EXERCISE
A PROSPECTIVE STUDY OF RECREATIONAL PHYSICAL ACTIVITY AND
BREAST CANCER RISK
Increased physical activity has been hypothesised to prevent
breast cancer, largely by reducing cumulative lifetime exposure
to circulating ovarian hormones. However, epidemiologic
findings are inconsistent, and there is no consensus on
the best way to quantify physical activity. Therefore, a
study was carried out to examine this issue in women in
the Nurses’ Health study. In 1980 and on subsequent
surveys, women were asked about the average number of hours
per week spent in various moderate and vigorous recreational
physical activity.
During 16 years of follow-up 3,137 cases of invasive breast
cancer were identified. It was found that women who were
more physically active in adulthood had a lower risk of
breast cancer than those who were less physically active.
Comparing those who reported engaging in moderate or vigorous
physical activity for 7 or more hours per week with those
who engaged in such activity for less than 1 hour per week,
the relative risk was 0.82. These results, therefore, support
the evidence suggesting that higher levels of adult physical
activity afford modest protection against breast cancer.
Rockhill, B et al
ARCH. INT. MED. 1999, 159 (19) 2290-96
ECHINACEA PROTECTS ATHLETES
A double-blind, placebo controlled study was carried out
to compare the effects of Echinacea, magnesium supplements,
and placebo on the immune function of 42 male athletes undergoing
an exhausting triathlon sprint.
The group taking Echinacea had significant decreases in
interleukin 2R (IL-2R) in blood and urine, and increased
IL-6, suggesting a protective effect of echinacea against
exertion-induced immunosuppression.
During the training, 3 of the 13 athletes in the magnesium
group and 4 of the13 in the placebo group developed colds,
while none of those taking Echinacea developed colds.
Berg A, et al,
J. CLIN RES. 1998, 1, 367-380
Courtesy HERBALGRAM
DYNAMIC EXERCISE NORMALISES RESTING BLOOD PRESSURE IN
MILDLY HYPERTENSIVE PREMENOPAUSAL WOMEN
Endurance exercise is advocated as adjuvant treatment for
hypertension because participation in a dynamic exercise
program lowers resting blood pressure. Recently, exercise
has been shown to acutely and transiently reduce systolic
blood pressure and/or diastolic blood pressure in hypertensive
men, an effect that has been termed post-exercise hypotension
(PEH). Therefore, a study was carried out on 18 premenopausal
women (7 hypertensive and 11normotensive) to determine if
PEH occurs in women and to elucidate possible haemodynamic
and hormonal mechanisms. Participants wore an ambulatory
blood pressure monitor throughout the day after 40 minutes
of a rest sham session and 40 minutes of cycle exercise,
of which 30 minutes was performed at 60% of maximal oxygen
consumption. It was found that systolic, diastolic, and
mean arterial blood pressure decreased in the hypertensive
women by a mean of 9.5 ? 2.8 mm Hg, 6.7 ? 2.4 mm Hg, and
7.7 ? 2.4 mm Hg, respectively, for up to 7 hours after versus
before exercise, whereas blood pressure was similar in the
normotensive women.
After exercise, total systemic vascular resistance was
lower, and cardiac output, catecholamines, and plasma renin
activity were greater than before exercise in both groups
of women. Thus, PEH was observed for up to 7 hours after
exercise in mildly hypertensive women and was not explained
by the haemodynamic and hormonal adjustments that occurred
after exercise. The magnitude and duration of PEH may be
sufficient to normalise the blood pressure of certain hypertensive
women throughout most of the day.
Pescatello, L.S. et al
AM. HEART J. 1999, 138 (5 pt 1) 916-21
COMPARISON OF PAST VERSUS RECENT PHYSICAL ACTIVITY IN
THE PREVENTION OF PREMATURE DEATH AND CORONARY ARTERY DISEASE
During the last four decades many studies have shown that
people who are more active tend to live longer. Exercise
has proven beneficial in many conditions, ranging from osteoporosis
to depression to cerebrovascular disease. An important issue
that has not been studied much is which is more important
in decreasing total and cardiovascular mortality rates:
physical activity that was done long ago or that which was
done more recently? Therefore, researchers assessed activity
levels in 5209 men and women in the Framingham Heart Study
from 1956 to 1958 and again from 1969 to 1973. Cox proportional
hazards regression was used to calculate the relative risk
of being sedentary, both unadjusted and controlling for
smoking, weight, systolic blood pressure, cholesterol, glucose
intolerance, left ventricular hypertrophy, chronic obstructive
pulmonary disease, and cancer. The overall 16-year mortality
rate was 37% for men and 27% for women. When both distant
and recent activity levels were included along with major
cardiovascular risk factors, for recent activity the most
active tertile had lower overall mortality rate than the
least active tertile for men (risk ratio 0.58) and women
(risk ratio 0.61). However, for distant activity there was
no difference in overall mortality rate between the most
and least active tertiles either for men or for women. Thus,
the reduction in overall mortality rates is more associated
with recent activity than distant activity and it appears
that for sedentary patients, it may never be too late to
begin exercising.
