ACE Personal Trainer Manual 5th Edition Chapter 11: Cardiorespiratory Training: Programming and Progressions Lesson 11.1

After completing this session, you will be able to: LEARNING OBJECTIVES After completing this session, you will be able to: Recognize physiological adaptations to acute and chronic cardiorespiratory exercise, and the time required for these to occur Recognize physiological adaptations to steady-state and interval-based exercise Identify three primary components of a cardiorespiratory workout session Interpret general guidelines for frequency of cardiorespiratory exercise for health, fitness, and weight loss

PHYSIOLOGICAL ADAPTATIONS TO CARDIORESPIRATORY EXERCISE Humans are meant to move – physical movement is essential for human survival: The organ systems involved in energy metabolism function best when subjected to regular physical challenges. Physical activity leads to improvements in work capacity, the sense of well-being, and overall health, as well as to fewer diseases. Adaptations to cardiorespiratory exercise occur in the: Muscular system Cardiovascular system Respiratory system

MUSCULAR SYSTEM ADAPTATIONS During low-intensity endurance exercise, adaptations occur in the type I muscle fibers: Increase in size and number of mitochondria to augment aerobic adenosine triphosphate (ATP) generation A growth of more capillaries around the recruited muscle fibers, enhancing the delivery of oxygenated blood Potential hypertrophy – adaptations in the contractile mechanism (i.e., actin and myosin filaments) During higher-intensity exercise, type II muscle fibers may be recruited and adapt: Increase in the number of anaerobic enzymes so that anaerobic energy production is enhanced Potential hypertrophy of contractile proteins with increased training intensity The muscle fibers that are recruited to perform exercise are the only ones stimulated to adapt.

CARDIOVASCULAR SYSTEM ADAPTATIONS Stroke volume – the amount of blood pumped per beat During endurance training, and with the expansion of blood volume, the heart muscle: Will hypertrophy Will enlarge its chambers and becoming a bigger and stronger muscle Is able to deliver a higher cardiac output to the muscles This increase in stroke volume is due to: Chamber enlargement Greater amounts of chamber filling (end-diastolic volume) Greater chamber emptying (ejection fraction) of the heart with each beat A number of studies suggest that the maximum heart rate (MHR) does not increase with training. There is also some evidence that the redistribution of the cardiac output to the active muscles (via vasodilation) may improve after training, thus making the increase in cardiac output more effective in terms of delivering oxygen where it is needed.

RESPIRATORY SYSTEM ADAPTATIONS With regular exercise, the respiration muscles adapt: Allow for increased ventilation of the alveoli Improvement in strength and fatigue resistance Increased ventilation for longer periods Increase in tidal volume Reduces the relative amount of respiratory dead space at high breathing frequencies The respiration muscles span the thorax, and abdomen: Diaphragm – the body’s key breathing muscle, and the external intercostals used during passive (resting) inspiration The group of muscles that pull the rib cage upward (i.e., sternocleidomastoid, scalene, and portions of the serratus anterior) during active (exercise) inspiration The group of muscles that pull the rib cage downward (i.e., rectus abdominis and quadratus lumborum) during active expiration Respiratory dead space (i.e., air trapped in the bronchial tubes that never reaches the alveoli) There is little evidence that the structures of the pulmonary system actually increase in size.

TIME REQUIRED FOR INCREASES IN AEROBIC CAPACITY Adaptations to exercise begin with the first exercise bout. VO2max: Increases with training Reaches a peak and plateaus within about six months Ventilatory threshold: Increased capillary growth Increased mitochondrial density (size and number) Changes may continue for years To support these cardiorespiratory adaptations: Increased capacity of the muscle to store additional glycogen Enhanced ability to mobilize and use fatty acids as a fuel source VO2max – the traditional standard marker of the aerobic-training effect Ventilatory threshold (VT) – a significant marker of metabolism that permits prediction of lactate threshold (LT) from the minute ventilation (VE) response during progressive exercise

IMPROVED EXERCISE CAPACITY

IMPROVED EXERCISE CAPACITY

PHYSIOLOGICAL ADAPTATIONS TO STEADY-STATE EXERCISE Steady state – the intensity of exercise where the energy and physiological demands of the exercise bout are met by the delivery of the physiological systems in the body Steady-state is achieved when the following levels are stable after a short period: Rate of oxygen uptake (VO2) Heart rate (HR) Cardiac output Ventilation Blood lactate concentration Body temperature Steady-state exercise duration is primarily limited by: The willingness to continue The availability of oxygen, muscle glycogen, and/or blood glucose When an exercise bout begins or exercise intensity changes, the body takes between 45 seconds and three to four minutes to achieve steady state. The time needed to achieve this level, sometime referred to as a “second wind,” varies according to several factors, including fitness level (more fit individuals achieve steady state faster) and exercise intensity (when working at higher intensities, people require longer periods to achieve steady state). The primary adaptations to exercise typically occur during steady-state exercise at moderate intensity.

