Timed up and go test as a screening tool for exercise capacity after lung cancer resection

Introduction

Pulmonary rehabilitation is performed for a variety of conditions related to respiratory function, such as chronic obstructive pulmonary disease (COPD), lung cancer, and interstitial lung disease (1). Lung cancer is the leading cause of cancer-related deaths (2). The implementation of pulmonary rehabilitation before and after surgery has been proven to exert beneficial effects on survival rates and to reduce postoperative complications; therefore, it is essential to establish rehabilitation goals based on a precise functional assessment of patients (3).

Exercise capacity is an important component of pulmonary rehabilitation, with treadmill or bicycle ergometry being the standard method of measurement; in practice the 6-minute walk test (6MWT) is more commonly used in clinical settings (4). In fact, previous literature has shown that lung cancer patients with a postoperative 6MWT result of <525 meters have a lower survival rate (5). These aerobic exercise tests are not always feasible because of barriers such as limited equipment, time, and expertise. In addition, some patients are unable to complete the cardiopulmonary exercise test (CPET) or 6MWT due to balance problems, musculoskeletal limitations, or postoperative chest wall pain. Therefore, these tests cannot be applied to assess functional capacity in all patients (6,7). For instance, CPET requires equipment, such as a treadmill, gas analyzer, blood pressure monitor, electrocardiograph machine, and a face mask, while 6MWT necessitates a corridor of at least 30 meters according to guidelines (8,9).

In contrast, the timed up and go test (TUGT) reflects lower-limb strength, dynamic balance, and neuromotor control, which are key determinants of postoperative functional recovery. While CPET and 6MWT primarily assess cardiopulmonary and vascular capacity, TUGT captures musculoskeletal and neuromotor performance, thereby serving as a surrogate marker of overall functional capacity rather than a direct indicator of cardiopulmonary endurance (10). In this context, the TUGT involves standing up from a chair, walking a 3-meter distance, turning, and sitting down again, providing a simple and practical assessment of functional mobility (10,11).

Previous studies have examined the correlation between TUGT and 6MWT results in older adults and in non-lung cancer patients undergoing cardiac rehabilitation or having conditions, such as COPD and multiple sclerosis, and have found significant correlations between the results of the two tests in various populations, thereby demonstrating that the TUGT is a useful outcome measure (12-16). Moreover, studies in patients with chronic respiratory and cardiovascular diseases such as COPD (14,17) and heart failure (15) have reported significant associations between TUGT performance and 6MWT distance, further supporting the validity of using TUGT as a functional assessment tool in populations with impaired pulmonary or cardiopulmonary function. These findings reinforce the appropriateness of applying TUGT to postoperative thoracic surgery patients, whose recovery and exercise tolerance are similarly influenced by cardiopulmonary and musculoskeletal factors.

However, no studies have postoperatively evaluated the utility of TUGT in patients with lung cancer, and thus the primary objective of this study was to examine the relationship between TUGT and established exercise assessments (6MWT and CPET) in patients after lung cancer resection, in order to determine whether TUGT can serve as a feasible screening tool for functional evaluation. As a secondary objective, we investigated whether TUGT, along with the 6MWT and CPET, could detect improvements in exercise capacity after pulmonary rehabilitation in a subgroup of patients who underwent 8 weeks of rehabilitation. We present this article in accordance with the STROBE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-aw-2036/rc).

Methods

Study design and participants

Patients who underwent surgical treatment for lung cancer at Chungbuk National University Hospital between March 2019 and June 2023 were referred to the outpatient department for rehabilitation. The inclusion criteria were as follows: (I) consent to pulmonary rehabilitation therapy and (II) no contraindications to exercise assessment. Seventy-nine patients met the inclusion criteria. The exclusion criteria were as follows: (I) inability to complete the exercise assessment (8 excluded); (II) neurological conditions or amputations that could affect the exercise assessment (2 excluded); and (III) lack of necessary medical records for analysis (7 excluded). A total of 62 individuals were finally included (Figure 1). Demographic characteristics (age, sex, body mass index, smoking status, stage, type of surgery performed, extent of lung resection, chemotherapy status, and time to first postoperative evaluation) were collected, and postoperative 6MWT, CPET, and TUGT were performed. Among them, patients who completed at least eight supervised rehabilitation sessions over an 8-week period were classified as the rehabilitation subgroup (n=35) for additional analyses. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Institutional Review Board of Chungbuk National University Hospital (IRB No. 2023-08-032-001). Informed consent was waived in this retrospective study.

