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Physical fitness: a pathway to health and resilience.

... physical fitness is not only one of the most important keys to a healthy body; it is the basis of dynamic and creative intellectual activity.

President-Elect John F. Kennedy (1)

Various groups representing a number of different perspectives (for example, operational, architectural, community, institutional, and individual resilience) have defined the term resilience. For the purposes of this article, we define resilience as the ability to withstand, recover, and grow in the face of stressors and changing demands. (2)

In recent reviews and papers on resilience, one factor that continues to appear as promoting and/or conferring resilience is physical fitness (3,4) and regular physical activity. (5-7) Thus, we focus on the role of physical fitness in overall individual resilience. The benefit of physical fitness on resilience is in part based on the recognition that physical fitness, achieved through physical activity and/or regular exercise, can induce positive physiologic and psychological benefits, protect against the potential consequences of stressful events, and prevent many chronic diseases. (8-11) After a brief historical overview of the health-promoting effects of exercise and physical activity, the following topics are discussed: the concept of hardiness and mental toughness and how they relate to resilience and physical fitness; how physical fitness promotes resilience; the clinical implications of a sedentary lifestyle; and the relevance of physical fitness and resilience to Army Medicine's Performance Triad. Throughout this article, the terms physical activity and exercise are used interchangeably, depending on the literature, recognizing that exercise represents a planned, structured, and regular form of physical activity.

HISTORICAL OVERVIEW

The quest for physical fitness has been unremitting, however, its importance and application have changed and/ or transitioned over time with both high and low points. Hunting and gathering for survival were the initial impetus for fitness, which was later followed by the recognition that selected physical movements and activities were important for developing the body and preventing and curing diseases. (12-14) In fact, the importance of regular exercise and physical activity has been touted for over 7,000 years. (12,13) In China, the philosophical teachings of Confucius encouraged participation in regular physical activity, as physical inactivity was recognized as associated with certain diseases. (12) The Chinese developed many perspectives on how to achieve and maintain health, and they deemed exercise essential for increasing strength, prolonging life, preventing and curing diseases, and minimizing the accumulation of fat. (12) Quigong, Cong fou (later Kung Fu), and Tai-Chi were some of the gymnastic/movement forms developed in China sometime around 3,000 BC. (12) Among the Greeks, Herodicus (circa 450 bc) was the first to promote physical activity, and he even considered exercise a form of medicine. Nonetheless, Hippocrates is usually considered the father of exercise and medicine. (13) These 2 Greeks were followed by Galen (129-210 ad) (15) who was perhaps the most advanced, as he wrote not only about when to exercise, but he also described various types of exercises, identified qualities of exercise, specific places to exercise, and factors to think about prior to exercise. (13) Although the importance of exercise and physical fitness diminished during various periods of time, such as after the fall of the Roman empire when the church became the dominant influence, (16) during the period of industrialization, (12) and notably during the 1920s (often called the Roaring Twenties) when relaxation and enjoyment were key. (12) However, the importance of exercise remains widely recognized. It is interesting to reflect on the comment of Edward Stanley, the 15th Earl of Derby, who stated in an address at Liverpool College on December 20, 1873 that:

   Those who think they have not time for bodily exercise
   will sooner or later have to find time for illness. (14)


It is discouraging to realize we have made little progress over the centuries.

PERSONALITY TRAITS/ATTRIBUTES ASSOCIATED WITH RESILIENCE

Although the term resilience, as it is used today, emerged from work on children living under conditions of deprivation, (17-20) it is now applied to diverse disciplines (5-7) and populations. (21-24) Identifying how and why some individuals are seemingly able to bear up, and sometimes thrive, under adverse conditions with no observable negative physical or psychological outcomes, is a continuous quest. (5-7,25-33) Personality traits associated with resilience include hardiness and mental toughness. (9,34-46) The term hardiness, as considered by Kobasa et al, (34,37-43) was typified by "interrelated orientations of commitment (vs alienation), control (vs powerlessness), and challenge (vs threat)." (41) This original characterization was later refined by Maddi, (11) who proposed that hardiness is an attitude (or set of attitudes) and personality trait that helps an individual restructure stressors into growth opportunities rather than allowing them to be or become catastrophes.

Bartone et al (47,48) developed the dispositional hardiness scale to assess hardiness, and this scale has been used in a number of studies to relate hardiness characteristics in persons exposed to challenging occupations and experiences. (45,49-52) Bonanno (53) noted that hardiness is one of the pathways to resilience. Crust et al (36) developed the model of mental toughness by applying the traits of hardiness to reflect the unique demands of sports and exercise; the trait of confidence was added to control, commitment, and challenge. (35,36,44,46,54,55) As noted by Crust et al (36):

   Mentally tough individuals are considered to be competitive,
   resilient to errors or stress, and have high self-confidence
   and low anxiety.


The literature clearly shows that both hardiness and mental toughness are highly related to resilience. (28,56-58) In addition to the personality traits of hardiness and mental toughness, other psychological attributes and social-cognitive variables have been associated with resilience, including self-esteem, self-efficacy and motivation. (20,21,59-62) How do these closely associated traits or attributes relate to physical fitness and physical activity?

PERSONALITY TRAITS/ATTRIBUTES ASSOCIATED WITH PHYSICAL FITNESS

Interestingly, regular physical activity and aerobic fitness have been shown to be associated with specific personality traits and psychological attributes (63-72) associated with resilience. For example, anxiety and depression are inversely related to maximal aerobic capacity, a primary indicator of physical fitness. (73,74) Moreover, our unpublished data show a significant positive association between aerobic capacity and hardiness (r = 0.24), and an inverse relation with perceived stress (r = -0.26) and trait anxiety (r = -0.17). Of note, Skirka et al (10) reported significantly higher hardiness scores, less perceived stress, and fewer psychological symptoms in varsity college athletes than college nonathletes, which further supports a strong association between regular exercise, aerobic fitness, and hardiness. Furthermore, mental toughness, the personality trait associated with athletes and athletic competition, has been shown to mitigate the relationship between high stress and depressive symptoms. (57)

Two determinants of physical activity, self-esteem and self-efficacy, be they enduring traits or modifiable attributes, are essential for resilience. (65,66,75) Self-efficacy generally reflects how self-confident a person is with regard to undertaking a particular action under challenging situations, (67,72,76,77) and self-esteem signifies ones sense of self-worth or personal value. (68) Multiple studies have shown that children and young adults who participate in regular exercise score higher on measures of self-esteem and self-efficacy (67,70-72,76,78-80) and competitiveness (81) compared to sedentary, untrained controls. Moreover, these two attributes are improved through regular physical activity. (69,72) Netz et al (72) conducted a meta-analysis of 36 studies examining how physical activity interventions affected well-being in healthy adults. Moderate intensity aerobic exercise was shown to be most beneficial and had a strong effect on self-efficacy, in addition to conferring improvements in aerobic capacity and strength. Ekeland et al (69) likewise conducted a systematic review of 12 studies to assess how exercise affected self-esteem in children and young people. They concluded that exercise has positive short-term effects on self-esteem and that it might be an important strategy for improving self-esteem. Interestingly, one hypothesis as to how physical activity enhances self-efficacy and self-esteem is that it requires the application of self-management strategies (eg, thoughts, goals, plans, and acts) to achieve a goal. (76)

