A comparison of new cardiovascular endurance test using the 2-minute marching test vs. 6-minute walk test in healthy volunteers: A crossover randomized controlled trial

Surapichpong, Suchai 1 ; Jisarojito, Sucheela1 ; Surapichpong, Chaiyanut2

Published Jul 24, 2024 on Dryad. https://doi.org/10.5061/dryad.31zcrjdv2

Data files

Jul 24, 2024 version files 15.35 KB

README.md
11.56 KB
Table_1_Baseline_characteristics.csv

580 B
Table_2_Equivalence_test_of_VO2max_between_2MMT_and_6MWT.csv

754 B
Table_3__Mean_and_standard_deviation_of_6MWT_and_2MMT.csv

1.10 KB
Table_4_Comparison_of_secondary_outcomes_between_6MWT_and_2MMT.csv

1.36 KB

Abstract

This was a 2×2 randomized crossover control trial to compare the cardiovascular endurance of healthy volunteers using a 2-minute marching test (2MMT) and a 6-minute walk test (6MWT). This study included 254 participants of both sexes, aged 20–50 years, with a height and body mass index (BMI) of ≥150 cm and ≤25 kg/m², respectively. Participants could perform activities independently and had normal annual chest radiographs and electrocardiograms. A group-randomized design was used to assign participants to Sequence 1 (AB) or 2 (BA). The tests were conducted over 2 consecutive days, with a 1-day washout period. On day 1, the participants randomly underwent either a 6MWT or 2MMT in a single-anonymized setup, and on day 2, the tests were performed in reverse order. We analyzed maximal oxygen consumption (VO_2max) as the primary outcome and heart rate (HR), respiratory rate (RR), blood pressure (BP), oxygen saturation, dyspnea, and leg fatigue as secondary outcomes. Data were collected from 127 participants, categorized into two groups for different testing sequences. The first (AB) and second groups had 63 and 64 participants, respectively. The estimated VO_2max was equivalent between both groups. The 2MMT and 6MWT estimated VO_2max with a mean of 41.00 ± 3.95 mL/kg/min and 40.65 ± 3.98 mL/kg/min, respectively. The mean difference was -0.35 mL/kg/min (95% confidence interval: -1.09 to 0.38; p <0.001), and no treatment and carryover effects were observed. No significant changes were observed in HR, RR, and systolic BP (p = 0.295, p = 0.361 and p = 0.389, respectively). However, significant changes were found in the ratings of perceived exertion (p <0.001) and leg fatigue scale (p <0.001). The 2MMT is practical, simple, and equivalent to the 6MWT in estimating VO_2max.

https://doi.org/10.5061/dryad.31zcrjdv2

We have submitted data tables 1-3 for the description of (Fig 1 CONSORT diagram of the study_figure.TIFF), (Fig 2 The trial design_figure.TIFF, and(Fig 3 The study protocol_figure.TIFF), and submitted of data analysis (Table 1 Baseline characteristics_data.CVS),(Table 2 Equivalence test of VO2max between 2MMT and 6MWT_data.CVS), (Table 3 Mean and standard deviation of 6MWT and 2MMT_data.CVS), and (Table 4 Comparison of secondary outcomes between 6MWT and 2MMT_data.CVS)

Description

Fig 1 CONSORT diagram of the study\Figure

Materials and Methods

The trial protocol and supporting Consolidated Standards of Reporting Trials (CONSORT) checklist are available as supporting information (S1 File CONSORT Checklist) and the CONSORT diagram is illustrated in Fig 1.

Fig 2 The trial design\Figure

Trial design

We conducted a group of randomized controlled trials, including a crossover study for the equivalence test of cardiovascular endurance (VO2max) between the 6MWT and 2MM, with a 1-day washout period between the 6MWT and 2MMT. The trial design is outlined in Fig 2.

