Abstract

Background

Cardiorespiratory fitness (CRF) is a prognostic factor regarding long time morbidity and mortality. To assess CRF the well-known gold standard is cardiopulmonary exercise testing (CPET), which is a time consuming and expensive test. Therefore, alternative methods for routine evaluation of CRF are needed for the general population as well as for specific patient groups such as children and young adults with congenital heart disease. The Stair Climbing Test (SCT) is a simple and resource saving test reported in the current literature. This test is used in various settings to assess different health associated risk factors including cardiorespiratory fitness, muscular resilience, therapy effectiveness or pre- and postoperative morbidity and mortality.

Objectives

To summarize the current knowledge on the use and the different protocols of the SCT in the medical context.

Method: An internet-based literature search for research articles on both clinical trials and controlled randomized trials containing the SCT was undertaken.

Results This crossover study design involved acute interventions (control and experimental: 3-sets of 60-seconds of PGLBT). After a 1-month control period, participants exerted moderate pressure (50-70% of maximal force) on the pelvic girdle with the PGLBT, 7-days per week (1-4 sets of 30-seconds) for 4-weeks. The Quebec Back Pain Disability Scale was completed at the start of each testing session. Pre- and post-testing measures for both the acute and chronic segments included sit and reach test, and supine straight leg raise test for range of motion, and neuromuscular efficiency (extent of electromyographic: (EMG) activity to perform an isometric box hold with 2.26 kg, box lifting task (4.5 kg), sit-to-stand-to-sit, and back extension endurance. Pain was assessed during the tasks with a visual analogue scale and pain pressure threshold ergometer.

We used Pub Med and Google Scholar for literature research. A total of 200 articles were included. The SCT is used for multiple purposes on various patient groups. Significant correlations to the results from established clinical tests such as spiroergometry and 6-minute walking test were shown repetitively. However, the SCTs were conducted and evaluated in various, not standardized ways.

ConclusionPGLBT training-induced reductions in pain permitted greater neuromuscular activation and increased range of motion.

The SCT is a simple, cost saving test with promising reliability for the assessment of physical and cardiorespiratory fitness. Due to its easy approach, it can be used for various objectives, such as the general fitness and for specific patients-groups (i.e. children and young adults with congenital heart disease). Unfortunately, the SCT is not universally accepted yet due to the missing standardization. This standardization of the SCT protocol is however required to establish the SCT as a comprehensive test in the medical field.

Keywords: Sta

Abbreviations: CHD congenital heart disease; CPET cardiopulmonary exercise testing; CT clinical trial; CCT controlled clinical trial; HR heart rate; 6MWT 6-minute walking test; RCT randomized controlled trial; SCT stair climbing test; VO2max max. oxygen consumption/uptake

Introduction

Health-associated significance of cardiorespiratory- and physical fitness

During the last decades medicine and health care has significantly changed. Prevention is gaining more and more significance. Today it is generally accepted that cardiorespiratory fitness (CRF) is another important risk factor regarding cardiovascular disease, morbidity and mortality. The higher the level of CRF, the lower the mortality rate. [1] CRF not only reduces the risk of the occurrence of obvious diseases such as cardiovascular disease or comorbidities like high blood pressure and atrial fibrillation but is also playing an increasingly important role in other areas such as cancer prevention. [2,3]

Therefore, current WHO recommendations suggest a physical activity level for different age groups, e.g. for adults, including at least 150-300 minutes moderate-intensity aerobic physical activity or alternatively at least 75-150 minutes of vigorous-intensity aerobic physical activity per week. Physical activity is defined as any movement, that increases the resting metabolic rate. Nevertheless, a lot of people do not meet these recommendations. Especially in adolescents the recommendations are not fulfilled.[4]

This is of raising concern since the cornerstones of a healthy, active lifestyle are placed in early childhood. Furthermore, this is even more important in people with congenital diseases, for instance children and adolescents with congenital heart disease. [5] As the consequences of a sedentary lifestyle such as metabolic syndrome, diabetes mellitus, cardiovascular disease and others might reduce quality of life severely in these patient groups and increase overall health care costs, it is important to assess and evaluate cardiorespiratory fitness levels more often, preferentially as a routine check-up.

Cardiorespiratory fitness defines the ability of the lungs and the cardiovascular system to supply the skeletal musculature with oxygen during physical activity.If measured and interpreted accurately, the level of an individual´s CRF can play an important role in the serious decision-making process for prevention and treatment plans. It could even be the decisive factor to evaluate whether the patient receives curative or palliative therapy. [6,7] Physical fitness defines the performance of the lungs, heart and skeletal muscles, therefore physical fitness testing actually includes the whole body and evaluates not only cardiorespiratory fitness but also, for example psychoneurological- or skeletomuscular function and mobility. [8]

Established tests for the evaluation of cardiorespiratory- and functional exercise capacity in the medical context

Currently, the clinical gold standard for evaluating cardiorespiratory fitness is cardiopulmonary exercise testing (CPET). [6,7] CPET evaluates the body’s overall response to physical exertion and therefore incorporates several organ systems. [9] In the standard usage, CPET is used as a maximum exercise test, it involves progressively increasing exercise intensity until reaching exhaustion or encountering symptoms or signs that impose limits. [10] Bicycle ergometer and treadmill are usually used for the physical exercise. [11]

While previously used clinical fitness tests such as bicycle ergometry simply recorded vital parameters including pulse, blood pressure and oxygen saturation, CPET adds a ventilatory expired gas analysis to these values. [7] By measuring the peak oxygen uptake (VO2), CPET accurately identifies the highest exercise capacity of the person examined. [21] Nevertheless, CPET currently is not used in routine check-ups, as it is a costly and time-consuming examination, which requires special equipment and trained health care professionals. It is not universally available and often limited to special institutions.