Figure 1 Flow chart of patient enrollment and analysis.

Pulmonary rehabilitation protocol

The pulmonary rehabilitation protocol was as follows. Rehabilitation was performed once or twice a week for 8 weeks and included the following: (I) aerobic exercise: bicycle or treadmill (20 minutes); (II) breathing exercises: breathing technique training (10 minutes); (III) strength training: upper and lower extremity large muscle strengthening exercises with Thera-Band and inspiratory muscle strengthening exercises (20 minutes); and (IV) stretching exercises: rib cage and upper extremity joint stretches (10 minutes) (3,18,19). Patients who attended at least eight supervised outpatient sessions over an 8-week period (mean 11.8±3.7 sessions) were classified as having completed the rehabilitation (n=35). In addition to these supervised sessions, patients were instructed to perform home-based exercises, which included aerobic, breathing, and strengthening exercises, based on the methods instructed during outpatient rehabilitation.

Outcome measures

The 6MWT was conducted according to the American Thoracic Society criteria and consisted of walking as far as possible for 6 minutes over a 30-meter course marked at 3-meter intervals (8). The units of measurement were meters (m). Maximal oxygen consumption (VO₂max) was measured during CPET performed on a treadmill using modified Bruce protocol (20) and a COSMED CPET^® machine (COSMED, Rome, Italy); the results were expressed in terms of oxygen consumption (VO₂, mL/kg/min). VO₂max was set as the value at which the oxygen uptake no longer increased relative to the amount of exercise (9). The patients performed TUGT by standing up from the chair, walking a distance of 3 m as quickly and safely as possible, turning around, walking back to the chair, and sitting down again; the time taken to complete the walk was measured (in seconds) (10). Measurements were performed three times, and the fastest result was used. The chair was a standard chair with armrests and was 46 cm high (10). The first TUGT assessment was performed during the early postoperative period (phase I rehabilitation), typically within 24–48 hours after surgery once hemodynamic stability was achieved and within one week postoperatively, and the second TUGT assessment was performed after completing the 8-week supervised outpatient rehabilitation.

Statistical analysis

Continuous variables were expressed as mean ± standard deviation, and categorical variables, as number and percentage. Pearson correlation coefficients were used to analyze the correlations between the results of 6MWT, CPET, and TUGT. Correlations were defined as very strong (≥0.8), strong (0.6–0.79), moderate (0.4–0.59), or weak (<0.4) based on the correlation coefficient (21). Receiver operating characteristic (ROC) curves were used to determine the sensitivity and specificity of TUGT for high-risk patients (6MWT <525 m). Based on a previous study, this high-risk group is known to exhibit poorer survival and postoperative complications after lung cancer surgery, and the demographics of the patients in this study were similar to those of the patients in our study (5). We analyzed the change in exercise capacity from pre- to post-rehabilitation using a paired t-test. All statistical analyses were performed using SPSS version 25.0 (IBM, New York, USA). The sample size for sensitivity and specificity was calculated using GPower 3.1 (Kiel University, Kiel, Germany), and 62 participants were required for a type 1 error (alpha error) of 0.05, power of 0.8, and area under the curve of 0.7. Only patients with complete datasets were included in the final analysis.

Results

Sixty-two patients were included in this study; the mean age was 63.0±8.8 years, and 38 patients (61%) were male. The average body mass index was 23.6±2.2 kg/m². Twenty-seven (44%) patients had never smoked. Thirty-five (56%) patients had stage I lung cancer, 14 (23%) had stage II, 6 (10%) had stage III, and 7 (11%) had stage IV. Seven (11%) underwent open thoracotomy, and the others underwent video-assisted thoracoscopic surgery. The majority of patients (n=56, 90%) underwent single lobectomy only. Ten (16%) patients had received chemotherapy prior to the evaluation. The mean time from surgery to evaluation was 31.3±22.2 days. The average 6MWT distance was 517.2±99.3 m, VO₂max during CPET was 21.1±4.6 mL/kg/min, and the mean time to complete the TUGT was 7.12±1.44 s (Table 1).

