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Fundamentals of Human Nutrition/Fitness basics

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Weight management Fundamentals of Human Nutrition
Fitness basics 		Energy systems

14.1 Fitness basics

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When people think of fitness, they think of the ability to be able to participate in physical activities such as running, swimming, or playing sports with their friends and peers. From a more scientific standpoint, fitness includes much more than just being able to go out and run around. Fitness includes nutritional health, such as getting enough vitamins and minerals from your diet, a healthy body composition, stronger bones and immune system, and cardiorespiratory health. Being fit can help lower the risks a person has of developing a multitude of cardiovascular diseases such as high blood pressure, certain types of cancer, and even lower the risks of someone suffering from severe anxiety and depression, and help improve a person's longevity. In older adults, physical activity has even been seen to lead to better cognitive function (Office of Disease Prevention, 2015)

To many, fitness is known as being able to be engaged in physical activities, without causing injury or distress to yourself. Physical activity, along with a healthy diet, is the safest way to lose weight, and improve your overall health, and help lower your risk of obesity (President's Council on Fitness)

Many Americans of today cannot be classified as physically fit. Two categories of fitness exist – health-related fitness and athletic-related fitness. Athletic-related fitness consists of much more demanding and sport-specific requirements. The health-related fitness components are for the general public (and are the focus of the rest of this section). It consists of muscle strength and endurance, flexibility, and cardiorespiratory fitness (Surgeon General, 1996). These components can be attained through physical activity, or “bodily movement produced by the contraction of skeletal muscle that increases energy expenditure above the basal level,” as defined by the Surgeon General (1996).

The American Heart Association recommends 150 minutes of moderate cardiorespiratory activity per week (30 minutes, 5 days per week), or 75 minutes of vigorous cardiorespiratory activity per week (25 minutes, 3 days per week). In addition to cardiorespiratory activity, one should engage in moderate to intense muscle building activities as well as flexibility exercises at least twice a week (American Heart Association, 2015).

Cardiorespiratory exercises consist of large muscle groups contracting repeatedly and rhythmically, and include exercises such as running, walking, elliptical, and climbing stairs. Note that “vigorous” and “moderate” can vary from person to person. Some beginners might find that a slow jog can raise their heart rate a significant amount and thus consider this activity vigorous, while more physically fit individuals would classify jogging as moderate. As fitness levels improve, some exercise's classifications can change from vigorous to moderate as the body grows stronger. Muscles can be exercised by lifting weights (machine or free), resistance training, or body weight exercises such as pushups and sit-ups. Muscular training sessions can be either full body or split body (i.e. arms and back one day, abs and legs the next). The American College of Sports Medicine (ACSM) recommends 2-4 sets of 8-12 reps per exercise, with a 48-72 hour rest period between sessions. Flexibility can be attained through static or ballistic (stretching while moving) stretches, or other practices such as yoga or Pilates. Hold the pose or stretch for 10–30 seconds, and repeat it 2-4 times (ACSM, 2011).

The most noticeable effects of exercise include improvements in the cardiovascular and muscular systems, as well as improved immune, endocrine, and metabolic function. Regular, moderate exercise can reduce the risk of multiple diseases, such as cardiovascular diseases, cancer, osteoporosis, obesity, and diabetes. However, it is important to note that the benefits of exercise diminish in two weeks and can completely disappear in as little as 2 months (Surgeon General, 1996). Thus, consistency could be considered one of the most essential components to not only achieving physical fitness, but also maintaining it.

14.1.1 Types of fitness

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Fitness is typically described as the combination of a number of aspects of health that ultimately contribute to increasing healthiness in different parts of the body.

These aspects include:

  • Flexibility- the capacity of the joints to move through a full range of motion; the ability to bend and recover without injury (Understanding Nutrition, 2015). Physical activities that increase this freedom of movement are ones that promote the movement of joints, such as yoga, and a variety of stretches. (National Institute of Health, 2012)
  • Cardiorespiratory Endurance- most aerobic activities promote this aspect of fitness. Physical activities that promote cardiorespiratory endurance do so by increasing heart rate and breathing rate over a period of time, keeping your cardiac and respiratory systems in functioning at an optimal level. Exercises that increase your cardiorespiratory endurance are activities such as fast walking, jogging, swimming, and other things that raise your heart and breathing rate. (NIH, 2012)
  • Muscle Strength and Endurance- a muscle's ability to perform a maximum contraction time after time while a single muscle's ability to perform sustained work (Conditioning, 2016). Strength and endurance exercises strengthen muscles by breaking apart and re-building muscle cells. These help to build and maintain muscle and bone mass. Activities that promote this are resistance training, such as weight lifting. (NIH, 2012)
  • Balance-the ability to control the body's position, either stationary or while moving (Conditioning, 2016). Balance exercises are typically needed by older adults who have a higher risk of falling. These activities help to strengthen the muscles specifically in the lower extremities that are involved in maintaining balance, including activities such as calf raises, and standing on one foot. (NIH, 2012)
  • Body Composition- though not a physical activity, body composition is an important part of fitness. It is the ratio of fat to lean tissue in your body, and we strive for more lean body tissues and less fat. It is important to recognize though, that fat is an important tissue in our body, and is essential to life, just not in excess.

Aerobic Endurance Training

Aerobic training or endurance training provides a multitude of benefits for the functioning and overall health of the body.

