Different energy sources in sports: Introductory software

Authors

  • Eduardo Galembeck,

    Corresponding author
    1. Departamento de Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas, Campinas-SP, Caixa Postal 6109, CEP 13083-970, Brazil
    • Dept. de Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo 13083-970, Brazil. Tel.: 55-19-3788-6138; Fax: 55-19-3788-6129
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  • Denise V. Macedo,

    1. Departamento de Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas, Campinas-SP, Caixa Postal 6109, CEP 13083-970, Brazil
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  • Bayardo B. Torres

    1. Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo-SP, Caixa Postal 26077, CEP 05508-900, Brazil
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  • The abbreviation used is: PBL, problem-based learning.

Abstract

This work describes software designed to promote the association between the content of a basic undergraduate biochemistry course and the professional activities of physical education students. The software contains three main content sections: (A) Structure of skeletal muscle, (B) Contraction mechanism, and (C) Adaptations to physical exercise. A fourth section asks questions of the students. The software offers students a brief introduction on muscle structure and function, focusing on the energy sources required by different kinds of physical activities. The software was field tested at Universidade Estadual de Campinas (Unicamp), Brazil and has been adopted by several Brazilian universities. The students are required to examine the software, to discuss its contents, and to produce a list of questions arising from their work with the software. These questions are answered during the development of the curriculum, thereby connecting biochemical knowledge with the energetic needs for the practice of sports.

A frequent criticism that students have is the lack of association between introductory level courses and the specific professional activities and concerns of their chosen careers. This lack of correlation often causes students to lose interest, particularly those aiming at a well defined professional activity such as physical education.

Entering physical education students at Universidade Estadual de Campinas (Unicamp) are required to take courses that provide them with a rigorous scientific basis for their chosen profession. Unfortunately there is often little correlation between the content of these courses and the needs of physical activity. In fact, most biochemistry courses follow an internally logical sequence that may initially appear irrelevant to students. This problem is exacerbated with physical education students because they are accustomed to visual and dynamic communication and therefore have difficulty understanding the abstractions and formal language through which biochemical concepts are usually presented.

Although perhaps most biochemical courses follow such a traditional mode, many different curricular approaches have been utilized successfully. One of the most widely used nontraditional approaches to biochemical education is problem-based learning (PBL),11 which has been successfully used in many medical schools [1]. However, the adoption of PBL requires careful curricular organization.

To better show the association between basic courses and professional activities, we have developed software22 to be used in teaching basic Biochemistry to undergraduate physical education students. The software contains three main sections: (A) Structure of skeletal muscle, (B) Contraction mechanism, and (C) Adaptations to physical exercise. A fourth section presents questions to the students. The software offers a brief introduction on muscle structure and function, focusing on the energetic support required by different kinds of physical activities.

The first two sections have a tutorial characteristic, while the third section gathers a set of information that is deliberately presented without great detail or explanation. The rationale for this organization is to allow its utilization as an advanced organizer [2].

Advanced organizers present a high degree of generalization and inclusiveness and a virtual lack of factual information or detail. These features make the advanced organizer conceptually different from the overviews presented in many introductory textbooks. Advanced organizers provide a conceptual framework to help the learner identify and even predict the learning tasks that lie ahead. The advanced organizer is based on the premise that the most important single factor that influences learning is what the learner already knows. It therefore acts as a bridge to span the gap between what the learner already knows and the knowledge he/she must acquire.

STRUCTURE OF THE SOFTWARE

Starting from the opening screen of the software (Fig. 1A), the student can go directly to any available section: (A) Structure of skeletal muscle, (B) Contraction mechanism, or (C) Adaptations to the exercise. Alternatively the students can go to the questions section.

The section on the structure of muscle presents a comprehensive visualization of the relevant structures from the macroscopic scale to muscle tissue proteins. There is a “horizontal” navigation structure with a sequence of predefined screens and some links that lead to details of the structures (Fig. 1B). In addition to the schematic drawings, the software also contains electron micrographs, animations, and tables.