Fig 3 The study protocol\Figure

Overview of study design

This study was conducted during two visits, 1 day apart. Notably, 254 healthy volunteers were enrolled. They were recruited through an announcement. All eligible participants were randomly assigned to one of two sequences using group randomization in a single anonymized setup. Sequences 1 (AB) and 2 (BA) involved the 6MWT and 2MMT, respectively. On day 1, the sequences were performed randomly, with a 1-day washout period between the tests. On day 2, the tests were performed in reverse order. The primary outcome, VO2max, was recorded in the posttest, and the secondary outcomes, including heart rate (HR), respiratory rate (RR), oxygen saturation (SpO2), systolic blood pressure (SBP), diastolic blood pressure (DBP), rating of perceived exertion (RPE), and leg fatigue scale (LFS), were recorded in 1 min, 5 min, and 10 min for pretest and posttest. The study protocol is outlined in Fig 3.

Table 1 Baseline characteristics_Data

BMI: body mass index
SD: standard deviation
2MMT:2-minute marching test
6MWT: 6-minute walk test

Characteristics:

Notably,127 healthy volunteers completed the data collection and protocol without experiencing adverse events. The study involved 31 males and 96 females aged 20–49 years, with a mean age of 29.65 ± 5.85 years. The participants’ average weight, height, and BMI were 56.96 ± 8.02 kg, 163.92 ± 6.72 cm, and 21.05 ± 2.08 kg/m2, respectively. Participants had an average of 233.16 ± 46.94 steps for the 2MMT and an average distance of 565.48 ± 56.88 m. for 6MWT. The participants’ characteristics are presented in Table 1.

Table 2 Equivalence test of VO2max between 2MMT and 6MWT_Data

2MMT: 2-minute marching test
6MWT: 6-minute walk test
VO2max: maximal oxygen consumption
SD: standard deviation
CI: confidence interval
_a: Analyses were conducted using the two-one-sided t-test procedure (TOST).
_b: Analyses were conducted using a paired t-test.
_*: Statistical significance set at p< 0.05

Overall, 127 participants were included in this study; 64 participants underwent sequence 1 (AB) (6MWT followed by 2MMT), whereas 63 underwent sequence 2 (BA) (2MMT followed by 6MWT). The results are presented in Table 2.

This study found that the 2MMT and 6MWT were equivalence in estimating VO2max The mean VO2max for the 2MMT was 41.00± 3.95 mL/kg/min, whereas it was 40.65 ±3.98 mL/kg/min for the 6MWT. The mean difference between the two tests was only 0.35 mL/kg/min, with a 95% confidence interval [CI] of -1.09 to 0.38 mL/kg/min. The p-value was < 0.001, indicating no treatment or carryover effect.

For sequence 1 (AB), the mean VO2max for both tests were 41.09 ± 4.13 mL/kg/min and 41.06 ± 3.88 mL/kg/min, respectively, with a mean difference of only 0.27 mL/kg/min (95% CI: 1.36, 1.42). The statistical analysis showed no significant difference between both methods (p-value 0.96), indicating that both tests yielded similar results for sequence 1 (AB).

Similarly, for sequence 2 (BA), the mean VO2max was 40.87 ± 3.80 mL/kg/min and 41.29 ± 3.94 mL/kg/min for the 2MMT and 6MWT, respectively, with a mean difference of 0.58 mL/kg/min (95% CI: -0.50, 1.65). The statistical analysis was not significant (p-value = 0.28), indicating that both tests yielded similar results for sequence 2 (BA).

Table 3 Mean and standard deviation of 6MWT and 2MMT_Data

2MMT: 2-minute marching test
6MWT: 6-minute walk test
HR: heart rate
RR: respiratory rate
SpO2: oxygen saturation
SBP: systolic blood pressure
DBP: diastolic blood pressure
LFS: leg fatigue scale
SD: standard deviation

Table 4 Comparison of secondary outcomes between 6MWT and 2MMT_Data

2MMT: 2-minute marching test
6MWT: 6-minute walk test
HR: heart rate
RR: respiratory rate
SpO2: oxygen saturation
SBP: systolic blood pressure
DBP: diastolic blood pressure
LFS: leg fatigue scale
CI: confidence interval
_a: Analyses were conducted using a paired t-test
_b: Analyses were conducted using a linear mixed-effects model adjusted for baseline value
*_**: Statistical significance set at p<0.05

Regarding the secondary outcomes, we compared the vital sign variables (HR, RR, SpO2, DBP, and SBP), dyspnea scale (RPE), and LFS which were analyzed using a linear mixed-effect model adjusted for baseline value. The results are outlined in Table 3 and Table 4.