Self-management strategies require commitment, control, and motivation, and although each strategy is important, motivation appears to be key in terms of regular physical activity. (70,78,82-85) Research has shown that motivation is very important with regard to commencing and maintaining participation in regular physical exercise. (76,84) According to the literature, motivation is some force or stimulus that leads an individual to undertake a particular task or activity in which they have a specific objective or derive personal meaning. (78,82,83) Overall, these studies strongly suggest that personality traits (hardiness and mental toughness) and other attributes (self-esteem, self-efficacy, motivation, self-management strategies) may contribute to the buffering effect of physical fitness and how fitness confers resilience. Further, one must be motivated to be committed, and possess self-efficacy and self-esteem to accept a challenge. Clearly, strong relationships exist between and among hardiness or mental toughness, self-efficacy, self-esteem, and motivation; all essential resources for resilience, and all associated with physical fitness.

PHYSICAL FITNESS AND STRESS RESILIENCE

That physical fitness is essential for health and well-being is not in question, as noted in the earlier historical overview. However, scientific data documenting the essentiality of physical activity for health did not emerge until the late 1800s and early 1900s when epidemiological studies demonstrated that sedentary persons were more likely to have coronary heart disease than those who led active lifestyles. (16,86-90) Since those first studies, the literature has become replete with evidence that physical fitness and regular exercise confer resilience and serve as a resistance resource in a variety of ways, including blunting stress reactivity in response to both physical and psychosocial stressors, conferring multiple physiologic and psychological benefits, serving as a buffer against stress, and protecting against stress-related disorders and many chronic illnesses. (57,74,78,91-95) A conceptual model of the personality traits and attributes associated with physical fitness and resilience is presented in the Figure.

Physical Fitness Blunts Stress Reactivity in Response to Both Physical and Psychosocial Stressors: Physiologic and Psychological Benefits

The 2 main neuroendocrine/neural systems that mediate the stress response are the hypothalamic-pituitaryadrenal axis, with the resultant release of cortisol, and the sympathetic nervous system, which releases the catecholamines epinephrine (adrenaline) and norepinephrine. Activation of these stress systems mediates the fight or flight response, which entails the rapid mobilization of energy from storage sites to critical muscles and the brain (getting one ready for action, increasing alertness/arousal). Moreover, increased heart rate, blood pressure, and breathing rate facilitate the rapid transport of nutrients and oxygen to relevant parts of the body. Together, these stress systems orchestrate the physiologic and behavioral adaptations to stress. However, chronic activation can lead to dysregulation of multiple physiologic and behavioral systems, leading to maladaptive stress responses, including anxiety and depression. (96,97) Physical fitness and aerobic fitness have been related to a reduction in stress reactivity, physiologically and psychologically, for both physical and mental/psychosocial stress. (65,98-107)

Interestingly, neuroendocrine and physiologic responses to exercise at the same absolute workload are significantly lower in physically fit than unfit persons. (108-111) Additionally, physically active people show reduced sympathoadrenal reactivity to physical stressors. (109,110) When untrained persons are enrolled in a regular exercise program for 8-12 weeks, their response to the same physical stress prior to beginning exercise training is significantly higher than after the training. (112) Thus, when trained and untrained persons have to work at the same rate, the untrained person will experience significantly more stress than someone who is physically fit and aerobically trained. (108-110) Therefore, the higher the level of aerobic fitness, the greater the ability to tolerate high workloads and be minimally stressed by low ones.

Physical training also appears to confer protection against nonphysical stressors, mental and/or psychological. (98,111,113,114) Rimelle et al (115) documented significantly lower cortisol and heart rate responses to psychosocial stress in trained men compared to untrained men. Moreover, significantly greater calmness and better mood, and a trend toward lower state anxiety were noted in the trained relative to untrained men. In addition, others have noted blunted cortisol responses (115) and reduced cardiovascular responses (98,99,115) to psychological laboratory stressors in physically active as compared to less active persons. Webb et al (111) administered a dual challenge of physical and mental stress and noted that low-fit participants had greater cortisol responses compared to high-fit individuals. Importantly, in a meta-review of 34 studies, Crews et al (99) reported that aerobically fit individuals had reduced responses to psychosocial stress in comparison to controls. These findings are consistent with those from the Aerobics Center Longitudinal Study, which found a significant inverse dose-response relationship between aerobic fitness and depressive symptomatology and a positive association between fitness and emotional well-being. (116)

In addition to cross-sectional studies, longitudinal studies have demonstrated positive effects of exercise training and regular physical activity, and negative effects of exercise withdrawal on mood and depressive symptoms. (68,117-121) Nabkasorn et al (117) studied adolescent females with depressive symptoms and noted significant decreases in total depressive score, as well as in 24-hour urinary cortisol and epinephrine excretion, following 8 weeks of physical training (jogging). Importantly, studies by Berlin et al (118) and Weinstein et al (121) demonstrated that when someone who exercises regularly is forced to withdraw from exercise for 2 weeks, negative mood increases significantly and correlates with decreases in fitness. (118,121) In addition, a reduction in parasympathetic nervous system activity, as measured by heart rate variability, predicted the development of negative mood after deprivation of exercise. (121) These findings are relevant to understanding both short-term exercise withdrawal and exercise initiation, and how they affect overall stress resilience and reactivity.

Despite the multiple positive findings, not all are consistent, (65,122,123) particularly with regard to catecholamine release, with both blunted and augmented responses noted in high- versus low-fit persons. (112,123) Along those same lines, de Geus et al (65) were unable to detect changes in psychological make-up (for example, personality traits of neuroticism, introversion, hostility, anger expression) or acute neurophysiologic reactivity (for example, heart rate, blood pressure, urinary catecholamine excretion, or cardiac beta-adrenergic drive) after 4 and 8 months of training. Thus, although the majority of studies support positive effects of regular exercise and aerobic fitness, not all studies are consistent.

