A WALK EACH DAY KEEPS THE DOCTOR AWAY

Transcription

1 A WALK EACH DAY KEEPS THE DOCTOR AWAY David C. Nieman, DrPH, FACSM Human Performance Laboratory Appalachian State University and The North Carolina Research Campus

2 Primary Objective: To investigate effective nutritional strategies for countering oxidative stress and immune dysfunction during physical and mental stress in athletes and individuals from the general community. Cannon Village 600 Laureate Way ASU-NCRC Human Performance Lab (Rm 1201)

3 Half life hours; Accumulates in lung, testes, kidney, heart, and liver 8-10 mg Source: USDA Database for the Flavonoid Content of Selected Foods, January, 2007.

4 Pure quercetin is extracted from uncaria in a plantation located in northern Brazil (owned and operated by Quercegen Pharma, Newton, MA).

5 Accumulating Days of Illness Nieman. Med Sci Sports Exerc Sep;39(9): Quercetin (N=20) Placebo (N=20) day intensified exercise (9h, 57% Watts max Kaplan-Meier Analysis Statistic = 10.5, P=0.004 Incidence = 9/20 Incidence = 1/20 21-day pre-test supplementation Days 14-d post-test supplementation ILLNESS RATES REDUCED FROM 45% IN PLACEBO TO JUST 5% IN THE QUERCETIN GROUP

6 THE COMMON COLD Adults suffer 2-4 colds/yr, and young children about 6-10 ($40 billion cost). Symptoms of the common cold usually begin 2-3 days after infection. Cold symptoms can last from 2-14 days, but twothirds of people recover in a week. There is no cure, and treatment is based on symptom relief.

7 COLD VIRUSES More than 200 different viruses cause colds. Rhinoviruses and coronaviruses are the culprits 25 to 60 percent of the time. Rhinoviruses often attack during the fall and spring seasons, while the coronavirus is common during the winter. Transmission is via self-innoculation or airborne. UNLIKELY that a unifying vaccine will be developed. Rhinovirus Coronavirus

8 COLD RISK FACTORS Whether one gets sick with a cold after a sufficient amount of virus has entered the body depends on many factors that affect the immune system: Old age Cigarette smoking Mental stress Poor nutrient status Lack of sleep Marital status Gender Obesity Education level Sedentary lifestyle

9 LINES OF EVIDENCE: EXERCISE IMMUNOLOGY AND INFECTION Surveys Animal data Human epidemiology Randomized exercise training studies

10 SURVEY DATA IN SUPPORT OF FEWER COLDS IN ACTIVE PEOPLE People who exercise regularly report fewer colds than their sedentary peers. Numerous surveys of fitness enthusiasts, runners, and masters athletes indicate that between 60% and 90% feel that they experience fewer colds than their sedentary peers

11 SURVEY OF 226 RUNNERS: NUMBER OF COLDS COMPARED TO SEDENTARY PEERS Nieman DC. Med Sportiva 13: , 2009.

12 Animal Data Indicate Heavy But Not Moderate Exertion Increases Infection Mortality J Appl Physiol Nov;83(5):

13 FEWER COLDS IN ACTIVE PEOPLE: EPIDEMIOLOGICAL EVIDENCE A one-year study of 547 adults showed a 23% reduction in URTI risk in those engaging in regular versus irregular physical activity. (Med Sci Sports Exerc 2002, 34: ). In healthy elderly subjects, URTI during a one-year period was reduced in those expending the most energy in moderate physical activity. (Med Sci Sports Exerc 2000, 32:46-51).

14 23% reduction in URTI risk, especially the fall Matthews et al. Moderate to vigorous physical activity and risk of upper-respiratory tract infection. Med Sci Sports Exerc 34: , Matthews et al. Med Sci Sports Exerc Aug;34(8):

15 URTI AND FITNESS, COMMUNITY TRIAL (N=1,002) Upper respiratory tract infection : Daily symptom checklist, Wisconsin Upper Respiratory Symptom Survey-21. Subjects filled out each evening before bedtime for 12 weeks. (Nieman DC, et al. Br J Sports Med, 2010).

