Resistance Training is Medicine: Stay Active and Reap the Reward, Live in your Life!

*Endang Ernandini and William Giovanni Mulyanaga*

### **Abstract**

The world of physical medicine and rehabilitation still believes that exercise is medicine. Muscle mass will naturally decrease with aging, 3–8% every decade after a person turns 30 years old, getting worse over the age of 50 years, which is 5–10% every decade. Some studies state that for healthy people, resistance training (RT) performed 2–3 times per week with 12–20 total sets of exercises will add muscle mass. The addition of 1.4 kg of muscle mass was accompanied by the disappearance of about 1.8 kg of fat. RT plus aerobic exercises (AE) complemented with caloric resistance (CR) can result in a reduction of 5.1 kg or 7.1% of fat. Some research papers state that for stable CAD patients starting with 3 months of AE followed by an RT program of 40–60% intensity 1x RM, 1–2 sets, 8–10 repetitions, 2–3 days per week, duration not more than 60 minutes. Recommendation for a person with intellectual disability can be simple and harmless RT tools. The prescription for COVID-19 survivors consists of AE for 5 to 30 minutes with low to moderate intensity, plus 1–2 sets of RT, 8–10 reps at 30–80% 1xRM.

**Keywords:** resistance training, exercise, medicine, special condition, prescription

#### **1. Introduction**

Resistance training (RT) is part of several types of exercises that can be recommended as one of the lifestyles and has a positive effect on a person's health status [1]. This is one of the exercises that should be done together with other exercises that will form or maintain endurance, balance, flexibility, and strength. Blending these four types of exercises is very important to maintain optimal health and to be able to carry out optimal activities in daily life. Strength training is a form of exercise that focuses on the use of weights or resistance to build muscles, as well as ligaments and bones, increase power, and maintain posture [2].

RT, also known as weight training or strength training, is a physical activity to improve neuromuscular and musculoskeletal fitness and physical performance by training muscles or a group of muscles, which is done by resisting weights from the outside [1, 3, 4]. External load can be in form of disc, barbells, dumbbells, and resistance bands. Folland et al., 2007 [5] and Spiering et al., 2008 [6] state that physical exercise using some kind of resistance exercise can also be incorporated into the

RT [5, 6]. Resistance training can also be performed by using body weight, such as push-ups and squats [1].

The first question that arises is "What is the main purpose of doing this RT activity as the chosen type of sport instead of doing other types of exercises?" It has been proven by many studies and articles that RT can produce a state of muscle hypertrophy [3–6] and produce additional muscle endurance, muscle strength, maximum strength, muscle explosion, and power [4, 7, 8]. In addition to the ability of RT to create muscle hypertrophy, it is also able to create functional additions to the body, besides only the esthetic function of body shape, which we will learn more about in the next chapter.

In contrast to aerobic exercise, which already has standards that are widely accepted in society, RT still needs to be studied for its needs and advantages for the various physical circumstances of a person who will do it, especially people with special conditions. The best procedure for identifying the most adequate and optimal RT exercises is through careful experimentation as well as observations and experiences. Through experiments, observations, and experiences, it can be analyzed and concluded how to obtain a method, a formulation for the dose of load applied to improve the state of health and even improve the quality of life of a person. RT is also expected to be applied not only to healthy individuals but also to individuals with certain health conditions. Suchomel et al., 2018 [9] also DeWeese et al., 2015 [10] remind us that: 1) it is necessary to pay attention to the selection of exercises to produce a balance between determining and using the weight of the load as well as its preparations to achieve the specified goals, 2) management of fatigue begins from anticipating the possibility of overtraining to carrying out rest procedures, and 3) it is necessary to pay attention to the right stages and timing to produce good performance [3, 9, 10].

### **2. Physiology of exercise**

Exercise forces the body to do more movement compared to when resting. Movement during exercise stimulates the sympathetic nervous system and will increase the body's response integrally. This response is necessary for the body to maintain hemostasis over the increased metabolism of the heart, lungs, muscles, brain, and other organs [11].

#### **2.1 Cardiovascular system response**

Physiologists say that when a person performs a heavy physical activity, the muscles only show 30% of their maximal capacity, while the respiratory and cardiovascular systems have reached much higher activity, 60% and 90% of their maximal capacity, respectively. Based on this data and information, some physiologists state that the greatest factor affecting the transportation of O2 and nutrients to the muscles that will support metabolism in aerobic exercise is the cardiovascular system. Thus, the exercise is aimed mainly to improve cardiovascular efficiency [2, 12, 13]. The increase in endurance levels of the cardiorespiratory system is not solely produced by AE but also RT. RT helps to add endurance values in cycling (47%), walking (38%), and running (12%) activities. The increase in this value is not due to an increase in the value of VO2max, but mainly because of the increase in fatigue threshold. This can occur due to the recruitment of muscle cells and mitochondria, so we can say that cardiorespiratory endurance is also affected by muscle strength in addition to muscle endurance [14].