Physical Fitness Serves as a Buffer against Stress and Stress-Related Disorders

Physical activity may provide a protective effect against stress-related disorders, as physically fit persons appear to be less susceptible to life stressors, in particular with regard to illnesses: physical fitness may serve as a buffer against stress, (63,124,125) with stress being highly associated with various illnesses. (20,34,73,124,126,127) A comprehensive review of the literature from 1982 to 2008 in which exercise was examined as a stress-buffer concluded that the majority of studies, both cross-sectional and prospective, found exercise to be an effective buffer, but the amount and type of exercise necessary for protection were not stated. (93) The concept of stress buffering was first proposed by Kobasa et al, (34) and later by others (9,11) who clearly showed that regular exercise and hardiness interact to decrease illness in the face of serious life stressors. (34) Persons who scored high in hardiness and participated in regular exercise were usually more healthy than those high only in hardiness or exercise alone. (34) Collectively, the data suggest that participation in leisure physical activity is important to the stress-buffering effect of exercise. (128)

Physical fitness and regular exercise also appear to buffer against depression (63,68,125,129-134) and anxiety. (100,125,134-136) In fact, the beneficial effects of physical activity on positive mood are well recognized. (83,137) Rethorst et al (131) conducted a meta-analysis of all studies investigating the effects of exercise on depression, and 12 of 16 exercise treatment groups with clinically depressed patients were classified as "recovered" or "improved" after the treatment. Similarly, a number of prospective studies have demonstrated reductions in state anxiety. (129,138) Manger et al (129) had persons diagnosed with posttraumatic stress disorder (PTSD) undergo a 12-session aerobic exercise program and showed significant reductions in PTSD, anxiety, and depression following the intervention. Moreover, these positive results were stable over 1 month of follow-up. (129) Finally, Wipfli et al (135) conducted a meta-analysis (based on 49 randomized, controlled trials) examining the effects of exercise on anxiety, and demonstrated clear reductions in anxiety among those who exercised compared to the respective control groups. Of interest was their finding that exercise was more effective in reducing anxiety relative to other anxiety-reducing treatments. (135)

CLINICAL IMPLICATIONS OF A SEDENTARY LIFESTYLE

The short- and long-term consequences of low physical fitness and a sedentary lifestyle are clear. Physical inactivity serves a major role in the rising prevalence of obesity, cardiovascular disease (CVD), hypertension, type II diabetes mellitus (T2DM), metabolic syndrome, insulin resistance, hyperlipidemia, and breast and colon cancers, to name a few. (91,94,95,116,139,140) Of course, excess energy intake also contributes to obesity, (78,94,95), but lack of physical activity is the leading contributor (91,94,95,116,139,140) and also the fourth leading cause of death worldwide. (95) In contrast to a sedentary lifestyle, high aerobic fitness is inversely related to obesity, metabolic syndrome, CVD, hypertension, and T2DM. (74,141-145)

In addition to the major chronic diseases mentioned above, low aerobic fitness has been associated with fibromyalgia (FM), (146,147) chronic fatigue syndrome (CFS), (148,149) osteoarthritis, (150-152) rheumatoid arthritis, (150,153,154) and inflammatory muscle disorders. (155,156) Low aerobic fitness is also associated with elevations in serum C-reactive protein (CRP), a well-known marker of inflammation. Many studies have shown that maximal aerobic capacity is inversely related to CRP, (142,157) and that exercise interventions, both aerobic and resistance in nature, reduce levels of CRP. (157-159) However, not all studies showed a significant effect. (160-162) A meta-analytic study by Kelley et al (162) of 5 randomized controlled trials reported an approximately 3% reduction in CRP levels across the exercise groups, which was not significant. However, the studies that were negative found other positive benefits of exercise, regardless of its effect on CRP.

With regard to FM, exercise as an intervention has been shown to be beneficial, particularly in relation to pain management. Ellingson et al (147) conducted a prospective study and emphasized how a sedentary lifestyle was likely deleterious for pain regulation in FM. Likewise, Curtis et al (163) conducted a study wherein women with FM who engaged in a 75-minute yoga class twice weekly for 8 weeks reported reduced pain and catastrophizing, and increased acceptance of pain. Chronic fatigue syndrome is another debilitating disorder characterized by minimal physical activity during daily life and lower muscle strength and aerobic capacity compared to healthy sedentary subjects. (149,154) As with FM, when persons with CFS are entered into a regular exercise program, significant benefits in terms of physical capacity, quality of life, fatigue severity, and depressive symptomatology are reported. (164,165) Interestingly, Heins et al (166) reported that physical activity is intentionally limited in CFS patients, possibly because they expect negative bodily symptoms and catastrophize in such a way as to negatively affect their performance. This underscores the importance of the exercise-derived resilience resources self-efficacy, self-esteem, and motivation, which, unfortunately, were not measured in the above studies.

Overall, the clinical implications of a sedentary, physically inactive lifestyle are profound, and the literature clearly demonstrates that having a valid measure of physical fitness, in particular aerobic fitness, may be one of the best indicators of resilience, as well as long-term health and risk of chronic diseases. Most of the above mentioned chronic diseases/disorders are also associated with depression, anxiety, low self-efficacy, and other barriers to critical resilience resources. Promoting regular physical activity in these populations has been shown to exert profound beneficial changes, and should be the key intervention for all such populations who are able to engage in regular physical activity.

LIMITATIONS AND FUTURE DIRECTIONS

Limitations of studies examining how physical fitness contributes to resilience must be acknowledged. First, many studies examining reactivity to both physical and psychosocial stress did not quantify aerobic fitness or regular physical activity. This is essential for being able to accurately interpret the results, as they may be important confounders. Secondly, the intimate relation between hardiness/mental toughness, and aerobic capacity/physical activity must be further evaluated to document their interrelationship. Certainly, the mental toughness model was specifically developed for athletes who are physically fit and have self-confidence, so one would expect them to have many resilience resources. However, what happens when they become injured? In addition, many people with chronic diseases are able to cope and are physically unfit (they may be unable to engage in regular exercise), so physical fitness is important, but not an absolute. (23,24)

CONCLUSIONS

Physical fitness is associated with many traits and attributes required for resilience. As such, it is one pathway toward resilience. Promoting physical fitness as a pathway to resilience is based on solid, scientific evidence as noted in many ancient and current sources showing that physical fitness blunts stress reactivity, confers physiologic and psychological benefits, serves as a buffer against stress, and can protect against stress-related disorders and chronic illness. Perhaps the role of physical fitness as a pathway to resilience was most eloquently stated by then President-Elect John F. Kennedy in 1960 when he said:

   ... physical fitness is not only one of the most important
   keys to a healthy body; it is the basis of dynamic and
   creative intellectual activity.... intelligence and skill can
   only function at the peak of their capacity when the body
   is healthy and strong; hardy spirits and tough minds usually
   inhabit sound bodies. (1)


RELEVANCE TO THE PERFORMANCE TRIAD

Physical activity is a key component of the Performance Triad and is clearly essential to optimal performance. However, physical activity in the absence of adequate fueling (ie, healthy dietary patterns, appropriate timing and types of nutrients) and an adequate quantity and quality of sleep and recovery is not the solution. Excessive activity can lead to overtraining, musculoskeletal injuries, and similar problems. Only when physical activity is balanced with a healthy diet and restorative sleep will the benefits described above be realized.