The other commonly utilized test for evaluation of the functional exercise capacity is the 6-min walk test (6MWT). [13] For the 6MWT the patient is tasked with walking (along a 30-meter route) for 6 minutes, aiming to cover the maximum distance achievable. The key metric assessed is the 6-minute walk distance (6MWD), measured in meters. [13] Three major advantages of the 6-minute walk test are that it is easy to perform, that patients usually tolerate it well and that it is inexpensive. [14] Particularly the ease with which the 6MWT can be performed and the good tolerance of patients makes it suitable for patient groups with limited fitness such as patients with heart failure. [14] Nevertheless, it must be considered, that the 6MWT is a submaximal exercise test for most patients. Only in patients with a significantly reduced CRF it can be used as a maximum exercise test.

Currently there is no cheap, universally available maximum exercise test to assess cardiorespiratory fitness. With the gaining importance of the cardiorespiratory fitness level regarding preventive and therapeutic approaches, a lot of working groups investigate alternative approaches such as the Stair-Climbing-Test (SCT)./p>

The SCT is used in various approaches and can give a lot of information about an individual’s general fitness, as well as its CRF and its motor function. Depending on its approach it also can differentiate between a loss in strength and a lack of coordination as well as whether there is a respiratory or cardiological restriction.

The aim of this review is to give an overview and compare the different SCT approaches used so far.

Materials and Methods

Search strategy

We conducted an internet-based literature search. For this purpose, we primarily used Pub Med as well as Google Scholar and the Cochrane Library to cross check. The search terms “stair climbing test OR stair-climbing test” was used on Pub Med to find original research articles on the topic. (The search was last conducted on January 03rd 2024) A total of 973 articles matched our initial searching criteria.

Inclusion Criteria

Randomized controlled trials, clinical trials and pilot studies, available as full text in English language that used the SCT in any form and described its use and implementation were included. Our literature search was not restricted to an age group.

Exclusion Criteria

We excluded articles that were not relevant to our research question, review articles, meta-analysis and articles that were only available as abstracts. Studies that used the SCT but did not describe the exact application and design were also eliminated.

Data Extraction

Of the 973 articles that matched our initial inclusion criteria on Pub Med, 319 mentioned the SCT and were accessible as full text. Ultimately, 200 of them matched our final inclusion criteria and were therefore included in our review. The others were discarded because they either mentioned the SCT but did not describe its implementation in more detail, or they were not original texts, or because they were not thematically relevant to our research question.

Results

In the Pub Med search a total of 200 articles matched the final searching criteria, described the usage of the stair climbing test and were therefore included in this review. In these 200 trials the SCT was used with different intentions and for the evaluation of various body functions. They were performed between 1986 and 2023. The most frequently investigated parameter during SCT was physical and neuromuscular function. (table 1) Cardiorespiratory fitness and exercise tolerance was evaluated in a smaller number of trials (table 2). Some studies evaluated additional effects such as blood sugar, the ability of complex thinking and others (table 3).

Moreover, the SCT was performed in various ways. In some trials the test was conducted with 10 steps or more. Most studies evaluated the ascending as well as the descending, others either or. The measured parameters differed a lot as well. With a total of 122 studies, the majority used the time needed to complete the SCT as the only recorded result, the total distance however varied. In only a few trials, other parameters were collected, including vital signs or the number of steps climbed. Several studies calculated the so-called stair-climbing power or VO2max of the collected values.

Some trials even showed, that the SCT can be a part of physiotherapy. Khan et al. for instance integrated stair climbing with and without audio feedback into the physiotherapy of 17 children with different diagnoses and then investigated whether the use of audio feedback made a difference to the outcome during SCT. [15] Overall, there is no standardization of the SCT and therefore its clinical use is not clearly recorded. The SCT has been used in completely different ways to evaluate different body functions. The implementation varied in the number of steps that patients had to climb, the parameters collected, the questions to be answered with the SCT, permitted aids during the test and the information that patients received before the test. All these aspects varied significantly and were not standardized.

