Impairments of body structure and function are not uncommon among AYA treated for cancer. Documented problems related to rehabilitation include fatigue, disordered sleep, pain, sensory loss, cardiovascular or pulmonary dysfunction, and neuromusculoskeletal or movement disorders.

Fatigue is a common, pervasive, and distressing complication of cancer treatment, which may persist after treatment is completed [87]. It can be described as physical, emotional, or cognitive tiredness not proportional to recent activity (National Comprehensive Cancer Network 2015) with a significant impact on activities, participation, and quality of life [75, 111]. The underlying etiology is likely multifactorial: initial onset is thought to be associated with reduced oxygen delivery to cells, and persistent fatigue may be associated with an inflammatory process as positive correlations between cytokine levels (IL-6, IL1ra) have been reported [110]. Davies et al. [21] categorized fatigue in children and adolescents receiving treatment for cancer as typical tiredness (normal tiredness from regular activities or circumstances), treatment fatigue (energy lost greater than energy replenished resulting from hospitalization, disrupted sleep, pain, chemotherapy, radiation therapy, anemia, psychological or emotional stress), or shutdown fatigue (sustained or profound loss of energy resulting in disengagement with surroundings). Impairments such as chronic pain and fatigue can contribute to social isolation from peers [48, 112].

Sleep quality and quantity are often impaired in AYA receiving treatment for cancer [67, 102]. A systematic review [101], summarizing 41 studies among 10–19-year-olds with a cancer diagnosis, reported problems with sleep initiation and sleep continuity, disordered breathing, parasomnias (bed-wetting, teeth grinding, sleepwalking, sleep eating), excessive napping, and excessive daytime sleepiness. Sleep disturbances are associated with fatigue and pain [112] and are exacerbated during chemotherapy administration [76].

Procedural, treatment-associated, and cancer-related pain are common and concerning problems during cancer treatment [48, 101]. Pain can limit activity to the extent that bed rest is necessary and can affect the quality and quantity of sleep. Specific examples include disease-related pain such as tumor pain or metastases to bones or the central nervous system, treatment-related pain including neuropathy, mucositis, constipation, myopathy and bone or joint pain, or pain during procedural postoperative periods [101].

Reduced cardiovascular and pulmonary function [32, 88], poor exercise tolerance, fitness, and endurance can occur [62]. These changes may be subtle during adolescence and young adulthood [109, 114], but are very likely to progress over time [95] and have a significant impact on health in long-term cancer survivors [82]. Anthracycline-induced cardiomyopathy [89], radiation-induced damage to vascular structures [93, 94], and/or treated-related impairments in pulmonary function [72, 80, 103, 116] contribute to reduced exercise capacity [35] which may interfere with motivation to exercise [103] or ability to participate optimally in rehabilitation programs [106]. Muscle wasting or excess fat deposition may also occur during treatment for cancer, resulting in an undesirable body image, poor self-esteem, and the risk of subsequent higher morbidity and mortality rates [1, 3]. Mechanisms may include disease mechanisms, cranial irradiation, chemotherapy, inactivity, and poor diet [3, 62].

Skeletal impairments are also prevalent. Osteopenia is a common complication of cancer therapy. Contributing factors include high-dose corticosteroids and possibly reduced activity during times of illness [62]. Glucocorticoids, particularly when given concomitantly with asparaginase [118], can result in osteonecrosis/avascular necrosis (AVN) of the hips, knees, ankles, or shoulders [91, 96]. AVN is the result of reduced intramedullary blood flow, marrow ischemia, and ultimately bone necrosis. Patients with AVN may exhibit a painful range of motion, antalgic gait, or difficulty in climbing steps, although AVN may be present even when clinical symptoms are not apparent [84]. Diagnosis is typically made by magnetic resonance imaging [44].