The section on adaptations to physical exercise also contains a simulation that allows the student to examine different kinds of exercise and to obtain information on the energy metabolism of the athlete during the chosen activity (Fig. 1C). Four alternative forms of exercise are offered: jumping, 100-m dash, 400-m dash, and the marathon. The user chooses one of them to start the “exercise.” The sources of energy used (ATP, phosphocreatine, glycogen, fatty acids, and proteins) are represented by graphic bars (histograms) that are filled in at the beginning of the physical activity. During the chosen exercise, the bars are reduced in height to indicate the utilization of their corresponding energy source during the muscular work. Additionally two other initially empty bars that indicate the oxygen consumption and lactate production during the ATP synthesis are filled during the process.

SOFTWARE USES

As an Advanced Organizer—

The first activity of the Basic Biochemistry course for Physical Education students at Unicamp consisted of using Section C of the software. The task suggested to the students (gathered in groups of two or three) is to examine the section, discuss its content, and produce a list of questions. At the end of the first class, all the questions proposed by the students were gathered and consolidated into a single list. This list was distributed to all the students and used as a reference throughout the course, although new content can be added.

As a Tutorial—

The sections on the structure of skeletal muscle and its contraction mechanism (Sections A and B) can also be used as a study guide because they contain brief explanations, schematic representations, and animations with the relevant information. An effective procedure is to use the software in two steps. First students familiarize themselves with its contents, and then they answer the questions asked by the software (Fig. 1D). Once they have answered the questions, the students go back to Sections A and B to check their answers and to resolve further questions.

RESULTS AND DISCUSSION

The main goal of the software described in this article is to explore the muscle contraction process as a way of introducing and discussing biochemical content. The use of Section C of the software (Adaptations to physical exercise) in the introductory classes of the Basic Biochemistry for Physical Education students produced a surprising result: 120 students working in pairs raised 420 questions, which were grouped into 94 consolidated questions (tabulated in Table I using the students' original questions). The questions proposed by the students were then arbitrarily grouped into themes. Although many of these questions could have been be included in any of several groups, those questions that make a narrow and explicit link between biochemical knowledge and the practice of sports are written in italics in Table I. Indeed such a link underlies the majority of the questions. These questions focus on catabolism and sources of energy for the muscles during physical exercise. As already mentioned, these questions are frequently revisited later in the course.

The list of questions brings together the basic and applied contents of the course by showing that it is possible to reconcile the treatment of fundamental topics in biochemistry with the students' future professional activities, thereby helping to motivate the students. Most of the questions do not have a simple answer and hence require comprehensive knowledge. This is a positive aspect of the course because of the need to integrate biochemistry with physiology and other areas of study to obtain satisfactory answers to the practical questions. The utilization of questions formulated by the students to introduce different subjects is an essential aspect of this methodology as it allows the development of the specific content of biochemistry, starting from doubts and curiosities. To summarize, the number and diversity of the questions elicited provide an excellent indication that the use of this software was successful. In the second class in which the software was utilized again (but now as a tutorial), some of the questions generated by the software were already answered. The fact that the software is not seen as a book containing all the answers made its use more dynamic.

CONCLUSIONS

The utilization of the software in the biochemistry introductory classes for the undergraduate physical education students produced excellent results as evaluated by the number and scope of the questions raised by the students. These introductory classes made students aware of the importance of biochemistry to their careers. The questions raised by the students are strongly motivating as they generate a positive expectation for the answers that will be elucidated during the semester; this gives sense to the learning and produces satisfaction and reinforcement when these questions are eventually answered [3].

Figure FIGURE 1..

A, opening screen of the software “Muscular Contraction”; B, screen with the links to other sections providing greater detail on the structures of myosin and actin; C, simulator of the consumption of different energy sources used during exercise; D, example of a question. Pc, phosphocreatine.

