Walking in the Fast Lane: High-Intensity Walking for Improved Fitness and Health Outcomes.

The World Population Prospects 2019 report by the United Nations estimated that one in six people in the world would be 65 years or older (16%) by 2050, up from one in 11 in 2019 (9%).1United Nations. World Population Prospects 2019: Highlights. United Nations website, https://www.un.org/development/desa/publications/world-population-prospects-2019-highlights.html. Accessed October 9, 2019.Google Scholar Although, the increases in the life expectancy and number of older people are considered positive developments, a major concern is whether this greater longevity constitutes years of healthy living and healthy aging, and what impact it will have on health care systems.2World Health Organization. The Global strategy and action plan on ageing and health. World Health Organization website, https://www.who.int/ageing/WHO-GSAP-2017.pdf?ua=1. Accessed October 9, 2019.Google Scholar For example, a secondary analysis of 2017 Global Burden of Diseases identified 92 diseases as age-related, accounting for 51.3% of the entire global burden among adults.3Chang A.Y. Skirbekk V.F. Tyrovolas S. Kassebaum N.J. Dieleman J.L. Measuring population ageing: an analysis of the Global Burden of Disease Study 2017.Lancet Public Health. 2019; 4: e159-e167Google Scholar Moreover, total health care costs per capita are projected to increase by 20% because of aging in the United States from 2000 to 2030 with an annual increase of 0.6%.4Alemayehu B. Warner K.E. The lifetime distribution of health care costs.Health Serv Res. 2004; 39: 627-642Google Scholar Among European Union countries, the projected increase in public health expenditure on elderly care in 2060, resulting purely from demographic changes, amounts to 1.2 percentage points of gross domestic product on average (from 1.6% in 2013 to 2.8% in 2060).5European CThe 2015 Aging Report. Economic and Budgetary Projections for the 28 EU Member States (2013-2060).2015http://ec.europa.eu/economy_finance/publications/european_economy/2015/pdf/ee3_en.pdfDate accessed: October 9, 2019Google Scholar On the other hand, regular physical activity (PA) may serve as a nonpharmacological prevention and treatment strategy for various comorbid conditions such as hypertension, obesity, or overweightness; improves mental health and quality of life; delays dementia onset6Fletcher G.F. Landolfo C. Niebauer J. Ozemek C. Arena R. Lavie C.J. Promoting Physical Activity and Exercise: JACC Health Promotion Series.J Am Coll Cardiol. 2018; 72: 1622-1639Google Scholar, 7Lavie C.J. Ozemek C. Carbone S. Katzmarzyk P.T. Blair S.N. Sedentary behavior, exercise, and cardiovascular health.Circ Res. 2019; 124: 799-815Google Scholar, 8Wisloff U. Lavie C.J. Taking physical activity, exercise, and fitness to a higher level.Prog Cardiovasc Dis. 2017; 60: 1-2Google Scholar; and can be used to reduce public health care costs considerably.9Dallmeyer S. Wicker P. Breuer C. How an aging society affects the economic costs of inactivity in Germany: empirical evidence and projections.Eur Rev Aging Phys Act. 2017; 14: 18Google Scholar Previous studies suggest that exercise performed at high intensities, albeit fewer sessions, provide similar or larger health benefits compared with the frequent, low-intensity activity of longer duration.8Wisloff U. Lavie C.J. Taking physical activity, exercise, and fitness to a higher level.Prog Cardiovasc Dis. 2017; 60: 1-2Google Scholar,10Swain D.P. Franklin B.A. Comparison of cardioprotective benefits of vigorous versus moderate intensity aerobic exercise.Am J Cardiol. 2006; 97: 141-147Google Scholar Emerging evidence also suggests that cardiorespiratory fitness (CRF) per se is superior to PA or exercise for predicting adverse health outcomes, and PA or exercise is associated with improvement in CRF in a dose-response manner.11Ross R. Blair S.N. Arena R. et al.Importance of assessing cardiorespiratory fitness in clinical practice: a case for fitness as a clinical vital sign: a scientific statement from the American Heart Association.Circulation. 2016; 134: e653-e699Google Scholar The new PA guidelines for Americans recommend that older adults follow the key guidelines for adults, ie, 150 to 300 weekly minutes of moderate-intensity, or 75 to 150 weekly minutes of vigorous-intensity aerobic PA, or an equivalent combination of moderate and vigorous-intensity exercise. In addition, older adults should determine the intensity of PA relative to the level of their CRF, and engage in activities that include balance training.12Piercy K.L. Troiano R.P. Ballard R.M. et al.The Physical Activity Guidelines for Americans.JAMA. 2018; 320: 2020-2028Google Scholar In the current issue of Mayo Clinic Proceedings, Masuki et al13Masuki S. Morikawa M. Nose H. High-intensity walking time is a key determinant to increase physical fitness and improve health outcomes after