Analysis of the Energy Expenditure of Water–Based Activities and of their effects on physical capacities and body composition after training

BACKGROUND A strong relationship between regular physical activity and health has been clearly established (Pate et al., 1995; US Department of Health and Human Service, 1996; Haskell et al., 2007). Particularly, some components of physical fitness such as cardiovascular endurance, muscular strength and endurance, flexibility, balance and a correct body composition seem to be strong health-related variables. The guidelines of the American College of Sport Medicine (1998; 2009) place a strong emphasis on these components of physical fitness and underline that, given the specific nature of exercise adaptation, a “well rounded” training program should consist of aerobic, resistance and flexibility exercises. The existing evidence concerning exercise prescription also underlines that the selection of an appropriate physical activity (in terms of exercise mode, intensity, frequency and duration) is essential in order to obtain actual training effects, to avoid injuries and to ensure exercise adherence. Water based activities (WA), in recent years, gained popularity and are considered as one of the possible alternatives among the traditional physical activities for well-being and health. These activities are performed by different types of subjects: young and adult healthy individuals who regularly take part in recreational training but also individuals with low levels of physical fitness (such us elderly people, subjects with orthopaedic or neurological disabilities, athletes with surgically, or otherwise, treated injuries and obese persons). Even if the physiological responses and training effects of WA have been investigated by several authors in different populations (e.g. Campbell et al., 2003; Takeshima et al., 2002; Colado et al., 2008; Colado et al., 2009 a and b; Barbosa et al., 2009), the accurate assessment of intensity during “water exercises” performed without specific equipment is not a simple task, expecially in a field setting, during water based classes. Thus, at present, there are still no sufficient tools to define the work intensity, to plan a training program adapted to different subjects and to monitor and verify the training effects of WA. AIM The aim of this doctoral Thesis is therefore to better define the role of water based activities for public health and to better understand whether these physical activities can be considered a “well rounded” training program according to the American College of Sport Medicine recommendations. The present work includes three studies. •The aim of the first study was to make a further step in the comprehension of the exercise intensity (EI) during water based activities by: i) measuring the exercise intensity of the most common water based exercises (WE) at different movement frequencies (f1 = 1.8-2.0 Hz; f2 = 2.0-2.2 Hz; f3 = 2.2-2.4 Hz) and at a standardize movement’s amplitude; ii) measuring EI during a combination (MIX) of these WE. •The aim of the second study was to determine the effectiveness of a nine weeks aquatic training program of known intensity (EI) on aerobic capacity, muscle strength, flexibility, balance and body composition, in healthy young adult women. •The aim of the third study was to compare different measurement techniques to estimate physical activity intensity during water based activity. STRUCTURE OF THE THESIS This Thesis is divided in four chapters. The first chapters includes a general introduction to the problem (section 1.1), a brief summary of the aquatic environment characteristics (section 1.2) and a section dedicated to the more important physiological adjustment to head-out immersion (section 1.3). In this first part of Thesis, the water based activities are also presented (section 1.4) and classified (section 1.5) in order to better define the characteristics of the water fitness exercises. The related scientific background is thus reviewed and discussed (section 1.6). Finally, the assessment of exercise intensity is discussed in general terms (section 1.7) as well as in regard to the physical activity performed in water (section 1.8). At the and of this chapter, the main aims of the three studies are schematically reported (section 1.9). In the second chapter, the study entitled “Exercise Intensity of head-out water based activities (water fitness)” is presented. After a brief introduction (section 2.1), the materials and methods (section 2.2) are explained in detail and the results are illustrated (sections 2.3). Finally, the results are discussed (section 2.4 and 2.5). In the third chapter, the study entitled “Water-based training enhance both physical capacities and body composition in healthy young adult women” is presented. After a brief introduction (section 3.1), the materials and methods (section 3.2) are explained in detail and the results are illustrated (sections 3.3). Finally the results are discussed (section 3.4 and 3.5). In the fourth chapter, the study entitled “Monitoring intensity during water based activities (head-out immersion): a comparison among different measurement techniques” is presented. After a brief introduction (section 4.1), the materials and methods (section 4.2) are explained in detail and the results are illustrated (sections 4.3). Finally the results are discussed (section 4.4 and 4.5). At the end of this Thesis, a general discussion of the results obtained in the three studies is reported to better define the role of water based activities for public health and to better understand whether these physical activities can be considered a “well rounded” training program (according to American College of Sport Medicine recommendations), in line with the main aim of this work.