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Original Research

Associations Between Fitness Tests and the International Physical Activity Questionnaire—Short Form in Healthy Men

Silva-Batista, Carla1; Urso, Rodrigo P.1; Lima Silva, Adriano E.2; Bertuzzi, Rômulo1

Author Information
Journal of Strength and Conditioning Research: December 2013 - Volume 27 - Issue 12 - p 3481-3487
doi: 10.1519/JSC.0b013e31828f1efa
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Abstract

Introduction

The development of industrialized society has provided several benefits to the modern man. However, the lack of physical activity (PA) could be considered one of the most harmful byproducts of this industrial development. Clinical evidence has suggested that PA is an important determinant of health throughout the lifespan (24). Physical inactivity is one of the main risk factors for chronic degenerative diseases (9,20); conversely, PA has been recommended as a nonpharmacological prevention strategy for the treatment of chronic degenerative diseases (7) and obesity (11).

The assessment of PA levels in large population-based studies has been conducted through the application of several self-administered questionnaires (14,16,17) because they are quick, low-cost, and noninvasive tools. Because the International Physical Activity Questionnaire (IPAQ) was adapted for multicultural populations, it has been considered one of the most widely used questionnaires (6). Twelve countries have participated in the formulation and validation of this questionnaire with the support of the World Health Organization, and both a long and a short version of IPAQ (IPAQ-SF) have been developed (21).

The IPAQ-SF consists of questions that aim to identify relevant information regarding the level of cardiorespiratory system stress during the execution of a specific PA (6,8). This form inquires about the respiratory and cardiac rhythm of the evaluated subject during transportation, work, household and gardening tasks, and leisure time. The outcomes of the IPAQ-SF are expressed as weekly energy expenditures, which are determined by the expressed metabolic equivalent task minutes per week (METs min·wk−1) of different categories (walking, moderate- and vigorous-intensity PA, and total PA score) and PA levels (low, moderate, and high PA). To date, the concurrent validity of the IPAQ-SF has been addressed using accelerometers (26), maximal oxygen uptake (V[Combining Dot Above]O2max) (12), peak velocity attained in an incremental treadmill test (21), and muscular endurance (8). Collectively, these studies have demonstrated a close association between these measurements and the outcomes of the IPAQ-SF.

Since 1998, the American College of Sports Medicine (1) has suggested that not only muscular endurance and cardiorespiratory fitness but also flexibility and muscular strength are essential components of health-related fitness. However, to the best to our knowledge, no study has analyzed the association of self-administered questionnaire outcomes with these variables of health-related fitness. This appears to be particularly important because low flexibility and poor muscular endurance are associated with certain osteomuscular diseases (2) and several neuromuscular disorders (1,10), respectively.

Therefore, the objective of the present study was to investigate the relationship between the IPAQ-SF and these components of health-related fitness. Because these components together indicate the general level of functional capacity for activities of daily living, we hypothesized that the outcomes of the IPAQ-SF might be positively associated with flexibility, muscular strength, muscular endurance, and cardiorespiratory fitness.

Methods

Experimental Approach to the Problem

We investigated the relationships between the outcomes of the IPAQ-SF and health-related fitness tests. The data were collected over 2 days. On the first day, the METs min·wk−1 of walking, moderate- and vigorous-intensity PA, total PA, and categorical PA levels (low, moderate, and high PA) of the previous 7 days were assessed by the self-administered IPAQ-SF questionnaire (6). On the second day, anthropometric measurements were taken and health-related fitness tests were performed. The sit-and-reach, hand grip dynamometer, 20-m shuttle run, and the sit-ups and push-ups tests were used to measure the flexibility of the lower back and hamstrings, muscular strength, cardiorespiratory capability, and muscular endurance, respectively. Before the tests, each subject performed a warm-up that included 10 minutes of cycling (a pedaling rate of 60 rpm was maintained). All tests were conducted at the same time of day and with similar weather conditions (∼25° C temperature and ∼60% relative air humidity). Each subject had 20 minutes of passive rest between the tests. A pilot study executed at our laboratory revealed that this interval was sufficient to prevent interference of residual fatigue from the previous test on the performance of the subsequent test. Subjects were instructed not to perform any type of exhaustive exercise or consume caffeine, diuretics, or alcohol 24 hours before the tests.