interval walking training in middle-aged and older people.Mayo Clin Proc. 2019; 94: 2415-2426Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar report the effects of interval walking training (IWT) for improvements in estimated CRF and lifestyle-related disease score, while focusing on exercise intensity and volume in middle aged and older people (mean age 65 years). During IWT program, participants performed five or more sets of fast (≥70% of estimated CRF) and slow (40% of estimated CRF) walking per day, each for 3 minutes for 4 or more days per week. After 5 months of the IWT program, the estimated CRF increased by 14%, and a composite lifestyle-related disease score decreased by 17% among men and women (n = 679). The results also showed that fast walking time per week was superior for CRF improvements to slow walking time or total walking time per week; an increase in fast walking time up to 50 min/wk was associated with improved CRF and a concurrent decrease in lifestyle-related disease score. The study by Masuki et al13Masuki S. Morikawa M. Nose H. High-intensity walking time is a key determinant to increase physical fitness and improve health outcomes after interval walking training in middle-aged and older people.Mayo Clin Proc. 2019; 94: 2415-2426Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar contributes important information about the effect of high-intensity interval walking on CRF and disease score in middle age and elderly population. The intensity thresholds of PA or exercise have been debated during the last 2 decades without any scientific consensus to define the optimal and generalizable intensity cutpoints appropriately. However, the relative intensity thresholds (ie, as a proportion of CRF) are thought to be more suitable than absolute terms (metabolic equivalents of task) to increase the CRF, and are associated with a favorable cardiovascular profile.11Ross R. Blair S.N. Arena R. et al.Importance of assessing cardiorespiratory fitness in clinical practice: a case for fitness as a clinical vital sign: a scientific statement from the American Heart Association.Circulation. 2016; 134: e653-e699Google Scholar A strength of the study by Masuki et al13Masuki S. Morikawa M. Nose H. High-intensity walking time is a key determinant to increase physical fitness and improve health outcomes after interval walking training in middle-aged and older people.Mayo Clin Proc. 2019; 94: 2415-2426Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar is that it used a percentage of estimated CRF to define intensity. Other strengths of this study included monitoring exercise intensity at almost every training session during a 5-month period, and the availability of key electronically captured data as part of the training and monitoring system. Of note, the study by Masuki et al13Masuki S. Morikawa M. Nose H. High-intensity walking time is a key determinant to increase physical fitness and improve health outcomes after interval walking training in middle-aged and older people.Mayo Clin Proc. 2019; 94: 2415-2426Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar observed no changes in CRF and lifestyle disease risk score associated with slow or total walking time. Their findings are consistent with the recommendations of the American Heart Association11Ross R. Blair S.N. Arena R. et al.Importance of assessing cardiorespiratory fitness in clinical practice: a case for fitness as a clinical vital sign: a scientific statement from the American Heart Association.Circulation. 2016; 134: e653-e699Google Scholar and the results of earlier studies showing superior beneficial health effects related to high intensity exercise that significantly increases the heart rates.8Wisloff U. Lavie C.J. Taking physical activity, exercise, and fitness to a higher level.Prog Cardiovasc Dis. 2017; 60: 1-2Google Scholar,14Nes B.M. Gutvik C.R. Lavie C.J. Nauman J. Wisloff U. Personalized activity intelligence (PAI) for prevention of cardiovascular disease and promotion of physical activity.Am J Med. 2017; 130: 328-336Google Scholar,15Karlsen T. Aamot I.L. Haykowsky M. Rognmo O. High Intensity Interval Training for Maximizing Health Outcomes.Prog Cardiovasc Dis. 2017; 60: 67-77Google Scholar In fact, we recently showed a positive association between a simple PA metric, personal activity intelligence, and objectively measured CRF across age groups and in both sexes.16Nauman J. Nes B.M. Zisko N. et al.Personal activity intelligence (PAI): a new standard in activity tracking for obtaining a healthy cardiorespiratory fitness level and low cardiovascular risk.Prog Cardiovasc Dis. 2019; 62: 179-185Google Scholar Interestingly, high levels of personal activity intelligence with PA at higher heart rates predicted both CRF and survival considerably better than following national PA guidelines.14Nes B.M. Gutvik C.R. Lavie C.J. Nauman J. Wisloff U. Personalized activity