 10, 1 being absolutely easy, and 10 being maximal effort. 

Image showing RPE scale. 

Opposed to percentage-based training, RPE training accommodates daily stressors, such as sleep, work related stress, and nutrition, thereby giving the lifter a chance to avoid feeling burned-out. 

If you are a beginner, performing 2-3 sets of each exercise with 10-15 sets per muscle group per week at an intensity of 60-80% is a good recommendation to follow. Gradually, as your body starts adapting to the stress of training, you could then focus on increasing the intensity of your training. 

Whether you are an advanced athlete or a beginner, right from the very first time your training should alway be in balance when it comes to training intensity and training volume. It helps in:

  • Reducing the risk of injury. 
  • Optimal adaptation to training. 
  • Optimal recovery. 
  • Avoiding the conditions of overreaching and overtraining. 
  • Keeping the process of training fun and motivating. 
  • Proper application of overload and progression. 

References

1Current Sports Medicine Reports. Journals.lww.com. 2021. https://journals.lww.com/acsm-csmr/pages/default.aspx (accessed 21 March 2021).

2Impellizzeri F, Marcora S, Coutts A. Internal and External Training Load: 15 Years On. International Journal of Sports Physiology and Performance 2019; 14: 270-273.

3Coffey V, Hawley J. Concurrent exercise training: do opposites distract?. The Journal of Physiology 2016; 595: 2883-2896.

4BarBend Newsletter – BarBend. BarBend. 2021. https://barbend.com/newsletters/ (accessed 21 March 2021).

5Chen M, Fan X, Moe S. Criterion-related validity of the Borg ratings of perceived exertion scale in healthy individuals: a meta-analysis. Journal of Sports Sciences 2002; 20: 873-899.

6Eston R. Use of Ratings of Perceived Exertion in Sports. International Journal of Sports Physiology and Performance 2012; 7: 175-182.

7ACE | Certified Personal Trainer | ACE Personal Trainer. Acefitness.org. 2021. https://www.acefitness.org (accessed 21 March 2021).

8Expert Strength Coaching + Free Content | Barbell Logic Online Coaching. Barbell Logic. 2021. https://barbell-logic.com (accessed 21 March 2021).

9Kasper K. Sports Training Principles. Current Sports Medicine Reports 2019; 18: 95-96.

10Lorenz D, Morrison S. CURRENT CONCEPTS IN PERIODIZATION OF STRENGTH AND CONDITIONING FOR THE SPORTS PHYSICAL THERAPIST. Int J Sports Phys Ther. 2015 Nov;10(6):734-47. PMID: 26618056; PMCID: PMC4637911.

11Bomgardner R. Rehabilitation Phases and Program Design for the Injured Athlete. Strength and Conditioning Journal 2001; 23: 24-25.

12Reiman MP, Lorenz DS. Integration of strength and conditioning principles into a rehabilitation program. Int J Sports Phys Ther. 2011 Sep;6(3):241-53. PMID: 21904701; PMCID: PMC3164002.

Sedentism – What it does to you?

Prolonged sitting or being sedentary has been linked to various musculoskeletal complications such as neck pain, lower back pain, and cervical spondylosis. These complications have a high socioeconomic cost as they result in lost working days, and lead to significant health expenses. 

Also, being sedentary is associated with an increased risk of developing chronic diseases such as cardiovascular diseases, obesity, hypertension, type-2 diabetes, arthritis, cancer, depression, metabolic syndrome and all cause mortality. WIth rapid advancements in the fields of technology and entertainment, time spent in sitting has significantly increased, resulting in severely low levels of physical activity. 

Truth is; this is not the first piece you will read about the effects of being sedentary on health, and I am certain that this won’t be the last one to talk about it as well.  

My sincere concern is for you, why do you choose to stay glued to your television and mobile phone while lying in your bed, why do you choose to stay ignorant about your health? Why have you forgotten the fact that your body is meant to move, it is meant to jump, climb, lift, run and do so many extraordinary things? 

I believe, you have been shackled by the perils of convenience that your phone and computer have to offer, you let it in, and now it has intruded into every aspect of your life, and nobody, but only you can save yourself! 

What Is Being Sedentary? 

