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Clinical Utility and Validity of Exercise Vital Sign in Children

Young, Julie A. MA, ATC1,2; Hand, Brittany N. PhD, OTR/L2; Onate, James A. PhD, ATC, FNATA2; Valasek, Amy E. MS, MD1,3

Author Information
Current Sports Medicine Reports: January 2022 - Volume 21 - Issue 1 - p 28-33
doi: 10.1249/JSR.0000000000000928
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Abstract

Introduction

School-age children, generally ages 5 to 18 years, should accrue an average of 60 min daily of moderate to vigorous physical activity (MVPA), equating to 420 min on a weekly basis (1). The benefits of physical activity in children cross all domains of health. Physically, exercise improves the strength of muscles and bones, increases coordination, and assists with weight control (2). Socially, physical activity allows for social interaction and a feeling of belonging (3). Mentally, physical activity improves sleep (4), reduces depression and anxiety (5), and also is associated with greater cognitive (6) and academic performance (7). Perhaps, the greatest impact of proper physical activity in children is on their future health. Children who are physically active are more likely to be active adults (8,9), which reduces all-cause mortality, in part by protecting against cardiovascular disease, type 2 diabetes, as well as certain cancers (2).

Physical activity levels among children are disturbingly low, with only about 20% to 30% of children participating in 420 min·wk−1 (10,11). Alarmingly, physical activity starts to decrease as early as age 5 years and continues to decline through adolescence (12). Physical activity levels that are inconsistent with the current guidelines cause a cascade of events that may lead to a decrease in functional motor skill development, motor skill competence, and motor skill confidence (13). This could lead to an increase in sedentary behaviors and development of disease risk factors (13). Decreased physical activity has been shown in a variety populations. Girls have lower levels of physical activity when compared with boys (14). A body mass index (BMI) percentile signaling overweight (85% to 94%) or obesity (≥95%) has been associated with lower levels of physical activity compared with their normal weight peers (15). Children with chronic diseases, such as asthma (16), attention-deficit hyperactivity disorder (ADHD) (17), depression (18), and diabetes (19), have been shown to have decreased physical activity levels as well, even though physical activity has been shown to be therapeutic in these conditions (20–22).

Recently, Exercise is Medicine® began an initiative built on the belief that physical activity is vital to overall health and should be assessed similarly to other vital signs (23). Health care systems currently track vital signs, such as BMI and blood pressure, at multiple intervals to provide continued support and counseling as needed to promote general health (24). Health care providers in contact with children are poised to assess physical activity levels and counsel patients and families. Indeed, almost all physicians agree that regular MVPA assists in disease prevention (25). Although pediatricians generally ask about physical activity during patient visits, many do not ask specifics about intensity, frequency, or duration, and only 7% use standardized questions (26), even though routine assessment of physical activity is a priority for children starting at age 5 years (27). While most physicians agree that routine MVPA screenings are important, a lack of time within a patient appointment has been reported as the largest barrier to evaluate MVPA in the pediatric setting (25). While there are a variety of self-report measures to assess MVPA in children, one of the most commonly used is the Physical Activity Questionnaire (28). This tool can require upward of 20 min to administer and score, making it difficult to implement in a clinical setting as part of routine care.

In adults, the Exercise Vital Sign (EVS) questions have been successfully implemented in clinical settings and these questions generally take less than 1 min to complete (24). In addition, EVS questions have high levels of discriminant validity between sexes, ages, body mass index categories, ethnic categories, and disease burden (24). Physicians who screen their adult patients can advise and counsel them regarding physical activity, which can result in significant increases in MVPA (29), although this has not been studied in a pediatric population.

A short, valid assessment of MVPA that could easily be implemented in a clinical setting for pediatrics is needed to increase standardized screening. The primary objective of this study was to assess the clinical utility and validity of the same EVS questions in a pediatric population. We hypothesized that we would find significantly lower rates of physical activity, as measured by the EVS, among girls and children with ADHD, overweight/obesity, depression, asthma, and diabetes. The hypotheses were based on previous research that suggests that these populations have lower MPVA (14,15,17–19). The secondary objective was to determine which variables are associated with greater odds of reporting physical activity.

Methods

Study Design

We performed a secondary analysis of cross-sectional electronic medical record data.

Study Population

All new patients between the ages of 5 and 18 years who reported to a tertiary sports medicine clinic for a musculoskeletal injury between March 2015 and March 2018 were eligible for inclusion in this study. For this study, we included the first EVS report if there was a participant with multiple visits during the study period.

