Sports Medicine: Just the Facts

CHAPTER 16 • EXERCISE AND CHRONIC DISEASE 95

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16 EXERCISE AND CHRONIC

DISEASE

Karl B Fields, MD

Michael Shea, MD

Rebecca Spaulding, MD

David Stewart, MD

INTRODUCTION

• Medical problems are common in athletes and lead to
  approximately 70% of the visits that athletes make to
  doctors.


• Chronic medical problems are common in athletes
  greater than 35 years of age.


• Certain conditions such as obesity, hypertension,
  asthma and thyroid disease occur in all age groups.


• This chapter addresses principles of healthy exercise
  in individuals who remain athletic but have chronic
  disease.


• Details of diagnosis, evaluation, and treatment are
  reserved for later chapters.

OBESITY

• According to 1998 estimates from NHLBI estimated
  97 million U.S. adults were overweight (BMI >25) or
  met the definition of true obesity (BMI >30) (NIH).


• Pediatric obesity has become a major public health
  issue with estimates of 25% of children being over-
  weight and as many as 15% having true obesity (NIH).


• Obesity contributes to excess mortality from hyperten-
  sion, type-2 diabetes, coronary artery diseases, stroke,
  gallbladder disease, sleep apnea, and osteoarthritis
  (OA) (NIH; Perry et al, 1998). Cancers occurring more
  commonly in these individuals include endometrial,
  breast, prostate, and colon cancers.
  
  
  • Centripetal obesity in which the waist-to-hip ratio is
    high indicates a subset of individuals at much higher
    risk of cardiovascular diseases (Perry et al, 1998).
  
  
  • In spite of the health risks of obesity, a number of over-
    weight athletes have achieved high levels of sports
    success. In some sports, including football, weight
    throws in track and field, heavyweight wrestling, and
    power lifting, excessive weight has generally been
    considered advantageous.
  
  
  • Athletes often pursue strategies that lead to dietary
    excess and pose health risks when they’re trying to
    gain excessive weight. These may include diets with
    excessive high fat and high glycemic foods.
  
  
  • Obesity has direct consequences in sport in that over-
    weight athletes experience a much greater risk of heat
    illness during competition, and injury rates in physi-
    cal training programs have been shown to parallel
    body fat measurement (Jones et al, 1993).
  
  
  • Highly competitive athletes may need to consume
    1500 to 2000 access calories per day to account for
    the calorie expenditure of intense training. Dietary
    calorie consumption appears to be a learned behavior
    and appetite often does not decline with a reduction
    in activity levels (King, Tremblay, and Blundell,
    1997).
  
  
  • Injured athletes and athletes who retire from a sport
    have a tendency to continue to ingest excessive calo-
    ries. This may lead to weight gain during injury
    recovery, the off-season, or after retirement in those
    who do not maintain high levels of physical activity.
    This can quickly lead to obesity.
  
  
  • All forms of muscular activity burn calories and con-
    tribute to weight loss with aerobic activity generally
    serving as the backbone of a weight-loss program.
    Individuals on a strength-training program or on a
    mixed exercise program may show comparable
    weight loss with a well-designed, vigorous program.
  
  
  • Athletes who are used to training may be more effi-
    cient at losing weight through exercise.
  
  
  • Nonathletes have trouble losing weight on an exercise
    program alone perhaps because effective weight-loss
    through exercise requires a consistent moderate-to-
    high level of activity.
  
  
  • While almost all successful weight-loss programs
    require dietary adjustments if individuals are to suc-
    ceed at maintaining weight loss they must begin an
    exercise program. A combination of a reduced calorie
    diet and increased physical activity has been given an
    evidence category A rating based on meta-analysis of
    15 RCTs as an effective way to achieve weight loss
    (National Heart, Lung, and Blood Institute (b)).
  
  
  • Epidemiologists have pointed out that we have seen a
    dramatic gain in weight of Americans in the last two
    decades, a period in which calorie consumption has