intelligence (PAI) for prevention of cardiovascular disease and promotion of physical activity.Am J Med. 2017; 130: 328-336Google Scholar,16Nauman J. Nes B.M. Zisko N. et al.Personal activity intelligence (PAI): a new standard in activity tracking for obtaining a healthy cardiorespiratory fitness level and low cardiovascular risk.Prog Cardiovasc Dis. 2019; 62: 179-185Google Scholar However, data from epidemiologic studies also suggest that middle age and older adults can boost their longevity even with just light PA.17Ekelund U. Tarp J. Steene-Johannessen J. et al.Dose-response associations between accelerometry measured physical activity and sedentary time and all cause mortality: systematic review and harmonised meta-analysis.BMJ. 2019; 366: l4570Google Scholar,18Klenk J. Kerse N. Every step you take.BMJ. 2019; 366: 15051Google Scholar In a recent meta-analysis of prospective cohort studies (n = 36,383; mean age, 62.6 years),17Ekelund U. Tarp J. Steene-Johannessen J. et al.Dose-response associations between accelerometry measured physical activity and sedentary time and all cause mortality: systematic review and harmonised meta-analysis.BMJ. 2019; 366: l4570Google Scholar higher levels of PA at any intensity were associated with a substantially reduced risk of premature mortality. The study from Masuki et al13Masuki S. Morikawa M. Nose H. High-intensity walking time is a key determinant to increase physical fitness and improve health outcomes after interval walking training in middle-aged and older people.Mayo Clin Proc. 2019; 94: 2415-2426Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar had different outcomes than mortality, and future studies with more extended intervention and follow-up times in various ethnicities are warranted to investigate the exact dose-response associations between different exercise intensities with health outcomes, as well as mortality. The CRF assessments by treadmill speed and incline or by an accelerometer during the graded walking test as performed by Masuki et al13Masuki S. Morikawa M. Nose H. High-intensity walking time is a key determinant to increase physical fitness and improve health outcomes after interval walking training in middle-aged and older people.Mayo Clin Proc. 2019; 94: 2415-2426Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar is not the same as the precise measurements of oxygen consumption by gas exchange analysis. However, the objective measurements of CRF are often considered impractical in clinical settings, presumably because of the costly and time-consuming procedure of exercise testing. Therefore, estimation of CRF without precisely measuring it using treadmill or by nonexercise assessments has been proposed as a practical and cost-effective tool in risk prevention settings, and to include in electronic medical records to help clinicians further stratify risk of future disease in their patients.11Ross R. Blair S.N. Arena R. et al.Importance of assessing cardiorespiratory fitness in clinical practice: a case for fitness as a clinical vital sign: a scientific statement from the American Heart Association.Circulation. 2016; 134: e653-e699Google Scholar At population level and especially in older adults, increasing PA and sustaining this change of behavior is challenging. A promising target for intervention in this regard could be walking, as it is simple, requires no training and equipment, and achievable even for older adults.19Kelly P. Kahlmeier S. Gotschi T. et al.Systematic review and meta-analysis of reduction in all-cause mortality from walking and cycling and shape of dose response relationship.Int J Behav Nutr Phys Act. 2014; 11: 132Google Scholar Of particular note is that interval training, a strategy used by elite athletes to achieve success in competitions, may benefit average citizens seeking to improve their health. Although fast walking can be used as a practical way to secure high CRF levels, the message7Lavie C.J. Ozemek C. Carbone S. Katzmarzyk P.T. Blair S.N. Sedentary behavior, exercise, and cardiovascular health.Circ Res. 2019; 124: 799-815Google Scholar,20Lavie C.J. Ozemek C. Kachur S. Promoting physical activity in primary and secondary prevention.Eur Heart J. 2019; (pii:ehz697)Google Scholar for policymakers, clinicians, public health professionals, and the general public must be to sit less and that even relatively small amounts of exercise are beneficial to reduce mortality and to improve quality-adjusted life years. High-Intensity Walking Time Is a Key Determinant to Increase Physical Fitness and Improve Health Outcomes After Interval Walking Training in Middle-Aged and Older PeopleMayo Clinic ProceedingsVol. 94Issue 12PreviewTo examine the effects of interval walking training (IWT) on the estimated peak aerobic capacity (e) and lifestyle-related disease (LSD) score while focusing on exercise intensity and volume in middle-aged and older people. Full-Text PDF