There was a strong negative correlation (r=−0.61, P<0.001) between the time to complete TUGT and the distance in 6MWT and a moderate negative correlation (r=−0.46, P<0.001) between the time in TUGT and VO₂max (Table 2, Figure 2). Regarding the ROC curve, the area under the curve was significant at 0.815 [95% confidence interval (CI): 0.72–0.91; P<0.001]. At the optimal cutoff value of 6.4 s in TUGT, determined by Youden’s index, patients with reduced exercise capacity, defined as a 6MWT <525 m, were identified with a sensitivity of 66% and a specificity of 93% (Figure 3). Among the 62 patients, 35 completed at least eight supervised sessions over 8 weeks and were included in the rehabilitation subgroup analysis. In this subgroup, the time to complete TUGT was reduced by an average of 0.37 s (P=0.004), the 6MWT distance increased by an average of 53.0 m (P<0.001), and the VO₂max increased by an average of 2.0 mL/kg/min (P=0.007); all the results were significantly different from those before the rehabilitation (Table 3).

Figure 2 Scatter plots of correlations between the TUGT and (A) 6MWT distance and (B) VO₂max. Regression line shown. 6MWT, 6-minute walk test; TUGT, timed up and go test; VO₂max, maximal oxygen consumption.

Figure 3 Receiver operating characteristic curve of the TUGT for detecting patients with reduced exercise capacity (6MWT <525 m). 6MWT, 6-minute walk test; AUC, area under the curve; TUGT, timed up and go test.

Discussion

The time to complete TUGT showed a strong correlation with exercise capacity measured by 6MWT and CPET in patients who underwent lung cancer resection. It also demonstrated significant improvements after pulmonary rehabilitation, comparable to the changes observed in 6MWT and CPET. TUGT, which is simpler and more feasible than these conventional tests, may therefore serve as a practical screening tool to identify patients with reduced postoperative exercise capacity who would benefit from further evaluation or rehabilitation.

In this study, there was a strong correlation between the time taken to complete TUGT and the distance achieved in 6MWT. Similar findings have been reported in other populations: a strong negative correlation (r=−0.70) between the two tests in patients with COPD (14), while a significant correlation (r=0.65) between 6MWT speed and TUGT performance in cardiac rehabilitation (13), suggesting that TUGT provides relevant information about functional capacity. The strong correlation between these two assessments is largely attributable to their shared reliance on walking speed, which was also the rationale for selecting TUGT as a simple mobility test in this study (8). Moreover, both 6MWT and TUGT reflect integrated functional domains beyond gait speed, such as balance, lower extremity strength, and endurance, which may further explain their strong correlation (10).

In this study, TUGT time showed a moderate negative correlation with VO₂max from CPET. Although few previous studies have directly compared TUGT with VO₂max, similar findings have been reported using other CPET parameters. For example, a moderate negative correlation (r=−0.44) between peak work rate on CPET and TUGT performance in patients with COPD (14). This relationship can be explained by the fact that VO₂max reflects the integrated function of cardiovascular, pulmonary, and musculoskeletal systems (22). In addition, the TUGT captures overall mobility by combining gait speed, balance, and lower extremity strength (10). Taken together, these findings suggest that TUGT, despite its simplicity, may reflect global exercise capacity in a manner that is consistent with more complex exercise testing.

The correlation coefficient (r=−0.46) between the time taken to complete TUGT and VO₂max tended to be lower than the correlation coefficient (r=−0.61) between the time taken to complete TUGT and 6MWT distance. The CPET is a maximal exercise test involving gradually increasing speed and incline on a treadmill (9), while 6MWT is a submaximal exercise test in which the patient is instructed to walk as far as possible in a set amount of time, which is less intense than CPET (8). TUGT is a simple test that involves getting up from a chair, walking 3 m, and returning (10), which is effectively a submaximal exercise test. Therefore, a stronger association between TUGT and 6MWT than with CPET is physiologically reasonable.