Subjects

Five hundred two healthy men from São Paulo (Brazil) were invited to participate in the study. Subjects with musculoskeletal diseases that would limit their ability to exercise, ischemic heart disease, high blood pressure at rest (systolic blood pressure ≥ 140 mm Hg and diastolic blood pressure ≥ 90 mm Hg), a body mass index (BMI) > 29.9 kg·m−2, and evidence of alcohol or drug abuse were excluded from the study. Thus, 94 subjects were excluded, and 408 subjects completed the study. These subjects' physical characteristics are shown in Table 1. Subjects received a verbal explanation of the possible benefits, risks, and discomforts associated with the study and signed an informed consent before participating in the study. The study was approved by an institutional review board for the use of human subjects.

Table 1
Table 1:
Subjects' physical characteristics (n = 408).*

Short Version of the International Physical Activity Questionnaire

Similar to Fogelholm et al. (8), the subjects answered the questionnaire in a classroom setting after a detailed description of the IPAQ-SF. For this study, an assistant remained in the classroom to answer any questions. The major aim of the IPAQ-SF is to sum up walking and moderate- and vigorous-intensity PA to generate a total PA score for weekly energy expenditure, expressed in metabolic equivalent task minutes per week (METs min·wk−1). We used the following recommended METs min·wk−1 estimates of the IPAQ-SF: walking PA = 3.3 METs min·wk−1, moderate-intensity PA = 4.0 METs min·wk−1, and vigorous-intensity PA = 8.0 METs min·wk−1. The total PA was calculated using the following equation: 3.3 × walking PA + 4.0 × moderate-intensity PA + 8.0 × vigorous-intensity PA. The PA level was subsequently classified as low, moderate, or high. Low PA represented subjects who did not meet the criteria for moderate- and vigorous-intensity categories (<599 METs min·wk−1). Moderate PA represented moderate- or vigorous-intensity activities achieving a minimum of at least 600 METs min·wk−1, whereas high PA represented achieving a minimum of at least 3,000 METs min·wk−1 (http://www.ipaq.ki.se/scoring.htm). The METs values were derived from an IPAQ-SF reliability and validity study (6).

Anthropometric Measurements

Body weight was measured to the nearest 0.1 kg using an electronic scale (model ID 1500; Filizola, São Paulo, Brazil). Height was measured to the nearest 0.1 cm with a stadiometer. Waist circumference was measured midway between the lowest rib and the iliac crest after a normal exhale. BMI was defined as the subjects' body weight divided by the square of the height (kg·m−2).

Flexibility Measurement

Flexibility of the lower back and hamstrings was evaluated using the sit-and-reach test according to the procedures described by Baltaci et al. (2). Briefly, subjects were instructed to sit on the floor with their legs stretched straight ahead and to place the soles of their feet against the sit-and-reach box. Next, the subjects were instructed to correct their posture, extend their arms, and place their hands on the top of the box, where a measuring tape was placed. Next, each subject was asked to slide his hands slowly on the measuring tape to the front as far as possible. This procedure was repeated 3 times, and the best result recorded in centimeters was used. Available data indicate excellent intraclass correlation coefficient (ICC) reliability scores (0.96) for this sit-and-reach test (18).

Muscular Strength and Endurance Measurements

Muscular strength of the dominant hand grip was measured by the Jamar (Lafayette Instrument, Co., Lafayette, IN, USA) hydraulic hand dynamometer. Each subject stood erect with the elbows flexed at 90°. The handle of the dynamometer was adjusted if necessary. The subjects were subsequently instructed to exert a maximal grip for approximately 3 seconds, interrupted by brief pauses of approximately 1 minute. No other body movement was allowed. Three trials were conducted, and the best score recorded in kilograms was chosen for analysis. It has been shown excellent ICC reliability scores (0.96) for this hand grip test (18).

Muscular endurance of the abdominal and hip flexor muscles was measured by the sit-ups test. In the starting position, the subjects were lying on the floor with their hands behind the neck and elbows pointing forward. The knees were flexed at an angle of 90°, the legs were slightly abducted, and an assistant supported the ankles. During the movement, subjects lifted their upper body and touched their knees with their elbows. The total number of correct sit-ups performed during 1 minute was recorded. Previous findings indicate excellent ICC reliability scores (0.97) for this sit-ups test (18).

Muscular endurance of the arm and shoulder extensor muscles was measured by the push-ups test. The subjects were positioned with hands and toes touching the floor, body and legs in a straight line, feet slightly apart, and with arms shoulder-width apart, extended and at right angles to the body. Keeping the back and knees straight, the subject then lowered his body to the point at which there was a 90° angle at the elbows with the upper arms parallel to the floor. The total number of correct push-ups performed during 1 minute was recorded. Available data indicate excellent ICC reliability scores (0.97) for this push-ups test (23).