Procedures

Patients were asked the following EVS questions, which have been validated in adults (24): 1) “On average, how many minutes per day of moderate to vigorous physical activity do you participate in?,” and 2) “On average, how many days per week do you participate in moderate to vigorous physical activity.” Parents assisted their children in answering these questions. Clinicians clarified answers as needed, such as ensuring normal MVPA versus MVPA after the injury. Duration of physical activity was recorded in 10-min increments. Clinicians entered patient responses into the electronic medical record. Minutes recorded per day was multiplied by recorded days per week to give a weekly total of MVPA. This study was reviewed and approved by the hospital’s institutional review board.

Measures

The primary outcome measures were presence of any MVPA and minutes per week of MVPA. Independent variables were extracted from the electronic medical record and included: age, sex, BMI category, as well as history of ADHD, depression, diabetes, and asthma. BMI category was determined by the BMI percentile at the time of visit, where less than 85% was normal weight, between 85% and 94.99% was overweight, and greater than 95% was obese.

Statistical Analyses

Participant demographics and disease presence were summarized descriptively. To assess factors related to physical activity, a two-step approach was used. First, a logistic regression was used to compare inactive and those with any activity (at least 10 min) on age, sex, and BMI category as well as presence of diabetes, asthma, AHDH, and depression. Second, a linear regression was used to compare average adjusted minutes per week of MVPA of active subjects between boys and girls as well as those with and without a history of asthma, ADHD, depression, diabetes, and BMI category while controlling for age. A post hoc power calculation revealed we were 100% powered to detect an effect size of 0.04 for our multivariable regression model with seven predictors and alpha set at 0.05. A priori significance was set at 0.05, and all tests were two-sided. All analyses were completed using SPSS v. 24 (Chicago, IL).

Results

A total of 19,672 children aged 5 to 18 years were eligible for this study. We included only the first visit for patients with multiple visits during the study period (n = 43.97 excluded). Those with missing BMI percentile data (n = 718) and those with missing or inaccurate (i.e., >7 d MVPA) EVS data were excluded (n = 76). Four participants with improbable values (>14 h·d−1) and one with missing sex were excluded. Overall, 14,476 participants with complete data were included in our analyses. Table 1 provides participant demographics. The average age of study participants was 13.91 ± 2.49 years (range, 5 to 18 years). Participants reported an average of 400.36 ± 280.04 min·wk−1 of MVPA. Girls made up 54% of our population. Approximately 16.1% of the sample had asthma, 5.7% had ADHD, 2.1% had depression, and 0.6% had diabetes. Children of normal weight made up 67.3%, children who were overweight made up 16.5% and 16.2% were obese. Overall, only 48% of children reported meeting the weekly physical activity guidelines, regardless of how many days they were active.

Table 1 - Demographics.
Age 13.91 ± 2.48
min·wk−1 400.77 ± 283.41
Females 54.1% (7809)
Asthma 16.2% (2330)
ADHD 5.6% (818)
Depression 2.1% (306)
Diabetes 0.6% (92)
BMI
 Normal weight 67.3% (9717)
 Overweight 16.5% (2386)
 Obese 16.2% (2343)

Odds of Any Activity

Results are shown in Table 2. Girls were 54% less likely to report MVPA than boys (P < 0.001; 95% confidence interval [CI], 0.39–0.54). The odds of those without ADHD reporting physical activity were 83% greater when compared with those with ADHD (P < 0.001; 95% CI, 1.38–2.42). The odds of those without depression reporting physical activity were 85% greater than those with depression (P < 0.001; 95% CI, 1.29–2.66). For every year older in age, the odds of reporting physical activity were 15% lower (P < 0.001; 95% CI, 0.82–0.88). Those who were overweight were not less likely to report physical activity than children of normal weight (P = 0.24; 95% CI, 0.07–1.09). Children who were obese were 48% less likely to report physical activity than those who were normal weight (P < 0.001; 95% CI, 0.43–0.62). Patients with diabetes or asthma did not significantly differ from those without these conditions in the odds of any self-reported physical activity (P = 0.14; 95% CI, 0.839–3.47, and P = 0.16; 95% CI, 0.95–1.42, respectively).

Table 2 - Factors associated with MVPA.
Odds Ratio (95% CI) P
BMI category a
 Overweight 0.88 (0.07–1.09) 0.239
 Obese 0.52 (0.43–0.62) <0.001
Age in years 0.85 (0.82–0.88) <0.001
Girls to boys 0.46 (0.39–0.54) <0.001
Presence of asthma 1.16 (0.95–1.42) 0.158
Presence of ADHD 1.83 (1.38–2.42) <0.001
Presence of depression 1.85 (1.29–2.66) 0.001
Presence of diabetes 1.71 (0.839, 3.47) 0.140
Bold values indicates statistically significance, P < 0.05.
aCompared with normal weight.