Outcome

Physical and neuromuscular function (and mobility)

Physical function is one of the commonly examined parameters when using the SCT. 155 of the included studies used the SCT to evaluate physical function of participants or patients. (table1)

a) Patients with orthopedic- or muscular conditions

The examined participants often had an orthopedic intervention and were in various stages of rehabilitation. Heiberg et al. for instance evaluated the effect of a walking skill training program in 68 patients who had undergone a total hip arthroplasty and used the SCT for measuring physical function 3 months post operation. [16] Other working groups also used a form of SCT to evaluate physical or motor function in patients with knee or hip arthroplasty, either to compare capacity before and after surgery, others to evaluate a special treatment. [17-51] Judd et al. compared patients with knee and hip replacement. They showed that functional performance and muscle strength recovery differ after total knee and total hip replacement. [52]

Another patient group in which a form of the SCT was applied repetitively are patients with knee or hip osteoarthritis. The SCT in these patients was also used to evaluate different treatment approaches for instance Kovacs et al. evaluated the effect of thermal water in patients with osteoarthritis. [53] Kraemer et al. examined the effect of a treatment combination in patients with osteoarthritis [54], whereas Laufer et al. assessed the effect of pulsed short-wave diathermy on pain and function of subjects with osteoarthritis of the knee.[55] Other studies also used the SCT in patients with osteoarthritis to evaluate physical or motor function. [27-56]

Other orthopedic patients were also analyzed using a SCT. For example, Beckman et al. assessed physical function in patients after hip fracture. [81] Moreover Adunsky et al. evaluated MK-0677 (ibutamoren mesylate) for the treatment of patients recovering from hip fracture with a SCT. [82] Ljungquist et al. evaluated physical performance in patients with spinal pain. [83] Smeets et al. used the SCT to test physical capacity tasks in chronic low back pain patients. [84,85] assessed physical function in patients with rheumatoid arthritis and ankylosing spondylitis. [86] Wetzel et al. used the SCT to examine functional lower-extremity strength power in patients with multiple sclerosis. [87] Nunes et al. assessed people with patellofemoral pain regarding their functional performance, in correlation to hip muscle capacity. [88] Alfano et al. used the SCT to evaluate the correlation of knee strength to functional outcomes in Becker muscular dystrophy. [89] Collado- Matteo et al. used the SCT to assess the performance of women with fibromyalgia. [90] Schwid et al. assessed the effect of sustained release of 4=aminopyridine on motor function as a symptomatic treatment of multiple sclerosis. [91] Suslov et al. evaluated the efficacy and safety of hydrokinesitherapy in patients with dystrophinopathy. [92]

b) Follow-up after Cerebrovascular accidents

Apart from orthopedic and surgical patients the SCT was also used to evaluate physical and motoric function in neuromuscular patients as for instance patients after stroke. Katz-Leurer et al. examined neurological patients with cerebrovascular accident, using a SCT. [93] used the SCT in patients after stroke to assess physical function, Mustafaoglu et al. assessed the effects of body weight-supported treadmill training on static and dynamic balance in stroke patients. [94,95] In another study they also evaluated the mobility of stroke patients using a SCT. [96] Ahmed Burq et al. assessed the effect of whole-body vibration on obstacle clearance and stair negotiation time in chronic stroke patients. [97] evaluated a multimodal prevention program after transient ischemic attack or minor stroke. [98] Other working groups also used the SCT to investigate patients after stroke for instance the effect on physical performance of strength- or other training approaches. [99-102] Van de Port et al. examined the effect of circuit training compared with usual physiotherapy in 126 patients with stroke. The SCT combined with a stand-up and go test was utilized to evaluate functional mobility. [103]/p>

Furthermore, the SCT was also used to examine children with cerebral palsy (CP). Zaino et al. used a timed SCT to assess 47 children aged 8-14 years, 27 of them with CP. [104] Bar-Haim et al. also assessed children with CP with the SCT. [105]

c) Obesity and weight reduction

Apart from the approaches mentioned above, the SCT was also used repeatedly to assess obese individuals, for example after weight reduction. Sartorio et al. assessed the effect after a short-term body mass reduction program in obese subjects on their motor function. [106] had a similar approach and assessed the effect of exercise training in obese women. [107] evaluated the changes in the Oswestry Disability Index after a 3-week in-patient multidisciplinary body weight reduction program in adults with obesity. [108] Bittel et al. assessed physical function in obese adults with type 2 diabetes mellitus and peripheral neuropathy, using a SCT. [109] Maffiuletti et al. examined the reproducibility of clinician-friendly physical performance measures in individuals with obesity using a SCT. [110] Sousa-Goncalves et al. evaluated the acute effects of whole-body vibration alone or in combination with maximal voluntary contractions on cardiorespiratory, musculoskeletal, and neuromotor fitness in obese male adolescents. [111]

