Introduction

Exercise training is a safe and effective therapy to ameliorate side effects associated with cancer treatment, including reduced fitness and quality of life [1], but has not been universally adopted as part of standard care for cancer in North America [2]. Outside of research studies, there is little capacity for cancer survivors to receive guidance and supervision from fitness professionals with the appropriate training and education in exercise prescription and supervision related to the effects of cancer treatment. Recently, education and certification programs have been developed [3–5] to provide training for exercise and allied health professionals to design individualized exercise program specific to diagnosis, treatment, and recovery status. Following in suit, cancer-specific rehabilitative exercise programs staffed by individuals with these training certifications are beginning to be developed within the community [6, 7].

Assessment of health-related physical fitness is important in rehabilitative exercise programs in order to set goals, appropriately prescribe exercise, and monitor change over time [8]. It has been suggested that physical performance measures may also play a role in objective assessment of patient functional status in clinical oncology practice [9]. To date, there has been very little research on an appropriate, effective, and comprehensive physical fitness assessment among cancer survivors in a community-based setting.

The purpose of this study was to evaluate the utility of a standardized fitness assessment comprised of a comprehensive series of tests of the components of health-related physical fitness in a cancer-specific, community-based rehabilitation program setting. In this study, the utility of each test within this setting was defined as (i) the feasibility and suitability, measured as completion rate of each test during baseline fitness assessments; and (ii) the ability to detect change, measured as change over time following enrollment in a cancer-specific, community-based rehabilitation program.

Methods

Participants and consent

New clients with a prior cancer diagnosis at two cancer-specific, community-based, out-of-pocket expense exercise programs in Vancouver and White Rock, Canada, were invited to participate in this study. All participants provided written informed consent, and the University of British Columbia Clinical Research Ethics Board approved the study.

Procedure

The study authors reviewed the research literature to identify objective tests of the components of health-related physical fitness that most closely met the following criteria: (1) have prognostic value; (2) moderate-to-high reliability and validity (and therefore likely to capture change); (3) have published expected values for comparison; and (4) be feasible (i.e., required relatively little space, equipment, personnel, cost, time to administer) and suitable (i.e., safe and appropriate for cancer survivors of all ages) in a cancer-specific, community-based setting.

The cancer-specific, community-based programs’ standard operating procedures include a baseline assessment for new clients performed by exercise trainers with a cancer-specific exercise certification [3, 10]. The baseline assessment includes collection of demographics, medical history, and assessment of physical fitness. The exercise trainers use the assessment results to develop an individualized 60-min exercise prescription for the client’s needs and goals, generally consisting of 20–30 min of aerobic (50 to 80 % heart rate reserve (HRR)), 15–20 min of resistance, and 5–10 min of flexibility, balance, and core strength exercises delivered in small groups or one-on-one sessions with an exercise trainer. Clients were encouraged to attend two sessions a week, but actual attendance was dependent on the client’s willingness to attend and pay for sessions. The programs offer a re-assessment 3 to 6 months after the baseline assessment, but completion is dependent on client availability, attendance, and willingness to pay for the re-assessment.

For the purposes of this study, both programs adopted the standardized fitness assessment in lieu of their usual fitness measures. The exercise trainers were trained on the standardized test procedures. There was no intervention with the programs’ other standard operating procedures, nor was there a minimum attendance of supervised sessions required for study participants. This was done to ensure that the study reflected real-life use of these out-of-pocket expense programs.

Table 1 summarizes the tests comprising the assessment. Administration of each test was at the discretion of the exercise trainer. There were no pre-specified criteria to exclude participants from completing any of the individual tests.

Table 1 Summary of standardized tests comprising physical fitness assessment
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Body composition: body mass index and waist circumference

The participant removed shoes and extra clothing layers for measurement of weight via digital scale and height via measuring tape [17]. To measure waist circumference, an inelastic tape was placed horizontally at the narrowest portion of the torso, above the umbilicus [8]. The average of two trials was used.

Estimated aerobic fitness: submaximal treadmill test

Resting blood pressure and heart rate were taken after 5 min of quiet, seated rest [11]. A heart rate target (75 % of HRR) at which the test is terminated was calculated: heart rate target = [(207 − 0.7 × age) − resting heart rate] × 0.75 + resting heart rate [18, 19]. The modified Balke or Bruce treadmill test protocols (varied by program site) were used with 3-min stages to allow for achievement of steady state heart rate at each stage [8]. Heart rate was recorded at the end of every minute. The test outcome was recorded as the time to achievement of the target heart rate. An active cool-down (2.0 mph and 0 % grade) was performed for 2 min. The difference between the target heart rate and the heart rate 2 min after target achievement was recorded as the heart rate recovery [20].