Sherman, S.E. et al
AM. HEART J. 1999, 138 (5 pt 1) 900-7
WALKING COMPARED WITH VIGOROUS PHYSICAL ACTIVITY AND RISK
OF TYPE 2 DIABETES IN WOMEN
Strong epidemiologic evidence suggests that physical activity
is associated with a reduced risk of type 2 diabetes. However,
the role of moderate-intensity activity such as walking
is not well understood. Therefore, a study was carried out
to examine the relationship of total physical activity and
incidence of type 2 diabetes in women and to compare the
benefits of walking versus vigorous activity as predictors
of subsequent risk of developing the disease. The study
group consisted of 70,102 women aged 40 to 65 years who
did not have diabetes, cardiovascular disease, or cancer
at baseline. During 8 years of follow-up there were 1,419
incident cases of type 2 diabetes. After adjusting for age,
smoking, alcohol use, history of hypertension, history of
high cholesterol, and other covariates, the relative risks
(RRs) of developing type 2 diabetes across quintiles of
physical activity (least to most) were 1.0, 0.77, 0.75,
0.62, and 0.54. After adjusting for body mass index (BMI),
RRs were 1.0, 0.84, 0.87, 0.77, and 0.74. Among women who
did not perform vigorous activity, multivariate RRs of type
2 diabetes across quintiles of MET score for walking were
1.0, 0.91, 0.73, 0.69, and 0.58. After adjusting for BMI,
the trend remained statistically significant. Faster walking
pace was independently associated with decreased risk. Equivalent
energy expenditures from walking and vigorous activity resulted
in comparable magnitudes of risk reduction.
Hu, F.B. et al
J.A.M.A. 1999, 282 (15) 1433-39
AGEING OF THE CARDIOVASCULAR SYSTEM DURING 33 YEARS OF
AEROBIC EXERCISE
With increasing age there is loss of aerobic capacity,
which can result in poorer quality of life, reduced chance
of survival in an emergency and greater potential for developing
hypokinetic diseases. Therefore, a study was carried out
to determine the effect of ageing on the circulatory system
in middle-aged men during 33 years of physical training.
The study group consisted of 15 men initially aged 45 years
who took part in an exercise-training programme for 25-33
years. The aerobic training consisted of swimming, jogging,
walking and cycling 3-4 times per week. Sessions were for
61-70 minutes at 77-84% of heart rate reserve.
There was no change in resting heart rate, blood pressure,
percentage fat or body composition. Minimal cardiovascular
losses at maximal work included 5.8-6.8% in minimal oxygen
uptake per decade, 25 beats in maximum heart rate and 26
beats in heart rate reserve. Thus, exercise training has
a favourable effect on ageing of the cardiovascular system
in older men, resulting in minimal loss of oxygen uptake,
no rise in resting blood pressure and no change in body
composition.
KASCH, F.W. et al
AGE & AGEING 1999, 28 (6) 531-6
EFFECTS OF PHYSICAL ACTIVITY AND VENTILATORY FUNCTION
ON RISK FOR STROKE IN MEN
Stroke is a major cause of illness, death, and health expenditures.
Physical activity has been found to confer favourable changes
on many cardiovascular risk factors and to reduce the risk
for cardiovascular disease and cancer. Therefore, a study
was carried out to examine the association of leisure-time
physical activity and pulmonary function with risk for stroke.
Participants in the study were 4,484 men aged 45 to 80
years who were followed for a mean of 10.6 ?3.6 years. It
was found that new stroke developed in 249 men (5.6%). Of
these 44 (18%) were haemorrhagic and 205 (82%) ischemic.
After controlling for known risk factors for cerebrovascular
disease, leisure-time physical activity maintained after
40 years of age was associated with a reduced risk for stroke:
relative risk, 0.69 for total stroke and 0.62 for ischemic
stroke. Also, risk for stroke increased with diminishing
ventilatory function: relative risk, 1.9 for the lowest
compared with the highest quintile.