Factors Associated with Greater MVPA

Almost 95% (13,712) reported at least 10 min of MVPA per week with an average of 422.76 ± 272.09 min·wk−1. Estimated group means are reported in Table 3. Those with a history of depression had 60 min·wk−1 less MVPA when controlling for age, sex, BMI category, asthma, ADHD, and diabetes (P = 0.001; 95% CI, −96.65 to −26.31). Girls reported about 50 min less MVPA than boys when controlling for age, BMI category, asthma, ADHD, depression, and diabetes (P < 0.001; 95% CI, −59.15 to −40.31). When controlling for age, sex, and chronic disease, overweight and obese children reported significantly less MVPA than their normal weight counterparts (P < 0.001; 95% CI, −42.65 to −17.29, and P < 0.001; 95% CI, −91.61 to −65.50, respectively). There were no differences in reported MVPA in diabetics and nondiabetics (P = 0.62; 95% CI, −79.84 to 44.41), those with or without asthma (P = 0.62; 95% CI, −15.97 to 9.45) or those with or without ADHD (P = 0.30; 95% CI, −31.06 to 9.69).

Table 3 - Adjusted mean MVPA.
Condition min·wk−1 P 95% CI for Difference
Sex
 Males 380.30 <0.001 a −59.15 to −40.31
 Females 330.57
BMI
 Normal weight 391.61
 Overweight 361.64 <0.001 a −42.65 to −17.29
 Obese 313.05 <0.001 a −91.61 to −65.50
Asthma
 Yes 357.06 0.615 −15.97 to 9.45
 No 353.80
ADHD
 Yes 350.09 0.304 −31.06 to 9.69
 No 360.78
Depression
 Yes 325.44 0.001 a −96.65 to −26.31
 No 385.43
Diabetes
 Yes 363.07 0.616 −79.84 to 44.41
 No 347.80
aStatistically significant.

Discussion

We found that EVS questions demonstrate strong discriminant validity for sex, age, BMI category, and history of depression in a pediatric population. Our findings are consistent with previous research assessing children’s MVPA by asking similar questions. In the United States, Kalman et al. (30) noted that between the years 2002 and 2010 the percentage of children meeting MVPA recommendations for boys decreased from 35% to 32% while girls remained stable at 21%. Similarly, Guthold et al. (11) described the percentage of adolescents aged 11 to 17 years in the U.S. meeting the MVPA guidelines as decreasing from 75% in 2001 to 72% in 2016. Collectively, these data are not encouraging as the World Health Organization set a target in 2018 to reduce adolescents not meeting the physical activity guidelines by 15% by 2030 (31). Particularly concerning is that self-reported minutes of MVPA may be overestimated when compared with objective measures (32); therefore, the actual proportion of children meeting the guidelines is likely lower.

There is great clinical utility of implementing EVS questions into the electronic health record as less than 1% were excluded because of missing or exceedingly elevated EVS scores. The department requested that the EVS questions be added into the electronic medical record as part of the patient history for new visits. Staff were then trained to help patients and families answer the questions, particularly in light of the current injury. Widespread integration of EVS questions could allow for increased counseling for physical activity in the pediatric population. In adults, integrating MVPA assessment of similar MVPA questions lead to increased physical activity counseling by providers, as well as cardiometabolic improvements (33,34). As the Institutes of Medicine have advocated for the inclusion of MVPA assessment into medical records (35), our results support adding EVS questions to pediatric medical records as well.

Sex

Girls were less active than boys. Specifically, the odds of reporting any physical activity was significantly lower among girls, which parallels other research (36). In addition, among children with at least some physical activity, we found girls had 14% lower weekly MVPA than boys after controlling for BMI percentile, age, and disease presence. This is similar to other authors who found that girls participate in 19% less activity than boys using objective step counts (14). There are a variety of proposed mechanisms for explaining lower MVPA in girls, including less participation in organized sports (37), less perceived parental and peer support (38), and decreased motor competence (39). As physical activity levels for girls remain lower than boys through adulthood (40), screening girls for physical activity is imperative to identify those who need intervention.

