Chapter 10 Aerobic Exercise Prescriptions for Public Health, Cardiorespiratory Fitness, and Athletics
Exercise and medical evaluations • Individuals are categorized as: • Low risk • Moderate risk • High risk Visit Physical Activity and Health Executive Summary at www.cdc.gov/nccdphp/sgr/sgr.htm
Risk categories for medical exams before beginning an aerobic training program. Population Risk Factors Low Risk Family history of coronary artery disease Cigarette smoking Hypertension men < 45 yrs. women < 55 yrs. No more than one Moderate Risk Hypercholesterolemia Impaired fasting glucose Obesity Sedentary lifestyle men ≥ 45 yrs. women ≥ 55 yrs. Two or more High Risk Known cardiovascular, pulmonary, or metabolic disease Ischemia Dizziness/syncope Orthopnea/paroxysmal nocturnal dyspnea Ankle edema Palpitations/tachycardia Intermittent claudication Known heart murmur Unusual fatigue All One or more
Risk categories for medical exams before beginning an aerobic training program (cont.) Prior Physical Exam Type Program Low Risk Moderate Vigorous NO NO Moderate Risk Moderate Vigorous NO YES High Risk All YES
Physiological changes during a warm-up • Muscles relax and contract faster. • Increased temperature decreases viscous resistance in muscles and improves efficiency. • Hemoglobin and myoglobin give up more oxygen and dissociate more rapidly. • The rates of metabolic processes increase with temperature.
Physiological changes during a warm-up (cont.) • Warm-up provides more time for aerobic metabolism to supply the energy needs of the activity and so may reduce lactate accumulation during actual exercise. • Vascular resistance decreases with increasing temperature. • Total pulmonary resistance to blood flow decreases with increasing temperature.
Warming up before exercise is important • Provides more time for aerobic metabolism to supply the energy needs of the activity • Reduces the risk of musculoskeletal injuries and improves heart function • Increases blood flow to muscles and the temperature of tendons and ligaments • Gradually increases blood flow to the heart
An effective warm-up • Involves low- to moderate-intensity exercise • Mimics the physical activity to follow • Stretching not a substitute
Benefits of cooling down • Helps to clear lactate from the blood more rapidly than an inactive cool-down • Prevents blood pooling in the lower extremities, which can cause dizziness • Helps maintain increased muscle and connective tissue temperature, increasing flexibility
Exercise for public health • Adults should accumulate 30 minutes or more of moderate-intensity activity on most, preferably all, days of the week. • The 30 minutes can be in one continuous bout or several smaller bouts of at least 10 minutes each. • Exercise can consist of a variety of activities. • Rigid, highly structured aerobic exercise programs are not necessary. Visit Physical Activity and Fitness: Healthy People 2010 at www.health.gov/healthypeople/default.htm
The ACSM considers four components for designing aerobic exercise programs • Mode of activity • Intensity of training • Duration of training • Frequency of training
ACSM’s recommendations regarding mode of activity for developing and maintaining fitness • Uses large muscle groups • Can be maintained continuously • Is rhythmical • Is aerobic
ACSM’s recommendations regarding intensity of activity • Approx. 55 to 90% maximum heart rate • Approx. 40 to 85% maximum heart rate reserve • Approx. 40 to 85% maximum V02 reserve • Metabolic equivalents (METs) • 20-39 yrs. 4.8-10.1 METs • 40-64 yrs. 4.0-8.4 METs • 65-79 yrs. 3.2-6.7 METs • RPE of approx. 12-16 (somewhat hard to hard)
Methods of determining exercise intensity include monitoring • Heart rate • Oxygen consumption rate • Metabolic equivalents • Perceived exertion
Recommended target heart rate range • Using percentage of maximum heart rate • 55-90% of maximum heart rate, depending on the person’s fitness level • 220 – age in years = maximum heart rate • Using percentage of maximum heart rate reserve • 40 to 85% of the maximum heart rate reserve • 220 – age in years = maximum heart rate • Maximum heart rate – resting heart rate = maximum heart rate reserve
Advantages of the percentage of heart rate reserve method over the percentage of maximum heart rate method • The percentage of heart rate reserve method more closely tracks the relationship between VO2 reserve and exercise intensity. • It takes into account training-induced changes in the resting heart rate.
