There is a wide consensus on the benefits of physical activity in health and in disease [1]. Accurate assessment of physical activity is important in determining the risk for cardiovascular disease, stroke, type 2 diabetes, cancer and obesity in developing countries [2, 3]. One viable strategy for stemming the rising incidence of chronic diseases in developing countries is to increase the population's level of physical activity [3, 4], but epidemiological studies on physical activity remain sparse in sub-Saharan Africa, due to the lack of culturally relevant physical activity tools in indigenous African languages and an appropriate system for monitoring [5].

The International Physical Activity Questionnaire (IPAQ) was developed as an instrument for cross-national assessment of physical activity and for standardizing measures of health-related physical activity behaviors of population in many countries and in different socio-cultural contexts [6, 7]. Both the long (31-item) and the short (7-item) versions of this instrument, which elicits information on physical activity over the 'last seven-day' period, have been used to compare physical activity behaviors among and between populations [6, 8–10]. The short form of IPAQ (IPAQ-SF) has been recommended for population prevalence studies, where time is limited, because it is easier and more feasible to complete than the long form [6].

The IPAQ has been translated into many languages and extensively tested in many countries around the world, except in sub-Saharan Africa [7, 11–15]. In order to make the IPAQ applicable for research among non-English speaking populations in sub-Saharan Africa, it needs to be translated, culturally adapted and properly evaluated for psychometric properties. In sub-Saharan Africa where the sociocultural and physical environments are distinct from those of other parts of the world [16], mere translation of the IPAQ may be insufficient to maintain content validity, as important cultural differences can produce a translated version that lacks experiential and conceptual equivalence [17].

Culturally adapting the IPAQ, rather than developing a new physical activity questionnaire, is economical and it may facilitate future comparisons among populations. In West Africa, Hausa is a widely spoken language with over 50 million native speakers and 15 million non-native speakers in Northern Nigeria, the Republic of Niger, Northern Cameroon and Ghana [18]. The purpose of this study was to translate and cross-culturally adapt the English IPAQ-SF, and to evaluate aspects of the validity and reliability of the Hausa-translated and culturally adapted version of the IPAQ-SF.

This study translated and cross-culturally adapted the English IPAQ-SF, and examined aspects of the validity and reliability of the Hausa-IPAQ-SF in Nigeria. The results indicated that Hausa IPAQ-SF had acceptable metric properties for assessing physical activity in healthy adults.

Participants in the pretesting of the Hausa IPAQ-SF misunderstood the question on "walking to travel from place to place" to mean walking to travel out of town rather than for recreation and for transportation to services and destinations as implied on the original English IPAQ-SF. Misunderstanding of the transportation domain item may be attributed to the distinct infrastructural pattern and transportation habit of the African population. Unlike in many countries in North America, Australia and Europe where leisure time physical activity and recreational walking are prevalent [9, 25–27], walking is not traditionally associated with recreation in African societies. Active walking may even be erroneously perceived as a sign of being socioeconomically disadvantaged among the urban African elites.

We found higher concurrent validity of the Hausa IPAQ-SF than that reported in a study that directly compared the long and short versions of IPAQ in one language in 12 countries (ρ = 0.83-0.92 vs ρ = 0.51 - 0.64) [6]. Perhaps a better concurrent validity was found in the present study because, unlike in the 12-country study, different languages of only the short IPAQ were compared. However, consistent with previous studies where comparisons of IPAQ data were made with accelerometer monitors [15, 28, 29], we found higher correlation value for the Hausa IPAQ-SF with vigorous intensity activity than with moderate activity and walking. This finding therefore affirms an earlier report that shows the IPAQ-SF to be more sensitive to intense physical activity than moderate and low intensity activities [12].

In the absence of objective criterion standards for evaluating an absolute estimate of physical activity, the consistency of items on IPAQ with variables known to be related to physical activity such as body mass index (BMI), blood pressure, heart rate, indicators of lipid and glucose metabolism, and fitness index have been used as important validation characteristics [12, 13, 28], referred to as indirect or construct validity [13, 28, 30]. Poor construct validity of the Hausa IPAQ-SF in the present study is indicated by a weak, albeit significant, correlation only between rate pressure product as an index of cardiorespiratory fitness index and sitting time (Min week^-1) (ρ = 0.21). Significant but tenuous correlation between time spent in sitting and rate pressure product implies that higher sitting time as measured on the Hausa IPAQ-SF is related to poor cardiorespiratory fitness (higher RPP indicates lower cardiorespiratory fitness).

The poor relationship between cardiorespiratory fitness and total physical activity, vigorous activity, moderate activity and walking is inconsistent with those of previous studies that reported weak but significant correlations between indices of cardiorespiratory fitness and time spent in vigorous-intensity activity [12, 13, 31, 32], moderate-intensity activity [28] and total physical activity [12, 13, 28]. Perhaps the contrasting finding between the present study and the previous ones is attributable to the disparate measures of cardiorespiratory fitness utilized. In the present study, RPP as the index of cardiorespiratory fitness incorporated resting heart rate and blood pressure unlike others that utilized submaximal heart rate derived from response to work load as the index of cardiorespiratory fitness [12, 13, 28]. It has been documented that heart rate response to submaximal workload estimates cardiorespiratory fitness or VO₂max better than resting heart rate [23].