Table Table I. Questions proposed by the students during the introductory class after examining the software
The questions are compiled and returned to them in the next class and used throughout the course. The questions in italics make an explicit link between biochemical knowledge and the practice of sports. Pc, phosphocreatine.
    1.What is the reason for the difference between red and white muscle fibers?
    2.How does heredity influence muscle performance?
    3.What and which are slow and fast fibers?
    4.Do men have more fibers than women? Do men have a greater possibility of having muscle hypertrophy than women?
    5.Does gender (male or female) have an influence that limits physical performance? If so, why?
    6.Are the proportions between fast and slow fibers equal in all muscles of the body?
    7.What are myofibrils and triglycerides?
    1.Why can't a marathon racer with 45% slow fibers in the quadriceps be a first rank athlete?
    2.Is it possible to acquire more slow fibers in order to become a first rank marathon racer?
    3.If a jumper becomes a marathon racer, will there be a change in the number of slow and fast fibers?
    4.Which kind of activity can be better performed by a person who has 50% slow fibers and 50% fast fibers?
    5.Which fibers are specialized in each type of metabolism?
    6.Is it possible to chemically change the type of predominating muscle fiber in any person?
    1.Why do muscles develop hypertrophy?
    2.Why is there an increase in the diameter of the fibers and in the number of mitochondria during training?
    3.Does muscle exercise increase only the number of fibers or only the fiber diameter?
    4.Do men have more fibers than women? Do men have a greater possibility of having muscle hypertrophy than women?
    5.Can athletic training increase significantly the number of myofibrils?
    6.Why can muscle hypertrophy range from 30 to 60% at most? Is this really true?
    1.Which kind of fiber is linked to which energetic source?
    2.Which are the different fuels utilized by muscle fibers? How are they produced, and where are they stored?
    3.What is the meaning of “predominating energetic system?”
    4.Where are the substances used as sources of energy stored?
    5.What is “energetic system?”
    6.Why is energy required for muscle contraction?
    7.Explain the relationship among the sources of energy utilized in all the exercises presented in the software.
    1.Why is the anaerobic capacity of an 800 m athlete larger than that of a 1500 m one?
    2.What does the O2 system mean?
    3.Describe the difference between aerobic and anaerobic metabolism.
    4.What is aerobic and anaerobic capacity?
    5.Is it the anaerobic capacity that increases as the time of activity decreases, or is it the anaerobic energy consumption that
 increases?
    6.Does the anaerobic capacity decrease with the increase of aerobic capacity?
    7.Is the anaerobic capacity larger in a speed racer than in a marathon racer?
    1.What is phosphocreatine?
    2.What is ATP?
    3.Why doesn't a marathon racer use any ATP, phosphocreatine, and lactate?
    4.When and with what kind of exercise do we produce ATP? Why?
    5.What is the difference between the “ATP-phosphocreatine-lactate” and the “lactate-O2” systems?
    6.Why doesn't ATP production stop completely with jumping or golf (short exercise of quick contraction)?
    7.What does ATP mean?
    8.Can ATP produced in an aerobic activity be reused in the same activity or in another one?
    9.When a person is doped, how does this change the ATP production system?
    10.Are phosphocreatine and Pc the same thing?
    11.Is energy always spent in the sequence ATP – Pc – Glycogen – Fatty Acid?
    12.How is ATP synthesized in exercise?
    13.What happens with the lactate and ATP produced after resting?
    1.Are substances such as lactic acid the cause of sore muscles?
    2.What is the meaning of the “lactate system?”
    3.How is lactate produced?
    4.What is the relationship between using energetic sources and the production of lactate and ATP?
    5.What is lactate; what is lactic acid?
    6.What is the relationship between time, energy expenditure, and the production of lactate and ATP?
    7.Why is it that during a 100-m swimming race, which is an exercise with high anaerobic demand, there is no production of lactate?
    8.Does a large rate of production of lactate mean a larger anaerobic capacity and performance?
    9.With which source of energy is the production of lactate related?
    10.As the production of lactate is proportional to the effort made, how can we explain that during the marathon race there is a smaller
 production of lactate than during the 400-m race?
    11.Is the expenditure of glycogen necessary for the production of lactate?
