Original researchIs the six-minute walk test appropriate for detecting changes in cardiorespiratory fitness in healthy elderly men?
Introduction
Chronic exercise has been recommended as an important tool to reduce the risk of cardiovascular and endocrine diseases and to improve bone and muscle conditioning in elderly people.1 It is well established that chronic aerobic exercise improves maximal oxygen uptake due to central and peripheral cardiac adaptations.2 Additionally, exercise interventions that improve endurance and neuromuscular performance in elderly people are becoming recognized as effective strategies to increase functional independence and to decrease the prevalence of many diseases associated with aging.1 In concurrent training, both endurance and strength performance can be simultaneously improved in untrained participants.3
Traditionally, improvements in aerobic power are assessed by increases in peak/max oxygen uptake . This physiological variable is considered the gold standard in the assessment of functional capacity and cardiorespiratory fitness (CRF) and is measured by cardiopulmonary exercise testing (CPET).4 CPET analyses the function of the cardiovascular, respiratory and neuromuscular systems, providing a global assessment of the integrative physiological response.5 Clinically, a low CRF is associated with all-cause mortality and cardiovascular diseases (CVD) events in healthy individuals.6 In addition, physical performance have great value when used as baseline factors to discriminate future health and function in elderly people.7 However, CPET is a high-cost exam and requires specially trained staff. Therefore, simple and inexpensive tests are required in the field to assess functional capacity.8
The 6-min walk test (6-MWT) is a simple, safe and low-cost field test often used for the elderly and patients with chronic heart failure or chronic obstructive pulmonary disease to regularly assess their functional exercise capacity and the effects of a rehabilitation/exercise program.4 Previous studies have used the 6-MWT performance to predict the in clinical populations,9 as well as in healthy elderly people.10 Kervio et al.10 estimated the in healthy elderly from anthropometric values and 6-MWT parameters. More recently, Ross et al.9 demonstrated that the 6-MWT is appropriate to estimate in patients with moderate-to-severe heart or lung disease, using only the covered distance.
Some studies have investigated the association between the distance covered obtained from CPET and the 6-MWT performance.11, 12 In this way, correlations have been observed between the distance covered during the 6-MWT and in elderly healthy participants.11, 12 However, to our knowledge, there are no studies that used the 6-MWT performance to evaluate improvement in cardiorespiratory parameters in healthy elderly men submitted to chronic exercise. We hypothesised that changes in CRF could be detected by changes in the 6-MWT performance. Thus, the aim of this study was to analyse whether the 6-MWT can detect changes in CRF induced by exercise training (endurance and concurrent) in elderly men.
Section snippets
Methods
The thirty-two participants, recruited using advertisements placed in local newspapers, were healthy men between 65 and 75 years old. The inclusion factors used for the healthy elderly were: untrained, no current smoking, no chronic disease, and a body mass index lower than 35 kg m−2. After a clear explanation of the procedures, including the risks and benefits of participation, written informed consent was obtained. Participants underwent a detailed medical examination and an electrocardiogram
Results
The treadmill performances of the participants are shown in Table 1. No significant differences were observed between groups before the training period. The obtained after the training period was significantly higher in the E and ER groups compared to pre-training values (15.0 and 12.6%, respectively). Moreover, the time to exhaustion was significantly higher when compared to pre-training values (E: 18.7% and ER: 11.4%).
All participants finished the 6-MWT without difficulty or
Discussion
The purpose of this study was to determine whether the 6-MWT is able to detect changes in the CRF of healthy elderly men submitted to two modes of exercise programs. Following 24 weeks of a training program performed by the E and ER groups, there was an increase in and covered distance in the 6-MWT (Table 1). However, these results did not support our hypothesis that changes in CRF could be detected by changes in the 6-MWT performance, since there was no a relationship between the
Conclusion
In conclusion, this study showed that, for healthy elderly men, the changes in 6-MWT performance and the changes in CPET measures are not correlated. Thus, the use of the 6-MWT is not appropriate to evaluate improvements in cardiorespiratory parameters resulting from endurance training or concurrent training. However, the 6-MWT is a notable tool to evaluate functional capacity improvements due to exercise programs. Therefore, in healthy elderly people, the information provided by a 6-MWT should
Practical implications
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The 6-MWT is a simple, useful test to evaluate improvements in functional capacity after exercise training.
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The 6-MWT is not appropriate to evaluate improvements in CRF of elderly healthy men who have undergone exercise training.
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Although the 6-MWT after exercise training has been sensitive to detect improves in the functional capacity, relevant to many daily activities, it reflect no improves on CRF as observed in CPET.
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The CPET and the 6-MWT could be used together in order to provide a complete
Acknowledgements
We would like to thank all of the participants who volunteered their time to participate in the study.
The authors would like to thank the institutions that made this manuscript possible: AFIP, FAPESP, CEPID/FAPESP, CEPE, CEMSA, and FADA/UNIFESP.
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