Beyond epidemiology: field studies and the physiology laboratory as the whole world

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  • J Physiol 587.23 (2009) pp 55695575 5569

    SYMPOS IUM REVIEW

    Beyond epidemiology: field studies and the physiologylaboratory as the whole world

    Hiroshi Nose1,2, Mayuko Morikawa1,2, Toshiaki Yamazaki1,3, Ken-ichi Nemoto1, Kazunobu Okazaki1,Shizue Masuki1, Yoshi-ichiro Kamijo1 and Hirokazu Gen-no2,3

    1Department of Sports Medical Sciences, Shinshu University Graduate School of Medicine, Matsumoto 390-8621, Japan2Jukunen Taiikudaigaku Research Center, Matsumoto 390-8621, Japan3Kissei Comtec Co., Ltd, Matsumoto 390-1293, Japan

    There is no exercise training regimenbroadly available in the field to increase physical fitness andprevent lifestyle-related diseases in middle-aged and older people. We have developed intervalwalking training (IWT) repeating five or more sets of 3 min fast walking at 70% peak aerobiccapacity for walking (wVO2peak) per day with intervening 3min slow walking at 40% wVO2peak,for 4 days week1, for 5months. Moreover, to determine wVO2peak in individuals and alsoto measure their energy expenditure even while incline walking, we have developed a portablecalorimeter. Further, to instruct subjects on IWT even if they live remotely from the trainers,we have developed e-Health Promotion System. This transfers individual energy expenditureduring IWT stored on the meter to a central server through the internet; it sends back theachievement to individuals along with advice generated automatically by the sever according toa database on 4000 subjects. Where we found that 5 months of IWT increased physical fitnessand improved the indices of lifestyle-related diseases by 1020% on average. Since our system isrun at low cost with fewer staff for more subjects, it enables us to develop exercise prescriptionsappropriate for individuals.

    (Received 27 July 2009; accepted after revision 10 September 2009; first published online 14 September 2009)Corresponding author H. Nose: Department of Sports Medical Sciences, Shinshu University Graduate School ofMedicine, 3-1-1 Asahi Matsumoto 390-8621, Japan. Email: nosehir@shinshu-u.ac.jp

    Introduction

    The rapid growth in the elderly population in manycountries has highlighted the importance of exercisetraining to decrease the likelihood of disability andage-associated diseases. In Japan, the population over65 years oldwas 20.8%of the total in 2006 butwill increaseto over 30.5% by 2025 (National Institute of Populationand Social Security Research, 2008). One of the seriousproblems in the rapid increase in the number of olderpeople is their healthcare cost. In 2006 it was 17.1 trillionJPY (171 billion USD) but is estimated to increase to 56trillion JPY (560 billion USD) in 2025 (Ministry of Healthand Welfare, 1999), equivalent to 63.2% of the annualnational budget in 2009.

    This review was presented at The Journal of Physiology Symposium onPhysiological regulation linked with physical activity and health, whichtook place at the 36th International Congress of Physiological Sciencesin Kyoto, Japan on 31 July 2009. It was commissioned by the EditorialBoard and reflects the views of the authors.

    Facing this national crisis, in 2008, the Japanesegovernment issued a law to reform the medical system toprovide preventive medicine (Health Insurance Bureau,2007) by which people are obliged to receive a healthcheck for age- and lifestyle-related diseases when theyreach 40 years old and, if abnormal results are indicated,they are encouraged to receive nutritional and/or exerciseprescriptions at local health care institutions. It is wellknown that an exercise prescription should conform toindividual physical fitness to achieve particular effects(Armstrong et al. 2006); however, no guidelines havebeen provided by the government, possibly because anexercise prescription would cost more than the standardwalking training and also because there is little evidenceto suggest that exercise prescription for individuals savesmore clinical expenditure than the development cost.

    To accumulate evidence, we have implemented a healthpromotion exercise programme for people 40 yearsold, named the Jukunen Taiikudaigaku Program, since1997 and developed three exercise training formats for

    C 2009 The Authors. Journal compilation C 2009 The Physiological Society DOI: 10.1113/jphysiol.2009.179499

  • 5570 H. Nose and others J Physiol 587.23

    middle-aged and older people: (1) interval walkingtraining (IWT), (2) use of a portable calorimeter, and(3) the e-Health Promotion System. Using these methods,we have accumulated a database (DB) on the effects ofIWT for the indices of age- and lifestyle-related diseases(LSD) in more than 4000 subjects, with healthcare cost asa consideration. Moreover, we have accumulated a DNAdatabase of more than 1400 subjects to examine whethergenetic variance causes any inter-individual variation inresponses to the training, which could be used to developan appropriate exercise prescription for individual geneticcharacteristics in the future.