HR

The comparison results in the posttest at 0 min of 2MMT and 6MWT presented a mean HR of 111.10 ± 21.82 bpm, and 105.81 ± 19.66 bpm, respectively. The 5 min posttest had a mean HR of 84.99 ± 12.75 bpm and 87.25 ± 11.72 bpm in 2MMT and 6MWT, respectively, and that for 10 min posttest was 82.73 ± 11.31 bpm and 84.64 ± 10.65 bpm, respectively. Changes in HR during the 2MMT had a statistically significant mean reduction of -2.672 (95%CI: -2.965, -2.379) (p-value <0.001), and those in 6MWT had a mean reduction of -2.282. (95%CI: -2.575, -1.989), which was statistically significant (p-value <0.001). The HR between the 2MMT and 6MWT had, a mean difference of -0.849 (95%CI: -2.438, 0.740) and was, not statistically significant (p-value = 0.295).

RR

The comparison results in the posttest at 0 min of the 2MMT and 6MWT presented a mean of RR 21.57 ± 2.64 bpm and 21.43 ± 2.58 bpm, respectively. The mean RR during the 5 min posttest was 18.48 ± 1.79 bpm and 18.22 ± 2.09 bpm in 2MMT and 6MWT, respectively, and that for the 10 min posttest was 17.35 ± 1.50 bpm and 17.19 ± 1.76 bpm, respectively. RR changes during the 2MMT had a statistically significant mean reduction of -0.415 (95%CI: -0.454, -0.376) (p-value <0.001), and those in 6MWT had a mean decrease of -0.431 (95%CI: -0.469, -0.392) which was statistically significant (p-value <0.001). The RR change between the 2MMT and 6MWT had, a mean difference of 0.121 (95%CI: -0.138, 0.379) and was, not statistically significant (p-value = 0.361).

SpO2

The comparison results in the posttest at 0 min of the 2MMT and 6MWT presented a mean of SpO2 of 99.35 ± 0.97 % and 99.57 ± 0.72%, respectively. The mean SpO2 at 5 min posttest was 99.34 ± 0.90% and 99.44 ± 0.78% in 2MMT and 6MWT, respectively, and that for the 10 min posttest was 99.41 ± 0.84% and 99.31 ± 0.80%. Changes in SpO2 2MMT had a statistically non-significant mean reduction of -0.010 (95%CI: -0.024, 0.004) (p-value= 0.163), and those in the 6MWT had a non-significant mean decrease of -0.011 (95%CI: -0.024, 0.003) (p-value = 0.141) the change in SpO2 between the 2MMT and 6MWT, a mean difference of -0.106 (95%CI: -0.195, -0.017) was statistically significant (p-value = 0.020).

SBP

The comparison results in the posttest at 0 min of the 2MMT and 6MWT presented a mean SBP of 132.86 ± 16.87 mmHg and 135.06 ± 16.48 mmHg, respectively. The mean SBP at the 5 min posttest was 117.50 ± 12.65 mmHg and 117.20 ± 12.49 mmHg in 2MMT and 6MWT, respectively, and that for 10 min posttest was 114.95 ± 11.62 mmHg and 114.43 ± 10.48 mmHg, respectively. SBP changed during 2MMT had a statistically significant mean reduction of -1.838 (95%CI: -2.077, -1.600) (p-value <0.001), and those during 6MWT had a mean decrease of -2.014 (95%CI: -2.253, -1.775), which was statistically significant (p-value <0.001). The SBP changes between the 2MMT and 6MWT had, a mean difference of 0.560 (95%CI: -0.715, 1.834) and was, not statistically significant (p-value = 0.389).