Tamini et al. evaluated the acute effects of whole-body vibration exercises at 2 different frequencies versus an aerobic exercise on some cardiovascular, neuromotor and musculoskeletal parameters in adult patients with obesity. [112] Rigamonti et al. assessed the impact of a three-week in-hospital multidisciplinary body weight reduction program on body composition, muscle performance and fatigue in a pediatric obese population with or without metabolic syndrome. A SCT was used to assess the effect on maximal anaerobic power. The protocol covered a staircase with a total height of 1,99m. The SCT could detect effects of the program. They could show a significant reduction in SCT-time in all groups. Whereas patients with metabolic syndrome profited even more than obese individuals without metabolic syndrome. Younger individuals also profited more than older ones. [113] Lazzer et al. also examined the effect of a 3-week inpatient bodyweight reduction program in obese individuals. The SCT was used to evaluate maximum anaerobic exercise capacity. The protocol also covered a total height of 1,99m. They could show that baseline SCT-time was significantly lower in males, compared to females. After the 3-weeks SCT time decreased significantly solely in females. [114] Usubini et al. used the SCT to assess maximum anaerobic power in obese patients before and after a 3-week multidisciplinary weight reduction program. The SCT protocol used, covered a total height of 1,99m. The test was performed at the fastest possible time and power was calculated according to the following formula: (bodyweight × 9:81 × 1.99) /SCT time. They could show a significant reduction in SCT time after the program. [115]

d) Endocrine factors

With gaining interest, the SCT was also used to evaluate the effect of testosterone or androgens on physical function. Knapp et al. examined the effects of a supraphysiological dose of testosterone on physical function, muscle performance, mood, and fatigue in men with HIV-associated weight loss. [116] Nilsen et al. evaluated the effects of strength training on body composition, physical functioning, and quality of life in prostate cancer patients during androgen deprivation therapy. [117] Storer et al. assessed the effects of testosterone supplementation for 3 years on muscle perperformance and physical function in older men. [118] Gagliano-Juca et al. showed that testosterone does not affect agrin cleavage in mobility-limited older men despite improvement in physical function, using a SCT. [119] assessed the effect of testosterone on physical function, using a SCT. [120,121] used the SCT in patients with prostate cancer to assess the effect of exercise on treatment side effects. [122] evaluated the impairment of anaerobic capacity in adults with growth hormone deficiency. [123]

e) Age and the elderly

Another approach for the SCT was to use it so assess mobility and physical function in otherweise healthy elderly. [118,124,153]. for example investigated the efficacy of whey protein supplementation in 80 mobility-limited older adults, using the SCT among other tests to evaluate physical function. [153] Daly et al. examined the effects of a multinutrient-fortified milk drink combined with exercise on functional performance, muscle strength etc. in middle-aged women. [154] assessed the reliability of a SCT to assess physical function and coordination in children aged 2-3. [155]

f) Patients of internal medicine and general surgery

Lanzi et al. examined functional performance during a 3-month supervised exercise training program in patients with symptomatic peripheral artery disease, using a SCT. [156] used the SCT in patients with hemodialysis to assess the effect of an exercise training on physical function [157-159] Dreher et al. used the SCT in patients with COPD. [160] Reddy et al. used a SCT to predict perioperative complications in patients undergoing abdominal surgery.[161]

g) Healthy adults

Apart from being used in special patient groups, the SCT is also used to assess therapy effects and health preventive approaches in healthy adults. Basaria et al. evaluated the safety, pharmacokinetics, and effects of LGD-4033, a novel nonsteroidal oral, selective androgen receptor modulator, in healthy young men. [162] also examined healthy adults with a SCT regarding musculoskeletal symptoms. [163,164] evaluated the effects of lower extremity strengthening delivered in the workplace on physical function and work-related outcomes among desk-based workers. [165]

Cardiorespiratory fitness / exercise capacity

Cardiorespiratory fitness and exercise tolerance are the second most important function assessed with the SCT. 37 of the included trials examined cardiorespiratory fitness (table 2); It could be outlined that the results in SCT showed a significant correlation to CPET-parameters, maximum heart and respiratory rate e.g. Pollok et al. [166] The participants in the trials, evaluating CRF and exercise capacity, were also orthopedic patients, patients before/ after lung transplantation and patients with chronic lung diseases for instance chronic airflow obstruction. For example, Elbasan et al. examined children with cystic fibrosis. [167] Moreover, there were several studies in healthy adults, for instance sedentary young women, or obese females. [168,169] Sartorio et al. examined obese children and adolescents. [170] Devendra et al. examined adults with newly diagnoses persistent foramen ovale with a SCT to assess deoxygenation. [171] Hetzler et al. used a SCT in American football athletes.[172]

a) Pulmonary patient groups

Mc Keon et al. evaluated the effect of inspiratory resistive training on patients with severe chronic airflow limitation. To assess exercise endurance, they used the SCT in addition to other exercise tests to determine the influence of the specific training on different types of exercise. The SCT did not follow a predefined protocol. The number of stairs completed by the patient at a normal rate under the supervision of a physiotherapist were recorded without a time limit and the test ended when symptoms of breathlessness or weakness occurred. [173]