Muscular strength: handgrip strength and 30-s chair stand

For the handgrip strength test, a hydraulic handgrip dynamometer (Jamar by Lafayette Instruments, Lafayette, IN; or Baseline Evaluation Instruments by Fabrication Enterprises Inc., White Plains, NY) was held at the side of the body in the standing position. The dynamometer was squeezed with as much force as possible over two trials with a 20-s rest in between. The highest force applied over two trials was recorded.

For the 30-s chair stand, the participant sat on a chair against the wall with a straight back, feet flat on the floor, and hands folded across their chest. On the command “go,” the participant rose to a full stand and returned to the starting position as many times as possible in 30 s [21]. The test outcome was the number of full stands completed.

Flexibility: back scratch test and chair sit-and-reach

To perform the back scratch test, the participant reached their right hand over their right shoulder while standing. Their right palm faced the back with the fingers extended. Their left hand reached behind the back with the palm facing out and fingers extended toward the neck. The participant attempted to touch or overlap the middle fingers of each hand, holding for 2–3 s. The test outcome was the distance measured between (or overlap of) the two middle fingers [22]. The best of two trials per side was recorded.

To perform the chair sit-and-reach, the participant sat on the front edge of a chair with one leg extended, the ankle flexed 90°, and the other leg bent with the foot flat on the floor. The participant bent forward, reaching their overlapped hands toward their toes, holding for 2–3 s without bending the knee [22]. The test outcome was the distance measured from the tip of the middle fingers to the middle of the shoe. The best of two trials per side was recorded.

Mobility and balance: timed up-and-go and single-leg standing

To perform the timed up-and-go, the participant sat on a chair against a wall with hands resting on the knees, feet flat on the floor. On the command, “go,” the participant stood, walked as quickly as possible to and around a cone eight feet away, then returned to the chair to sit down. There was one practice trial, and the test outcome was the time taken to perform the whole task [22].

To perform the single-leg standing test, the participant raised one foot off the ground and attempted to balance for up to a maximum of 30 s. If 30 s were reached with eyes open, the procedures were repeated with eyes closed [16]. Three attempts were given and the longest held time over the three trials for the most difficult test (closed eyes) was the test outcome.

Analysis

The completion rate for each test was calculated as the percentage of times the test was performed in all of the baseline assessments. Change between the initial and re-assessment of each test was assessed by paired t tests for parametric variables and Wilcoxon signed-rank tests for non-parametric variables. Independent t tests were used to compare baseline differences in demographics and fitness test results between those who were re-assessed and those who were not. R 3.0.02 for Linux was used for statistical analysis; significance set at α = 0.05.

Results

Of a possible 281 new clients, 60 (21 %) agreed to participate between May 2011 and January 2014. Participants were primarily female (83 %) and middle-aged (median 58, range 20–78 years) (Table 2).

Table 2 Baseline demographics and cancer diagnosis and treatment characteristics (n = 60)
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The completion rate of tests at the baseline assessment is outlined in Fig. 1. Reasons for non-completion related to the participant’s inability to perform the test were recorded (e.g., orthopedic dysfunction or injury limiting treadmill walking). However, the exercise trainers had to prioritize some tests over others if the available assessment time was running low, and in some cases, the skipped test was based on their perception of low utility of tests (e.g., timed up-and-go not often performed in younger participants). In the cases of the latter two reasons, the trainers did not always record the reason for non-completion of the test. The completion rate reflects all of these reasons, and therefore the overall utility of each test in this population and setting. Resting heart rate was most commonly performed, followed by blood pressure, body mass index, grip strength, and 30-s chair stand (all in ≥88 % of baseline assessments). The submaximal treadmill test, heart rate recovery, and the timed up-and-go were the least commonly completed tests: 67, 63, and 73 % of assessments, respectively.

Fig. 1
figure 1

Completion rate of individual tests in baseline assessment for a cancer-specific, community-based exercise program (n = 60, mixed diagnoses, age range 20–78)

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Thirty-four participants were re-assessed 22 ± 11 weeks after their baseline assessment and had attended an average of 1.1 ± 0.8 (range 0–2.9) supervised sessions/week. The main reasons for non-completion of re-assessment were illness, withdrawal from the program, and participant refusal based on cost or perception of lack of change. The completion rate of tests was similar to the baseline findings (data not shown). Compared to those who completed the re-assessment, at baseline those who were not re-assessed had significantly lower aerobic fitness levels (i.e., less time to heart rate target) (13.8 vs. 11.1 min, p = 0.04) and significantly lower left handgrip strength (28.5 vs. 24.5 kg, p = 0.05), but no differences in demographics, time since diagnosis, cancer stage, or treatment status were observed.