Metabolic equivalent (METs) is used to estimate how much energy is expended in doing an activity. Spending prolonged hours in activities of low energy expenditure (reading, screen-time, video games, driving, and viewing TV) of 1-1.5 METs is defined as sedentary behavior. 

The Price You Pay For Being Sedentary: 

Enjoying your TV a bit too much? You’re 50% more likely to die prematurely than those who sit the least. 

  • Being sedentary causes severe damage to your muscle and bone health. Your body is meant to perform movement, and the lack of it leads to loss of muscle and connective tissue health. It is one of the major causes of sarcopenia (loss of muscle due to immobility).  
  • It leads to an increased risk of obesity, and obesity related complications. 
  • It leads to reduced insulin sensitivity, increased levels of inflammation in the body, and impaired blood sugar regulation in the body, thereby increasing the risk of developing type-2 diabetes, metabolic syndrome,  and cardiovascular diseases. 
  • Reduced physical activity leads to impaired endothelial function, and increased risk of developing hypertension. 

Image 1 showing the effects of physical inactivity. 

  • It results in impaired balance between bone resorption and formation, causing severe loss in bone mineral content. Consequently, leading to diseases such as osteoporosis, and arthritis. 
  • Chronic low levels of physical activity could result in painful and irregular menstrual cycles. 

How Do We Address The Issue of Sedentary Behaviour? Answer: Physical Exercise. 

Physical exercise is a non-invasive means to reduce the risk of chronic diseases, and improve the quality of life. Yet, so many people across all age-groups struggle to meet the recommended guidelines. 

Current Guidelines For Physical Exercise For Various Age Groups By World Health Organisation (WHO): 

  • Infants stay physically active numerous times in a day via a variety of activities. 
  • Children aged 1-2 years should spend a minimum of 180 minutes per day in moderate to vigorous physical activities. 
  • Children aged 3-4 years should perform a minimum of 180 minutes of physical activity, out of which 60 minutes should be of moderate to vigorous nature. 
  • Children and adolescents aged 5-17 years should participate in 60 minutes per day of moderate to vigorous daily physical exercise, and should include vigorous physical exercise three times per week. 
  • Adults aged 18-64 years should perform 150–300 minutes of moderate-intensity exercise; or at least 75–150 minutes of vigorous-intensity physical activity; or an equivalent combination of moderate and vigorous-intensity activity throughout the week.
  • Pregnant and postpartum women without contraindication should do at least 150 minutes of moderate-intensity aerobic physical activity throughout the week.

 Benefits of Physical Exercise: 

  • Improves muscular health, and cardiorespiratory fitness.
  • Reduces the risk of chronic diseases, such as hypertension, cardiovascular diseases, type-2 diabetes, metabolic syndrome, cancer, and depression. 
  • Improves mental health. 
  • Reduces the risk of  developing osteoporosis and arthritis, and improves bone mineral density. 
  • Reduces tremors, the risk of falls and fractures. 
  • Reduces the risk of obesity. 
  • Promotes optimal mental development in children, improves concentration and academic performance. 
  • Reduces the risk of gestational hypertension, excessive gestational weight gain, delivery complications, postpartum depression, newborn complications in pregnant and postpartum women.

Go, get up, and move – you will feel a whole lot better. Unshackle yourself from this self-imposed prison of convenience! 

Author details:

Shikhar Suman Bassi

Exercise physiologist and strength Coach. 

M.Sc. Sport and Health Sciences

University Of Exeter, 

Exeter, United Kingdom.