Pollock et al. investigated if a SCT can be used to estimate VO- 2max in patients with chronic airway obstruction (CAO). The SCT was conducted as a symptom limited SCT with a maximum of 10 flights, most patients achieved at least 4 flights=13,3m height. The test was conducted twice. A resting gas sample and a gas sample during exercise was collected. VO2, CO2 output, minute ventilation (VE), and tidal volume were calibrated using standard techniques. The subject’s blood pressure, pulse, and respiratory rate were measured at rest and immediately after the test. Saturation and heart rate was measured throughout the test. The results in CPET were compared to those achieved in bicycle CPET. The number of steps climbed, correlated well with peak VO2. They could show a linear correlation between peak VO2 for stair climbing and cycle ergometry. Whereas VO2max, HR, RR, BP were higher during SCT as in CPET. According to their results, the study shows that 1-2 flights of stairs is not exhausting enough. Nevertheless, considering this, the study implies that the SCT can be used to estimate VO2max. [166] Elbasan et al. assessed the effects of chest physiotherapy and aerobic exercise training on physical fitness in children with cystic fibrosis. 16 patients between 5-13 years were examined. All children were assessed at the beginning and the end of a 6-week training. A 10-step SCT was conducted, as well as bicycle CPET. They could detect a positive effect on anaerobic power and speed, which was reflected in the results of SCT and CPET. [167]

b) Lung resection

Pate et al. assessed patients with non-small lung cancer. In this patient group it is stated to be often difficult to decide whether a surgical resection is possible or not, especially in cases with coexisting chronic airway obstruction or ischemic heart disease. They used a symptom limited protocol for SCT. A stair climb of 3 flights or more was associated with reduced postoperative morbidity and therefore a proof for lobectomy, or 5 flights or more for pneumonectomy. The flight height was not standardized. [174]

The working group Brunelli et al. conducted several studies, using a SCT to assess cardiopulmonary fitness/aerobic capacity and oxygen consumption preoperative in patients considered for surgical lung resection. After a cardiovascular evaluation and a spirometry with assessed carbon monoxide diffusion capacity, a predicted postoperative lung function was calculated. Values below 60% indicated further testing. Therefore, a SCT or 6MWT was used. The SCT protocol covered a total of 16 flights, patients were asked to climb at a pace of their choice and stop for exhaustion or symptoms like dyspnea. An achieved altitude >12m was considered satisfying and surgery was offered. Operative morbidity and mortality using this SCT cut-off values were comparable to the data collected with full CPET. They showed a significant correlation between VO2max and the climbed altitude. In patients with a predicted postoperative function <30%, CPET was indicated. In another study of this working group, they even stated that a reached altitude of >12m was the only predictor of cardiopulmonary complications. Patients, unable to climb 12m, had a 2.5 to 13fold higher risk for cardiopulmonary complications and mortality, compared to those climbing >22m. An achieved altitude of >18m was significantly correlated with long-term survival. This working group also calculated stair climbing work, VO2max, oxygen- pulse, using the following formula:

Work = (height of the step-in meters x steps per minute x body weight in kilograms x 0.1635). VO2 max in milliters per minute = (5.8 x body weight in kilograms + 151 + 10.1 x work). Maximum oxygen pulse = (VO2 max/maximum heart rate). [175-182]

Koegelenberg et al. performed another preoperative study in patients with considered lung resection. The used symptom limited SCT protocol in this study covered a total of 20 m vertical height. Patients were asked to climb as fast as possible. The altitude reached and the average speed was compared to VO2max during bicycle CPET. They could show that the average climbing speed was an accurate semiquantitative predictor of VO2max/kg. [183] Pancieri et al. used a SCT protocol, covering a total height of 12,16m to examine patients before and after lung resection. As they did before in their working group with Cataneo et al. 40 patients were included. The time needed to complete the stair climb was recorded and the number of functioning lung segments planned for resection, used to predict postoperative test results. The aim was to find an easy exercise test to predict if the patient could tolerate the surgery. [184,185]

Bernasconi et al. compared SCT to treadmill CPET to define cut-off values for lung resection. 56 patients were examined. The SCT protocol included a maximum height of 20m. A portable spirometry was used. The patients reached a mean altitude of 16,9m. 22 patients did not reach 20m. VO2max differed not significantly between SCT and treadmill CPET. Speed of climbing was significantly associated with VO2 max. The group stated that patients climbing 20m with a speed of 15 m/min, are eligible for surgery. [186] Refai et al. investigated the max. inspiratory and exspiratory pressure generated in the mouth before and after SCT in 283 patients before lobe- or pneumectomy. 61% of the patients experienced a reduction in PImax. It showed that a precticted loss of >10% was associated with complications. [187] Ito et al. retrospectively analyzed data of 65 old people with non-small cell lung cancer and lobectomy. They used a SCT protocol, covering a total of 18m, 5 flights. They could show that patients without desaturation >4% were eligible for lobectomy. [188]

Kubori et al. compared a SCT with the 6MWT in patients before and after lung resection. The SCT was more sensitive than the 6MWT to detect changes in CRF. The used SCT protocol covered a symptom limited SCT with a maximum of 36 flights. The patients reached a mean altitude of 26.3m before and 18.2 meters 4 weeks after lung resection. The difference in the distance reached in the 6MWT before and after resection was not significant. [189] Nakamura et al. also evaluated patients before and after lung resection, using a SCT. They evaluated if a desaturation of 4% during the SCT could predict complications after lung resection. The symptom limited SCT protocol covered 6 flights with a total height of 22.2m. They could show that patients who underwent the SCT without desaturation had a normal risk for postoperative complications, whereas patients with a desaturation had a higher rate of complications. [190]