ACKNOWLEDGMENTS

This research was supported by a grant from Comprehensive Soldier and Family Fitness (CSF2; HT9404-12-1-0017; F191GJ).

We appreciate the support in preparation and review of this article by LTC Sharon A. McBride, MS, USA.

REFERENCES

(1.) Kennedy JF. The soft American. Sports Illustrated. 1960; 13(26):14-17. Available at: http:// sportsillustrated.cnn.com/vault/article/magazine/ MAG1134750/2/. Accessed August 15, 2013.

(2.) CJCSInstruction 3405.01: Chairman's Total Force Fitness Framework. Washington, DC: Office of the Chairman, Joint Chiefs of Staff; 2011. Available at: http://www.dtic.mil/cjcs_directives/cdata/unlim it/3405_01.pdf. Accessed July 24, 2013.

(3.) Baker DG, Nash WP, Litz BT, et al. Predictors of risk and resilience for posttraumatic stress disorder among ground combat Marines: methods of the Marine Resiliency Study. Prev Chronic Dis. 2012; 9:E97.

(4.) Meredith LS, Sherbourne CD, Gaillot S, et al. Psychological Resilience in the U.S. Military. Santa Monica, CA 90407-2138: Rand Corporation; 2011.

(5.) Perna L, Mielck A, Lacruz ME, et al. Socioeconomic position, resilience, and health behaviour among elderly people. Int J Public Health. 2012; 57(2):341-349.

(6.) Skrove M, Romundstad P, Indredavik MS. Resilience, lifestyle and symptoms of anxiety and depression in adolescence: the Young-HUNT study. Soc Psychiatry and Psychiatr Epidemiol. 8 2012.

(7.) Wells M, Avers D, Brooks G. Resilience, physical performance measures, and self-perceived physical and mental health in older Catholic nuns. J Geriatr Physical Ther. Jul-2012; 35(3):126-131.

(8.) Acevedo EO, Webb HE, Weldy ML, Fabianke EC, Orndorff GR, Starks MA. Cardiorespiratory responses of Hi Fit and Low Fit subjects to mental challenge during exercise. Int J Sports Med. 2006; 27(12):1013-1022.

(9.) Roth DL, Wiebe DJ, Fillingim RB, Shay KA. Life events, fitness, hardiness, and health: a simultaneous analysis of proposed stress-resistance effects. J Pers Soc Psychol. 1989; 57(1):136-142.

(10.) Skirka N. The relationship of hardiness, sense of coherence, sports participation, and gender to perceived stress and psychological symptoms among college students. J Sports Med Phys Fitness. 2000; 40(1):63-70.

(11.) Maddi SR. On hardiness and other pathways to resilience. Am Psychol. 2005; 60(3):261-262; discussion 265-267.

(12.) Dalleck LC, Kravitz L. The history of fitness. IDEA Health and Fitness Source. 2002; 20(2):26-33.

(13.) Berryman JW. Exercise is medicine: a historical perspective. Curr Sports Med Reports. Jul-2010; 9(4):195-201.

(14.) Fletcher GF. The history of exercise in the practice of medicine. J Med Assoc Georgia. 1983; 72(1):35-40.

(15.) Berryman JW. The tradition of the "six things non-natural": exercise and medicine from Hippocrates through ante-bellum America. Exerc Sport Sci Rev. 1989; 17:515-559.

(16.) MacAuley D. A history of physical activity, health and medicine. JR Soc Med. 1994; 87(1):32-35.

(17.) Herrman H, Stewart DE, Diaz-Granados N, Berger EL, Jackson B, Yuen T. What is resilience? Can J Psychiatry. Revue canadienne de psychiatrie. 2011; 56(5):258-265.

(18.) Seligman ME. Building resilience. Harv Bus Rev. 2011; 89(4):100-106, 138.

(19.) Ong AD, Bergeman CS, Boker SM. Resilience comes of age: defining features in later adulthood. J Pers. 2009; 77(6):1777-1804.

(20.) Yi JP, Vitaliano PP, Smith RE, Yi JC, Weinger K. The role of resilience on psychological adjustment and physical health in patients with diabetes. Br J Health Psychol. 2008; 13(Pt 2):311-325.

(21.) Howe A, Smajdor A, Stockl A. Towards an understanding of resilience and its relevance to medical training. Med Educ. 2012; 46(4):349-356.

(22.) Mertens VC, Bosma H, Groffen DA, van Eijk JT. Good friends, high income or resilience? What matters most for elderly patients? Eur J Public Health. 2012; 22(5):666-671.

(23.) Robottom BJ, Gruber-Baldini AL, Anderson KE, et al. What determines resilience in patients with Parkinson's disease? Parkinsonism Relat Disord. 2012; 18(2):174-177.

(24.) West C, Stewart L, Foster K, Usher K. The meaning of resilience to persons living with chronic pain: an interpretive qualitative inquiry. J Clin Nurs. 2012; 21(9-10):1284-1292.

(25.) Jeffcott SA, Ibrahim JE, Cameron PA. Resilience in healthcare and clinical handover. Qual Saf Health Care. 2009; 18(4):256-260.

(26.) Levine SZ, Laufer A, Stein E, Hamama-Raz Y, Solomon Z. Examining the relationship between resilience and posttraumatic growth. J Trauma Stress. 2009; 22(4):282-286.

(27.) Mancini AD, Bonanno GA. Predictors and parameters of resilience to loss: toward an individual differences model. J Pers. 2009; 77(6):1805-1832.

(28.) Pickering MA, Hammermeister J, Ohlson C, Holliday B, Ulmer G. An exploratory investigation of relationships among mental skills and resilience in Warrior Transition Unit cadre members. Mil Med. 2010; 175(4):213-219.

(29.) Pickering RP, Grant BF, Chou SP, Compton WM. Are overweight, obesity, and extreme obesity associated with psychopathology? Results from the national epidemiologic survey on alcohol and related conditions. J Clin Psychiatry. 2007; 68(7):998-1009.

(30.) Pietrzak RH, Johnson DC, Goldstein MB, Malley JC, Southwick SM. Psychological resilience and postdeployment social support protect against traumatic stress and depressive symptoms in soldiers returning from Operations Enduring Freedom and Iraqi Freedom. Depress Anxiety. 2009; 26(8):745-751.

(31.) Ri-Li G, Chase PJ, Witkowski S, et al. Obesity: associations with acute mountain sickness. Ann Intern Med. 2003; 139(4):253-257.

(32.) Sawka MN, Young AJ, Cadarette BS, Levine L, Pandolf KB. Influence of heat stress and acclimation on maximal aerobic power. Eur J Appl Physiol Occup Physiol. 1985; 53(4):294-298.