    12.In what moment of the physical exercise does the production of lactate start?
    13.What is the advantage of the production of lactate in physical exercise?
    14.What is the lactate system?
    15.If we increase the intensity of an aerobic activity, while the production of lactate remains the same, the clearance of lactate does not
 follow its rate of production. Does this activity become anaerobic?
    1.Why is it that during 100- and 400-m races there is no consumption of glycogen?
    2.If there is not enough glycogen in the muscle, will it be taken from the liver, or will fatty acids be used directly?
    3.What is the relationship between the time of activity to the consumption of glycogen and fatty acids?
    4.Is the utilization of glycogen necessary for the production of lactate?
    1.What is the relationship between the time of activity and the consumption of glycogen and fatty acids?
    2.On the average, how long does it take to burn fatty acids?
    3.Is there a relationship between triglycerides and fatty acids?
    4.Is fat only made of fatty acids?
    5.Does the consumption of fatty acid inhibit the production of lactate?
    6.What are triacylglycerols?
    7.Is there a possibility that fatty acids are used up before the other sources of energy or in larger amounts then the latter?
    1.How and in what moment of the metabolism of muscle cells does a deterioration of the proteins of the muscle itself occur in order
 to provide energy for aerobic exercise and for anaerobic exercise?
Exercises 
    1.Why is there no production of lactate during a 100-m swimming race?
    2.Why does the amount of available glycogen decrease and the production of lactate increase during a 400-m swimming race?
    3.Why are all sources of energy and both aerobic and anaerobic metabolism utilized during a marathon?
    4.What do jumping and golf have in common?
    5.Why does the anaerobic capacity vary so much even though the difference between the times of the exercises isn't very large?
    6.Does production of lactate have anything to do with the speed of a test in athletics?
    7.What is the relationship between the time of a test and the predominating metabolism?
    8.Is the anaerobic capacity larger in a speed racer than in a marathon racer?
    9.Are there any physiological adaptations in swimming? How does lactate production and ATP system function?
    1.Why do muscles hypertrophy?
    2.Why can't a marathon racer with 45% slow fibers in his/her quadriceps become a first rank athlete?
    3.Is it possible to acquire more slow fibers in order to become a first rank marathon racer?
    4.What is aerobic and anaerobic muscle capacity?
    5.Why does the diameter of fibers and the number of mitochondria increase with athletic training?
    6.Does weight lifting increase only the number of fibers or only their diameter?
    7.Do men have more fibers than women? Do men have a greater capacity for muscle hypertrophy than women?
    8.If a jumper becomes a marathon racer, will there be a change in his/her number of slow and fast fibers?
    9.Can athletic training significantly increase the number of myofibrils in a muscle?
    1.How is the ideal heartbeat frequency range determined for each type of exercise and for each individual?
    2.What is the maximum cardiac rate, and what benefits or losses can be generated by activities putting the heartbeat rate above the
 maximum of this range?
    3.What warning mechanism indicates that an energetic source has been exhausted?
    4.Does a large production of lactate mean larger anaerobic capacity and performance?
    5.What is the relationship between breathing and practicing different types of sports?
    6.How can we know the predominant muscle fiber in an individual?
    7.How long does it take to remove accumulated lactate?
    8.What is a biopsy?
    9.Can a creatine supplement improve performance?
    10.How are the percentage of slow and quick fibers determined in an individual?
    11.What are the criteria for analyzing aerobic and anaerobic metabolism?
    1.Do steroids overload the liver?
    2.Can urine act as an indicator of hepatic cell damage?
    3.What does everything in the software have to do with life?
    4.What does everything in the software have to do with muscle injury?

Footnotes

  1. 1

    The software is available in Portuguese and English and runs in Microsoft Windows or MacOS. Contact the corresponding author for more information.

  2. 2

    This work was supported by the Brazilian agencies Fundação de Amparo à Pesquisa do Estado de São Paulo (Process 97/01325-6 and 01/08346-6) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Grant PROIN 004/1997).

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