Age

We found higher self-reported MVPA as children aged. In our study, for every year older, children participated in an additional 18 min of reported MVPA, which contrasts findings from other studies (40,41) and our hypothesis. Those presenting to sports medicine clinics for musculoskeletal complaints may be more likely to participate in organized sports thereby explaining the higher levels of MVPA. However, the odds of reporting any activity significantly declined as children aged. Although these results appear contradictory, they suggest that older children and adolescents are more likely to not do any MVPA but those that continue physical activity behavior have an overall higher weekly volume. One possible explanation for this could be children drop out of organized sports as they age (42) and those who continue in sports would require more physical activity at higher levels. As physical activity habits developed throughout childhood predict MVPA later in life (43) and can aid in the prevention of chronic disease (44), reporting no activity is a cause for concern.

BMI

Overweight children were not less likely to report activity than normal weight children. However, they did report 31 min less MVPA per week, which also is clinically significant; increasing MVPA by 15 min can improve children's cardiorespiratory risk profile (45). Obese children were significantly less likely to report any activity compared with normal weight children. In addition, obese children reported 78 min less MVPA than normal weight children after controlling for age, sex, and chronic disease. Others have found that BMI category was associated with self-reported PA level in younger adolescents but this was not true in older adolescents (46). Similarly, overweight adolescents reported nearly an hour less PA per week than normal weight peers (47). Conversely, Hwang et al. (48) found no differences in physical activity between normal weight, overweight, and obese adolescents. Another study found no difference in BMI in those who met and did not meet physical activity recommendations (49). Children who are overweight or obese may have less MVPA, although the role of BMI on child MVPA is not completely clear.

Chronic Diseases

The disease variable most strongly associated with a decline in physical activity was history of depression. In our study, participants with a history of depression reported almost an hour less of MVPA per week. This is consistent with previous work that demonstrated reduced MVPA in those with a history of depression and those with current depression compared with controls (18). A recent meta-analysis demonstrated that physical activity had a significant protective effect for presenting the development of depression and a strong treatment effect when used to manage depression (50). A targeted approach to track and increase MVPA needs to be implemented to decrease the incidence and burden of depression in children and adolescents.

We anticipated finding lower MVPA among those with asthma as previous work has found that asthmatic children participate in less MVPA than their nonasthmatic peers (51). However, we did not find a greater odds in reporting MVPA or weekly volume of MVPA (P = 0.16 and P = 0.39, respectively). In a meta-analysis examining MVPA and asthma, almost half of the included studies show no association of asthma and low levels of MVPA (52). Smith et al. (42) found that asthma did reduce MVPA in boys but not sport participation and that girls' MVPA and sport participation was unaffected. We were unable to differentiate between those with active asthma and those who were currently not affected by asthma. Approximately half of children with asthma may go into remission in adolescence and adulthood (53), which may explain why we did not show differences in between those with and without asthma.

We anticipated children with diabetes would report lower MVPA. Several studies found that those with type 1 diabetes had significantly fewer MVPA minutes compared with peers (19,54). However, we did not find a difference between those with and without diabetes on odds of activity or minutes of activity (P = 0.14 and P = 0.47 respectively). In our study, the number of subjects with diabetes in the medical history was quite small (0.6%) and did not distinguish between type 1 and type 2 diabetes. A larger sample size and separation of type 1 and type 2 is needed to further explore the relationship between pediatric diabetes and MVPA.

We found that that the odds of reporting any MVPA was significantly lower among those with ADHD. However, there was no difference in weekly minutes of MVPA between those with and without ADHD. While some research has suggested that children with ADHD may report less MVPA, a small study reported no differences in MVPA levels between children with and without ADHD (55). Given the positive impact of physical activity on cognition (56), further investigation is warranted.

Limitations and Future Directions

There are several limitations inherent with a retrospective study. As with many self-report tools for physical activity, there may be an underestimation of MVPA as children often have intermittent and sporadic activity during their day that was not considered in answering EVS questions. Conversely, there may be an overestimation of MVPA measured by EVS when children and families count the entire time of an activity, such as sports practices, as MVPA when there is a substantial time during sports practices that does not meet this threshold (57). Because parents and clinicians assisted younger children in answering EVS questions, it is unclear if younger children would be able to accurately assess their MVPA without help. For the disease conditions, we were not able to control for condition severity or to ascertain the extent to which any of the conditions were being actively treated and well managed. Future work should prospectively assess disease burden and physical activity, as well as validate the EVS questions with objective measurements in children.

Conclusions

EVS questions can be easily administered in a clinical setting within pediatrics. This short screening has strong discriminant validity for age, sex, BMI, and chronic disease states. Although the subjective nature of EVS questions may reduce the accuracy of measuring MVPA, EVS can be used by clinicians to flag children who may need a more in-depth history to assess for adequate MVPA levels.

The authors declare no conflict of interest and do not have any financial disclosures.

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