(33.) Taliaz D, Loya A, Gersner R, Haramati S, Chen A, Zangen A. Resilience to chronic stress is mediated by hippocampal brain-derived neurotrophic factor. JNeurosci. 2011; 31(12):4475-4483.

(34.) Kobasa SC, Maddi SR, Puccetti MC. Personality and exercise as buffers in the stress-illness relationship. J Behav Med. 1982; 5(4):391-404.

(35.) Connaughton D, Wadey R, Hanton S, Jones G. The development and maintenance of mental toughness: perceptions of elite performers. J Sports Sci. 2008; 26(1):83-95.

(36.) Crust L, Clough PJ. Relationship between mental toughness and physical endurance. Percept Mot Skills. 2005; 100(1):192-194.

(37.) Kobasa SC. Stressful life events, personality, and health: an inquiry into hardiness. J Pers Soc Psychol. 1979; 37(1):1-11.

(38.) Kobasa SC. Personality and resistance to illness. Am J Community Psychol. 1979; 7(4):413-423.

(39.) Kobasa SC, Maddi SR, Courington S. Personality and constitution as mediators in the stress-illness relationship. J Health Soc Behav. 1981; 22(4):368-378.

(40.) Kobasa SC, Maddi SR, Kahn S. Hardiness and health: a prospective study. J Pers Soc Psychol. 1982; 42(1):168-177.

(41.) Kobasa SC, Maddi SR, Puccetti MC, Zola MA. Effectiveness of hardiness, exercise and social support as resources against illness. J Psychosom Res. 1985; 29(5):525-533.

(42.) Kobasa SC, Puccetti MC. Personality and social resources in stress resistance. J Pers Soc Psychol. 1983; 45(4):839-850.

(43.) Kobasa SC, Spinetta JJ, Cohen J, et al. Social environment and social support. Cancer. 1991; 67(suppl 3):788-793.

(44.) Mack MG, Ragan BG. Development of the mental, emotional, and bodily toughness inventory in collegiate athletes and nonathletes. J Athl Train. 2008; 43(2):125-132.

(45.) Ramanaiah NV, Sharpe JP, Byravan A. Hardiness and major personality factors. Psychol Rep. 1999; 84(2):497-500.

(46.) Simpson RJ, Gray SC, Florida-James GD. Physiological variables and performance markers of serving soldiers from two "elite" units of the British Army. J Sports Sci. 2006; 24(6):597-604.

(47.) Bartone PT. Test-retest reliability of the dispositional resilience scale-15, a brief hardiness scale. Psychol Rep. 2007; 101(3 Pt 1):943-944.

(48.) Bartone PT, Ursano RJ, Wright KM, Ingraham LH. The impact of a military air disaster on the health of assistance workers. A prospective study. J Nerv Ment Dis. 1989; 177(6):317-328.

(49.) Ford IW, Eklund RC, Gordon S. An examination of psychosocial variables moderating the relationship between life stress and injury time-loss among athletes of a high standard. J Sports Sci. 2000; 18(5):301-312.

(50.) Funk SC. Hardiness: a review of theory and research. Health Psychol. 1992; 11(5):335-345.

(51.) Maddi SR, Harvey RH, Khoshaba DM, Lu JL, Persico M, Brow M. The personality construct of hardiness, III: Relationships with repression, innovativeness, authoritarianism, and performance. J Pers. 2006; 74(2):575-597.

(52.) Britt TW, Adler AB, Bartone PT. Deriving benefits from stressful events: the role of engagement in meaningful work and hardiness. J Occup Health Psychol. 2001; 6(1):53-63.

(53.) Bonanno GA. Loss, trauma, and human resilience: have we underestimated the human capacity to thrive after extremely aversive events? Am Psychol. 2004; 59(1):20-28.

(54.) Gucciardi DF. Measuring mental toughness in sport: a psychometric examination of the psychological performance inventory-a and its predecessor. J Pers Assess. 2012; 94(4):393-403.

(55.) Richardson M. Developing mental toughness. Nurs Times. 2011; 107(45):inside back cover.

(56.) Gucciardi DF, Jones MI. Beyond optimal performance: mental toughness profiles and developmental success in adolescent cricketers. J Sport Exerc Psychol. 2012; 34(1):16-36.

(57.) Gerber M, Kalak N, Lemola S, et al. Are adolescents with high mental toughness levels more resilient against stress. Stress Health. 2013; 29(2):164-171.

(58.) Miller L. Stress and resilience in law enforcement training and practice. Int J Emerg Ment Health. 2008; 10(2):109-124.

(59.) Barrow FH, Armstrong MI, Vargo A, Boothroyd RA. Understanding the findings of resilience-related research for fostering the development of African American adolescents. Child Adolesc Psychiatr Clin N Am. 2007; 16(2):393-413, ix-x.

(60.) Richardson GE. The metatheory of resilience and resiliency. J Clin Psychol. 2002; 58(3):307-321.

(61.) Richardson GE, Waite PJ. Mental health promotion through resilience and resiliency education. Int J Emerg Ment Health. 2002; 4(1):65-75.

(62.) Rutter M. Psychosocial resilience and protective mechanisms. Am J Orthopsychiatry. 1987; 57(3):316-331.

(63.) Norris R, Carroll D, Cochrane R. The effects of physical activity and exercise training on psychological stress and well-being in an adolescent population. J Psychosom Res. 1992; 36(1):55-65.

(64.) Rimmele U, Seiler R, Marti B, Wirtz PH, Ehlert U, Heinrichs M. The level of physical activity affects adrenal and cardiovascular reactivity to psychosocial stress. Psychoneuroendocrinology. 2009; 34(2):190-198.

(65.) de Geus EJ, van Doornen LJ, Orlebeke JF. Regular exercise and aerobic fitness in relation to psychological make-up and physiological stress reactivity. Psychosom Med. 1993; 55(4):347-363.

(66.) Delignieres D, Marcellini A, Brisswalter J, Legros P. Self-perception of fitness and personality traits. Percept Mot Skills. 1994; 78(3 pt 1):843-851.'

(67.) Dzewaltowski DA. Physical activity determinants: a social cognitive approach. Med Sci Sports Exerc. 1994; 26(11):1395-1399.

(68.) Scully D, Kremer J, Meade MM, Graham R, Dudgeon K. Physical exercise and psychological well being: a critical review. Br J Sports Med. 1998; 32(2):111-120.

(69.) Ekeland E, Heian F, Hagen KB, Abbott J, Nordheim L. Exercise to improve self-esteem in children and young people. Cochrane Database Syst Rev [serial online]. 2004(1):CD003683.

(70.) Kwan BM, Bryan AD. Affective response to exercise as a component of exercise motivation: Attitudes, norms, self-efficacy, and temporal stability of intentions. Psychol Sport Exerc. 2010; 11(1):71-79.