Muscle weakness and loss of joint motion are not uncommon during and after cancer therapy. Treatment with corticosteroids is associated with myopathy of the proximal musculature [62] and is compounded by lack of activity due to bed rest, malaise, fatigue, or nausea. Loss of joint range of motion and skeletal deformity may be the result of general or specific chemotherapy-induced weakness like peripheral neuropathy or related to surgical procedures that either damage the joint or require prolonged immobilization. AYA whose treatments included neurotoxic chemotherapy agents, whose tumor location necessitates radiation to surrounding bone or muscle, and those who have solid tumors located in the extremities are particularly vulnerable. Vincristine-induced peripheral neuropathy is characterized by reduced deep tendon reflexes, paresthesia, pain or muscle cramps, and weakness that can result in contractures and gait abnormalities [98]. Those who have remaining growth and who receive either asymmetrical radiation or radiation near a growth plate are often left with a skeletal deformity like scoliosis or a shortened limb [73, 78, 104, 105]. Surgical reconstruction or amputation is required for many extremity sarcomas and can result in a permanent loss of function [10, 54, 100].

Central nervous system (CNS) damage from CNS tumors or treatments can result in cognitive and perceptual deficits and loss of motor control. These problems, compounded by other impairments such as weakness, decreased range of motion, and obesity, can contribute to multisystem impairments such as difficulties with balance, coordination, and motor learning [107]. Learning and cognitive skills may be affected due to neurosurgery, radiation therapy, or other central nervous system treatments which can impact success in educational or vocational activities [70]. Oral motor dysfunction of neurogenic or mechanical origin can disrupt communication, eating, and associated quality of life among AYA who are exposed to head and neck surgery or radiation, or chemotherapy agents that impact the cranial nerves [74, 115].

Physical and psychosocial impairments have the potential to impact all areas of activity. The associated limitations and participation restrictions can have a reciprocal impact on impairments, as disuse and inactivity perpetuate muscle weakness, poor fitness, and general feelings of well-being. Limitations in gross motor function are obvious in AYA treated for bone and CNS tumors; however, gross motor proficiency can also be compromised during treatment and following treatment in AYA receiving treatment for other cancers including leukemia and lymphoma [29, 97, 108]. Problems with fine motor skills including poor handwriting, manual dexterity, and drawing performance have also been identified [29]. Self-care skills such bathing, toileting, dressing, personal care, and grooming can also be affected [90]. This can be very devastating for AYA who are striving to be independent and maintain their privacy. Other activities of daily living such as establishing or maintaining a household or employment may be limited and affect the transition to and maintenance of productive and healthy adult life [81, 85, 86, 99]. These may not be immediate priorities for adolescents, but they are important skills to learn to enable independent living as an adult.

Many papers have reported decreased participation in physical exercise amounts and intensities [14, 39, 64], whereas others have demonstrated levels similar to peer or sibling comparison groups but with both groups not meeting recommended levels [53, 68] and therefore not achieving optional health gains. Many AYA also make friends and maintain their social network through sports and identify with a strong and fit body [1]. Given that cancer and its treatment may result in impairments that make sports participation difficult, the impact of physical loss among AYA has social and emotional as well as physical implications. Studies of adolescents who had received treatment for cancer showed many reported decreased participation in leisure-time physical activity while receiving treatment and for some into survivorship [38, 39]. Those who remained active throughout their cancer experience reported better self-concept, perception of physical abilities, interactions with parents, and same and opposite sex relationships; many of the psychosocial areas are compromised in AYA with cancer [38]. A long-term follow-up study found that adolescents treated for acute lymphoblastic leukemia reported feeling less competent in physical activities were less likely to participate in physical versus sedentary activities, enjoyed physical education less, and were more prone to sports injury. These findings were associated with decreases in health-related quality of health measures [117]. These AYA are less likely to reap the potential physical and psychological benefits of physical activity.

Participation in normal activities may also be affected by isolation restrictions, hospitalization, or preconceived ideas of people they encounter in their school, workplace, or community [37, 71, 77, 83, 92]. Teachers, coaches, employers, peers, or family members may overprotect or over-restrict the AYA with cancer [79] and should be informed to allow/encourage the AYA with cancer to engage in as many as usual physical activities as he/she is capable during and after cancer therapy.

