**1.2 General effects of physical activity**

Effects of physical activity can be divided into acute effects and long term effects. The acute effects include physical responses such as increased ventilation and breathing frequency, increased heart rate, stroke volume, systolic blood pressure, body temperature, and reduction in blood lipoproteins and glucose (Bouchard, et al., 2007). The immediate elevations in levels of endorphins, serotonin and dopamine are suggested as a reason why many report a positive impact of physical activity on mood, positive and negative affects

Physical Activity and Exercise in Bulimia Nervosa: The Two-Edged Sword 169

of weekly physical activity among female inpatients across both anorexia nervosa (AN), BN and eating disorders not otherwise specified (EDNOS) compared to non-clinical agematched controls. Despite this difference, the patient sample showed a large heterogeneity when it comes to weekly amount of physical activity. Although a high mean physical activity level, almost 10 percent of the patients were considered physically inactive

Another important aspect with the self report methods used in the studies by Pirke et al. (1991) and Sundgot-Borgen et al. (1998) is the possibility for response bias. Our study (Bratland-Sanda et al., 2010a) discovered that adult inpatient females with longstanding eating disorders, included BN and atypical BN, tended to underreport physical activity when it was compared to objectively assessed physical activity through a motion sensor or accelerometer. This discrepancy between self reported and objectively assessed physical activity was not found among females without eating disorders. We believe that this underreport can be deliberate due to fear of restrictions of the physical activity or fear of needing to increase energy intake. On the other hand, there is a possibility that the patients define and interpret the term "physical activity" different from us as researchers and clinicians. As previously mentioned, the definition of physical activity include all human movement produced by skeletal muscles, and therefore factors such as intensity and/or duration of the physical activity is irrelevant. However, a clinical experience is that patients with eating disorders, including BN, only consider the very vigorous intensity activity to be defined as physical activity or exercise. To these patients, incidental physical activity (i.e. the physical activity performed as part of the daily routine such as household activities such as vacuuming, or walking as a transport activity) does not count as physical activity. This interpretation of the term physical activity was illustrated by the quote of one of our patients participating in the study: *"I'm not physically active – I only go for walks."* (Bratland-Sanda et al., 2010a:91). This patient, diagnosed with BN, reported that she went for walks every day, and these walks lasted approximately one hour each. Despite this, she was convinced that this was not enough to be defined as physically active. This case is an

In a sample of 29 adult female inpatients with longstanding BN, 39% reported to perform aerobic endurance activities only (e.g. running, walking, cycling and swimming), whereas 50% reported to perform both aerobic and non-aerobic activity forms including strength

The motives for being physically active can vary over time and from person to person. The motives are influenced by factors such as age, BMI, mood, personality, knowledge and attitudes (Dishman, Sallis, & Orenstein, 1985). The motives can be extrinsic, intrinsic or a combination of these. In females from both the general population and from eating disordered populations, weight control and/or regulation are perceived as very important reasons for physical activity and exercise (Furnham, Badmin, & Sneade, 2002; Mond & Calogero, 2009). Other motives and reasons for physical activity and exercise are physical fitness, health, well-being, regulation of mood and affects, and socializing (Cash, Novy, &

Bratland-Sanda et al. (2010a) found no differences in importance of exercise as a weight regulator between patients with eating disorders and age-matched non-clinical controls.

(Bratland-Sanda, 2010).

training (see Figure 1).

**2. Motivation for exercise in BN** 

Grant, 1994; Plonczynski, 2000).

example of how the underreporting can be unintentional.

(Martinsen, 2005). These effects are temporary, but persistent physical activity behavior will among others positively affect circulatory and respiratory factors, metabolism, bone mass, and regulation of blood glucose (Pedersen & Saltin, 2006). Physical activity has also shown positive impact on psychological factors such as sleep quality, self esteem, self efficacy and well-being (Meyer & Broocks, 2000).

## **1.3 Physical activity recommendations**

The most recent updates were published by American College of Sports Medicine (ACSM) and The American Heart Association published in 2007 (Haskell et al., 2007). These recommendations state that healthy adults need to perform at least 5 x 30 minutes of moderate intensity physical activity or 3 x 20 min of vigorous intensity physical activity per week to maintain health. For additional health benefits, up to 60 minutes of moderate-tovigorous intensity physical activity per day is recommended. In addition, the ACSM (2009) published guidelines regarding strength training which state that strength training should be performed at least twice per week with different loading depending upon the main goal of the strength training. For example, individuals who want to increase maximum muscle strength need to perform fewer repetitions with higher loading (e.g. four repetitions of 90% of 1 repetition maximum, 1RM ) compared to individuals whose main goal is hypertrophy (e.g. 8-12 repetitions of 80% of 1RM).

For individuals who are overweight or obese, the recommendations for healthy adults are insufficient to achieve significant weight loss. With moderate, but not severe, nutritional restrictions it is possible for obese individuals to achieve adequate weight loss, and maintenance of this weight loss, with about 250 minutes per week of moderate intensity physical activity (Donnelly et al., 2009). Other studies have suggested that the duration of the physical activity can be reduced with increased intensity, but there is a need for studies to examine this by randomized controlled trials with follow up design.

In 2009, Handbook of Activity was published by the Norwegian Directorate of Health (Bahr, 2009). In this handbook, recommendations for physical activity in prevention and treatment of a list of different diseases are provided. Unfortunately, as of today there are inadequate levels of knowledge regarding the effects of physical activity in prevention and treatment of eating disorders, therefore eating disorders are not included in this handbook. Hopefully, the level of knowledge will increase within the next years, and it will then be easier to make recommendations for physical activity in treatment of the different types of eating disorders.