Thus, middle-aged men who participate in leisure-time physical
activity and have good pulmonary function seem to have a
lower risk for stroke than men who are not active or have
diminished pulmonary function.
Agnarsson, U. et al,
ANN. INT. MED. 1999, 130 (12) 987-90
WALKING TO WORK AND THE RISK FOR HYPERTENSION IN MEN
There is good evidence that physical activity reduces the
risk for cardiovascular disease, possibly by lowering blood
pressure. However, it is not known whether mild physical
activity, especially walking, reduces the risk for hypertension.
Therefore, a study was carried out to investigate the association
of the duration of the walk to work and leisure-time physical
activity with the risk for hypertension.
The study group comprised 6,017 Japanese men aged 35 to
60 years with systolic blood pressure less than 140 mm Hg,
diastolic blood pressure less than 90 mm Hg, normal glucose
intolerance, and no history of hypertension or diabetes
at baseline. During 59,784 person-years of follow-up, 626
cases of hypertension were confirmed. It was found that
the duration of the walk to work was associated with a reduction
in the risk for incident hypertension. The multivariate-adjusted
relative risks were 1.00 for a walk of 10 minutes or less
(reference category), 0.88 for an 11- to 20-minute walk,
and 0.71 for a walk of 21 minutes or more.
It is therefore estimated that for every 26.3 men who walk
more than 20 minutes to work, one case of hypertension will
be prevented.
Hayashi, T. et al,
ANN. INTERN. MED. 1999, 130 (1) 21-6
EFFECTS OF LIFESTYLE ACTIVITY VS STRUCTURED AEROBIC EXERCISE
IN OBESE WOMEN
Obesity is a serious and common health problem. Physical
inactivity contributes to weight gain, but only 22% of Americans
are regularly active. Therefore, a study was carried out
to examine the short- and long-term changes in weight, body
composition, and cardiovascular risk profiles produced by
diet combined with either structured aerobic or moderate-intensity
lifestyle activity. Such activity would include increasing
the amount of walking in the daily routine, performing more
yard work, and using the stairs when possible. Participants
in the study were given a program of either structured aerobic
exercise or moderate lifestyle activity and a low-fat diet
of about 1200 kcal/d. Changes in body weight, body composition,
cardiovascular risk profiles, and physical fitness were
assessed at 16 weeks and at 1 year. Mean weight losses during
the aerobic group and 7.9 kg for the lifestyle group. The
aerobic group lost significantly less fat-free mass (0.5
kg) than the lifestyle group (1.4-kg).
During the 1-year follow-up, the aerobic group regained
1.6 kg, while the lifestyle group regained 0.08 kg. At week
16, serum triglyceride levels and total cholesterol levels
were reduced significantly from baseline but did not differ
significantly between groups. Thus a program of diet plus
lifestyle activity may offer similar health benefits and
be a suitable alternative to diet plus structured aerobic
activity for obese women.
Anderson, R.E. et al,
J.A.M.A. 1999, 281 (4) 335-40
LEISURE-TIME PHYSICAL ACTIVITY AND THE RISK OF PRIMARY
CARDIAC ARREST
It is now generally accepted that regular exercise is associated
with an overall reduction in the risk of coronary heart
disease, including sudden cardiac death. However, less understood
is the exercise intensity required to achieve the cardiac
benefit of regular exercise. Therefore, researchers used
data from a population-based case-control study to assess
the associations of regular high-intensity and moderate-intensity
leisure-time physical activity with primary cardiac arrest.
It was found that, compared with subjects who performed
none of the activities, the odds ratio for primary cardiac
arrest from matched analyses was 0.34 among subjects who
performed only gardening activities for more than 60 minutes
per week; 0.27 among subjects who walked for exercise for
more than 60 minutes per week; and 0.34 among subjects who
engaged in any high-intensity activities, after adjustment
for age, smoking, education, diabetes, hypertension, and
health status. The results suggest, therefore, that regular
participation in moderate-intensity activities such as walking
and gardening are associated with a reduced risk of primary
cardiac arrest.
Lemaitre, R.N. et al
ARCH.INTERN.MED. 1999, 159 (7) 686-90
PHYSICAL ACTIVITY AND BENIGN PROSTATIC HYPERPLASIA
Benign prostatic hyperplasia (BHP), a condition characterised
by hyperplastic nodules in the periurethral region and transition
zone of the prostate, overall prostatic enlargement, and
lower urinary tract symptoms, is highly prevalent among
middle-aged and elderly men. Sympathetic nervous system
activity, which is decreased by physical activity, is associated
with increased prostatic symptoms. Therefore a study was
carried out to determine whether physical activity leads
to fewer lower urinary tract symptoms. Men who were aged
40-75 years at baseline in 1986 were observed for subsequent
incidence of surgery for BHP.
