## 3 Results and Discussion  
When considering the years of publication, an evident increase in papers on the focused topics of interest was observed. Until the beginning of the 21 st century, there is no continuity on production. From 1978 (lower limit defined during the analysis) to 2006, only 14 articles were published (28%). In the last 10 years (from 2007 to 2016), a mean of more than three publications per year (M = 3.1) was evidenced, with two peaks during 2011 and 2014 with a mean of 5.5 selected articles (Figure 1).  
Regarding the origin of the published papers, the results evidenced a wide diversity of interest areas, as previously listed. Up to 22 journals have been published on the topics investigated. Journals with a greater number of publications were as follows: International Journal of the History of Sport with three articles and Applied Ergonomics, Journal of Sport Management and Managing Leisure (now Managing Sport and Leisure) with two papers each. These nine publications represent more than a third (40.90%) of the journals on the subject studied (Table 2).  
\begin{table}
\begin{tabular}{l c} \hline \hline  & **Number of Publications** \\
**Journal Title** & **per Journal** \\ \hline The International Journal of the History of Sport & 3 \\ \hline Applied Ergonomics & 2 \\ Journal of Sport Management & \\ Managing Leisure (now: Managing Sport and Leisure) & 1 \\ \hline ACSM’s Health \& Fitness Journal \\ Acta Astronautica & \\ Current Sports Medicine Reports & \\ European Business Review & \\ European Journal of Cultural Studies & \\ European Journal of Marketing & \\ Expert Systems with Applications & \\ Gender, Place and Culture: A Journal of Feminist Geography & \\ Human Resource Management Journal & 1 \\ International Journal of Precision Engineering and Manufacturing & \\ International Journal of Sports Marketing and Sponsorship & \\ Journal of Beijing Sport University & \\ Journal of Sport History & \\ Perceptual and Motor Skills & \\ Presence: Teleoperators and Virtual Environments & \\ Scientia Iranica & \\ Social Marketing Quarterly & \\ Sport Science Review & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Journal titles and number of related publications.  
Figure 1: Number of publications by year.  
A geographical analysis may also be as enlightening following some sample studies encountered in literature, mostly focused on European [25] and North American [26] environments and their revenues, cash flows and profitability.  
Regarding the geographical distribution from which the selected studies have been performed (both first author and co-author), the most active academics have been in Europe with 41.57% (22 articles) of the total sample assessed, followed by the Asia-Pacific area, with 33.96% (n = 18) and North America, with 20.75% (n = 11). The lowest representation was in the Middle East, with 3.77% (n = 2). No publication matched the established criteria for Africa (including an association for the Middle East and North Africa (MENA) area, as unified by the descriptors for the northern part of the continent) or Latin America (Table 3).  
The European robust performance, but above all evidently spread in all the continent and confirmed by sectoral investigation, led in first position by the UK with annual revenue of 6.1 billion dollars/year [2,6]. Even in the Asia-Pacific area there is a correlation with the investigation's findings; these countries are home to maturing industries and current growth, and main examples are found in cities such as Beijing, Shanghai, Kuala Lumpur and Jakarta. For North America, this analysis was represented exclusively by the US; the latest annual revenue obtained was 27.6 billion dollars/year, accounting for more than 35,000 facilities among all states [2]. No criteria matched studies from Canada. Despite conflicts in several MENA countries, there is a demand for fitness, as consumers seek to exercise and reap the benefits of an active lifestyle. Recently, successful international fitness operators have expanded their operations into this area.