Training Considerations for Special Populations

Chapter OBJECTIVES Understand that not everyone should be presented with the same exercise stimulus. Describe the physiological differences that exist between men and women that might affect exercise prescription. Discuss the limitations that pregnancy might place on a woman’s capacity to exercise safely. Describe what factors must be considered when designing exercise programs for children and older adults.

Introduction to Sex Differences in Sport and Exercise For decades, culture, athletic governing bodies, and PE curricula perpetuated the myth that girls and women should not compete in sport Last 30 to 40 years, girls and women have achieved great athletic feats Sex differences in performance still exist Separating biological versus other factors

Body Size and Composition Testosterone leads to –  Bone formation, larger bones –  Protein synthesis, larger muscles –  EPO secretion,  red blood cell production Estrogen leads to –  Fat deposition (lipoprotein lipase) Faster, more brief bone growth Shorter stature, lower total body mass –  Fat mass, percent body fat

Physiological Responses to Acute Exercise Muscle strength differs between sexes Upper body: women 40 to 60% weaker Lower body: women 25 to 30% weaker Due to total muscle mass difference, not difference in innate muscle mechanisms No sex strength disparity when expressed per unit of muscle cross-sectional area

Physiological Responses to Acute Exercise Cardiovascular function differs greatly For same absolute submaximal workload Same cardiac output Women: lower stroke volume, higher HR (compensatory) Smaller hearts, lower blood volume For same relative submaximal workload Women: HR slightly , SV , cardiac output  Leads to  O2 consumption

Physiological Responses to Acute Exercise Women compensate for  hemoglobin via  (a-v)O2 difference (at submaximal intensity) (a-v)O2 difference ultimately limited, too Lower hemoglobin, lower oxidative potential Sex differences in respiratory function Due to difference in lung volume, body size Similar breathing frequency at same relative workload Women  frequency at same absolute workload

Physiological Responses to Acute Exercise Women’s VO2max < men’s VO2max Untrained sex comparison unfair Relatively sedentary nonathlete women Relatively active nonathlete men Trained sex comparison better Similar level of condition between sexes May reveal more true sex-specific differences

Physiological Adaptations to Exercise Training Body composition changes Same in men and women –  Total body mass, fat mass, percent body fat –  FFM (more with strength vs. endurance training) Weight-bearing exercise maintains bone mineral density Connective tissue injury not related to sex

Physiological Adaptations to Exercise Training Strength gains in women versus men Less hypertrophy in women versus men, though some studies show similar gains with training Neural mechanisms more important for women Variations in weight lifted for equivalent body weight For given body weight, trained men have more FFM than trained women Fewer trained women Factors other than FFM?

Physiological Adaptations to Exercise Training Cardiorespiratory changes not sex specific Aerobic, maximal intensity –  Qmax due to  SVmax ( preload, contractility) –  Muscle blood flow, capillary density –  Maximal ventilation Aerobic, submaximal intensity Q unchanged –  SV,  HR

Physiological Adaptations to Exercise Training VO2max changes not sex specific ~15 to 20% increase –  Qmax,  muscle blood flow Depends on training intensity, duration, frequency Lactate threshold  Blood lactate for given work rate  Women respond to training like men do

Effect of Menstruation on Performance No reliable data indicate altered athletic performance across menstrual phases No physiological differences in exercise responses across menstrual phases World records set by women during every menstrual phase

Female Athlete Triad Amenorrhea Osteoporosis Disordered Eating

Female Athlete Triad Syndrome of interrelated conditions Energy deficit  secondary amenorrhea  low bone mass Disordered eating may (not) be involved Three disorders can occur alone or in combination, must be addressed early Treatment:  caloric intake,  activity (in some cases)

Pregnancy Recommendations Moderate exercise 3x/week Reduces T3DM risk Resistance training recommended Ensure adequate caloric intake No supine exercise after first trimester Non-weight-bearing exercise preferable No risk of falling, loss of balance, etc. Decrease vigorous exercise in third trimester

Children and Exercise Historic reflections on exercise and resistance training outdated Cardiovascular differences ↓ heart size, ↑ HR both at rest and during ex Limited anaerobic energy supply ↓ blood lactate ↓ glycolyic enzymes Hyperthermia risk ↑ due to less efficient sweat mechanism

Children and Exercise

Older Adults and Exercise ↓ in physiological capacity is inevitable “Psychomotor Slowing” Cardiovascular ↓ in Q, SV, HRmax, VO2max, a-vO2 diff Sarcopenia - Skeletal muscle loss results in ↓ isometric and dynamic muscle strength Apoptosis Bone mineral density ↓

Older Adults and Exercise Baseline assessment for everyone Aerobic prescription – 150+ minutes of moderate aerobic activity/wk Resistance exercises on 2 or more days a week that work all the major muscles (1s, 10-15r).