DBP

The comparison results at 0 min of 2MMT and 6MWT presented a mean DBP of 70.85 ± 10.26 mmHg and 75.27 ± 11.17 mmHg, respectively. The mean DBP at the 5 min posttest was 70.57 ± 9.03 mmHg and 71.39 ± 9.15 mmHg in 2MMT and 6MWT, respectively, and that for the 10 min posttest was 70.28 ± 8.50 mmHg and 71.36 ± 9.57 mmHg, respectively. DBP changes during 2MMT had a statistically significant mean reduction of 0.263 (95%CI: -0.412, -0.114) (p-value = 0.001). The DBP changes in 6MWT had a mean reduction of 0.185 (95%CI: -0.334, -0.036), which was statistically significant (p-value = 0.015). The DBP changes between the 2MMT and 6MWT had a statistically significant mean difference of -1.759 (95%CI: -2.589, -0.928) (p-value < 0.001).

Dyspnea

The dyspnea scale was presented using RPE and the comparison result in the posttest at 0 min of 2MMT and 6MWT presented a mean RPE of 1.96 ± 1.25 and 2.35 ± 1.40, respectively. The mean RPE at the 5 min posttest was 0.29 ± 0.51 and 0.56 ± 0.74 in 2MMT and 6MWT, respectively, and that for the 10 min posttest was 0.04 ± 0.16 and 0.11 ± 0.34 in 2MMT and 6MWT, respectively. RPE changes during 2MMT had a statistically significant mean reduction of 0.215 (95%CI: -0.237, -0.194) (p-value <0.001), those during 6MWT had a statistically significant mean decrease of -0.201 (95%CI: -0.222, -0.180) (p-value < 0.001), and those between the 2MMT and 6MWT had, a statistically significant mean difference of -0.227 (95%CI: -0.350, -0.105) (p-value < 0.001).

Leg Fatigue Scale

LFS was modified from Borg’s scale, and the comparison results in the posttest at 0 min of 2MMT and 6MWT presented a mean LFS of 1.85 ± 1.23 and 2.11 ± 1.44, respectively. The 5 min posttest presented a mean of 0.42 ± 0.63 and 0.71 ± 0.83 in 2MMT and 6MWT, respectively, while the 10 min posttest had 0.11 ± 0.31 and 0.22 ± 0.53 in 2MMT and 6MWT, respectively. LFS changes during 2MMT had a statistically significant mean decrease of 0.193 (95%CI: -0.216, -0.169) (p-value <0.001), those during 6MWT had a statistically significant mean decrease of -0.171 (95%CI: -0.195, -0.148) (p-value < 0.001), and those between the 2MMT and 6MWT had a statistically significant, mean difference of -0.226 (95%CI: -0.341, -0.111) (p-value < 0.001).

Conclusion

We investigated the equivalence of the new cardiovascular endurance test using the 2MMT and 6MWT in healthy volunteers. These tests can provide valid estimates of VO2max in epidemiological studies. The 2MMT may be more relevant than expected. However, further studies are needed to determine the 2MMT’s sensitivity and MCID.

Sample size

The sample size required for the equivalence study was estimated using nQuery software and calculated using two one-sided equivalence tests for crossover design. To calculate the sample size, we set the alpha error probability, statistical power, the lower equivalence limit, and upper equivalence limit at 5%, 90%, -2.00, and +2.00, respectively, using the clinical margin (minimal clinically important difference [MCID] of VO_2max from a previous study, which was 2 ml/kg/min [15], and standard deviation was 8.6 [16]. Based on these values, we needed 101 participants for the crossover design, allowing for a 20% dropout rate. Therefore, we decided to randomize 127 patients per arm, resulting in 254 participants. However, due to the COVID-19 pandemic, data collection was incomplete, and we could only analyze 127 data sets in this study.