Cardiorespiratory Measurement

Cardiorespiratory fitness was represented by V[Combining Dot Above]O2max and the maximal aerobic speed (MAS), which were estimated from a 20-m shuttle run test (15). This test involved the subjects' running back and forth between 2 lines separated by 20 m. The test began with running at an initial velocity of 8.5 km·h−1, which was increased by 0.5 km·h−1 at every stage (approximately 1 minute in length). The run pace was determined by a sound signal emitted from a stereo system. When the sound was emitted, the subject had to pass or have already passed at least 1 foot over the marked line. An exclusion area was marked 2 m in front of the 20-m lines, and the test ended when the subject was not able to reach this area for 2 consecutive stages. The last stage reached was recorded to represent MAS (km·h−1) and to estimate V[Combining Dot Above]O2max (ml·kg−1·min−1) using the equation described by Léger et al. (15). The literature indicates excellent ICC reliability scores (0.98) for this 20-m shuttle-run test (18).

Statistical Analyses

Standard statistical methods were used for the calculation of the mean values and SDs. Spearman rank correlation coefficients were used to analyze the level of association between each IPAQ-SF category and the health-related fitness variables. A 1-way analysis of variance and Tukey post hoc test were used to compare the health-related fitness variables with the PA levels. A power analysis was used to determine the number of subjects required to detect statistically significant correlations between IPAQ-SF outcomes and the health-related fitness variables. A minimum effect size of 0.19 was assumed based on the lowest coefficient of correlation reported in the literature (14); an alpha of 0.05 and a desired power of 0.95 were also assumed. With these assumptions, the total effective sample size necessary to achieve statistical significance was 349 subjects. Assuming that ∼20% of subjects would not fully comply with instructions or would drop out of the study, 408 subjects were recruited and included in the statistical analyses. The precision of the estimated mean values and mean differences was assessed by 95% confidence intervals. A stepwise linear multiple regression approach was used to identify variables of health-related fitness that could explain the total PA score for weekly energy expenditure (METs). Data were analyzed using SPSS 13.0 (Statistical Product and Service Solutions - SPSS Inc., Chicago, IL, USA). The statistical significance was set at p ≤ 0.05.

Results

The subjects' physical characteristics are shown in Table 1. Table 2 shows data and confidence intervals of the health-related fitness tests for all the subjects.

Table 2
Table 2:
Mean (±SD) and confidence interval of the components of health-related fitness (n = 408).*

Figure 1 shows the amount of METs min·wk−1 for each IPAQ-SF category. The walking PA was 662 ± 418.9 METs min·wk−1, the moderate-intensity PA was 1,514 ± 789.1, and the vigorous-intensity PA was 5,949 ± 2,264.3 METs min·wk−1. The total PA score was 8,125.3 ± 3,472.3 METs min·wk−1.

Figure 1
Figure 1:
Amount of metabolic equivalent task minutes per week (METs min·wk−1) in International Physical Activity Questionnaire–Short Form's (IPAQ-SF's) categories. PA = physical activity.

The correlations between the amount of METs min·wk−1 for each IPAQ-SF category and the components of health-related fitness were weak (Table 3). However, the METs min·wk−1 of walking PA were significantly correlated with the flexibility of the lower back and hamstrings, the muscular endurance of the abdominal and hip flexor muscles, the MAS, and the estimated V[Combining Dot Above]O2max (p < 0.05). The METs min·wk−1 of moderate-intensity PA were also significantly correlated with the flexibility of the lower back and hamstrings, the MAS, and the estimated V[Combining Dot Above]O2max (p < 0.01). In addition, the METs min·wk−1 of vigorous-intensity and total PA score showed a significant correlation with the flexibility of the lower back and hamstrings, the muscular endurance of the abdominal and hip flexor muscles, the muscular endurance of the arm and shoulder extensor muscles, the MAS, and the estimated V[Combining Dot Above]O2max (Table 3).

