The cardiorespiratory endurance component (variable name prefix CEX) measured cardiorespiratory fitness using a treadmill exercise test. The goals of this component were to provide nationally representative data on cardiorespiratory endurance: 1) to provide endurance time reference values based on age-specific protocols; and 2) to study the association between cardiorespiratory endurance and other health conditions and risk factors, such as obesity, physical activity, and dietary patterns.
Participants aged 6-11 years, who did not meet any of the exclusion criteria, were eligible for this component.
Participants were excluded from this component based on medical conditions, certain medications, physical limitations, and safety limitations. Exclusions included the following; 1) if a participant was told by a doctor that he/she should not participate in sports or other activities because of a heart condition or do only sports or other physical activities recommended by a doctor; 2) if a participant had a close biological relative whom died of heart problems or sudden death before the age of 35; 3) if a participant was unable to walk on a treadmill due to a physical limitation, such as amputations of a leg or foot; 4) if a participant had a pacemaker or automatic defibrillator; 5) if a participant was pregnant; 6) if a participant had untreated asthma or was prescribed medication for asthma before participating in exercise or sports, but had not brought the inhalant to the mobile examination center; or 7) if a participant was taking medications that indicated treatment for a medical condition that would be contradictory to performing a treadmill test, or if a medication taken affected the validity of the test results (i.e., beta blockers). Exclusionary medications include anti-arrhythmics, nitrates, beta-blockers, cardiac glycosides, ophthalmic beta-blockers, and antihypertensive/beta-blocker/diuretic combinations.
Cardiorespiratory endurance was assessed using age-specific maximal exercise test treadmill protocols (Appendix A). Each participant was assigned to one of three treadmill test protocols (varying in grade and speed). Each protocol was designed so that the participant walks and runs. The treadmill test protocols consisted of a 1-minute warm-up, seven 2-minute exercise periods, three 1-minute exercise periods designed for exceptionally fit youth, and a 2-minute recovery period. The goal of each protocol was to exercise the participant to volitional fatigue in 5-12 minutes. Two examiners were present at all times, one coaching the participant and the other one monitoring the equipment and heart rate.
Heart rate was monitored continuously using an automated monitor with four electrodes connected to the thorax and abdomen of the participant and was recorded at the end of warm-up, each exercise stage, and each minute of recovery.
The main outcome of this component is endurance time.
Detailed descriptions of the protocol are provided in the NNYFS Treadmill Examination Manual available on the NNYFS website at: http://www.cdc.gov/nchs/data/nnyfs/Treadmill.pdf
Examiners were regularly monitored by NCHS staff and field supervisors. Retraining sessions were conducted periodically with the examiners to reinforce the proper protocols and techniques. Inspection, calibration, and maintenance of the equipment and supplies were performed on a regular basis.
As part of on-going quality control practices, all data were reviewed systematically for logical or operational inconsistencies and examiner errors.
During the data processing, edits were made to ensure the logical consistency and analytic usefulness of the data. Extreme values were reviewed and cross-checked with other available data. When there was insufficient information to conclude that the values were invalid, they were retained in the dataset.
Variable specific editing
CEDEXSTS (Cardiorespiratory endurance exam status)
This derived variable indicates the following for each participant:
1. Exam completed maximal test conducted;
2. Exam was stopped early; or
3. Not done.
While we believe a maximal test was performed for most participants, we cannot rule out the possibility that the participant could have continued longer. Heart rate was the only objective measure collected during the treadmill test. Subjective indicators were also recorded, such as: 1) participants requesting to stop despite verbal encouragement of examiner/coach to continue; 2) unsteady gait; 3) breathlessness; and 4) inability to keep up with treadmill speed. These indicators are also included in the dataset. Analyst will need to determine what heart rate cut-offs to use in terms of assuming a maximal test. Additionally, in cases in which a participant did not meet the identified cut-off, the analyst should determine if the subjective indicators warrant the assumption of a maximal test.
CEDEXCMT (Comment code for Cardiorespiratory endurance fitness exam component status)
This derived variable denotes the reason the treadmill test was not done or data are missing. About 2.3% of participants who were eligible met exclusion criteria and an additional 5.0% have missing data because of refusal, not enough time, a safety issue that arose during testing, or inability to adhere to the protocol or because of a technical issue.
0 = None: the exam was completed with no missing data point present.
1 = Met exclusion criteria: exam was not done due to the participant meeting the exclusion criteria of the component as discussed above under eligible sample.
2 = Participant refusal: participant refused to undergo or continue the test.
3 = No time: the exam was not done because there was not enough time.
4 = Data acquisition problem: equipment failure or operator error.
5 = Safety issue: a safety concerns arose during the test that warranted an early stop of the protocol (e.g., shoes untied).
6 = Unable to adhere to the protocol: despite coaching from the examiner, the participant was unable to walk or run on the treadmill safely.
7 = Other.