Recommended VO2 range for improving fitness • 40 to 85% of maximum VO2 reserve • VO2max - VO2resting = maximum VO2 reserve
Recommended METsrange for improving fitness • 20 to 30 yrs. • 4.8 to 10.1 METs • 40 to 64 yrs. • 4.0 to 8.4 METs • 65-79 yrs. • 3.2 to 6.7 METs • 80 yrs. and over • 2.0 to 4.25 METs
Basketball Game playing Non-game playing Bicycling (<10 mph) Circuit weight training Football (touch) Golf Power cart Walking (carrying bag or pulling cart) 8.0 6.0 4.0 8.0 8.0 3.5 4.5 Leisure activities in METs. Activity Average MET
Running 5 mph 6 mph 7 mph Stair climbing Walking 2 mph 3 mph 4 mph Weightlifting 8.0 10.0 11.5 8.0 2.5 4.5 6.5 3.0 Leisure activities in METs (cont.) Activity Average MET
Rating of Perceived Exertion (RPE) • RPE is used to quantify an individual’s subjective experience of exercise intensity. • Advantage is simplicity. • Disadvantage is its subjective nature. • 12 to 16 (somewhat hard to hard) is recommended intensity range for improving cardiorespiratory fitness.
Duration of training • Should range from 20 to 60 minutes • Can be accomplished in single continuous bout or multiple bouts of at least 10 minutes each • Intermittent bouts may result in better adherence to program
Frequency of training • ACSM recommends three to five days per week. • Payoff for six or seven vigorous exercise sessions per week may not outweigh potential for injuries, decrease in adherence, and risk of overtraining.
Detraining • Decreases in fitness may occur in as little as two weeks after stopping exercise • Can result in loss of almost all improvement in 10 weeks • If intensity is unchanged, can maintain fitness with substantial reductions in frequency and duration
Aerobic training for endurance athletes • Training differs substantially from exercise prescriptions recommended for improving public health. • Athletes must train at higher intensities, for longer durations, more frequently. • Athletes perform much greater volume of training. • Athletes must use a mode of training that mimics the sport in which they compete.
VO2 max and athletic performance • VO2 max describes the maximum amount of oxygen that can be used in the ETS to produce ATP. • Successful endurance athletes are characterized by high VO2 max values. Visit Sports Coach—VO2 max at www.brianmac.demon.co.uk/vo2max.htm
Physiological factors that determine performance in endurance events • Maximal oxygen consumption rate (VO2 max) • The fraction of VO2 max that can be maintained • Economy of movement
Anaerobic threshold • The fraction of VO2 max that can be maintained during an endurance event • The intensity of exercise just below that at which lactic acid buildup in the blood and the associated changes in gas exchange occur Visit Anaerobic Threshold at www.rice.edu/~jenky/sports/anaerobic.threshold.html
Theoretical representation of the anaerobic threshold from respiratory (ventilatory threshold) and lactate (lactate threshold) responses to incremental exercise
Factors that influence economy of movement • Age • Muscle fiber type • Altitude • Gender • Fatigue • Temperature • Wind • Acceleration–deceleration versus smooth movement • Pace and efficiency • Velocity of running, walking, and cycling
Factors to consider when designing training programs for endurance athletes • Set goals and then determine the best training regimen based on those goals • Consider the athlete’s strengths and weaknesses when developing the program • Place early season emphasis on weaknesses and late season emphasis on strengths
Key elements of an effective training program • Efficient long-range planning • Wise use of rest and recovery days • Gradual increases in training intensity and duration
Training methods for distance events • LSD training • Tempo-pace training • Interval training • REP training • Fartlek training • Hypoxic training • Analysis of pace Visit Gatorade Sports Science Institute at www.gssiweb.com
Characteristics of training methods listed from easiest to hardest (slowest to fastest). Easy (E) Long (L) Tempo (T) Skeletal and cardiac muscle adaptation Improve endurance by raising lactate threshold Warm up, Recovery, Cool down, Early season buildup Purpose Intensity Comfortably hard 85% of VO2 max 15 seconds per mile slower than 10 K race pace Conversational, 70% of VO2 max Duration of each work bout 20-60 minutes 60-120 minutes 20 minutes Recovery time between work bouts Not applicable Not applicable Not applicable Number of work bouts in one session Not applicable Not applicable Not applicable
Characteristics of training methods listed from easiest to hardest (slowest to fastest) (cont.) Cruise (C) Interval (I) Reps (R) Improve endurance by raising lactate threshold Improve VO2 max Improve speed and running economy Purpose Intensity Comfortably hard 85% of VO2 max 15 seconds per mile slower than 10 K race pace 5 K race pace or slightly slower 95%-100% of VO2 max 5 seconds per 400 m faster than interval pace or race pace, whichever is fastest Duration of each work bout 3-10 minutes 11/2-5 minutes 30-90 seconds Recovery time between work bouts 1 to 1 work: rest ratio 1 mile 1 to 5 work: rest ratio Number of work bouts in one session Repeat work bouts until quality work totals 8% of 1 weekly mileage; not over 6 miles/session 5% of weekly mileage; not over 5 miles/session