ROC analysis identified a TUGT cutoff of 6.4 s as the threshold for detecting patients with reduced exercise capacity (6MWT <525 m), which has been associated with poorer survival and higher postoperative complication rates after lung cancer surgery (5). This cutoff has important clinical implications, providing a simple and feasible criterion that can be applied in daily practice to identify patients who may benefit from further evaluation or pulmonary rehabilitation, particularly when CPET or 6MWT are not available. Previous studies have reported higher TUGT thresholds in other populations, such as ≥10 s for predicting postoperative complications in patients with COPD or for identifying fall risk in older adults (14,17), and lower 6MWT thresholds of 300–400 m in COPD compared with approximately 500 m in lung cancer patients (5,14,23). In patients with chronic heart failure, longer TUGT thresholds have also been suggested, reflecting the greater degree of functional impairment in that population (15). These comparisons highlight that cutoff values differ across diseases depending on age, comorbidities, and baseline mobility.

The relatively shorter TUGT cutoff observed in our study (6.4 vs. ≥10 s in COPD or older adults) and the higher 6MWT threshold (525 vs. 300–400 m in COPD) reflect the distinct clinical characteristics of lung cancer patients after surgery. Although these patients may have better preserved mobility compared with frail older adults or those with advanced COPD or heart failure, they still face significant functional limitations. To our knowledge, this is the first study to propose a disease-specific TUGT cutoff value for patients after lung cancer surgery, representing an important contribution by providing a practical tool to stratify risk and guide rehabilitation planning in this population.

In the subgroup of patients who completed an 8-week pulmonary rehabilitation, significant improvements were observed across all three assessments, including a shorter TUGT time, longer 6MWT distance, and increased VO₂max. These findings indicate that TUGT, like CPET and 6MWT, is responsive to rehabilitation-induced changes, highlighting its potential as both a screening tool for identifying patients with reduced postoperative exercise capacity and an outcome measure for monitoring functional improvement in clinical practice.

In addition, ROC curve analysis identified a TUGT cutoff of 6.4 s for detecting patients with reduced exercise capacity (6MWT <525 m), a group known to be at higher risk of poor postoperative outcomes. Taken together, these results support TUGT as a simple and practical tool to screen for reduced exercise capacity and to guide rehabilitation strategies when CPET or 6MWT cannot be performed. Adjusted analyses were not performed because of the limited sample size and the exploratory nature of this study.

However, this study has several limitations. The limited sample size made subgroup analyses according to disease stage or sex infeasible. This single-center retrospective design also lacked an external control group, which restricted causal inference. In addition, the analyses of rehabilitation effects were limited to patients who completed the 8-week of rehabilitation, which may have led to an overestimation of the intervention effect due to preferential inclusion of more adherent patients. Finally, this cutoff value may not be directly generalisable beyond our single-center Korean cohort, and validation in larger, more diverse populations is required. Despite these limitations, the study has notable strengths. To our knowledge, it is the first to propose a disease-specific TUGT cutoff value for patients after lung cancer surgery. By demonstrating significant correlations of TUGT with 6MWT and CPET, and by establishing a practical cutoff for identifying high-risk patients, this study highlights the potential of the TUGT as a simple and feasible screening tool in clinical practice.

Conclusions

This study provides novel evidence for a disease-specific cutoff value of TUGT in patients after lung cancer surgery. TUGT demonstrated significant correlations with the 6MWT and CPET, and the identified cutoff provides a practical threshold for detecting patients at risk of reduced postoperative exercise capacity. These findings highlight the potential of TUGT as a simple and feasible screening tool in clinical practice. In addition, TUGT can be easily incorporated into routine postoperative evaluations to identify patients with reduced exercise capacity and to guide early referral for pulmonary rehabilitation. Its simplicity and feasibility make it a valuable tool for enhancing functional assessment and optimizing recovery after lung cancer surgery.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-aw-2036/rc

Data Sharing Statement: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-aw-2036/dss

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-aw-2036/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-aw-2036/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Institutional Review Board of Chungbuk National University Hospital (IRB No. 2023-08-032-001). Informed consent was waived in this retrospective study.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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