The test results for those who completed both assessments are shown in Table 3. There were no changes in body mass index (p = 0.80), waist circumference (p = 0.68), or resting heart rate (p = 0.84). Systolic and diastolic blood pressure decreased (p = 0.02).

Table 3 Test results for participants who completed the baseline and re-assessments (n = 34)
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Despite a mean increase of 62 s, the change in length of submaximal treadmill test time was not significant (p = 0.17), nor was heart rate recovery (p = 0.35). Significant improvements in strength were captured by handgrip dynamometry and 30-s chair stands (all p < 0.01). Improvements in lower body flexibility using the chair sit-and-reach test were significant and nearly significant for the left and right, respectively (p = 0.03, p = 0.09). There were no changes in upper body flexibility as measured by the back scratch test (left, p = 0.21, right, p = 0.89). No change in balance was shown using the single-leg standing tests (left, p = 0.49, right, p = 0.87). A significant improvement in the timed up-and-go was observed (p < 0.01).

Discussion

Cancer-specific, community-based, exercise programs are needed to increase the opportunities for cancer survivors to receive safe and effective exercise programming outside of a research setting. There is little to no research regarding appropriate, informative, and standardized fitness assessments in this setting. The objective of this study was to test the utility of a standardized fitness assessment within cancer-specific, community-based rehabilitation programs. In developing the standardized assessment, specific tests were chosen based on their anticipated feasibility in this setting, suitability for use in a wide age and function range, and evidence of moderate-to-high reliability and criterion validity. An additional consideration was published expected values, although not available for age 59 and younger for some tests. None of the tests had expected values, reliability, or validity established specifically for cancer populations.

While no change in body composition or resting heart rate was noted, a clinically meaningful decrease in systolic and diastolic resting blood pressure of 7 and 5 mmHg was observed. At the population level, a systolic blood pressure change of 5 mmHg is estimated to reduce all-cause mortality by 7 % [23]. Despite a lack of change in body composition and resting heart rate, inclusion of these measures in a community-based assessment of a clinical population is likely warranted because they were feasible to collect and have established prognostic value [11].

Although maximal exercise testing with open-circuit spirometry is the gold standard for aerobic fitness assessment, a submaximal exercise test is more feasible in a community setting as it does not require expensive gas analysis equipment and, in most cases, requires less medical supervision. There is some error associated with the use of a submaximal test to estimate peak oxygen consumption, yet the reduction in heart rate for a fixed work rate, which results in a longer test time, can be assumed to indicate improved aerobic fitness [8]. One consideration is that this assumption may not hold for cancer survivors who may have autonomic dysfunction as a side effect of cancer treatment, which was not assessed in the current study [24, 25]. Although the change in treadmill time was not statistically significant, the mean improvement was clinically meaningful. A 1-min increase in incremental treadmill test time, as noted in the study, is associated with an 8 % decline in mortality [26]. However, this test was only completed in two thirds of participants. This test can last substantially longer for more fit individuals, which may limit its feasibility in this setting where assessments are restricted to a finite length of time. A shorter incremental treadmill test protocol may increase feasibility by accommodating individuals with higher baseline fitness. Additionally, a cycle ergometer test may also increase feasibility by accommodating individuals with balance or mobility issues. The 6-min walk or incremental shuttle walk tests are alternative options, but were not selected for this study as they were not feasible in this setting due to space restrictions in the program facilities. As well, steady state walking tests may have a ceiling effect in the younger individuals who enroll in these programs.

Handgrip strength and 30-s chair stands were performed in most participants in this study and captured change over time. Furthermore, the change in 30-s chair stand exceeded the minimally clinically important difference, which has been reported as two stands in patients with hip osteoarthritis [27]. The change in grip strength did not meet the minimally clinically important difference, noted as 5–6 kg early after stroke or in healthy women [28, 29]. Other upper body strength tests such as the chest press estimated one repetition maximum may not be appropriate for this population due to surgery restrictions and may not be feasible for the setting due to the equipment required. Handgrip strength is considered a good proxy of overall strength and functioning [30], has a strong established relationship with disability and mortality [30], and has published expected values [13]. Therefore, grip strength may still be the most appropriate test and reliability should be investigated specifically for this population and setting.