#### **2.2 Muscle response**

The human body has three types of muscle tissue: skeletal muscle, smooth muscle, and special muscle, called the cardiac muscle. As the name implies, most skeletal muscles are attached to skeletal bones, and they have the main function for active movement [2]. Skeletal muscles make up most of the body mass, it is estimated to be about 40% of body mass in total. Tendon is further classified into two parts, one part is immobile and attached closer to the torso, called origo. The other part of a tendon can relatively move and is attached farther to the body, called insersio [2].

What requirements are needed to move the skeleton? How can muscles move the skeleton? The answer is by contracting. The muscle contraction will bring the bone closer or away according to the condition. The movement is possible due to the presence of joints, which connect the bones. The driving muscle is called the flexor when the task is to bring the two bones connected to the joint closer, and the movement is called flexion. In contrast, when the contraction of the skeletal muscle drives the two bones away, the muscle is called extensor and the movement is called extension. The flexor muscle will be paired with the extensor muscle, and together they are called antagonist muscle group. The task of these antagonist muscles is to move closer and further from the fulcrum point. Contracting alternately, relaxing alternately. The coordinated movement between these muscles allows us to do daily activities effectively [15].

Active muscle contraction requires a supply of energy coming from adenosine triphosphate (ATP), while relaxation of the muscle is a state of relinquishment from a state of contraction. Muscle movement always requires energy, both when contracting and relaxing. When contracting, muscles need energy to move interlocking. When relaxing, muscle requires energy to pump Ca2+ ions back into the sarcoplasmic reticulum, and also to return Na + ions to extracellular and K+ ions to intracellular [15].

Where do muscles get energy (ATP) from to perform their duties? Can muscles run out of ATP? The amount of ATP energy available in the muscle fibers is only enough to do about 8 to 10 wrinkles. As the source of energy stored in the muscle, it is very limited in quantity. Muscles must use other sources of energy to still be able to carry out their duties, that is to transfer energy from chemical bonds stored in nutrients into ATP. Carbohydrates, especially glucose, are the fastest and most efficient sources of energy. Glucose molecules will produce 30 ATP when metabolized using oxygen (called aerobic metabolism). However, when the oxygen supply is exhausted, this metabolism will enter the anaerobic process, which only produces 2 ATP. Muscles also get energy from fatty acids, which also always require oxygen, and this process is relatively slow. Skeletal muscles in carrying out their tasks still prefer to rely on glucose. Protein is also not a major producer of energy sources for muscle contraction, preferably used for cell repair [15].

#### **2.3 Hormones response**

The fundamental difference in physiology exercises can be seen from gender differences, where the hormone testosterone gives the different characteristics in males and females. This hormone has a more influential role for males in exercise in terms of increasing male muscle mass. Besides testosterone, it turns out that there are many other hormones that are affected and affecting the ability to carry out the exercise as well as in terms of the results of the exercise. Gharahdaghi et al., 2021 [16] mentioned that the body during exercise requires work initiated by these hormones, especially when we talk about maintaining and even developing muscle mass as a goal of exercising. Hormones such as testosterone, estrogen, growth hormone (GH), and insulin-like growth factor (IGF) have a role in the success of an exercise [16].

Hooper et al., 2017 [17] stated that muscle contraction exercises in RT remain the leading major role in muscle hypertrophy through the formation of muscle protein synthesis (MPS) [17]. This response is controlled by the combination of weight training and the associated hormone release. Skeletal muscle mass, which at least comprises 40–45% of the entire body mass, will be preserved from sarcopenia problems caused by aging [18].

The RT pathway of inducing an anabolic response to the skeletal muscles can be traced from several studies and statements from experts in the field. RT will stimulate the work of the hormone testosterone, GH, and estrogen (in accordance with the rhythm of the body of a menstrual woman), as well as IGF. Basically, stimulation of these hormones functions to repair the damaged cells that occur in the muscles while doing exercises. Owing to the balanced work between MPS and muscle protein breakdown (MPB), muscle cells can be repaired, maintained, and developed to increase muscle fiber [16].

The release of testosterone is induced by exercise, both acutely and chronically (as exercise becomes a habit of life), and affected by sex and age. Hooper et al. stated that in the acute phase of exercising, the level of serum testosterone rises from 13 (resting level) to 38 (in 30 minutes) nmol.L−1. Then it will decrease back to the baseline immediately after finishing the exercise [17]. If this exercise becomes a habit of life, it is not impossible that this phenomenon will play a very long role in the development and growth of muscles. This is reinforced by statements from Hansen et al., 2001 [18] and Ahtiainen et al., 2003 [19], where they confirmed that after 9 weeks of RE, the level of serum of these hormones was found to be increased steadily, leading to even more optimal muscle growth [18, 19]. There are authors who also state that the role of testosterone response and adaptation of exercise in women must still be tested and studied further.

Hermansen et al., 2017 [20] stated that the physiological increment of GH values after doing RT is basically adding protein synthesis, which also has the ability to repair muscle tissue and also affects muscle mass without affecting the ability to function muscles [20]. It was also reported that there was a correlation between RT stimulating an increase in GH and the presence of muscle hypertrophy of type I and II muscle fiber types [21].