Inclusion and exclusion criteria

The inclusion criteria were male and female healthy volunteers, aged 20–50 years, with height: ≥150 cm and, BMI ≤25 kg/m2. Participants could perform activities independently and had normal annual chest radiographs and electrocardiograms. The exclusion criteria were significantly unstable vital signs, a history of COVID-19, and underlying heart disease or neuromuscular/skeletal impairment.

Procedure and measurement

We conducted a 2MMT and compared the results with those of the standard test, the 6MWT, to test the equivalence of both tests in estimating VO_2max

Condition A: According to the standard protocol, the 6MWT was performed indoors on a flat surface in a 30-m straight corridor, with 180º turns every 30 m. [10].The walk test was performed with stable vital signs, and SpO₂ was maintained at >95%, all monitored by a cardiopulmonary physical therapist.

Condition B: The 2MMT was developed to determine the number of steps performed within 2 min. After the “start” command, the participants began marching in place and lifting their knees to an appropriate height of 30 cm. The participants were instructed to perform as many steps as possible (reaching a height of 30 cm) within 2 min. The participants were allowed to perform a few training steps to adjust to the marching technique and verify their ability to complete the task. The participants marched at their own pace; they could slow down or even stop, if necessary, and continue marching until the end of the 2-minute test period. The investigator determined the number of steps performed, informed the participants about the time left until the end of the trial, and motivated them to achieve the best possible result. The test results were expressed as the number of performed steps during which the right foot touched the ground.

When the participants exhibited severe symptoms of exercise intolerance in both tests, such as severe dyspnea, fatigue, or other alarming symptoms, they were allowed to slow down or stop and rest. However, they were encouraged to resume the test as soon as possible. Adverse events were monitored during and after test completion. Both tests were terminated and interpreted as incomplete if any of the following symptoms were present: chest pain, intolerable dyspnea, leg cramps, staggering, diaphoresis, and ashen appearance.

Data regarding the sex, age, BMI, HR, and RR were collected, and SpO₂ was assessed using the NONIN Onyx2 9590 Oximeter, SBP and DBP were measured using the Philip Patient Monitor Efficia CM100, RPE, and LFS were assessed using the Borg’s scale. All parameters were recorded at 1 min, 5 min, and 10 min for pretest and posttest.

VO_2max estimated the cardiovascular endurance using the following formula:

VO_2max estimated in the 6MWT: 70.161 + (0.023 × 6MWT [m]) - (0.276 × weight [kg]) - (6.79 × sex, where m = 0, f = 1) - (0.193 × resting HR [beats per minute] - (0.191 × age [years]) [15]. where resting HR is the 10-min resting HR of posttest.

VO_2max estimated in the 2MMT: 13.341 + 0.138 × total up and down steps (UDS) – (0.183 × BMI) [16].

Data analysis

Due to the COVID-19 pandemic in Thailand and hospital policies, only 127 of the 254 participants, who were healthy volunteers, could complete data collection. Descriptive statistics were used to evaluate demographic characteristics. Continuous variables were reported as mean ± standard deviation, whereas binary variables were reported as percentages. The primary outcome (VO_2max), evaluated using Statgraphics software, was analyzed through a two-one-sided t-test procedure. The analysis was conducted with an equivalence bound of ± 2 mL/kg/min from the margin of VO_2max observed in a previous study [17]. The carryover and treatment effects were insignificant, and the equivalence result was significant for the test. For the secondary outcome, all parameters were analyzed using a linear mixed-effect model to compare 2MMT and 6MWT with STATA software.