A few of the benefits include:

  • Boosts of High Density Lipoprotein cholesterol levels
  • Helps control blood pressure
  • Strengthens the bones in the spine
  • Helps maintain a healthy weight
  • Higher levels of energy
  • Stronger heart
  • Stronger immune system

Types of Aerobic Exercises

There are many different types of aerobic exercises that can be put into the categories of low intensity or high intensity. If the exercise is categorized as High Intensity, it is further defined as low impact or high impact. Examples of each include: 1. Low to moderate impact exercises – Brisk walking, swimming, rowing, stationary bike riding, cross-country skiing. 

    a.	Who can take part in these exercises? Nearly anyone in a reasonable level of fitness should be able to take part in many of the low to moderate impact exercises. Brisk walking is a great alternative to running for people who cannot take the impact that running has on the body. Stationary biking is great cross-training for runners as it helps in increasing turnover and in keeping up cardiovascular endurance.

2. High-impact exercises – Running, tennis, soccer, backpacking, biking, rollerblading 

    a.	Who should do these types of exercises? If you are in good physical health already, it is recommended to do high impact exercises no more than every other day. Those who are elderly, overweight, or out of good physical condition should rule out high impact exercises, until they get back into good physical condition.

A good way to incorporate aerobic exercises into you daily exercise routine would be to add a mix of low and high impact exercises. If you wish to see improvements in aerobic capacity, 3–4 hours per week of aerobic exercise is the ideal amount. For healthy adults, the best approach to incorporating aerobic exercise is to start with a mix of low impact and high impact exercises. If maintaining a level of fitness is the goal, two weekly aerobic workouts are ideal. If you wish to increase aerobic capacity, three to five aerobic exercises will get you to where you want to be. For out of shape or elderly people, it is best to slowly start incorporating aerobic exercises into your daily routine. For example, start out with 10–15 minutes of low impact aerobic exercise every other day, and gradually work up to 30 minutes and then 35–40 minutes and so one. As you can increase the time spent doing each sessions of aerobic activity, work towards a goal of 30 minutes of aerobic exercise per day, anywhere from three to seven days each week.

A great way of gauging the aerobic intensity of an exercise session is trying to aim for a “conversational pace.” This type of pace is just enough to work up a sweat and still able to talk to a friend without gasping for breath when you are working out. As your level of fitness increases, your “conversational pace” will increase with it.

14.1.2 Recommendations

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The recommendations for physical activity varies based on a wide variety of circumstances, such as age and weight. For adults aged 18 years of age to 64 years of age, a minimum of two and a half hours consisting of moderate-intensity activities is recommended for overall health. This can be substituted with an hour and a half of vigorous-intensity activities (Office of Disease Prevention, 2015). In addition to this, all major muscle groups should be worked out with muscle strengthening activities on at least two days per week. Even greater health benefits can be seen by increasing these recommendations. (Center for Disease Control, 2008)

Moderate-intensity activity is considered as such when your heart rate is elevated to 50% to 70% of one's maximum heart rate. For a vigorous-intensity activity, the heart rate is elevated to 70% to 85% of a person's maximum heart rate (CDC, 2008). When it comes to each individual person though, one must go at their own pace, recognizing the cues of their body, and know how far they can push themselves without hurting themselves. When you begin to exercise, one should be very aware of their body, and listen to the cues of it. If you are not sure of how to start an exercise routine, or the best way to achieve your own personal fitness, make sure to contact your doctor and make a plan that is safe, but effective for you as an individual.

14.1.3 Fitness Progression

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How do we know what changes to make in our routine in order to progress our fitness level and enhance our health through exercise? In order to answer this question we need to determine the difference between physical activity and exercise. Physical activity is any methodology of muscular activation that causes the body to use energy. Exercise is a planned subset of physical activity that has a set objective of building or maintaining physical fitness. In order to lead a healthy lifestyle, one must engage in planned exercise and know the tenants of exercise progression. This is vital to ensuring one is able to advance safely and sensibly in an exercise routine. Physical activity is also beneficial, but the most therapeutic effect to the body comes from planned exercise (Howley & Powers, 1996).

Progression in any health related exercise program must emphasize progressing from lighter activity to more intense activity slowly and steadily, without drastic changes. Recommended exercise programs include dynamic, multi muscle group activities such as jogging, rowing, cycling, dancing, and swimming. The effects of these programs is dependent on several factors: Frequency, duration, and intensity of the exercise sessions. When changing a program to advance to a higher level of exercise for physical fitness, it is important to focus on changing only one of these factors at a time to ensure safety and to ensure that the body adapts to the stress of exercise adequately (Howley & Powers, 1996).

  • Frequency - Improvements in cardiorespiratory fitness increase with the frequency of exercise sessions. The lowest number of sessions required for improvements of cardiorespiratory fitness is two (2). Improvements in cardiorespiratory fitness begin stagnating after three to four sessions per week. Depending on the desired results, one can substitute high intensity exercise at less frequency for moderate intensity exercises at high frequency (Howley & Powers, 1996).
  • Duration - Duration must be taken into account when analyzed in tandem with frequency. The total work accomplished per exercise session is paramount to determining the amount of calories burned weekly which must be factored into the Total Daily Energy Expenditure (TDEE) of the exerciser (Howley & Powers, 1996).
  • Intensity - Intensity describes the total metabolic stress on the cardiovascular system which is crucial to bring about training adaptations. If intensity is not high enough, then the participant will not make optimum gains in cardiorespiratory fitness because the body is used to the demands being placed on it. Different ways of measuring intensity include the Borg rate of perceived exertion scale and target heart rate range (Howley & Powers, 1996).

References

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