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17 Previous research with this question shows that responses correlate well with objective fitness measures, perceived total well-being, and sleep habits. (Gerber, et al., 2010; Plante et al., 1998) In general, compared to other persons your age, rate how physically fit you are: Not at all Somewhat Extremely physically fit physically fit physically fit Low Medium High

18 Outside of your normal work or daily responsibilities, how often do you engage in exercise that at least moderately increases your breathing and heart rate, and makes you sweat, for at least 20 minutes (such as brisk walking, cycling, swimming, jogging, aerobic dance, stair climbing, rowing, basketball, racquetball, vigorous yard work, etc.). 5 or more times per week 3 to 4 times per week 1 to 2 times per week Less than 1 time per week Seldom or never High Medium Low

19 %, 3.8 d %, 3.7 d URTI Days- Fitness Tertiles URTI Days- Exercise Tertiles Days With URTI During 12-Wk Period Low Medium High

20 URTI Symptoms- Fitness Tertiles % 41% URTI Symptoms- Exercise Tertiles Total URTI Symptom Score During 12-Week Period Low Medium High

21 URTI (days during 12 week period) %, 3.8 d Age Fitness Education Marital Sex BMI Fruit (yrs) Level (yrs) Status (kg/m 2 ) Intake

22 FEWER COLDS IN ACTIVE PEOPLE: RANDOMIZED TRAINING STUDIES Data from four randomized studies support the viewpoint that near-daily physical activity reduces the number of days with sickness. (Int J Sports Med 1990, 11: ; Med Sci Sports Exerc 1993, 25: ; Med Sci Sports Exerc 1998, 30: ); (Am J Med 119: , 2006). Women walked briskly minutes, five days a week, for weeks during the winter/spring or fall, while the control groups remained physically inactive. Walkers experienced about half the days with cold symptoms of the sedentary controls.

23 Int J Sports Med 1990, 11: ; Med Sci Sports Exerc 1998, 30:

24 MODERATE EXERCISE REDUCES INCIDENCE OF COLDS AMONG POSTMENOPAUSAL WOMEN (AM J MED 119: , 2006) P= overweight postmenopausal women randomized to 40 min exercise 4 d/wk for one year or control group (stretching). 30% of exercisers had at least one cold during one year study compared to 48% of controls.

25 Highly Conditioned Mean age, 73; 11 yr training; 1.6 h exercise/day N=30, Mean age, 73 Role of Exercise in Immune Senescence 1. Cross-sectional comparison of highly conditioned vs sedentary elderly women 2. Randomized, 12-wk brisk walking Nieman et al. MSSE 25: , 1993; 26: , 1994

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27 56% Higher T-Cell Function In Highly Conditioned Elderly Women Highly Conditioned (N=12) Sedentary (N=30)

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30 Mean Fold Increase in Influenza Antibody Titer Moderate Exercise Training for 10 Months Improves Antibody Response to Influenza Immunization In the Elderly Kohut et al. Vaccine 22: , Controls Exercise Young Month 3 Months

31 WALKING IMPROVES IMMUNITY Brisk walking compared to sitting causes modest and transient changes in: neutrophils and natural killer cells T lymphocyte function Little or no change is measured for stress hormones and cytokines. Med Sci Sports Exerc., 37, pp (2005).

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33 Blood

34 Pathogens NK Activity Innate Immunity Oxidative burst; MPO Adaptive Immunity PHA-Induced Lymphocyte Proliferation B-cell, antibody (salivary IgA)

35 1 Elevated URTI Risk Normal 0 Reduced -1 Sedentary Moderate Exercise Heavy Exertion Exercise Workload

36 CONCLUSION The percent reduction in sick days with near-daily moderate exercise exceeds levels reported for most medications and supplements, and bolsters public health guidelines urging individuals to be physically active on a regular basis.

37 REST OR EXERCISE WHEN SICK? If one has common cold symptoms, intensive exercise training may be safely resumed a few days after symptoms. Mild-to-moderate exercise when sick with the common cold does not appear to be harmful. In two studies using nasal sprays of a rhinovirus, subjects were able to engage in exercise without any negative effects on severity of symptoms or performance (Med Sci Sports Exerc 1997, 29: ; Med Sci Sports Exerc 1998, 30: ). With symptoms of fever, extreme tiredness, muscle aches, and swollen lymph glands, 2-4 weeks should probably be allowed before resumption of intensive training.

38 EXERCISE IMMUNOLOGY: FUTURE Do exercise-induced perturbations in immunity help explain decreased risk of cancer, heart disease, type 2 diabetes, arthritis, and other chronic conditions? Acute exercise: circulation surge in cells of the innate immune system Chronic exercise: antiinflammatory effects