References

Chu P, Gotink RA, Yeh GY, Goldie SJ, Hunink MG. The effectiveness of yoga in modifying risk factors for cardiovascular disease and metabolic syndrome: A systematic review and meta-analysis of randomized controlled trials. Eur J Prev Cardiol. 2016;23: 291-307. doi: 10.1177/2047487314562741.
Khushoo TN, Rafiq N, Qayoom O. Assessment of cardiovascular fitness (VO2 max) among medical students by Queens College step test. Int J Biomed Adv Res. 2015;6: 418-421. doi: 10.7439/IJBAR.V6I5.1965.
Haas F, Sweeney G, Pierre A, Plusch T, Whiteson JH, editors. Validation of a 2 minute step test for assessing functional Improvement 2017. OJTR. 2017;05: 71-81. doi: 10.4236/ojtr.2017.52007.
Oliveros MJ, Seron P, Román C, Gálvez M, Navarro R, Latin G, et al. Two-minute step test as a complement to six-minute walk test in subjects with treated coronary artery disease. Front Cardiovasc Med. 2022;9: 848589. doi: 10.3389/fcvm.2022.848589.
Kammin EJ. The 6-minute walk test: indications and guidelines for use in outpatient practices. J Nurse Pract. 2022;18: 608-610. doi: 10.1016/j.nurpra.2022.04.013.
Cazzola M, Biscione GL, Pasqua F, Crigna G, Appodia M, Cardaci V, et al. Use of 6-min and 12-min walking test for assessing the efficacy of formoterol in COPD. Respir Med. 2008;102: 1425-1430. doi:10.1016/j.rmed.2008.04.017.
Pollentier B, Irons SL, Benedetto CM, Dibenedetto AM, Loton D, Seyler RD, et al. Examination of the six minute walk test to determine functional capacity in people with chronic heart failure: a systematic review. Cardiopulm Phys Ther J. 2010;21: 13-21. doi: 10.1097/01823246-201021010-00003.
ATS Committee on Proficiency Standards for Clinical Pulmonary Function Laboratories. ATS statement: guidelines for the six-minute walk test. Am J Respir Crit Care Med. 2002;166: 111-117. doi: 10.1164/ajrccm.166.1.at1102.
Rasekaba T, Lee AL, Naughton MT, Williams TJ, Holland AE. The six-minute walk test: a useful metric for the cardiopulmonary patient. Intern Med J. 2009;39: 495-501. doi: 10.1111/j.1445-5994.2008.01880.x.
Bohannon RW, Crouch RH. Two-minute step test of exercise capacity: systematic review of procedures, performance, and clinimetric properties. J Geriatr Phys Ther. 2019;42: 105-112. doi: 10.1519/JPT.0000000000000164.
Wells CL, Kegelmeyer D, Mayer KP, Kumble S, Reilley A, Campbell A, et al. APTA cross sections and academies recommendations for COVID-19 core outcome measures. J Acute Care Phys Ther. 2022;13: 62-76. doi: 10.1097/JAT.0000000000000172.
Berlanga LA, Matos-Duarte M, Abdalla P, Alves E, Mota J, Bohn L. Validity of the two-minute step test for healthy older adults. Geriatr Nurs. 2023;51: 415-421. doi: 10.1016/j.gerinurse.2023.04.009.
Vilarinho R, Caneiras C, Montes AM. Measurement properties of step tests for exercise capacity in COPD: A systematic review. Clin Rehabil. 2021;35: 578-588. doi: 10.1177/0269215520968054.
Burr JF, Bredin SS, Faktor MD, Warburton DE. The 6-minute walk test as a predictor of objectively measured aerobic fitness in healthy working-aged adults. Phys Sportsmed. 2011;39: 133-139. doi: 10.3810/psm.2011.05.1904.
Ricci PA, Cabiddu R, Jürgensen SP, André LD, Oliveira CR, Di Thommazo-Luporini L, et al. Validation of the two-minute step test in obese with comorbibities and morbidly obese patients. Braz J Med Biol Res. 2019;52: e8402. doi: 10.1590/1414-431X20198402.
