Six-Minute Walk Test as a Predictive Measure of Exercise Capacity in Adults With Type 2 Diabetes

Abstract

Objective The 6 Minute Walk Test (6MWT) is a measure that is routinely used to assess a response to treatment for cardiopulmonary diseases such as pulmonary fibrosis and congestive heart failure. The measure has never been verified as a valid measure of exercise capacity in the highly prevalent patient population of type 2 diabetes (T2DM). This study investigated the correlation between the 6MWT and graded exercise testing (GXT) in an effort to validate the 6MWT as a quality tool for assessing exercise capacity in adults with T2DM. Research Design and Method This is a secondary data analysis of Program ACTIVE II, a randomized controlled trial designed to assess the effectiveness of two behavioral interventions on depression and glycemic outcomes in adults with T2DM. The correlation of 6MWT and predicted VO2 max (PVO2M) using GXT was examined in a subsample of participants at the time of study enrollment and at post-intervention. Results PVO2M showed a significant correlation with 6MWT distance both at baseline (r=0.57, p=0.014) and post-intervention (r = 0.66, p = 0.037). The regression analysis of baseline data revealed that 6MWT distance alone explained 45% (F = 13.03, p = .0024) of the variability in PVO2M. When combined with the SF-12 physical health component score (PCS), 6MWT explained 66% (F = 13.62, p < .001) of the variance in PVO2M. After adjusting for PCS, 6MWT distance explained an additional 30% variability in PVO2M. Conclusions Findings from this study indicate that the 6MWT and predicted exercise capacity are significantly correlated. The 6MWT can be used to estimate exercise capacity in adults with T2DM.

The 6-minute walk-test in type 2 diabetics predicts to some extent maximal aerobic capacity but not its training-induced improvement

“…Interestingly, Nolen-Doerr [11], reports a higher coeffi cient of correlation after training (r=0.66) compared to pre-training (r=0.57), and this is fully consistent with the current study which shows r=0.456 before training and r=0.714 after training. This may refl ect an improvement in cardiovascular regulatory adaptation to exercise strengthening the agreement between the two measurements.…”

“…In fact, it is not surprising to fi nd some discrepancies between 6MWT and VO2max data, which by essence are not the same measurement and cannot provide exactly the same information. Correlations between VO 2max and 6MWT found in the 3 previous studies [10][11][12] yield quite the same values of coeffi cients of correlation, ranging between 0.456 and 0.66. Nolen-Doerr [11] analyses this fact as refl ecting that 6MWT distance alone 'explains' 45% of the variance of VO 2max , so that 55% of this variance is not 'explained' by it.…”

“…However, the basis for this use was until recently poorly documented. Recently three papers evidenced relationships between 6MWT and maximal oxygen uptake (VO 2max ) in specifi c groups of diabetic patients [10][11][12]. All of them concluded that 6MWT is correlated to VO 2max and concluded that it can be employed as a marker of aerobic capacity.…”

“…DOI: https://dx.doi.org/10.17352/amm.000020 encouraging reports are still preliminary. They rely on quite limited samples of subjects: 54 South-Korean T2D women aged 50-70 years [10], 18 north American T2Ds included in the randomized controlled trial ACTIVE II [11] and 42 Spanish T2M with a mean age of 61.1 years [12]. Whether conclusions of these studies in selected populations can be safely extended to other populations remains to be more investigated.…”

Type 2 diabetes and reduced exercise tolerance: a review of the literature through an integrated physiology approach

“…Furthermore, imaging-CPET might also be considered for rehabilitation programmes in T2DM patients. Currently, T2DM per se is not an official indication for performing CPET, a population in which the 6 min walking test is often seen as the first choice-since it is validated against exercise test [138]-yet quite uninformative. On the contrary, CPET allows a precise estimate of oxygen dynamics (which is also preserved in patients with coronary artery disease, appearing safe and very informative-even at very reduced workloads [139]), together with a multivariable cardiopulmonary, muscular and metabolic assessment; therefore, it might be envisaged not only for the assessment of cardiorespiratory fitness, but also for HF risk stratification and rehabilitation prescription and surveillance alike.…”