After controlling for age, race or ethnicity, alcohol consumption,
and smoking, physical activity was inversely related with
total BHP (Odds ratio, OR, 0.75), surgery for BHP (OR, 0.76),
and symptomatic BHP (OR, 0.75). Walking, the most prevalent
activity, was inversely related to BHP risk; men who walked
2-3 h/wk had a 25% lower risk of total BHP. Therefore, the
results indicate that more physically active men have a
lower frequency of urinary tract symptoms.
Platz, E.A. et al
ARCH. INT. MED. 1998, 158 (21) 2349-56
MANUAL LABOUR HELPS LOWER BREAST CANCER RISK
Researchers in the US have found that when women work hard
physically it is the toil itself, not the lack of energy,
that stops menstruation. The physical work causes progesterone
levels to drop and ovulation to cease. Exercise is known
to lower the risk of breast cancer, and this may be why
the incidence of breast cancer is lower in the developing
world.
NEW SCIENTIST, 17th Oct. 1999
EXERCISE PREVENTS STROKE AND IMPROVES RECOVERY FROM STROKE
A 13-year study of more than 11,000 men showed that those
who took moderate exercise (equivalent to a hour’s
brisk walk 5 days a week) had a 46% lower stroke risk than
those who did little or no exercise. The biggest reduction
in stroke risk was associated with an energy expenditure
of 2000-2999 kcal/week. The US study showed that walking,
stair climbing, dancing, cycling and gardening reduced the
risk of stroke and that the lowest risk was associated with
walking 20 km or more each week. Patients who had had a
mild or moderate stroke were given three 1.5-hour intensive
sessions every week for 8 weeks. These patients had greater
improvement in lower extremity motor function and gait speed
than control patients who received usual physician care
only.
Bonn, D.
LANCET 1998, 352 (9135) 1201
ASSOCIATION OF PHYSICAL ACTIVITY AND HUMAN SLEEP DISORDERS
Symptoms of disturbed sleep are common in the general population,
with overall prevalence rates of between 35% and 41%. A
study was carried out to investigate the influence of moderate
exercise or physical activity on self-reported sleep disorders
among a randomly selected population of adults. Sleep disorders
were classified as disorders in maintaining sleep, excessive
daily sleepiness, nightmares, and any sleep disorder. The
results showed that more women than men reported participating
in a regular exercise program and having sleep symptoms
of disorders in maintaining sleep and nightmares, and that
more men than women did regular vigorous activity and walking
at a brisk pace for more than 6 blocks per day. Both men
and women had significantly reduced risk of disorders in
maintaining sleep associated with regular activity at least
once a week, participating regularly in an exercise program,
and walking at a normal pace for more than 6 blocks per
day. Therefore, the data supports the evidence that a program
of regular exercise may be a useful therapeutic modality
in the treatment of patients with sleep disorders.
Sherrill, D.L. et al
ARCH. INTERN. MED. 1998, 158 (17) 1894-98
EFFECT OF A LOW-IMPACT EXERCISE PROGRAM ON BONE MINERAL
DENSITY IN CROHN'S DISEASE
Osteoporosis is a common complication of inflammatory bowel
disease, and people with Crohn's disease are at particular
risk. Since physical exercise increases bone mineral density
(BMD) in healthy young adults and slows the rate of bone
loss in later life, a randomised controlled trial was carried
out to investigate the effect of exercise on BMD in patients
with Crohn's'disease. Participants in the trial were randomised
to a control group or a low-impact exercise program of increasing
intensity. BMD was measured at baseline and 12 months at
the hip and spine.
Nonsignificant gains in BMD occurred at the hip and spine
in the exercise group compared with controls, but in fully
compliant patients BMD increased by 3.54% at the femoral
neck, 2.97% at the spine, 4.1% at Ward's triangle, and 7.77%
at the greater trochanter. Increases in BMD were significantly
related to the number of exercise sessions completed. Thus,
progressive low-impact exercise is a potentially effective
method of increasing BMD in Crohn's disease and, if sustained,
the increases may reduce the risk of osteoporotic fracture.
Robinson, RJ. et al
GASTROENTEROL. 1998, 115 (1) 36-41