(71.) Craft LL, Perna FA, Freund KM, Culpepper L. Psychosocial correlates of exercise in women with self-reported depressive symptoms. J Phys Act Health. 2008; 5(3):469-480.

(72.) Netz Y, Wu MJ, Becker BJ, Tenenbaum G. Physical activity and psychological well-being in advanced age: a meta-analysis of intervention studies. Psy chol Aging. 2005; 20(2):272-284.

(73.) Taylor MK, Markham AE, Reis JP, et al. Physical fitness influences stress reactions to extreme military training. Mil Med. 2008; 173(8):738-742.

(74.) Deuster PA, Kim-Dorner SJ, Remaley AT, Poth M. Allostatic load and health status of African Americans and whites. Am J Health Behav. 2011; 35(6):641-653.

(75.) McMurray I, Connolly H, Preston-Shoot M, Wigley V. Constructing resilience: social workers' understandings and practice. Health Soc Care Community. 2008; 16(3):299-309.

(76.) Dishman RK, Motl RW, Sallis JF, et al. Self-management strategies mediate self-efficacy and physical activity. Am J Prev Med. 2005; 29(1):10-18.

(77.) Dishman RK, Saunders RP, Felton G, Ward DS, Dowda M, Pate RR. Goals and intentions mediate efficacy beliefs and declining physical activity in high school girls. Am J Prev Med. 2006; 31(6):475-483.

(78.) Bauman AE, Reis RS, Sallis JF, Wells JC, Loos RJ, Martin BW. Correlates of physical activity: why are some people physically active and others not? Lancet. 2012; 380(9838):258-271.

(79.) Lee LL, Arthur A, Avis M. Using self-efficacy theory to develop interventions that help older people overcome psychological barriers to physical activity: a discussion paper. Int J Nurs Stud. 2008; 45(11):1690-1699.

(80.) Magnan RE, Kwan BM, Bryan AD. Effects of current physical activity on affective response to exercise: physical and social-cognitive mechanisms. Psychol Health. 2013; 28(4):418-433.

(81.) Frederick CM. Competitiveness: relations with GPA, locus of control, sex, and athletic status. Percept Mot Skills. 2000; 90(2):413-414.

(82.) Andre N, Dishman RK. Evidence for the construct validity of self-motivation as a correlate of exercise adherence in French older adults. J Aging Phys Act. 2012; 20(2):231-245.

(83.) Anthony J. Psychologic aspects of exercise. Clin Sports Med. 1991; 10(1):171-180.

(84.) Dishman RK, Sallis JF, Orenstein DR. The determinants of physical activity and exercise. Public Health Rep. 1985; 100(2):158-171.

(85.) Motl RW, Dishman RK, Felton G, Pate RR. Self motivation and physical activity among black and white adolescent girls. Med Sci Sports Exerc. 2003; 35(1):128-136.

(86.) Morris JN, Chave SP, Adam C, Sirey C, Epstein L, Sheehan DJ. Vigorous exercise in leisure-time and the incidence of coronary heart-disease. Lancet. 1973; 1(7799):333-339.

(87.) Chave SP, Morris JN, Moss S, Semmence AM. Vigorous exercise in leisure time and the death rate: a study of male civil servants. J Epidemiol Community Health. 1978; 32(4):239-243.

(88.) Morris JN, Everitt MG, Pollard R, Chave SP, Semmence AM. Vigorous exercise in leisure-time: protection against coronary heart disease. Lancet. 1980; 2(8206):1207-1210.

(89.) Paffenbarger RS, Jr., Hyde RT. Exercise in the prevention of coronary heart disease. Prev Med. 1984; 13(1):3-22.

(90.) Paffenbarger RS Jr, Hyde RT, Wing AL, Hsieh CC. Physical activity, all-cause mortality, and longevity of college alumni. N Engl J Med. 1986; 314(10):605-613.

(91.) Pratt M, Norris J, Lobelo F, Roux L, Wang G. The cost of physical inactivity: moving into the 21st century. Br J Sports Med. 2012; Nov 7 [epub].

(92.) Blair SN, LaMonte MJ, Nichaman MZ. The evolution of physical activity recommendations: how much is enough? Am J Clin Nutr. 2004; 79(5):913S-920S.

(93.) Gerber M, Puhse U. Review article: do exercise and fitness protect against stress-induced health complaints? a review of the literature. Scand J Public Health. 2009; 37(8):801-819.

(94.) Wen CP, Wu X. Stressing harms of physical inactivity to promote exercise. Lancet. 2012; 380(9838):192-193.

(95.) Kohl HW III, Craig CL, Lambert EV, et al. The pandemic of physical inactivity: global action for public health. Lancet. 2012; 380(9838):294-305.

(96.) McEwen BS. Central effects of stress hormones in health and disease: understanding the protective and damaging effects of stress and stress mediators. Eur J Pharmacol. 2008; 583(2-3):174-185.

(97.) Chrousos GP. Stress and disorders of the stress system. Nat Rev Endocrinol. 2009; 5(7):374-381.

(98.) Claytor RP. Stress reactivity: hemodynamic adjustments in trained and untrained humans. Med Sci Sports Exerc. 1991; 23(7):873-881.

(99.) Crews DJ, Landers DM. A meta-analytic review of aerobic fitness and reactivity to psychosocial stressors. Med Sci Sports Exerc. 1987; 19(suppl 5):S114-S120.

(100.) Deboer LB, Tart CD, Presnell KE, Powers MB, Baldwin AS, Smits JA. Physical activity as a moderator of the association between anxiety sensitivity and binge eating. Eating Behav. 2012; 13(3):194-201.

(101.) Deuster PA, Petrides JS, Singh A, Chrousos GP, Poth M. Endocrine response to high-intensity exercise: dose-dependent effects of dexamethasone. J Clin Endocrinol Metab. 2000; 85(3):1066-1073.

(102.) Dienstbier RA. Behavioral correlates of sympathoadrenal reactivity: the toughness model. Med Sci Sports Exerc. 1991; 23(7):846-852.

(103.) Horowitz M, Robinson SD. Heat shock proteins and the heat shock response during hyperthermia and its modulation by altered physiological conditions. Prog Brain Res. 2007; 162:433-446.

(104.) Lambiase MJ, Dorn J, Chernega NJ, McCarthy TF, Roemmich JN. Excess heart rate and systolic blood pressure during psychological stress in relation to metabolic demand in adolescents. Biol Psychol. 2012; 91(1):42-47.

(105.) McEwen BS. The neurobiology and neuroendocrinology of stress. Implications for post-traumatic stress disorder from a basic science perspective. Psychiatr Clin North Am. 2002; 25(2):469-494, ix.