    In this report, we present the recent status and futuredirection of our research project based on the JukunenTaiikudaigaku Program.

    Interval walking training

    Moderately paced walking at 6 km h1, thought toprotect against disability and age- and lifestyle-relateddiseases, is widely recommended for middle-aged andolder people; however, the pacemay not be intense enoughto increase peak aerobic capacity (VO2peak) and othermarkers of physical fitness. Indeed, a higher intensityof aerobic exercise of more than 50% VO2peak has beenrecommended in recent guidelines to increase VO2peakin older people (Armstrong et al. 2006). Therefore, in2003 we started to study the effects of IWT on physicalfitness for middle-aged and older people, using repeatfast walking above 70% peak aerobic capacity for walking(wVO2peak) for 3 min with intervening slow walking below40% wVO2peak at the target of five sets per day, morethan 4 days week1, for 5 months (Nemoto et al. 2007).The reason for adopting interval walking was that mostsubjects could not accomplish a training regimen ofcontinuous fast walking 15min day1, 4 days week1,for 5 months in our preliminary study (unpublished data)and, moreover, that more enhanced aerobic adaptationsin shorter training time were expected by high-intensityinterval training than by moderate-intensity continuoustraining as suggested in young subjects (Dausin et al. 2007;Helgerud et al. 2007; Burgomaster et al. 2008).

    To determine wVO2peak, after baseline measurements atrest for 3 min, subjects wearing a triaxial accelerometer,as detailed below, on the midclavicular line of thewaist, walked on a flat floor at three graded subjectivevelocities, slow, moderate and fast, for 3 min each whilethree-dimensional accelerations were measured with theaccelerometer (JD Mate: Kissei Comtec, Matsumoto,Japan) and heart rate (HR) with a near infrared earpickup probe at 20ms intervals and recorded with 5 smemory as an average value. The total impulse froman accelerometer was transferred to a computer andconverted to the oxygen consumption rate. wVO2peakand peak HR are those for the last 30 s at the

    fastest velocity. We confirmed that the peak HR was140 beats min1, almost reaching the age-expectedmaximal HR, and that wVO2peak (ml min

    1, y) was almostidentical to that (x) determined by graded cycle ergometerexercise simultaneously determined for each subject withy = 0.81x + 247 (R2 = 0.83, P < 0.0001). Thus, we candetermine wVO2peak for many middle-aged and olderpeople simultaneously in the field with no limitation ofinstruments such as a treadmill and cycle ergometer.

    Before the start of IWT, subjects were invited toa community office near their homes and receivedinstruction in the exercise programme for the first 2 weeks.Once subjects had learned the programme, they couldchoose when to perform it each day. A beeping signal fromthe device alerted subjects when a change in intensity wasscheduled and another beep told them when the walkingintensity had reached the target level every minute. Every2 weeks, subjects visited a local community office, anddata from the tracking device were transferred to a centralserver at the administrative centre through the internetfor automatic analysis by the e-Health Promotion Systemand reporting. The details for this system are describedbelow. Trainers used these reports to track daily walkingintensity and other parameters given to instruct subjectson how best to achieve the target levels. If the targets werenot met, the trainers encouraged the subjects to increasetheir efforts to achieve them.

    Figures 1 and 2 show the results of a study examiningthe effects of IWT on physical fitness and blood pressures(Nemoto et al. 2007). As in the figures, wVO2peakincreased by 10% and knee extension and flexionforces increased by 17% and 13%, respectively, whilesystolic and diastolic pressures decreased by 10mmHgand 5mmHg, respectively. On the other hand, thechanges were all minimal after standard walking training:moderate intensity continuous walking at 50% wVO2peakfor 60min day1, 4 days week1, for 5 months, whichwas similar to after sedentary life for the same period.Moreover, we found that wVO2peak was significantlycorrelated with isometric knee extension force (R2 = 0.49,P < 0.0001), suggesting that thigh muscle strength is akey determinant for wVO2peak in subjects of this age.Further, these results indicate that increased wVO2peak wasaccompanied by a marked reduction in blood pressure.

    Although several epidemiological studies havesuggested the merits of increased physical fitness todecrease the incidence of LSD including hypertension(Blair et al. 1984; Sawada et al. 2003; Lee et al. 2005), fewintervention studies by exercise training have suggested alinkage between increased physical fitness and improvedindices of LSD in a large population of middle-aged andolder people. This might have