The reproducibility of the Hausa IPAQ-SF evidenced by substantial agreement for vigorous (ICC = 0.73) and total physical activity (ICC = 0.61), moderate agreement for walking (ICC = 0.56), and sitting activities (ICC = 0.56) and by fair agreement for moderate activity (ICC = 0.33) is similar to those of other studies [12, 33]. A study on a Nordic population reported substantial to almost perfect correlations for vigorous activity and sitting, but similar fair correlation (ICC = 0.34) for moderate activity on IPAQ-SF [12]. Another study that assessed the reliability of four physical activity measures including the IPAQ short form in an Australian population found ICC for the questions on moderate activities to be the lowest, ranging from poor to fair agreement (0.16-0.44) [33]. Papathanasiou et al. [34], in a population of Greek young adults found weaker ICC (0.76) for moderate physical activity compared to walking (ICC = 0.78), vigorous (ICC = 0.88) and total physical activity (ICC = 0.92) on the Greek version of IPAQ-SF.

Relatively low reliability for moderate intensity activities compared to vigorous intensity activities as found in the present study may be explained by the low salience nature of moderate activities as previously hypothesized [35]. It is plausible that the time spent in moderate physical activities may be incidental and not easily remembered by participants in the present study. Structured vigorously physical activities like sports and exercise can be more easily recalled compared to some vaguely defined moderate physical activity like "carrying light load" or "multiple household tasks at once" as indicated on the IPAQ-SF [34]. Overall good to acceptable reliability coefficients for all items on the Hausa IPAQ-SF indicate that the instrument is reproducible and internally consistent and is comparable to the findings in previous studies [12, 33, 34].

Our finding of meaningfully higher reliability coefficient for vigorous intensity activity among men than women is not surprising, because the participants who are men also reported spending more time in all physical activity categories except in sedentary time than the women. Consistently, men have been found to be more physically active than women in a Nigerian population [36]. It is therefore plausible for men in Nigeria to be more consistent in response to items that pertained to intense physical activity than to sedentary activity. Similarly, no statistical significance differences were found in the socioeconomic-based analyses, but participants with higher socioeconomic status as indicated by education (high school education) and employment (those employed) were more physically active than those with low socioeconomic status, and more consistent in their response to questions on vigorous and total physical activity. While it may be difficult to draw any definite conclusion from these findings, they reflect the potential influence of gender and socioeconomic status on physical activity assessment.

Direct comparison of our findings with previous studies should be made with caution, because in the majority of these studies, the accelerometer was utilized as a common objective criterion standard to validate the IPAQ [14, 15, 28]. In low-income developing countries, the availability and cost of accelerometers remain important research issues [6], and poor receptivity to wearing accelerometers for physical activity assessment has been reported in a sample of urban African adults [5]. Furthermore, the divergent reports on construct validity may suggest that a single measure of aerobic capacity may not be sufficient to determine the construct validity of the physical activity questionnaire. In order to prevent spurious validity of physical activity questionnaires, the selection of comparison instruments that can accurately assess the construct or related dimension measured by the questionnaire has been advocated [37].

Non-utilization of a physical activity diary or any objective measure as a criterion standard to evaluate the validity of the Hausa IPAQ-SF is one limitation of the present study. The choice and availability of appropriate criterion measures are particular issues of concern for the validation of physical activity questionnaires in the low-income countries of Africa [5, 38]. In addition, the generalizability of this study may be limited due to the convenience sampling technique utilized and the relative low sample size. Also, the majority of participants were government employees and students with potential higher comprehension and recall ability than may be found in the general population. However, recruitment from diverse workplaces and neighborhoods allowed for a sample with reasonable heterogeneity in age, educational level and ethnic backgrounds.

Despite these limitations, the study demonstrated the feasibility of using the Hausa IPAQ-SF to reliably collect physical activity data in a diverse segment of the Nigerian population. This is the first study in an African country to explore the cultural adaptation and translation of the IPAQ, warranting the need for further validation studies of the Hausa version of IPAQ-SF in other African populations. However, because some of the participants in the present study required assistance to complete the survey, participants in any future national studies in Africa would need to be asked about their ability to independently complete the Hausa IPAQ-SF.

In conclusion, our results indicate that the Hausa IPAQ-SF has acceptable concurrent validity and test-retest reliability for assessing vigorous intensity, walking, sitting and total physical activity in Nigerian adults. Moderate intensity activity demonstrated almost perfect concurrent validity, but only fair test-retest reliability. The construct validity of Hausa IPAQ-SF provided poor agreement with the rate pressure product and with the BMI, reflecting the need for further assessment in a large sample with objective physical activity and fitness measures, such as the accelerometer and VO₂Max.