(106.) Ribeiro F, Campbell CS, Mendes G, et al. Exercise lowers blood pressure in university professors during subsequent teaching and sleeping hours. Int J Gen Med. 2011; 4:711-716.

(107.) Steptoe A, Kearsley N, Walters N. Cardiovascular activity during mental stress following vigorous exercise in sportsmen and inactive men. Psycho physiology. 1993; 30(3):245-252.

(108.) Luger A, Watschinger B, Deuster P, Svoboda T, Clodi M, Chrousos GP. Plasma growth hormone and prolactin responses to graded levels of acute exercise and to a lactate infusion. Neuroendocrinology. 1992; 56(1):112-117.

(109.) Luger A, Deuster PA, Kyle SB, et al. Acute hypothalamic-pituitary-adrenal responses to the stress of treadmill exercise. Physiologic adaptations to physical training. N Engl J Med. 1987; 316(21):1309-1315.

(110.) Deuster PA, Chrousos GP, Luger A, et al. Hormonal and metabolic responses of untrained, moderately trained, and highly trained men to three exercise intensities. Metabolism. 1989; 38(2):141-148.

(111.) Webb HE, Rosalky DS, Tangsilsat SE, McLeod KA, Acevedo EO, Wax B. Aerobic fitness affects cortisol responses to concurrent challenges. Med Sci Sports Exerc. 2013; 45(2):379-386.

(112.) Sothmann MS, Hart BA, Horn TS. Plasma catecholamine response to acute psychological stress in humans: relation to aerobic fitness and exercise training. Med Sci Sports Exerc. 1991; 23(7):860-867.

(113.) Cox RH. Exercise training and response to stress: insights from an animal model. Med Sci Sports Exerc. 1991; 23(7):853-859.

(114.) Sothmann MS, Buckworth J, Claytor RP, Cox RH, White-Welkley JE, Dishman RK. Exercise training and the cross-stressor adaptation hypothesis. Exerc Sport Sci Rev. 1996; 24:267-287.

(115.) Rimmele U, Zellweger BC, Marti B, et al. Trained men show lower cortisol, heart rate and psychological responses to psychosocial stress compared with untrained men. Psychoneuroendocrinology. 2007; 32(6):627-635.

(116.) Galper DI, Trivedi MH, Barlow CE, Dunn AL, Kampert JB. Inverse association between physical inactivity and mental health in men and women. Med Sci Sports Exerc. 2006; 38(1):173-178.

(117.) Nabkasorn C, Miyai N, Sootmongkol A, et al. Effects of physical exercise on depression, neuroendocrine stress hormones and physiological fitness in adolescent females with depressive symptoms. Eur J Public Health. 2006; 16(2):179-184.

(118.) Berlin AA, Kop WJ, Deuster PA. Depressive mood symptoms and fatigue after exercise withdrawal: the potential role of decreased fitness. Psychosom Med. 2006; 68(2):224-230.

(119.) van Gool CH, Kempen GI, Bosma H, van Boxtel MP, Jolles J, van Eijk JT. Associations between lifestyle and depressed mood: longitudinal results from the Maastricht Aging Study. Am J Public Health. 2007; 97(5):887-894.

(120.) Hamer M, Endrighi R, Poole L. Physical activity, stress reduction, and mood: insight into immunological mechanisms. Methods Mol Biol (Clifton, N.J.). 2012; 934:89-102.

(121.) Weinstein AA, Deuster PA, Kop WJ. Heart rate variability as a predictor of negative mood symptoms induced by exercise withdrawal. Med Sci Sports Exerc. 2007; 39(4):735-741.

(122.) Jackson EM, Dishman RK. Cardiorespiratory fitness and laboratory stress: a meta-regression analysis. Psychophysiology. 2006; 43(1):57-72.

(123.) Moyna NM, Bodnar JD, Goldberg HR, Shurin MS, Robertson RJ, Rabin BS. Relation between aerobic fitness level and stress induced alterations in neuroendocrine and immune function. Int J Sports Med. 1999; 20(2):136-141.

(124.) Li G, He H. Hormesis, allostatic buffering capacity and physiological mechanism of physical activity: a new theoretic framework. Med Hypotheses. 2009; 72(5):527-532.

(125.) Steptoe A, Edwards S, Moses J, Mathews A. The effects of exercise training on mood and perceived coping ability in anxious adults from the general population. J Psychosom Res. 1989; 33(5):537-547.

(126.) Morgan CA III, Wang S, Southwick SM, et al. Plasma neuropeptide-Y concentrations in humans exposed to military survival training. Biol Psychiatry. 2000; 47(10):902-909.

(127.) O'Donnell K, Brydon L, Wright CE, Steptoe A. Self-esteem levels and cardiovascular and inflammatory responses to acute stress. Brain Behav Immun. 2008; 22(8):1241-1247.

(128.) Carmack CL, Boudreaux E, Amaral-Melendez M, Brantley PJ, de Moor C. Aerobic fitness and leisure physical activity as moderators of the stress-illness relation. Ann Behav Med. 1999; 21(3):251-257.

(129.) Manger TA, Motta RW. The impact of an exercise program on posttraumatic stress disorder, anxiety, and depression. Int JEmerg Ment Health. 2005; 7(1):49-57.

(130.) Southwick SM, Vythilingam M, Charney DS. The psychobiology of depression and resilience to stress: implications for prevention and treatment. Annu Rev Clin Psychol. 2005; 1:255-291.

(131.) Rethorst CD, Wipfli BM, Landers DM. The anti-depressive effects of exercise: a meta-analysis of randomized trials. Sports Med. 2009; 39(6):491-511.

(132.) Paluska SA, Schwenk TL. Physical activity and mental health: current concepts. Sports Med. 2000; 29(3):167-180.

(133.) Oman RF, Oman KK. A case-control study of psychosocial and aerobic exercise factors in women with symptoms of depression. J Psychol. 2003; 137(4):338-350.

(134.) Oeland AM, Laessoe U, Olesen AV, Munk-Jorgensen P. Impact of exercise on patients with depression and anxiety. Nordic J Psychiatry. 2010; 64(3):210-217.

(135.) Wipfli BM, Rethorst CD, Landers DM. The anxiolytic effects of exercise: a meta-analysis of randomized trials and dose-response analysis. J Sport Exerc Psychol. 2008; 30(4):392-410.

(136.) Fox KR. The influence of physical activity on mental well-being. Public Health Nutr. 1999; 2(3A):411-418.

(137.) Moses J, Steptoe A, Mathews A, Edwards S. The effects of exercise training on mental well-being in the normal population: a controlled trial. J Psycho som Res. 1989; 33(1):47-61.

(138.) DiLorenzo TM, Bargman EP, Stucky-Ropp R, Brassington GS, Frensch PA, LaFontaine T. Long-term effects of aerobic exercise on psychological outcomes. Prev Med. 1999; 28(1):75-85.