References
  • Ahrens, K., Vladutiu, C., Mumford, S., Schliep, K., Perkins, N., Wactawski-Wende, J. and Schisterman, E., 2014. The effect of physical activity across the menstrual cycle on reproductive function. Annals of Epidemiology, 24(2), pp.127-134.
  • Biddle, S., García Bengoechea, E. and Wiesner, G., 2017. Sedentary behaviour and adiposity in youth: a systematic review of reviews and analysis of causality. International Journal of Behavioral Nutrition and Physical Activity, 14(1).
  • Booth, F., Roberts, C., Thyfault, J., Ruegsegger, G. and Toedebusch, R., 2017. Role of Inactivity in Chronic Diseases: Evolutionary Insight and Pathophysiological Mechanisms. Physiological Reviews, 97(4), pp.1351-1402.
  • Hardman, A. and Stensel, D., 2009. Physical activity and health 2e. London: Routledge.
  • Omidvar, S., Nasiri Amiri, F., Firouzbakht, M., Bakhtiari, A. and Begum, K., 2019. Association Between Physical Activity, Menstrual Cycle Characteristics, and Body Weight in Young South Indian Females. International Journal of Women’s Health and Reproduction Sciences, 7(3), pp.281-286.
  • Shrestha, N., Kukkonen-Harjula, K., Verbeek, J., Ijaz, S., Hermans, V. and Pedisic, Z., 2018. Workplace interventions for reducing sitting at work. Cochrane Database of Systematic Reviews,.
  • Warburton, D., 2006. Health benefits of physical activity: the evidence. Canadian Medical Association Journal, 174(6), pp.801-809.
  • Who.int. 2021. Physical activity. [online] Available at: <https://www.who.int/news-room/fact-sheets/detail/physical-activity> [Accessed 25 February 2021].
  • Wu, X., Han, L., Zhang, J., Luo, S., Hu, J. and Sun, K., 2017. The influence of physical activity, sedentary behavior on health-related quality of life among the general population of children and adolescents: A systematic review. PLOS ONE, 12(11), p.e0187668.
  • Wullems, J., Verschueren, S., Degens, H., Morse, C. and Onambélé, G., 2016. A review of the assessment and prevalence of sedentarism in older adults, its physiology/health impact and non-exercise mobility counter-measures. Biogerontology, 17(3), pp.547-565.

Unlock your Potential with these Facts.

Training or performing physical exercise has numerous health and mental benefits and must be a part of your daily life. It helps you build strength, speed, power, endurance, improve skill, build confidence and ambition, and  improve self-esteem. It helps you gain knowledge about your body; how it performs, what are its physical and mental capacities, and how you could improve them. It also makes your body more resilient against injuries and illness. 

Principles of training

Training is the practical application of science of sport and health sciences to improve the quality of life, improve athletic performance, reduce the risk of injury, and assist in injury rehabilitation. For training to be effective in achieving its desired outcome, few key elements, such as training intensity, training volume, training load, specificity, progression and periodization need to be in perfect harmony. 

Let’s learn about some of the key principles of training and how you could apply them to your training to achieve your goals.

  1. Training Load or training intensity:  Exercise is a stressor that produces physical and mental responses in the body. It is this stress that helps us adapt to training. For training to be effective, and for optimal adaptation, this stress needs to be appropriately controlled. This is achieved by careful application of training load. It has two variables:
  • External load: This is determined by the organization, quality, and  quantity of exercise. For example: in resistance training external load is the amount of weight lifted. Total work done, distance covered, or velocity achieved are other examples of external load. 
  • Internal load: Specific external load creates a specific internal load in the body (termed as psychophysiological response). Heart rate, skin color, sweating, genetics, nutrition, lactate threshold, hydration, and sleep are some examples of internal load. 

Image showing training structure. 

  1. Training Volume: Training Volume and load are inversely proportional. Meaning, as the intensity (load) goes up, training volume goes down. In resistance training, number of sets and repetitions represent total volume of training. Whereas, the amount of weights lifted in training intensity. A good training program should strive to strike the right balance between training load and training volume. 
  1. Individuality: Every individual is different (anatomy, training age, genetics lifestyle), and training should be planned as per the individual differences. 
  1. Specificity: Simply put, if you want to improve your 100 mt sprint, you shouldn’t be training like a marathon runner. Specific training induces specific responses, meaning your training should mimic the demands and skill of your actual activity or sport. 
  2. Progressive Overload: In order to continue making progress, training demands placed on the systems of the body must be increased (overloaded) as they adapt and become capable of producing better performance (speed, strength, power and endurance). This is why training must always be progressive in nature, barring when the body is reaching the state of overreaching or overtraining. 

Application of principles of training

Now that you know about some of the core principles of training, let’s learn how to apply the principles of training intensity and training volume to your training. 