#### **1.4 Physical activity among patients with BN**

Several studies have examined physical activity among females with and without eating disorders including BN. Pirke et al. (1991) found no differences in minutes per day of physical activity reported through a physical activity diary. However, the lack of difference can be due to a type II error because the sample size was quite small (BN patients, n=8, controls, n=11). This lack of difference in weekly duration of physical activity among BN patients and controls was also found in Sundgot-Borgen et al. (1998). This study included a larger sample size compared to Pirke et al. (1991), however use of parametric statistics on non-parametric data can have influenced on whether the statistical analysis showed significance differences or not. In a study by our research group, we assessed physical activity both objectively through an accelerometer, and through self report by a seven-days physical activity diary (Bratland-Sanda et al., 2010a). We discovered a mean higher amount

(Martinsen, 2005). These effects are temporary, but persistent physical activity behavior will among others positively affect circulatory and respiratory factors, metabolism, bone mass, and regulation of blood glucose (Pedersen & Saltin, 2006). Physical activity has also shown positive impact on psychological factors such as sleep quality, self esteem, self efficacy and

The most recent updates were published by American College of Sports Medicine (ACSM) and The American Heart Association published in 2007 (Haskell et al., 2007). These recommendations state that healthy adults need to perform at least 5 x 30 minutes of moderate intensity physical activity or 3 x 20 min of vigorous intensity physical activity per week to maintain health. For additional health benefits, up to 60 minutes of moderate-tovigorous intensity physical activity per day is recommended. In addition, the ACSM (2009) published guidelines regarding strength training which state that strength training should be performed at least twice per week with different loading depending upon the main goal of the strength training. For example, individuals who want to increase maximum muscle strength need to perform fewer repetitions with higher loading (e.g. four repetitions of 90% of 1 repetition maximum, 1RM ) compared to individuals whose main goal is hypertrophy

For individuals who are overweight or obese, the recommendations for healthy adults are insufficient to achieve significant weight loss. With moderate, but not severe, nutritional restrictions it is possible for obese individuals to achieve adequate weight loss, and maintenance of this weight loss, with about 250 minutes per week of moderate intensity physical activity (Donnelly et al., 2009). Other studies have suggested that the duration of the physical activity can be reduced with increased intensity, but there is a need for studies

In 2009, Handbook of Activity was published by the Norwegian Directorate of Health (Bahr, 2009). In this handbook, recommendations for physical activity in prevention and treatment of a list of different diseases are provided. Unfortunately, as of today there are inadequate levels of knowledge regarding the effects of physical activity in prevention and treatment of eating disorders, therefore eating disorders are not included in this handbook. Hopefully, the level of knowledge will increase within the next years, and it will then be easier to make recommendations for physical activity in treatment of the different types of eating disorders.

Several studies have examined physical activity among females with and without eating disorders including BN. Pirke et al. (1991) found no differences in minutes per day of physical activity reported through a physical activity diary. However, the lack of difference can be due to a type II error because the sample size was quite small (BN patients, n=8, controls, n=11). This lack of difference in weekly duration of physical activity among BN patients and controls was also found in Sundgot-Borgen et al. (1998). This study included a larger sample size compared to Pirke et al. (1991), however use of parametric statistics on non-parametric data can have influenced on whether the statistical analysis showed significance differences or not. In a study by our research group, we assessed physical activity both objectively through an accelerometer, and through self report by a seven-days physical activity diary (Bratland-Sanda et al., 2010a). We discovered a mean higher amount

to examine this by randomized controlled trials with follow up design.

well-being (Meyer & Broocks, 2000).

(e.g. 8-12 repetitions of 80% of 1RM).

**1.4 Physical activity among patients with BN** 

**1.3 Physical activity recommendations** 

of weekly physical activity among female inpatients across both anorexia nervosa (AN), BN and eating disorders not otherwise specified (EDNOS) compared to non-clinical agematched controls. Despite this difference, the patient sample showed a large heterogeneity when it comes to weekly amount of physical activity. Although a high mean physical activity level, almost 10 percent of the patients were considered physically inactive (Bratland-Sanda, 2010).

Another important aspect with the self report methods used in the studies by Pirke et al. (1991) and Sundgot-Borgen et al. (1998) is the possibility for response bias. Our study (Bratland-Sanda et al., 2010a) discovered that adult inpatient females with longstanding eating disorders, included BN and atypical BN, tended to underreport physical activity when it was compared to objectively assessed physical activity through a motion sensor or accelerometer. This discrepancy between self reported and objectively assessed physical activity was not found among females without eating disorders. We believe that this underreport can be deliberate due to fear of restrictions of the physical activity or fear of needing to increase energy intake. On the other hand, there is a possibility that the patients define and interpret the term "physical activity" different from us as researchers and clinicians. As previously mentioned, the definition of physical activity include all human movement produced by skeletal muscles, and therefore factors such as intensity and/or duration of the physical activity is irrelevant. However, a clinical experience is that patients with eating disorders, including BN, only consider the very vigorous intensity activity to be defined as physical activity or exercise. To these patients, incidental physical activity (i.e. the physical activity performed as part of the daily routine such as household activities such as vacuuming, or walking as a transport activity) does not count as physical activity. This interpretation of the term physical activity was illustrated by the quote of one of our patients participating in the study: *"I'm not physically active – I only go for walks."* (Bratland-Sanda et al., 2010a:91). This patient, diagnosed with BN, reported that she went for walks every day, and these walks lasted approximately one hour each. Despite this, she was convinced that this was not enough to be defined as physically active. This case is an example of how the underreporting can be unintentional.

In a sample of 29 adult female inpatients with longstanding BN, 39% reported to perform aerobic endurance activities only (e.g. running, walking, cycling and swimming), whereas 50% reported to perform both aerobic and non-aerobic activity forms including strength training (see Figure 1).