Rehabilitation can involve restorative, compensatory, adaptive, or supportive approaches. It is provided by healthcare professionals who work collaboratively in acute care, outpatient, hospice, school, community, and recreational settings. Interdisciplinary rehabilitation teams may include physiotherapists, occupational therapists, speech and language pathologists, child life specialists, psychologists, nurses, physicians, recreation therapists, dieticians, social workers, prosthetists, and orthotists. Roles often overlap allowing professionals to support each other in helping AYA achieve their goals.

Rehabilitation should be incorporated into all stages of the cancer care continuum, from diagnosis, throughout treatment, following treatment, and in some cases at the end of life [58, 69]. Goals should be realistic, prevent or ameliorate impairments, promote participation in meaningful life activities, be matched with psychometrically rigorous outcome measures, and be coupled with reasonable interventions. They should be determined collaboratively with the AYA and customized to unique needs, strengths, and preferences within the context of family and peers, support systems, and environments. Respect for variation, values, culture, and autonomy reflect the tenets of client-centered care. During active cancer treatment, AYA may experience constant transitions in and out of their typical social, recreational, educational, and vocational roles depending on protocol phases, chemotherapy routines, hospitalizations, varying states of wellness, and vulnerability to infection or injury [14, 63]. Short-term goals and interventions may need to be realigned, sometimes on a daily basis, to be sensitive to a constantly changing array of impairments and associated physical and psychosocial issues. Long-term goals during and following treatment should emphasize function and a healthy lifestyle across the lifespan.

AYA and their families need and want knowledge across all phases of cancer care [5, 11, 57]. This includes education about vulnerability to and implications of current and future cancer-related impairments and limitations, awareness of the safety and multiple benefits of exercise, and an understanding that follow-up visits, surveillance testing, and preservation of health are lifelong responsibilities. This knowledge can have an impact on modifiable personal factors such as attitude and motivation, contribute to adherence, and build capacity for the autonomy, informed decision-making, and self-management skills AYA need to develop in order to accept responsibility for their outcomes [11, 57]. Completion of treatment, characterized by a transition from a focus on cancer interventions to an emphasis on wellness while dealing with late effects, is a pivotal time for education [27, 46]. AYA may become complacent with less frequent appointments and develop an attitude that cancer is part of a past life [27, 46]. Information regarding the transition from pediatric to adult services will be important for those experiencing this event [27, 46]. Education is also important for others who can provide informed, encouraging, and supportive environments for participation in rehabilitation and exercise programs. This knowledge can address attitudinal barriers, low expectations, overprotection, and unnecessary restrictions, which can limit opportunities for optimal participation in exercise and other activities [8, 63, 69].

Knowledge of oneself can be facilitated through the use of mobile applications. AYA can use these to track various symptoms, pain management, or eating patterns [61].

The most researched, efficacious, and efficient intervention to address many of the adverse effects of cancer and its treatment is physical activity. However, many of the impairments associated with cancer and its treatment can make participation in physical activity challenging. This paradoxical effect can result in perpetuation of weakness, fatigue, and decreased fitness and endurance.

An increasing body of research has shown that exercise is safe, feasible, and beneficial during and after cancer treatment [7, 14, 16]. However, intervention studies tend to lack sufficient sample sizes/enrollment, adequate randomization, and adherence [8, 14, 31]. Despite challenging methodology and varying results, the evidence shows overall clinically and statistically positive effects on physiological and psychological cancer-related impairments, functioning, quality of life, and the prevention of future cancers [7, 9, 13, 14, 25, 31, 56, 64]. Randomized control trials including AYA have shown exercise to benefit muscle flexibility, body composition as measured by physical fitness, and cardiorespiratory fitness [9]. Other studies have documented beneficial associations between and effects of physical activity on pain, nausea, fatigue, sleep efficiency and duration, hematological indexes, muscle strength, aerobic capacity, exercise tolerance, body composition, anthropometrics, cardiopulmonary fitness, metabolic risk factors, physical functioning, and components of psychological and emotional well-being including anxiety, depression, mood, feelings of control, self-esteem, self-confidence, perceived physical competence, and satisfaction with life [1, 7, 14, 20, 31, 33, 36, 38, 42, 64]. There is some evidence that physical activity can have a beneficial effect on various immune system parameters. However additional research is necessary to understand the mechanisms underlying the impact of exercise on the immune system [41].