RT also provides a rapid response to an increase in systemic levels of IGF-1 from 45 (resting state) to 65 nM when performing RT and returning to the baseline after completing RT. Ogasawara et al., 2016 [22] stated that this situation is also alleged to be an important thing in muscle growth [22]. Likewise, the statement of Bjersing et al., 2017 [23], who proved the existence of an increase in muscle strength after doing RT by taking into account IGF-1 levels [23]. Similar to the influence of GH, the role of IGF-1 will stimulate a pathway that will improve the state of muscle hypertrophy, which also greatly affects the absorption of glucose into the muscles to be able to produce available energy for the continuation of the active movement of muscles [24].

#### **2.4 Fats metabolism response**

Research explains that after 30 minutes from the start of physical exercise, particularly aerobic, the concentration of free fatty acids in the blood will increase *Resistance Training is Medicine: Stay Active and Reap the Reward, Live in your Life! DOI: http://dx.doi.org/10.5772/intechopen.109973*

significantly. That is, at that 30th minute, the fat will be mobilized from the adipose tissue. However, the process of breaking down these fatty acids is slower than glucose metabolism through the glycolysis process, so the energy production that occurs in the muscles is both from fatty acids and glucose. In lower-intensity and aerobic physical exercise, the largest source of energy production, ATP, comes from fat with a time of more than 30 minutes, while during medium–high-intensity physical exercise, the main source of energy is carbohydrates [2].

#### **3. Resistance training is medicine**

RT is now publicly known, not necessarily only applicable to athletes, such as weightlifters, bodybuilders, and footballers. In these sports, athletes are demanded to have much higher muscle strength or be esthetically pleasing for competitions. However, people in general do not have a reason to do RT, especially people with certain medical conditions. Fear and disbelief, despite of popularity of RT, still do not make RT a part of everyday life [25]. The world of physical medicine and rehabilitation still believes that exercise is medicine. Many authors implement endurance exercise as a therapeutic exercise for patients with stroke, heart disease, and DM while emphasizing RT for patients with postinjury. Nowadays, some of the authors, through their experience and personal daily clinical observations, began to show the courage to choose RT as a type of therapeutic exercise for patients with certain diseases. Prescription of RT as a medicine seems to have more advantages than disadvantages, when done carefully and full of caution (always looking at the patient's response and vital signs).

Muscle mass will naturally decrease with aging, 3–8% every decade after a person turns 30 years old. Flack et al. and Frontera et al. stated that at least 0.2 kg of muscle is lost annually [26, 27]. Marcell also gives even more surprising data for muscle mass loss over the age of 50 years, which is 5–10% every decade [28]. Nelson et al. [29] stated that muscle mass was close to 0.4 kg per year [29]. Skeletal muscles that weigh about 40% of our body have a role in burning glucose and triglyceride, so losing muscle mass will increase glucose intolerance. Even in untrained muscles, skeletal muscles are responsible for a massive overhaul and synthesis of proteins. This overhauling metabolism will be responsible for calorie expenditure needed even at rest. Calories that must be prepared for this metabolic process have values ranging from 11 to 12 cal.d−1.kg−1 [30]. One can imagine the disadvantages of losing muscle that occurs both due to sarcopenia and sedentary lifestyle. Inactive living habits will decrease muscle mass, which will lead to a decrement in the metabolic rate of the body. A decrease in metabolic rate will lead to the growth of body fat tissue, especially intraabdominal fat. The accumulation of fat and the reduction of muscle mass will certainly have an impact on decreasing metabolic rates. This condition will occur as a cyclic process and affect one another, becoming the so-called vicious circle. Efforts are needed to break the loop, and according to some studies it turns out that RT can give quite promising answers.

Some studies state that RT exercises performed 2–3 times per week with 12–20 total sets of exercises will add muscle mass in all adults in a wide age range. The addition of an average of 1.4 kg of muscle mass occurs after performing 3 months of RT. It can be concluded that RT helps restore muscle mass gain, even in nonathlete population. The addition of 1.4 kg of muscle mass was accompanied by the disappearance of about 1.8 kg of fat [31–34]. The research become more interesting because it

showed a reduction in abdominal adipose fat tissue in elderly women who do RT, not just a reduction in abdominal fat in elderly men. Participants who regularly do RT for 2 years were able to remove 2/3 of intra-abdominal fat, compared to the participants who did not do exercise [35–38]. Hurley et al. [39] believe that the addition of metabolic rates, even at rest, plays a major role in increasing insulin sensitivity and sympathetic nerve activation, two of many factors affecting intraabdominal fat accumulation. The addition of metabolic rate is an intraabdominal fat loss factor with this calculation: if RT is done twice per week for 20 minutes each day, it will be close to the energy use of 5000 calories per month [39].

In a study of nursing home residents (with an average age of 89 years), the participants performed 1 set of exercises of RT with 6 machines twice per week for 14 weeks. At the end of this study, an evaluation was obtained and the results of the analysis found that all the participants increased their muscle strength by 60%, with the addition of 1.7 kg of muscle mass as well as a functional increase in independence by 14 [25].