PHYSIOLOGICAL ADAPTATIONS TO INTERVAL TRAINING Interval training – a few repetitions of higher-intensity exercise followed by recovery periods Anaerobic adaptations include improved tolerance for the buildup of lactate Enhances the ability to sustain higher intensities of exercise for longer periods During higher intensities – the overload on the heart to deliver blood to exercising muscles causes stroke volume to increase more so than with lower-intensity steady-state training. Studies suggest that interval training promotes similar or greater improvements in VO2max and fitness than steady-state exercise. While this may prove to be a more time-efficient method of training, the appropriateness of this training modality must always be considered for deconditioned clients. A universal principle to training is that it is necessary to progressively perform higher intensities of exercise to effectively challenge or overload the cardiorespiratory system. Since muscle fibers that are not recruited are not likely to adapt, it is probable that there is little or no adaptation of type II muscle fibers during moderate-intensity aerobic training, whereas there would be with higher-intensity training. Generally, these intensities are not sustained through steady-state exercise. During higher intensities, the overload on the heart to deliver blood to exercising muscles causes stroke volume to increase more so than with lower-intensity steady-state training. This is probably attributable to large increases in venous blood return that occur with very high-intensity exercise that increases end-diastolic volume (i.e., chamber filling).

COMPONENTS OF A CARDIORESPIRATORY WORKOUT There are basically three components of any training session: Warm-up phase Conditioning phase Cool-down phase Exercise programming may differ: A gradual increase from the warm-up, stabilized for conditioning, and then decreased for the cool-down Distinct transitions from the warm-up, to conditioning, to cool-down

WARM-UP PHASE Warm-up – a period of lighter exercise preceding the conditioning phase: Should last for 5–10 minutes for most healthy adults Should begin with low- to moderate-intensity exercise or activity that gradually increases in intensity The harder the conditioning phase and/or the older the exerciser, the more extensive the warm-up should be: If higher-intensity intervals are planned, include higher-intensity exercise in the latter portion of the warm-up to prepare. The warm-up should not be so demanding that it creates fatigue that would reduce performance.

Elements of the conditioning phase should be based on: Frequency Duration Intensity (steady-state or interval-training) Modality The client’s current fitness and training goals Consider programming higher-intensity elements fairly early in the conditioning phase. Conclude the conditioning phase with more steady-state exercise. Aerobic-interval training: Typically involves bouts of steady-state exercise performed at higher intensities for sustained periods (typically a minimum of three minutes), followed by a return to lower aerobic intensities for the recovery interval. These intervals often utilize exercise-to-recovery ratios between 1:2 and 1:1 (e.g., a four-minute steady-state bout is followed by an eight-minute recovery period at a lower intensity when following a 1:2 exercise-to-recovery ratio). It should also be noted that higher-intensity intervals of 15 to 30 seconds may effectively recruit (and thus stimulate) type II muscle fibers, and are essentially aerobic from the standpoint of the overall metabolic response to training. Assuming that aerobically trained type II muscle fibers may serve as “lactate sinks” (structures that are proficient at using lactate for energy) during hard steady-state exercise, the aerobic-training stimulus should include at least some higher-intensity segments in programs for clients with goals that go beyond basic cardiorespiratory conditioning.

COOL-DOWN PHASE The cool-down: Should be of approximately the same duration and intensity as the warm-up 5–10 minutes of low- to moderate-intensity activity Prevents the tendency for blood to pool in the extremities, which may occur when exercise ends An active cool-down helps remove metabolic waste from the muscles to be metabolized by other tissues. Stretching after the cool-down period can improve flexibility. The cessation of significant venous return from the “muscle pump” experienced during exercise can cause blood to accumulate in the lower extremity, reducing blood flow back to the heart and out to vital organs (e.g., the brain, potentially causing symptoms of lightheadedness).

GENERAL GUIDELINES FOR CARDIORESPIRATORY EXERCISE Specific guidelines for adults 18–64 years: Perform 150 minutes per week of moderate-intensity aerobic physical activity, or 75 minutes per week of vigorous-intensity aerobic physical activity, or a combination of both Additional health benefits are obtained from performing greater amounts of activity than those quantities Perform aerobic bouts that last at least 10 minutes, preferably spread throughout the week Participate in muscle-strengthening activities involving all major muscle groups at least two days per week Specific guidelines for ages 6–17: Perform at least 60 minutes of moderate-to-vigorous physical activity every day Include vigorous-intensity activity a minimum of three days per week Participate in muscle-strengthening and bone-strengthening activity a minimum of three days per week From the 2008 Physical Activity Guidelines for Americans released by the U.S. Department of Health & Human Services

F.I.T.T. F – Frequency I – Intensity T – Time or duration T – Type or modality Trainers generally progress their clients’ programs by manipulating these variables Each client’s health status, exercise tolerance, available time, and goals all affect the rate of program progression Consider adding an “E” – F.I.T.T.E. E – Enjoyable or experience: Clients should always enjoy the exercise experience Enjoyment influences the thoughts and emotions that can ultimately dictate participation and adherence rates Improvement in cardiorespiratory fitness occurs most quickly from progressive increases in exercise intensity, and fades when training intensity is reduced. Changes in fitness are more sensitive to changes in intensity than to changes in the frequency or duration of training.

CARDIORESPIRATORY RECOMMENDATIONS

SUMMARY Physical activity or structured exercise performed with regularity causes adaptation and promotes the ability to perform even more exercise. This is the classical cardiorespiratory training effect. Both steady-state and interval training promote improvements in VO2max and fitness. The three components of a cardiorespiratory workout session all serve a purpose and are specific to each client and their training goals, health status, and current level of conditioning. While minimal health benefits can be attained in as little as one to two sessions per week, current guidelines recommend physical activity on most days of the week.