CEXPROT (Assigned exercise protocol)
Each participant was assigned to one of three exercise test protocols depending on his/her age. Protocol one was assigned to participants aged 6-7 years, protocol two was assigned to participants aged 7-8 years, and protocol three was assigned to participants aged 9-10 years.
CEDEXLEN (Maximal endurance time [sec]) versus CEDTOTEX (Length of cardiorespiratory endurance exam component [sec])
There are two variables indicating time. The first one, CEDEXLEN, denotes the maximal endurance time, which is the time excluding warm-up and recovery in seconds. This is the actual exercise test endurance time. On the other hand, CEDTOTEX denotes the time of the entire exam, including warm-up and recovery time, in seconds.
CEDMAXHR (Maximal heart rate [bpm]) versus CEDENDHR ( Heart rate [bpm] at the end of test)
While CEDMAXHR (maximal heart rate) and CEDENDHR (heart rate at the end of test) are typically very similar, there are cases in which they differ. CEDMAXHR is the highest heart rate recorded during the exercise test and CEDENDHR is the heart rate recorded at the point in which the exercise period of the test protocol is stopped.
In two cases, during the end of the test, the heart rate monitor had difficulty recording accurately the heart rate. Information from the examiner indicated that the test was completed and the participant did likely exercise to volitional fatigue. In order to retain these participants, we provided as much information as possible on their ending heart rate. Therefore, in variable CEDMAXHR (maximal heart rate) and CEDENDHR (heart rate at the end of test), there are codes, 6666 and 8888, that indicate that although we do not know the final heart rate, we do know it was greater than a certain value. Analyst will need to decide on how to handle these cases. It is important that analysts not keep in the codes (i.e., 6666 and 8888) as this will influence an estimate of the mean or other parameters.
This dataset also includes information on the temperature and humidity pre-test and post-test, the grade(%) and speed (mph) at each warm-up, exercise test stage, and recovery stage, the amount of time spent in each stage, and the heart rate at the end of each stage.
The NNYFS examination sample weights should be used to analyze the cardiorespiratory endurance test data. Please refer to the NNYFS Analytic Guidelines for details on the use of sample weights and other analytic issues.
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 | Exam completed maximal test conducted | 682 | 682 | |
2 | Exam was stopped early | 17 | 699 | |
3 | Not Done | 33 | 732 | |
. | Missing | 0 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | None | 682 | 682 | |
1 | Met exclusion criteria | 16 | 698 | |
2 | Participant refusal | 4 | 702 | |
3 | No time | 9 | 711 | |
4 | Data acquisition problem, equipment failure, or operator error | 6 | 717 | |
5 | Safety issue | 4 | 721 | |
6 | Unable to adhere to the protocol | 3 | 724 | |
7 | Other | 8 | 732 | |
. | Missing | 0 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
28 to 1024 | Range of Values | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
215 to 1227 | Range of Values | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
105 to 229 | Range of Values | 680 | 680 | |
6666 | >=185 | 1 | 681 | |
8888 | >=199 | 1 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
70 to 222 | Range of Values | 680 | 680 | |
6666 | >=185 | 1 | 681 | |
8888 | >=199 | 1 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 | A0 NYFS Ages 6-7 | 244 | 244 | |
2 | A1 NYFS Ages 8-9 | 214 | 458 | |
3 | A2 NYFS Ages 10-11 | 224 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
60.9 to 79.4 | Range of Values | 681 | 681 | |
. | Missing | 51 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
21.5 to 72.2 | Range of Values | 675 | 675 | |
. | Missing | 57 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
64.1 to 76.8 | Range of Values | 681 | 681 | |
. | Missing | 51 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
21.5 to 72.9 | Range of Values | 675 | 675 | |
. | Missing | 57 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
2 to 2.5 | Range of Values | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | 0 | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
60 | 60 | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
90 to 168 | Range of Values | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
2.5 to 3 | Range of Values | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | 0 | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
28 to 120 | Range of Values | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
95 to 259 | Range of Values | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
2.8 to 3.3 | Range of Values | 677 | 677 | |
. | Missing | 55 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | 0 | 677 | 677 | |
. | Missing | 55 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
20 to 120 | Range of Values | 677 | 677 | |
. | Missing | 55 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
92 to 199 | Range of Values | 677 | 677 | |
. | Missing | 55 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
3 to 3.5 | Range of Values | 674 | 674 | |
. | Missing | 58 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
2.5 | 2.5 | 674 | 674 | |
. | Missing | 58 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