Ozeki et al. also evaluated patients with stage I lung cancer before and after lung resection with a SCT to predict whether postoperative exercise capacity will probably be severely reduced or not. The used symptom limited SCT protocol included a total height of 12m. The test was performed at the fastest possible time. Estimated VO2max was calculated, according to Cataneo et al. Patients with complications needed a significant longer time in SCT preoperative. In patients with complications the postoperative exercise capacity was reduced by 4%. [185,191] Dong et al. showed that a SCT could predict postoperative complications in patients with non-small lung cancer. They used a SCT-protocol, covering a maximum height of 18,4m. Desaturation in patients was associated with prognosis. [192]

c) Cardiological and other patient groups of internal medicine

Devendra et al. used a SCT to provoke exercise oxygen desaturation in patients with a persistent foramen ovale. 50 patients were examined. The protocol included climbing and descending 4 flights of stairs. During this procedure oxygen saturation was measured. Provoked exercise desaturation (PED) was defined as a desaturation of at least 8% and a saturation <90%. 17patients had a PED. 13 of them underwent PFO-disclosure. 10 were followed up. The desaturation improved after closure by a mean of 10%. [171]

Njoeten et al. assessed patients with long Covid. They used a SCT protocol, covering 18 steps, which had to be climbed 3 times up and down as fast as possible. Patients with a normal exercise capacity in CPET were significantly faster as those with reduced exercise capacity. [193] Hellberg et al. showed that a decline in glomerular filtration rate is associated with a reduced endurance, strength and other symptoms. Endureance was assessed, using a SCT. The SCT covered a total of 12 flights. [194]

d) Patients requiring general surgery

Servio et al. used the SCT to investigate CRF in patients before and after laparoscoptic Nissen-fundiplicatio. The working group used the SCT protocol of Cataneo et al. It covered a total height of 12,24m, which had to be climbed as fast as possible. Time was recorded and power calculated. Several measurements on different times were collected. They could show that the patients regained their preoperative results shortly (at the 5th postoperative day) after operation. [195] Arruda et al. assessed cardiopulmonary postoperative complications in comparison between upper abdominal and thoracic surgery, using a SCT. [196] Khenaifes et al. evaluated CRF in patients before and after cholecystectomy, using a SCT. For the SCT a protocol according to Cataneo et al. was used. A total height of 12,24 meters was covered. They could show a rapid recovery of CRF after surgery. [197]

Cataneo et al. used a standardized protocol in their studies to establish a submaximal exercise test in hospital settings where CPET is not available, to evaluate if the cardiorespiratory system of an individual has the capacity to undergo surgery. They used a SCT protocol, covering 6 flights (12,16m), measured time and calculated the individuals work to climb the stairs. To calculate the work needed to climb the stairs, the body mass, the covered height and gravity was multiplied. The calculated work was divided by the time needed to climb, to get the stair climbing power in Watt. The results were compared to VO2max during CPET. They could show a significant correlation between VO2max and SCT as well as SCT power. As a conclusion they stated that the SCT is a simple cost effective and widely available test to assess an individual’s cardiorespiratory capacity, as patients with an impaired cardiac or pulmonary function have difficulty climbing stairs. The working group stated that a SCT should cover a height of at least 12m to get convincing results. [185,198]

e) Normal-weight and overweight healthy study participants

Coll et al. used a modified Chester step test in healthy adults. They used a 20cm step, which had to be stepped on and off on a standardized cadence, which was increased every 2 min. The test was stopped, either symptom limited, or when the individuals reached a heart rate equal to 80% of their maximum HR (220-age). A modification was added in individuals, who reached a cadence of 35 steps/min without reaching any of the mentioned criteria. They were handed 2kg dumbbells. The test was performed twice, and the results were almost equal in both rounds. They found the SCT a reliable test to assess aerobic capacity. [199]

Hetzler et al. developed a football stair climb protocol, including 20 steps with a total height of 3,12m. As football is described as a highly explosive sport, the group was looking for a test to assess peak anaerobic power. 58 football players were included. They performed 25 trials with 30-40sec rest in between. Time was recorded and power calculated. Power was calculated according to the following formula: Power = body mass (kg) x 9.81 ms-2 x vertical distance x time-1. The players were divided in 3 groups, according to their position in the game. The skill-group was significantly less powerful. They could show that the test is reliable for measuring peak anaerobic power. To assess the reliability of the test 34 football players repeated the test within a week. [172]