Jones PW, Beeh KM, Chapman KR, Decramer M, Mahler DA, Wedzicha JA. Minimal clinically important differences in pharmacological trials. Am J Respir Crit Care Med. 2014;189: 250-255. doi: 10.1164/rccm.201310-1863PP.
Chetta A, Zanini A, Pisi G, Aiello M, Tzani P, Neri M, et al. Reference values for the 6-min walk test in healthy subjects 20–50 years old. Respir Med. 2006;100: 1573-1578. doi: 10.1016/j.rmed.2006.01.001.
Andrade CH, Cianci RG, Malaguti C, Corso SD. The use of step tests for the assessment of exercise capacity in healthy subjects and in patients with chronic lung disease. J Bras Pneumol. 2012;38: 116-124. doi: 10.1590/s1806-37132012000100016.
Webb CV, Vehrs PR, George JD, Hager RL. Estimating VO2max using a personalized step test. Meas Phys Educ Exer Sci. 2014;18: 184-197. doi: 10.1080/1091367X.2014.912985.
Bohannon RW, Bubela DJ, Wang YC, Magasi SS, Gershon RC. Six-minute walk test vs. three-minute step test for measuring functional endurance. J Strength Cond Res. 2015;29: 3240-3244. doi: 10.1519/JSC.0000000000000253.
Beutner F, Ubrich R, Zachariae S, Engel C, Sandri M, Teren A, et al. Validation of a brief step-test protocol for estimation of peak oxygen uptake. Eur J Prev Cardiol. 2015;22: 503-512. doi: 10.1177/2047487314533216.
Węgrzynowska-Teodorczyk K, Mozdzanowska D, Josiak K, Siennicka A, Nowakowska K, Banasiak W, et al. Could the two-minute step test be an alternative to the six-minute walk test for patients with systolic heart failure? Eur J Prev Cardiol. 2016;23: 1307-1313. doi: 10.1177/2047487315625235.
Dreher M, Walterspacher S, Sonntag F, Prettin S, Kabitz HJ, Windisch W. Exercise in severe COPD: is walking different from stair-climbing? Respir Med. 2008;102: 912-918. doi: 10.1016/j.rmed.2008.01.002.
Sharma P, Ganai J, Dwivedi S. Normative data of distance covered, heart rate, blood pressure and rate of perceived exertion during 6 minute walk test on 20 meter long corridor among smokers. Int J Pharm Med Res 2347. 2016;4;7008: 388-393. Available from: https://ijpmr.org/pdf/1-Normative-data-of-distance-covered-heart-rate-blood-pressure-and-rate-of-perceived.pdf.
Jothi K, Subradeepan A, Vinu D, Wise Y, Singh B. Arterial blood pressure and heart rate response to exercise. 2011;3(2). Available from: https://updatepublishing.com/journal/index.php/rrst/article/view/613.
Holland AE, Spruit MA, Troosters T, Puhan MA, Pepin V, Saey D, et al. An official European Respiratory Society/American Thoracic Society technical standard: field walking tests in chronic respiratory disease. Eur Respir J. 2014;44: 1428-1446. doi: 10.1183/09031936.00150314.
Beaumont M, Losq A, Péran L, Berriet AC, Couturaud F, Le Ber C, et al. Comparison of 3-minute Step Test (3MStepT) and 6-minute Walk Test (6MWT) in Patients with COPD. COPD. 2019;16: 266-271. doi: 10.1080/15412555.2019.1656713.
Shah V. Response to 6 minute walk test in healthy adults. Int J Physiother. 2015;2. doi: 10.15621/ijphy/2015/v2i6/80755.
Roberts MM, Cho JG, Sandoz JS, Wheatley JR. Oxygen desaturation and adverse events during 6-min walk testing in patients with COPD. Respirology. 2015;20: 419-425. doi: 10.1111/resp.12471.
Kothmann E, Batterham AM, Owen SJ, Turley AJ, Cheesman M, Parry A, et al. Effect of short-term exercise training on aerobic fitness in patients with abdominal aortic aneurysms: a pilot study. Br J Anaesth. 2009;103: 505-510. doi: 10.1093/bja/aep205.