71 to 120 | Range of Values | 674 | 674 | |
. | Missing | 58 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
107 to 200 | Range of Values | 674 | 674 | |
. | Missing | 58 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
3.2 to 5 | Range of Values | 671 | 671 | |
. | Missing | 61 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
5 | 5 | 671 | 671 | |
. | Missing | 61 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 to 120 | Range of Values | 671 | 671 | |
. | Missing | 61 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
119 to 219 | Range of Values | 671 | 671 | |
. | Missing | 61 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
3.5 to 5 | Range of Values | 622 | 622 | |
. | Missing | 110 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
7.5 | 7.5 | 622 | 622 | |
. | Missing | 110 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 to 120 | Range of Values | 622 | 622 | |
. | Missing | 110 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
135 to 221 | Range of Values | 621 | 621 | |
. | Missing | 111 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
4.2 to 5 | Range of Values | 449 | 449 | |
. | Missing | 283 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
10 | 10 | 449 | 449 | |
. | Missing | 283 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 to 120 | Range of Values | 449 | 449 | |
. | Missing | 283 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
70 to 221 | Range of Values | 447 | 447 | |
. | Missing | 285 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
4.5 to 5 | Range of Values | 206 | 206 | |
. | Missing | 526 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
12.5 | 12.5 | 206 | 206 | |
. | Missing | 526 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 to 120 | Range of Values | 206 | 206 | |
. | Missing | 526 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
76 to 222 | Range of Values | 206 | 206 | |
. | Missing | 526 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
4.8 to 5.2 | Range of Values | 48 | 48 | |
. | Missing | 684 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
12.5 | 12.5 | 48 | 48 | |
. | Missing | 684 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
2 to 116 | Range of Values | 48 | 48 | |
. | Missing | 684 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
172 to 219 | Range of Values | 48 | 48 | |
. | Missing | 684 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
5 to 5.4 | Range of Values | 19 | 19 | |
. | Missing | 713 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
12.5 | 12.5 | 19 | 19 | |
. | Missing | 713 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
2 to 60 | Range of Values | 19 | 19 | |
. | Missing | 713 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
96 to 213 | Range of Values | 19 | 19 | |
. | Missing | 713 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
5.2 to 5.6 | Range of Values | 9 | 9 | |
. | Missing | 723 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
12.5 | 12.5 | 9 | 9 | |
. | Missing | 723 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
6 to 64 | Range of Values | 9 | 9 | |
. | Missing | 723 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
196 to 213 | Range of Values | 9 | 9 | |
. | Missing | 723 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
2 | 2 | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | 0 | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
122 to 202 | Range of Values | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
83 to 214 | Range of Values | 682 | 682 | |
. | Missing | 50 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
79 to 185 | Range of Values | 681 | 681 | |
. | Missing | 51 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 | Yes | 203 | 203 | |
. | Missing | 529 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 | Yes | 516 | 516 | |
. | Missing | 216 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 | Yes | 318 | 318 | |
. | Missing | 414 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 | Yes | 625 | 625 | |
. | Missing | 107 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 | Yes | 357 | 357 | |
. | Missing | 375 | 732 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 | Yes | 34 | 34 | |
. | Missing | 698 | 732 |
TREADMILL PROTOCOL AGES 6-7 |
|||
Stage |
Seconds in stage |
Speed (mph) |
Grade (%) |
WARM-UP |
60 |
2.0 |
0.0 |
1 |
120 |
2.5 |
0.0 |
2 |
120 |
2.8 |
0.0 |
3 |
120 |
3.0 |
2.5 |
4 |
120 |
3.2 |
5.0 |
5 |
120 |
3.5 |
7.5 |
6 |
120 |
4.2 |
10.0 |
7 |
120 |
4.5 |
12.5 |
8 |
60 |
4.8 |
12.5 |
9 |
60 |
5.0 |
12.5 |
10 |
60 |
5.2 |
12.5 |
RECOVERY |
120 |
2.0 |
0.0 |
TREADMILL PROTOCOL AGES 8-9 |
|||
Stage |
Seconds in stage |
Speed (mph) |
Grade (%) |
WARM-UP |
60 |
2.0 |
0.0 |
1 |
120 |
2.8 |
0.0 |
2 |
120 |
3.0 |
0.0 |
3 |
120 |
3.3 |
2.5 |
4 |
120 |
3.5 |
5.0 |
5 |
120 |
4.5 |
7.5 |
6 |
120 |
4.5 |
10.0 |
7 |
120 |
4.5 |
12.5 |
8 |
60 |
5.0 |
12.5 |
9 |
60 |
5.2 |
12.5 |
10 |
60 |
5.4 |
12.5 |
RECOVERY |
120 |
2.0 |
0.0 |
TREADMILL PROTOCOL AGES 10-11 |
|||
Stage |
Seconds in stage |
Speed (mph) |
Grade (%) |
WARM-UP |
60 |
2.5 |
0.0 |
1 |
120 |
3.0 |
0.0 |
2 |
120 |
3.3 |
0.0 |
3 |
120 |
3.5 |
2.5 |
4 |
120 |
5.0 |
5.0 |
5 |
120 |
5.0 |
7.5 |
6 |
120 |
5.0 |
10.0 |
7 |
120 |
5.0 |
12.5 |
8 |
60 |
5.2 |
12.5 |
9 |
60 |
5.4 |
12.5 |
10 |
60 |
5.6 |
12.5 |
RECOVERY |
120 |
2.0 |
0.0 |