Calavalle et al. used the SCT as a simple method to analyze overall individual physical fitness in firefighters.[200] Boreham et al. performed a „training program” including stair-climbing in a group of sedentary female students. The effect of this program on CRF was assessed, using a SCT before and after the program. During a 135sec SCT VO2 and HR was measured with a portable spirometry. After the program a reduction in VO2 and HR was measured, which suggested a cardiovascular health benefit. [168] The working group Lafortuna and Sartorio et al. examined obese individuals with a SCT. In their first study they assessed the anaerobic power output in adult obese individuals (BMI 30-60kg/m2). A modification of the Margaria stair climbing test, covering a flight with 13 steps was used. The individuals were asked to climb at their highest speed possible. With the collected data, they calculated the average mechanical power output: W= (Mb x g x h)/t (Mb=body mass, g=gravity, h=vertical height, t=- time). They showed a significant correlation between mechanical power output and BMI. A higher BMI was associated with a higher mechanical power output. The power output also correlated significantly with the amount of fat free mass, whereas men had a higher amount of fat free mass. With aging the fat free mass decreases in both genders. In their second study the group used the same SCT. In this population of obese women, not all were able to perform the test. In this study a <40 BMI had a significant effect on power output, values >40 had not. In the third study severly obese children and adolescents were examined with the same protocol as the obese adults before. They also showed a significant correlation between power output and fat free body mass. Up to the age of 13 they could not detect a significant difference between boys and girls. Due to age a significant increase in power output could be shown. From the age of 13 boys further gained power output, whereas girls started to build a plateau. [106,169,170] Oesch et al. examined patients with lower back pain. They used a SCT protocol, covering 100 steps. [201]

other parameters

Apart from the approaches mentioned above, there are a few trials, which investigated the effect of stair climbing regarding blood sugar [202-205], or cognitive function. [206] Another working group investigated the effect of a musical prompt on the pace of stair climbing. [15] Poppius et al. used a SCT to simulate exercise and evaluated whether doxantrazole can prevent exercise- induced asthma. [207] Aveline et al. assessed pain and recovery after knee arthroplasty. [208]

SCT-protocols and implementations

In most trials the test was conducted with 10 steps or more. Almost all studies evaluated the ascending as well as the descending. Other studies focused solely on ascending, as for example Lee et al. who used the SCT for evaluating the walking ability of stroke patients. [94] Step height was mentioned in the majority of the included trials (table 1-3). The used stairs varied in step height between 7,8 and 20 cm. (table 1-3) Some of the studies specified the total amount of steps to be covered and thus the total vertical height. A trial by Novoa et al. showed an adequate exertion level from 12 meters and more, comparable to an unlimited approach. [209] Several studies used a variation of the Margaria-SCT protocol, covering a total vertical height of 1,99m. [210] Other groups orientated towards the protocol used by Cataneo et al., covering a total vertical height of 12m. [185] Various trials used one staircase repetitively and instructed their patients to climb up and down for a certain amount of time. (table 1-3) This approach was for instance used by Smeets et al., who investigated the physical capacity of patients with lower back pain. [84]

measured SCT performance parameters

With a total of 122, most of the included trials used the total time needed to complete the SCT as the only measured parameter. 15 other trials counted the number of steps completed in a fixed time. Some trials calculated the cadence.

Other parameters collected included vital signs, the number of steps climbed and the so-called stair-climbing power (table 1-3). Capturing stair-climbing power was mentioned in 41 articles. To calculate the stair-climbing power, the height climbed, the body weight, the acceleration of gravity and the time required to complete the SCT were used in most of the cases. (table 1-3) The Cadence of stair-climbing was assessed in 6 trials. Predicted VO- 2max was calculated in 7 studies.

Discussion

Participants

This overview shows how broadly the SCT can be used. Varying from age 2 to the elderly, healthy or ill. However, in most of these studies, the focus was solely set on the achieved time during SCT, or the number of steps climbed. Therefore, a lot of significant information was not collected. Even if the maximum oxygen collection during SCT may not always be directly the same as in CPET, a lot of trials could show a significant correlation, depending on the protocol that was used to perform the SCT.

Nevertheless, the information that can be gathered while preforming an SCT are often not used detailed enough.

While almost all the included studies used time as the main recorded parameter, vital signs were not gathered in all trials, although this should be possible in significantly more studies and could provide important additional information regarding the physical condition of the participants without major effort. A lot of important information seems to unremarkably fade away. For instance, a direct comparison of parameters gathered with CPET would be interesting. Brunelli et al. even showed that it is possible to obtain conclusive VO2-peak values during SCT with a portable gas analyzer. They were also able to demonstrate that there is a correlation between the altitude climbed and the VO2-peak recorded, which could also be interesting in terms of using the SCT as a maximal exercise test, for example. [182]

Moreover, it must be mentioned that the design and evaluation of the SCT differs a lot in between the trials. A guiding thread lacks, even as a basic protocol. For example, the number of steps ranges from a minimum of 1 step [199] to an unlimited number or not even a detailed description. Some used 1 flight repetitively, others used an unlimited staircase. The total height was not always entitled. Some used a given time frame and assessed the number of steps climbed, others used an unlimited time, and subjects were asked to climb until reaching fatigue, others used a given staircase or number of steps/flights and assessed the time needed to complete. There is also a wide variation regarding the instruction, some trials allowed the use of a handrail or other walking aids.