To promote exercise in the AYA cancer population, it is important to be aware of and anticipate the determinants of physical activity, particularly those that are modifiable. Motivators include the desire to feel good about oneself, have control over one’s body, socialize, have fun, and achieve health benefits such as weight management, stress reduction, strength, flexibility, improved fitness, and increased energy [39, 40, 43, 68]. Barriers can include pain, anxiety, weakness, fatigue, nausea, neuropathies, overall poor health, safety concerns, and limitations in motor skills such as running and jumping [4, 20, 63, 68, 69]. Low levels of pre-diagnostic activity, female gender, and challenges with cognitive, communication, and psychosocial abilities have been shown to be negative predictors of participation of physical activity during and following treatment [20, 38]. Survivors of CNS cancer are also more likely to be nonparticipants. Personal factors such as culture, preferences, intrinsic motivation, self-efficacy, availability of time, and age and environmental factors such as facilities, season, economics, readily available alternative sedentary activities, the support of family, friends, health professionals, educators, and even the media can be influential factors, many of which have the potential to be modified ([40, 53, 69]; Arroyave et al. 2014). Cancer-specific barriers including overprotection, isolation precautions, hospitalizations, and multiple medical appointments can also impact participation in physical activity ([4, 28, 68]).

Ongoing encouragement and reinforcement of the importance of regular activity by rehabilitation professionals should be a standard of care during and following cancer treatment. Extra effort should be focused on individuals with low incentive or other barriers, as they are most at risk for inactivity and its associated problems. Adolescence is a particularly critical lifespan period as patterns of physical activity and inactivity during these years have been shown to track into adulthood [59] impacting future fitness, obesity, bone density, and cardiovascular disease, factors associated with cancer late effects. Although there is a role for sedentary pastimes such as watching television, using the Internet, or playing video games, particularly when hospitalized or unable to be participate in other pursuits, AYA should be encouraged to choose more active pursuits when able. A tendency to partake in these activities may continue following completion of treatment.

Rehabilitation professionals are well positioned to combine general health promotion with individually targeted, tailored, or adapted interventions. Input should begin shortly after diagnosis, including pre-habilitation when appropriate (Jones 2013), and continue through all phases and transitions to prevent, mitigate, or treat treatment-related impairments ([18, 58]; Jones 2013). Service delivery models can include individual- or group-supervised exercise interventions, home-based programs, or combinations of these [7]. It is important to take personal preferences into account. For all age groups, menus of potential activities that involve fun, recreational, or daily activities and respect individual pre-diagnosis and current interests, preferences for timing, location, and service delivery options may optimize adherence, confidence, and self-management which can contribute to sustainable active lifestyle outcomes [11, 14, 53, 68].

Adolescents with or surviving cancer have indicated preferences for exercising with their friends or families reflecting the importance of relationships as critical sources of support for participation in physical activity (PA); few wanted to exercise with other teens with cancer [9, 39, 68]. They have shown an inclination for being active through recreational or daily activities as opposed to specific exercise programs, exercising in the afternoon or evening rather than the morning, and being active at home, school, or a club instead of hospitals or clinics and report enjoying activities that provide typical teen experiences such as swimming, biking, hockey, dance, basketball, and walking for transportation [68, 69]. Many of these activities can promote flexibility, strength, endurance, balance, and motor skills. Some AYA are able to maintain or resume competitive sports, although adaptations may be necessary at certain times.