(139.) Blair SN. Physical inactivity: the biggest public health problem of the 21st century. Br J Sports Med. 2009; 43(1):1-2.

(140.) Goetzel RZ, Pei X, Tabrizi MJ, et al. Ten modifiable health risk factors are linked to more than one-fifth of employer-employee health care spending. Health Aff(Milwood). 2012; 31(11):2474-2484.

(141.) Zeno SA, Deuster PA, Davis JL, Kim-Dorner SJ, Remaley AT, Poth M. Diagnostic criteria for metabolic syndrome: caucasians versus African-Americans. Metab Syndr Relat Disord. 2010; 8(2):149-156.

(142.) Zeno SA, Kim-Dorner SJ, Deuster PA, Davis JL, Remaley AT, Poth M. Cardiovascular fitness and risk factors of healthy African Americans and caucasians. J Natl Med Assoc. 2010; 102(1):28-35.

(143.) Kuo LE, Abe K, Zukowska Z. Stress, NPY and vascular remodeling: implications for stress-related diseases. Peptides. 2007; 28(2):435-440.

(144.) Kim-Dorner SJ, Simpson-McKenzie CO, Poth M, Deuster PA. Psychological and physiological correlates of insulin resistance at fasting and in response to a meal in African Americans and whites. Ethn Dis. 2009; 19(2):104-110.

(145.) Kim-Dorner SJ, Deuster PA, Zeno SA, Remaley AT, Poth M. Should triglycerides and the triglycerides to high-density lipoprotein cholesterol ratio be used as surrogates for insulin resistance?. Metabolism. 2010; 59(2):299-304.

(146.) McLoughlin MJ, Stegner AJ, Cook DB. The relationship between physical activity and brain responses to pain in fibromyalgia. J Pain. 2011; 12(6):640-651.

(147.) Ellingson LD, Shields MR, Stegner AJ, Cook DB. Physical activity, sustained sedentary behavior, and pain modulation in women with fibromyalgia. J Pain. 2012; 13(2):195-206.

(148.) Puetz TW, Flowers SS, O'Connor PJ. A randomized controlled trial of the effect of aerobic exercise training on feelings of energy and fatigue in sedentary young adults with persistent fatigue. Psycho ther Psychosom. 2008; 77(3):167-174.

(149.) Nijs J, Aelbrecht S, Meeus M, Van Oosterwijck J, Zinzen E, Clarys P. Tired of being inactive: a systematic literature review of physical activity, physiological exercise capacity and muscle strength in patients with chronic fatigue syndrome. Disabil Rehabil. 2011; 33(17-18):1493-1500.

(150.) Gualano B, Pinto AL, Perondi MB, et al. Therapeutic effects of exercise training in patients with pediatric rheumatic diseases. Rev Bra Reumatol. 2011; 51(5):490-496.

(151.) Semanik PA, Chang RW, Dunlop DD. Aerobic activity in prevention and symptom control of osteoarthritis. PMR. 2012; 4(suppl 5):S37-S44.

(152.) Stevenson JD, Roach R. The benefits and barriers to physical activity and lifestyle interventions for osteoarthritis affecting the adult knee. J Orthop Surg Res. 2012; 7:15.

(153.) Baillet A, Zeboulon N, Gossec L, et al. Efficacy of cardiorespiratory aerobic exercise in rheumatoid arthritis: meta-analysis of randomized controlled trials. Arthritis Care Res. 2010; 62(7):984-992. 34 http://www.cs.amedd,

(154.) Weinstein AA, Drinkard BM, Diao G, et al. Exploratory analysis of the relationships between aerobic capacity and self-reported fatigue in patients with rheumatoid arthritis, polymyositis, and chronic fatigue syndrome. PM R. 2009; 1(7):620-628.

(155.) Lundberg IE, Nader GA. Molecular effects of exercise in patients with inflammatory rheumatic disease. Nature Clin Pract Rheumatol. 2008; 4(11):597-604.

(156.) Nader GA, Lundberg IE. Exercise as an anti-inflammatory intervention to combat inflammatory diseases of muscle. Curr Opin Rheumatol. 2009; 21(6):599-603.

(157.) Thomson RL, Buckley JD, Moran LJ, et al. Comparison of aerobic exercise capacity and muscle strength in overweight women with and without polycystic ovary syndrome. BJOG. 2009; 116(9):1242-1250.

(158.) Arikawa AY, Thomas W, Schmitz KH, Kurzer MS. Sixteen weeks of exercise reduces C-reactive protein levels in young women. Med Sci Sports Exerc. 2011; 43(6):1002-1009.

(159.) Martins RA, Neves AP, Coelho-Silva MJ, Verissimo MT, Teixeira AM. The effect of aerobic versus strength-based training on high-sensitivity Creactive protein in older adults. Eur J Appl Physiol. 2010; 110(1):161-169.

(160.) Wong PC, Chia MY, Tsou IY, et al. Effects of a 12-week exercise training programme on aerobic fitness, body composition, blood lipids and C-reactive protein in adolescents with obesity. Ann Acad Med Singapore. 2008; 37(4):286-293.

(161.) Stewart LK, Earnest CP, Blair SN, Church TS. Effects of different doses of physical activity on Creactive protein among women. Med Sci Sports Exerc. 2010; 42(4):701-707.

(162.) Kelley GA, Kelley KS. Effects of aerobic exercise on C-reactive protein, body composition, and maximum oxygen consumption in adults: a meta-analysis of randomized controlled trials. Metabolism. 2006; 55(11):1500-1507.

(163.) Curtis K, Osadchuk A, Katz J. An eight-week yoga intervention is associated with improvements in pain, psychological functioning and mindfulness, and changes in cortisol levels in women with fibro myalgia. J Pain Res. 2011; 4:189-201.

(164.) Edmonds M, McGuire H, Price J. Exercise therapy for chronic fatigue syndrome. Cochrane Database Syst Rev [serial online]. 2004(3):CD003200.

(165.) Gordon BA, Knapman LM, Lubitz L. Graduated exercise training and progressive resistance training in adolescents with chronic fatigue syndrome: a randomized controlled pilot study. Clin Rehabil. 2010; 24(12):1072-1079.

(166.) Heins M, Knoop H, Nijs J, et al. Influence of symptom expectancies on stair-climbing performance in chronic fatigue syndrome: effect of study context. Int J Behav Med. 2013; 20(2):213-218.

Patricia A. Deuster, PhD, MPH

Marni N. Silverman, PhD

AUTHORS

Dr Deuster is Director and Professor, Consortium for Health and Military Performance, Department of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.

Dr Silverman is Senior Scientist, Human Performance Laboratory, Consortium for Health and Military Performance, Department of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.
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Date:Oct 1, 2013
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