Table 3
Table 3:
Correlation between the components of health-related fitness and the amount of METs min·wk−1 in IPAQ-SF categories (n = 408).*

Among the 408 subjects evaluated, 17% (n = 73) presented with a low PA level, 38% (n = 159) presented with a moderate PA level, and 44% (n = 176) presented with a high PA level. The subjects with moderate and high PA levels performed better with regard to the flexibility of the lower back and hamstrings compared with the subjects with low PA levels (p < 0.05). In addition, the subjects with high PA levels also performed better on the tests of muscular endurance of the abdominal and hip flexor muscles than did the subjects with low PA levels (p < 0.05), and on the tests of muscular endurance of the arm and shoulder extensor muscles compared with the subjects with moderate PA levels (p < 0.05). The MAS and the estimated V[Combining Dot Above]O2max were greater in the subjects with high PA levels (p < 0.05) compared with both the moderate and low PA level subjects (Figure 2).

Figure 2
Figure 2:
Comparison between the components of health-related fitness tests and International Physical Activity Questionnaire–Short Form's (IPAQ-SF's) physical activity levels. *Significantly different (p < 0.05) from low PA. #Significantly different (p < 0.05) from moderate PA. PA = physical activity.

The stepwise multiple regression model selected 2 independent variables to explain the total PA score for weekly energy expenditure (METs min·wk−1) variance. The flexibility variable explained 28.1% of the shared variance (p = 0.01), whereas the V[Combining Dot Above]O2max variable accounted for an additional 22.3% of the shared variance (p = 0.03).

Discussion

The purpose of this study was to evaluate the relationships between the IPAQ-SF outcomes and the main components of health-related fitness. The main findings were that subjects who had a high PA level also demonstrated greater flexibility, upper-body muscular endurance, MAS, and estimated V[Combining Dot Above]O2max compared with the subjects with moderate and low PA levels. In addition, the METs min·wk−1 from all IPAQ-SF categories were significantly correlated with the flexibility, MAS, and the estimated V[Combining Dot Above]O2max.

Previous studies have investigated the validity of the IPAQ-SF by associating it with V[Combining Dot Above]O2max (8,12,21) and muscular endurance (8). These studies demonstrated significant correlations between these variables and IPAQ-SF outcomes (14). However, it has been postulated that not only muscular endurance and cardiorespiratory fitness but also flexibility and muscular strength are essential components of health-related fitness (1). To the best of our knowledge, this study is the first to verify an association between IPAQ-SF outcomes and a larger group of health-related fitness variables, i.e., flexibility, muscular strength and endurance, and cardiorespiratory fitness. These factors are important because previous evidence has suggested that low flexibility and poor muscular endurance are related to some osteomuscular diseases (2) and several neuromuscular disorders (1,10), respectively.

Our results showed that 44% of the subjects who demonstrated a high PA level had a better performance for the sit-and-reach test (Figure 2). Moreover, the METs min·wk−1 from all IPAQ-SF categories showed a significant association with flexibility (Table 3). These findings indicate that although the IPAQ-SF has been mainly designed to assess the level of cardiorespiratory fitness during the execution of a specific PA, the outcomes of this questionnaire also reflect the level of flexibility of healthy adult men. Additionally, it is relevant to emphasize that in the present study, the flexibility level accounted for 28.1% of the total PA score for weekly energy expenditure variance, whereas the variable V[Combining Dot Above]O2max accounted for the remaining 22.3%. Taken together, these findings suggest that flexibility is an important component of global PA in healthy adult men and it has a relevant contribution to activities of daily living.

Maximum oxygen uptake is one of the most important physiological variables that has been associated with the outcomes of the IPAQ-SF (14). Data from present study corroborated previous studies that found a positive association between IPAQ-SF outcomes and V[Combining Dot Above]O2max. Fogelholm et al. (8) evaluated 951 men aged 21–43 years and verified that their METs min·wk−1 of vigorous-intensity PA were significantly associated with their estimated V[Combining Dot Above]O2max (p < 0.05). Kurtze et al. (12) evaluated 108 young men, 20–39 years of age, and also observed that METs min·wk−1 of vigorous-intensity PA and total PA score were significantly associated with V[Combining Dot Above]O2max (p < 0.01). Similarly, Papathanasiou et al. (21) observed a significant association (p < 0.05) between V[Combining Dot Above]O2max (based on maximal treadmill time) and METs min·wk−1 of vigorous-intensity PA and total PA score in 113 young men (23–30 years of age). Therefore, the findings of present study demonstrated that the estimated V[Combining Dot Above]O2max of healthy adult men was significantly associated with the METs min·wk−1 for all IPAQ-SF categories.

