Sports Medicine: Just the Facts

158 SECTION 3 • MEDICAL PROBLEMS IN THE ATHLETE

kidney and bladder injury while laceration and rup-

ture may be life threatening. Individual sports rather

than team sports account for the majority renal

injuries (McAleer, Kaplan, and Lo, 2002). Bicycle

riding is the most common sports-related cause of

renal injury (Gerstenbluth, Spirnak, and Elder,

2002).

• The male genitalia are often subjected to trauma rang-
  ing from testicular contusions to penile frostbite.
  Bikers are at risk for overuse pudendal nerve injury
  and straddle injuries.


• The prevalence of sexually transmitted diseases
  (STDs) in athletes is similar to that of the general
  population, although a study of college athletes
  showed they tend to be at higher risk for certain
  lifestyle behaviors. These maladaptive behaviors
  include less safe sex, greater number of sexual part-
  ners, and less contraceptive use when compared with
  their nonathlete peers (Nattiv, Puffer, and Green,
  1997).

PATHOPHYSIOLOGY

ANATOMY

• The genitourinary system is comprised of the kidneys,
  ureters, bladder, urethra, and genital organs and is
  located in the lower abdomen and pelvis.


• The kidneys can be found high in the retroperitoneum
  bilaterally and are well protected. A solitary or mal-
  positioned kidney is prone to injury. The urinary blad-
  der is located in the anterior pelvis and is rarely
  acutely injured.

PHYSIOLOGY

• The kidneys receive more blood flow per unit weight
  than any other organ in the body. Renal blood travels
  to the glomerulus via the afferent arteriole and exits
  through the efferent arteriole. With afferent arteriole
  constriction, a pressure drop occurs within the
  glomerulus and filtration fraction decreases. With
  efferent arteriole vasoconstriction, pressure increases
  within the glomerulus thereby increasing the filtration
  fraction.
  •Exercise causes acute changes in a variety of organ
  systems, as exercising muscle requires a significantly
  larger proportion of cardiac output. Blood flow is
  shunted away from the kidney to meet the demands of
  working muscle. Studies have noted a drop in renal
  blood flow from 1000 mL/min to as little as 200 mL/
  min with exercise (Jones, 1997).
  
  
  • In an attempt to maintain glomerular filtration rate,
    the efferent arteriole constricts to a greater degree
    than the afferent arteriole creating a “pressure-head”
    at the glomerulus. This increases filtration fraction
    accounting for many of the renal changes seen with
    exercise.
  
  
  • The increase in filtration fraction is proportional to
    the intensity of exercise and is attenuated by improv-
    ing the runner’s hydration status. Poorly hydrated
    individuals have a significantly larger decrease in
    renal blood flow compared with normally hydrated
    individuals.
    •With moderate exercise (50% VO2max) renal plasma
    flow decreases by 30% while with heavy exercise
    (65% VO2max) renal plasma flow decreases by 75%.
    These changes are temporary as renal blood flow typ-
    ically returns to preexercise levels within 60 min of
    exercise cessation (Cianflocco, 1992).
  
  
  
  

HEMATURIA

CLINICAL FEATURES

•Exercise-induced hematuria is known by a variety of

names to include sports hematuria, stress hematuria

and 10,000-m hematuria. Sports hematuria is defined

as hematuria, gross or microscopic, that occurs follow-

ing vigorous exercise and resolves promptly with rest.

• The longer and more strenuous the event, the more
  prominent the hematuria. Sports hematuria is most
  common in swimmers and runners. Sports hematuria
  does not appear to be gender specific (Boileau et al,
  1980).
  •A thorough history should be obtained in athletes who
  present with gross hematuria, to include the presence
  of urinary urgency, dysuria, frequency, or clots.
  Further history includes trauma, penile discharge, or a
  history of nephrolithiasis. General historical questions
  include the presence of bleeding disorders, ongoing
  menses, recent streptococcal infection, generalized
  swelling, or risk factors for urologic cancer, such as
  tobacco use, age greater than 40, and pelvic irradia-
  tion. Other important questions include prescription
  and over-the-counter drug use, dietary supplement use,
  family history, and diet history.
  •A complete exercise history should be obtained when
  microscopic hematuria is discovered incidentally.


• The timing of gross hematuria is an important histor-
  ical feature. Presence of blood on initiating urination
  is likely urethral in origin. Hematuria on termination
  of urination originates from the bladder or posterior
  urethra. Continuous hematuria likely originates from
  the upper urinary tract.