Volume is the number of sets and repetitions you perform. If you perform three sets of five repetitions, your total volume is fifteen repetitions. Volume and intensity are conversely proportional – as intensity goes up, volume reduces. It is humanly not possible to perform multiple sets or reps with one-rep-maximum load. 

It is common to prescribe training volume on the basis of one repetition-maximum (1-RM). Here is how you can find your one repetition-maximum of a particular exercise.  1-RM strength could be predicted using repetitions-to-fatigue with a submaximal weight. 

Beginners: 1-RM (kg) = 1.554  X 7 – to 10-RM weight (kg) – 5.181

Advanced: 1-RM (kg) = 1.172  X 7 – to 10-RM weight (kg) + 7.704

For example, estimate 1-RM bench press score for a trained individual whose 10-RM bench press is 70 kg as follows:

1-RM = 1.172 X 70 KG + 7.704 = 89.7 kg. 

Image showing the relation between intensity and volume of training.

Ratings of perceived exertion: Another widely used and reliable tool for prescribing exercise intensity is Borg’s Ratings of perceived exertion (RPE). Developed by Gunnar Borg, the scale allows the user to rate how easy or how hord the exercise is, providing an indication of exercise intensity. 

The scale goes from 1 – 10, 1 being absolutely easy, and 10 being maximal effort. 

Image showing RPE scale. 

Opposed to percentage-based training, RPE training accommodates daily stressors, such as sleep, work related stress, and nutrition, thereby giving the lifter a chance to avoid feeling burned-out. 

If you are a beginner, performing 2-3 sets of each exercise with 10-15 sets per muscle group per week at an intensity of 60-80% is a good recommendation to follow. Gradually, as your body starts adapting to the stress of training, you could then focus on increasing the intensity of your training. 

Whether you are an advanced athlete or a beginner, right from the very first time your training should alway be in balance when it comes to training intensity and training volume. It helps in:

  • Reducing the risk of injury. 
  • Optimal adaptation to training. 
  • Optimal recovery. 
  • Avoiding the conditions of overreaching and overtraining. 
  • Keeping the process of training fun and motivating. 
  • Proper application of overload and progression. 

References

1Current Sports Medicine Reports. Journals.lww.com. 2021. https://journals.lww.com/acsm-csmr/pages/default.aspx (accessed 21 March 2021).

2Impellizzeri F, Marcora S, Coutts A. Internal and External Training Load: 15 Years On. International Journal of Sports Physiology and Performance 2019; 14: 270-273.

3Coffey V, Hawley J. Concurrent exercise training: do opposites distract?. The Journal of Physiology 2016; 595: 2883-2896.

4BarBend Newsletter – BarBend. BarBend. 2021. https://barbend.com/newsletters/ (accessed 21 March 2021).

5Chen M, Fan X, Moe S. Criterion-related validity of the Borg ratings of perceived exertion scale in healthy individuals: a meta-analysis. Journal of Sports Sciences 2002; 20: 873-899.

6Eston R. Use of Ratings of Perceived Exertion in Sports. International Journal of Sports Physiology and Performance 2012; 7: 175-182.

7ACE | Certified Personal Trainer | ACE Personal Trainer. Acefitness.org. 2021. https://www.acefitness.org (accessed 21 March 2021).

8Expert Strength Coaching + Free Content | Barbell Logic Online Coaching. Barbell Logic. 2021. https://barbell-logic.com (accessed 21 March 2021).

9Kasper K. Sports Training Principles. Current Sports Medicine Reports 2019; 18: 95-96.

10Lorenz D, Morrison S. CURRENT CONCEPTS IN PERIODIZATION OF STRENGTH AND CONDITIONING FOR THE SPORTS PHYSICAL THERAPIST. Int J Sports Phys Ther. 2015 Nov;10(6):734-47. PMID: 26618056; PMCID: PMC4637911.

11Bomgardner R. Rehabilitation Phases and Program Design for the Injured Athlete. Strength and Conditioning Journal 2001; 23: 24-25.

12Reiman MP, Lorenz DS. Integration of strength and conditioning principles into a rehabilitation program. Int J Sports Phys Ther. 2011 Sep;6(3):241-53. PMID: 21904701; PMCID: PMC3164002.