Interestingly, our findings also revealed that V[Combining Dot Above]O2max and MAS were significantly associated with the METs min·wk−1 for the IPAQ-SF categories (p < 0.05). Previous studies proposed that the MAS reflects adaptations in the neuromuscular system related to aerobic capacity, whereas others reported that the V[Combining Dot Above]O2max is mainly dependent on the cardiorespiratory system (4,5). Thus, these data suggest that the IPAQ-SF was able to distinguish subjects with different levels of both V[Combining Dot Above]O2max and MAS, which are considered the main variables associated with central (3) and peripheral system (19) determinants of aerobic fitness, respectively.

With regard to muscular endurance, only 1 study investigated its association with IPAQ-SF outcomes. Fogelholm et al. (8) found a significant association between the METs min·wk−1 of vigorous-intensity PA and muscular endurance (p < 0.05). Similarly, our results demonstrated that subjects with high PA levels performed better on the muscular endurance tests (sit-ups and push-ups) than the subjects with low and moderate PA levels (Figure 2). In addition, significant associations between the muscular endurance tests and METs min·wk−1 of moderate-intensity PA, vigorous-intensity PA, and total PA score were found in this study (Table 3). These findings suggest that IPAQ-SF outcomes also reflect muscular endurance in healthy adult men.

Surprisingly, we did not find any significant associations between muscular strength (hand grip test) and IPAQ-SF outcomes. Our results indicated that although the IPAQ-SF outcomes may be associated with muscular endurance, the weekly energy expenditure of different categories and the PA levels determined by IPAQ-SF were not influenced by muscle strength. It is important to note that we used the same reproducible hand grip protocol used by other studies (18,22,25) to verify muscular strength performance. It has been suggested that hand grip muscular strength may be an indicator of the general level of functional capacity (1). Moreover, the hand grip test has been considered a noninvasive test with low operating costs and easy applicability (1). However, these findings must be examined with caution because the hand grip dynamometer may not necessary reflect the muscular demand of the main activities of daily living.

In conclusion, the present study adds relevant support to the current recommendation advocating for the use of the IPAQ-SF to assess the weekly energy expenditure in different categories and PA levels for large population-based studies. One limitation of this study is that, as in earlier cited studies (8,13,21), these factors were evaluated only in adult men. Thus, our results should not be extended for women, younger men, or older men. Therefore, future studies should verify the relationship between IPAQ-SF outcomes and components of health-related fitness in different populations.

Practical Applications

The lack of PA is one of the main risk factors for chronic degenerative diseases. Conversely, PA has been recommended to reduce the risk of all-cause mortality. Findings of the present study suggest that the outcomes of the IPAQ-SF were related not only with cardiorespiratory fitness but also with flexibility and upper-body muscular endurance in healthy adult men. These findings indicate that IPAQ-SF outcomes reflect the main variables associated with fitness, as proposed by the American College of Sports Medicine. Thus, IPAQ-SF can be used as a practical tool to determine the efficacy of training strategies that aim to improve PA and health levels in large populations.

Acknowledgments

The authors thank all the subjects who participated in this research and Dr. Pedro Hallal, Dr. Nilo Massaru Okuno, and Dr. Flávio Pires for providing helpful comments. C. Silva-Batista holds a Master's degree scholarship from Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) (process: 2011/04242-3). C. Silva-Batista and R.P. Urso contributed equally to the study.

