increased modestly but the decline in physical activity
has been dramatic.HYPERTENSION
- Blood pressure above the 95th percentile for age-
adjusted norms is considered hypertension (National
Heart, Lung, and Blood Institute (a)). Blood pressures
above the 99th percentile of age-adjusted norms are
considered severe hypertension.
•For adults any levels above 140 systolic or 90 dias-
tolic indicate hypertension. - JNC 7 report defined levels above 120 systolic or 80
diastolic as pre hypertension (National Heart, Lung,
and Blood Institute (a)). - Blood pressure is a product of cardiac output multi-
plied by peripheral resistance. Peripheral resistance
must fall dramatically or else blood pressure rises
excessively during exercise since the cardiac output
must remain high to support activity. - In patients whose blood pressure rises too dramati-
cally during dynamic exercise the relative risk of sub-
sequent hypertension is higher (Wilson et al, 1990;
Tanji et al, 1989). - Heavy resistance exercise can cause dramatic rises in
blood pressure (MacDougall et al, 1985). - The effect of exercise on hypertension has been stud-
ied extensively. A Meta-analysis of 54 clinical trials of
aerobic exercise showed reductions of systolic and
diastolic blood pressure in both hypertensive and nor-
motensive individuals (Whelton et al, 2002). - The Osaka Health Survey demonstrated that a daily
walk of 20 min or more reduced the risk of hyperten-
sion in men. In fact, for every 26 men who walked, one
case of hypertension was prevented (Hayashi et al,
1999). Vigorous exercise for as little as 30 min, just
once weekly, also reduced risk. - Hypertensive patients do best by starting with a low
intensity warm-up and pursuing aerobic exercise at
about 55–70% of maximum heart rate (ACSM, 2000). - Most resistance exercise seems to benefit hyperten-
sive athletes, although maximal resistance efforts pose
theoretical risks. - The American College of Sports Medicine recom-
mends that resistance training in hypertensive patients
be mixed with aerobic activity (ACSM, 2000).
CORONARY ARTERY DISEASE
•Patients with known coronary artery disease can
reduce their risk of coronary events by maintaining
high fitness levels (Myers et al, 2002).
- Moderate exercise is recommended for individuals
with coronary artery disease and the individual’s exer-
cise capacity should be measured by exercise toler-
ance testing.
•Formal cardiac rehabilitation programs help coronary
artery disease patients get started on a therapeutic
exercise regimen.
•Patients with coronary artery disease who develop the
fitness to achieve a 10.7 MET level workload have a
normal age adjusted mortality rate (Myers et al, 2002). - Recent research suggests that exercise lowers C-
reactive protein (CRP) levels. Athletes such as
swimmers and runners have significantly lower CRP
levels than the average individual and the more
intensely they train, the greater the decline in their
CRP level. Speculation centers as to whether this
may be one of the mechanisms by which exercise
lowers the risk of cardiovascular disease (Zebrack
and Anderson, 2002).
DIABETES- There are 16 million Americans with diabetes melli-
tus, with approximately 10% having type-1 diabetes.
CARDIOVASCULAR BENEFITS- Cardiovascular disease is high in diabetics. Maintaining
a good fitness level lowers the risk of cardiac death and
is associated with longevity (Blair et al, 1989). - Diabetics improve fitness levels with training (VO2max)
(Wallberg-Henriksson, 1992). - Blood pressure (BP) is improved with moderate aero-
bic exercise (Uusitupa, 1992).
•Exercise may improve hyperlipidemia by reducing
total cholesterol, triglyceride, LDL, and VLDL; and
increasing HDL concentration. These changes inhibit
the development and progression of atherosclerotic
plaques and ultimately, adverse cardiovascular events
(Schneider, Vitug, and Ruderman, 1996; Laaksonen
et al, 2000). - Lehmann et al demonstrated that type-1 diabetics
reduced abdominal fat content, blood pressure, and
adverse lipid levels by exercising 135 min/week
(Lehmann et al, 1997).
IMPROVED METABOLIC CONTROL- Metabolic control usually improves with exercise,
although improvements in FBG or A1C in type-1
diabetics has not consistently been shown in studies
(Tanji, 1995).
96 SECTION 1 • GENERAL CONSIDERATIONS IN SPORTS MEDICINE