Flexibility assessment is important because shoulder range of motion and hamstring flexibility are factors in the ability to perform activities of daily living [8, 31]. There are mixed reports on whether the chair sit-and-reach test can capture changes in flexibility following an exercise intervention, despite high reliability (r = 0.92–0.96) and moderate criterion validity (r = 0.76–0.81) compared to goniometer measurement of hamstring flexibility [32]. In this study, a mean change of 3 cm per side was noted. The chair sit-and-reach test was designed to allow more older adults who may have trouble getting up from the floor version of the test to participate [32], and was performed in 88 % of participants in this study. The back scratch test is a reliable and common proxy for upper body flexibility [33], yet there were no changes, despite most of the baseline tests being below expected values (data not shown). Although these flexibility tests were performed in 88 % of participants, there may be an alternative upper body flexibility test better able to capture change in this population.

The timed up-and-go test has been shown to predict mortality [34]. It is easily performed in elderly individuals [35], but was not performed in 27 % of participants in this study. The individuals who attended the community programs in this study, at a median age of 58 years, were younger than the population for which this test is suggested to work best [35]. The change in timed up-and-go test performance was statistically significant, but the mean change of 0.6 s did not exceed the minimal detectable change of 2.9 s in chronic stroke [36]. Therefore, further research into the suitability of this test in a cancer-specific setting is needed to establish if this test has clinical utility, or is most appropriate for use in cancer survivors aged 65 years and older.

Single-leg standing can predict functional dependence [37] and mortality [38]. This test was performed in 88 % of participants in this study, but it did not capture a change. This finding differs from the change in standing time noted in 7 of 15 randomized controlled trials of supervised exercise in community-dwelling older adults [37]. Although some of these positive trials included yoga, Tai Chi, or intensive balance training in the interventions, others involved programs similar to the one current study participants performed.

Only 57 % of enrolled participants completed re-assessment in this study. Consistent with a study of a community-based program in older adults [12], individuals who completed the re-assessment had higher fitness in some measures at baseline, compared to those who did not complete the re-assessment. This finding has relevance for community programs for two reasons. First, if those individuals with lower levels of baseline fitness are identified to potentially have lower adherence or greater risk of dropout, strategies to boost adherence can be employed. Second, the typical 60-min session could be too difficult for those with lower initial fitness levels, which could contribute to eventual drop-out [11]. Shorter initial sessions or rest segments could be employed in this case to increase adherence. In addition, data on comorbid conditions and previous exercise experience were not collected, and if these factors differed in those with lower levels of baseline fitness, it could help to explain their non-compliance.

The use of private for-profit cancer-specific rehabilitative exercise programs in this study incorporates some methodological limitations for this research study. First, there was no quality assurance over the extent that program staff followed the standardized procedures for each test. Second, due to the appointment-based nature of these programs, if the assessment was taking longer than expected, some components had to be skipped to meet with the next client on time. Third, the out-of-pocket expense of attending the program likely played a factor in completion of the re-assessment and may have resulted in recruitment of individuals with high socioeconomic status. Fourth, a lack of measured change in any test could be due to either the inability of this test to capture change in this population or a lack of effect of the exercise programs on the aspect of physical fitness being measured. As the aim of this study was to determine the utility of specific tests, we did not collect information on the specific goals of each individuals’ program (e.g., improve aerobic fitness, strength, etc.), which likely varied. However, the program staff have received training and certification for designing individualized programs for cancer survivors to target the health-related components of physical fitness that were captured by the standardized fitness assessment. These methodological limitations are a reality of the nature of the community-based programs. However, this approach also provides results that are more generalizable than tightly controlled, laboratory-based research.

In summary, a fitness assessment composed of established tests of health-related physical fitness was assessed for feasibility, suitability, and ability to detect change in fitness within a community-based, cancer-specific rehabilitation setting. A submaximal treadmill test combined with handgrip dynamometry, chair stand, and sit-and-reach tests provided meaningful information on aerobic, strength, and flexibility changes in the cancer-specific, community-based setting. However, a shorter treadmill test protocol or cycle ergometer alternative would likely help to increase the feasibility and suitability of estimated aerobic fitness assessment in this population and setting. Simple body composition and resting cardiovascular measures are easily measured and can provide prognostic value to the assessment. The back scratch, single-leg standing, and timed up-and-go tests failed to capture changes in performance. Further investigation is required to determine if there are tests that are more sensitive to changes in upper body flexibility, balance, and mobility, or whether exercise programs in this setting do not adequately address these aspects.