References

1. American College of Sports Medicine Position Stand. The recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness, and flexibility in healthy adults. Med Sci Sports Exerc 30: 975–991, 1998.
2. Baltaci G, Un N, Tunay V, Besler A, Gerceker S. Comparison of three different sit and reach tests for measurement of hamstring flexibility in female university students. Br J Sports Med 37: 59–61, 2003.
3. Bassett DR Jr, Howley ET. Limiting factors for maximum oxygen uptake and determinants of endurance performance. Med Sci Sports Exerc 32: 70–84, 2000.
4. Cao ZB, Miyatake N, Higuchi M, Miyachi M, Ishikawa-Takata K, Tabata I. Predicting VO2max with an objectively measured physical activity in Japanese women. Med Sci Sports Exerc 42: 179–186, 2010.
5. Cao ZB, Miyatake N, Higuchi M, Miyachi M, Tabata I. Predicting VO(2max) with an objectively measured physical activity in Japanese men. Eur J Appl Physiol 109: 465–472, 2010.
6. Craig CL, Marshall AL, Sjostrom M, Bauman AE, Booth ML, Ainsworth BE, Pratt M, Ekelund U, Yngve A, Sallis JF, Oja P. International physical activity questionnaire: 12-country reliability and validity. Med Sci Sports Exerc 35: 1381–1395, 2003.
7. Durstine JL, Thompson PD. Exercise in the treatment of lipid disorders. Cardiol Clin 19: 471–488, 2001.
8. Fogelholm M, Malmberg J, Suni J, Santtila M, Kyrolainen H, Mantysaari M, Oja P. International physical activity questionnaire: Validity against fitness. Med Sci Sports Exerc 38: 753–760, 2006.
9. Haskell WL, Lee IM, Pate RR, Powell KE, Blair SN, Franklin BA, Macera CA, Heath GW, Thompson PD, Bauman A. Physical activity and public health: Updated recommendation for adults from the American College of Sports Medicine and the American Heart Association. Med Sci Sports Exerc 39: 1423–1434, 2007.
10. Jansen M, De Jong M, Coes HM, Eggermont F, Van Alfen N, De Groot IJ. The assisted 6-minute cycling test to assess endurance in children with a neuromuscular disorder. Muscle Nerve 46: 520–530, 2012.
11. Joshi P, Bryan C, Howat H. Relationship of body mass index and fitness levels among schoolchildren. J Strength Cond Res 26: 1006–1014, 2012.
12. Kurtze N, Rangul V, Hustvedt BE. Reliability and validity of the international physical activity questionnaire in the Nord-Trondelag health study (HUNT) population of men. BMC Med Res Methodol 8: 63, 2008.
13. Kurtze N, Rangul V, Hustvedt BE, Flanders WD. Reliability and validity of self-reported physical activity in the Nord-Trondelag Health Study: HUNT 1. Scand J Public Health 36: 52–61, 2008.
14. Lee PH, Macfarlane DJ, Lam TH, Stewart SM. Validity of the International Physical Activity Questionnaire Short Form (IPAQ-SF): A systematic review. Int J Behav Nutr Phys Act 8: 115, 2011.
15. Léger LA, Mercier D, Gadoury C, Lambert J. The multistage 20 metre shuttle run test for aerobic fitness. J Sports Sci 6: 93–101, 1988.
16. Macera CA, Powell KE. Population attributable risk: Implications of physical activity dose. Med Sci Sports Exerc 33: S635–S639; discussion 640–631, 2001.
17. Mader U, Martin BW, Schutz Y, Marti B. Validity of four short physical activity questionnaires in middle-aged persons. Med Sci Sports Exerc 38: 1255–1266, 2006.
18. Marta CC, Marinho DA, Barbosa TM, Izquierdo M, Marques MC. Physical fitness differences between prepubescent boys and girls. J Strength Cond Res 26: 1756–1766, 2012.
19. Noakes TD, Myburgh KH, Schall R. Peak treadmill running velocity during the VO2 max test predicts running performance. J Sports Sci 8: 35–45, 1990.
20. Padilla-Moledo C, Ruiz JR, Ortega FB, Mora J, Castro-Pinero J. Associations of muscular fitness with psychological positive health, health complaints, and health risk behaviors in Spanish children and adolescents. J Strength Cond Res 26: 167–173, 2012.
21. Papathanasiou G, Georgoudis G, Georgakopoulos D, Katsouras C, Kalfakakou V, Evangelou A. Criterion-related validity of the short International Physical Activity Questionnaire against exercise capacity in young adults. Eur J Cardiovasc Prev Rehabil 17: 380–386, 2010.
22. Rhea MR, Alvar BA, Gray R. Physical fitness and job performance of firefighters. J Strength Cond Res 18: 348–352, 2004.
23. Roberts MA, O'Dea J, Boyce A, Mannix ET. Fitness levels of firefighter recruits before and after a supervised exercise training program. J Strength Cond Res 16: 271–277, 2002.
24. Sabia S, Dugravot A, Kivimaki M, Brunner E, Shipley MJ, Singh-Manoux A. Effect of intensity and type of physical activity on mortality: Results from the Whitehall II cohort study. Am J Public Health 102: 698–704, 2012.
25. Visnapuu M, Jurimae T. Handgrip strength and hand dimensions in young handball and basketball players. J Strength Cond Res 21: 923–929, 2007.
26. Wolin KY, Heil DP, Askew S, Matthews CE, Bennett GG. Validation of the international physical activity questionnaire-short among Blacks. J Phys Act Health 5: 746–760, 2008.
Keywords:

flexibility; aerobic fitness; muscular strength; muscular endurance

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