The given instructions concerning the use of aids can of course influence the test results. For instance, if mobility is examined with the SCT and the participants are for example stroke patients with gait instability, as conducted by Mustafaoglu et al. [96] it obviously makes a difference whether the participants are allowed to use walking aids or not. Another example is the use of a handrail if leg strength is investigated and, in some studies, e.g. Daly et al. the participants are allowed to support themselves with the handrail, while in others they are not, which again could lead to different results. [154]

The different numbers of steps used seem to be due to the different research questions and patient groups. For example, Pate et al. used a staircase with 21 steps per flight and unlimited steps taken to evaluate the cardiorespiratory fitness of their patients. [174] They wanted to use the SCT as a maximal exercise test. Whereas in trials, using only a few steps, as is the trials of Bruun- Olsen et al. who evaluated physical function and mobility in patients during early rehabilitation after knee arthroplasty [212], the SCT was used as a submaximal exercise test for most individuals. This difference is also obvious in the different trials, focusing on anaerobic capacity and therefore using the Margaria protocol [210], which only covers 1,99m vertical height in comparison to the trials, focusing on aerobic fitness and aiming on maximum exertion, using the protocol of Cataneo et al. [185]

Furthermore, it is interesting to note that among the studies included, only a limited number have attempted to standardize the SCT or build upon previously collected data. One notable approach within this context is the utilization of stair-climbing power, as described earlier. This is for instance used by Storer et al. and Harmer et al.[21,115,118,170,185,195,197,215] It is an important beneficial information gain, as some trials which for example used the SCT to determine the cardiorespiratory fitness of their patients [174] could show a significantly correlation to VO2max in CPET, as it has been shown in studies before. [185] Considering this correlation, especially SCT power, defined as body weight x total vertical height divided by SCT time could be a crucial information regarding the CRF assessment with a simple SCT and vice versa a huge lack of information when not gathered while performing SCT.

Almost all the included studies recorded the time required to complete the test whereas only a few recorded other parameters such as vital signs or even blood lactate. (table 1-3) In general, there seems to be a lot of potential in performing a SCT. Nevertheless, the approaches should be focused on a standardized protocol to gather as much information as possible with this simple test. One possible limitation of the SCT is that the patients may need to be accompanied by staff. This could be necessary for safety reasons, as mentioned for instance by Kraemer ete al. [54] but also, for example, to collect additional data during the test. This may make the SCT more staff-intensive. However, compared to other tests such as CPET, it would still probably require less know-how, equipment and preparation time and is therefore easier to include in less time-consuming examinations.

Limitations

This review has limitations. There is only a limited number of trials, using a SCT. The reviewed studies also have limitations, such as small sample sizes, varying levels of evidence, and different approaches regarding protocols and recorded results. Moreover, the search was conducted by only two researchers; therefore, the false exclusion of articles cannot be fully dismissed. Nevertheless, the methods and results were approved by the other researchers.

Conclusion

The significance of CRF as a prognostic indicator for long-term health outcomes cannot be overstated. Despite its pivotal role, a thorough assessment of CRF is not yet part of routine medical evaluations. While established methods like CPET provide comprehensive insights into CRF, their extensive resource requirements limit their widespread application in routine check-ups.

The SCT presents a promising alternative due to its simplicity and resource-efficiency as well as its wide applicability during age groups. However, the diverse unstandardized protocols and the wide distributed applications across various studies underscore the need for standardization in its implementation. With the significant correlations shown between SCT results and established clinical tests, such as spirometry and the 6-minute walking test, the SCT holds potential for assessing CRF and functional exercise capacity in diverse patient groups. However, it would again be necessary to obtain comparative data, for example from healthy test subjects, in order to be able to use this test also in patients and even pediatric patients.

Establishing standardized SCT protocols could pave the way for its integration into routine medical assessments, benefiting both general populations and specific patient cohorts, particularly children and young adults with congenital diseases such as congenital heart disease. Nonetheless, further research with larger sample sizes and consensus on standardized SCT protocols are imperative to solidify its position as a comprehensive assessment tool within the medical field.

Future Goal – Standardization

Studying all those different trials, we developed a standardized protocol, covering all important points of the previous trials.

We aimed for an easy exercise test, which can be used as submaximal and/or maximum test as a supplement to CPET. Our protocol therefore covered 4 flights with a total vertical height of 13,14m. As previous trials showed that a total of at least 12meters vertical height was needed to achieve maximum exertion. The test should be conducted at an individual’s maximum pace, without the use of a handrail and without taking 2steps or more. At the top of the 4 flights the individual should turn around and climb down the stairs. Vital signs before and after the test should be recorded. The time needed to complete the test was stopped and the SCT power calculated using the following formula: SCT-Index = (body weight × staircase height )/(SCTtime). Moreover, we compared the results in SCT (SCTtime and SCTpower) with the results in 6MWT (distance) and CPET (VO2max(ml/min); VO2max (ml/ min/kg); oxygen pulse). We could show a significant correlation in different study groups as previously described in the studies above.

We assessed the clinical validity of the SCT in healthy adults as well as in obese adults. Furthermore, in healthy children and adolescents as well as children and adolescents with congenital heart disease. Overall, we could show promising results for the clinical use of the SCT with this standardized protocol in both, healthy and ill patients, as long as they are able to climb stairs. The SCT is an easy tool to assess CRF, either as a tool in preventive medicine or in the assessment of clinical treatment or condition control.

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