The Mechanisms Underlying the Beneficial Impact of Aerobic Training on Cancer-Related Fatigue: A Conceptual Review

Cancer-related fatigue (CRF) is a prevalent and persistent issue affecting cancer patients, with a broad impact on their quality of life even years after treatment completion. The precise mechanisms underlying CRF remain elusive, yet its multifaceted nature involves emotional, physical, and cognitive dimensions. The absence of effective medical treatments has prompted researchers to explore integrative models for potential insights. Notably, physical exercise emerges as a promising strategy for managing CRF and related symptoms, as studies showed a reduction in CRF ranging from 19% to 40%. Current recommendations highlight aerobic training at moderate intensity as beneficial, although questions about a dose-response relationship and the importance of exercise intensity persist. Despite the positive impact of exercise on CRF, the underlying mechanisms remain elusive. This review aims to provide a theoretical model explaining how aerobic exercise may alleviate CRF. Focusing on acute exercise effects, this review delves into the potential influence on peripheral and neural inflammation, immune function dysregulation, and neuroendocrine system disruptions. The objective is to enhance our understanding of the intricate relationship between exercise and CRF, ultimately paving the way for tailored interventions and potential pharmacological treatments for individuals unable to engage in physical exercise.

Effects of combined exercise training on the inflammatory profile of older cancer patients treated with systemic therapy

Cancer-related fatigue (CRF) is a major issue in older cancer patients as it is associated with functional decline and a lower quality of life, and an increased inflammatory activity during cancer therapy is suspected to play a key role in CRF etiology. Combined aerobic and resistance exercise training is known to reduce CRF, and this could be mediated by a protective effect against this increased inflammatory activity. Hence, the main objective was to measure the effect of a 12-week combined exercise training on the inflammatory profile of older cancer patients undergoing systemic therapy. A secondary objective was to verify if there was an association between inflammatory profile and CRF.

Methods

Twenty older non-metastatic cancer patients initiating chemotherapy and/or hormone therapy were randomly assigned to 12 weeks of supervised, combined exercise or a control group (static stretching). Primary outcomes were the inflammatory profile, Indoleamine 2,3-deoxygenase activity (KYN/TRP ratio), and CRF (FACIT-F questionnaire). Control outcomes were the fasting nutritional and hormonal blood profiles, body composition (iDXA), physical activity habits (PASE questionnaire), nutritional habits (3-day log), and treatment-related variables.

Results

No worsening of the inflammatory profile was observed in both arms of the study after the intervention. No significant change in CRF was observed, although there was a trend for a reduction in the experimental group (p ​= ​0.10). Significant correlations were found at both timepoints between the KYN/TRP ratio and the delay with the previous treatment received (p ​≤ ​0.03).

Conclusion

These results suggest that exercise might have elicited a positive effect on CRF, which was not mediated by the modulation of the pro-inflammatory cytokine profile. However, the decrease in IL-6/IL-10 ratio in the exercise group might reflect a possible anti-inflammatory effect of exercise. Moreover, exploratory analyses suggest that an acute effect of chemotherapy treatments influenced the inflammatory profile measurements, which could explain the absence of change in the fasting inflammatory profile.

Effect of a mixed-exercise program on physical capacity and sedentary behavior in older adults during cancer treatments

BACKGROUND

Aging, cancer and its treatment all contribute to increase the risk of deconditioning and sedentary behaviors. Mixed exercise is recognized to counteract the effects of aging and deconditioning as well as improving physical capacity during cancer treatment in adults.

AIMS

To determine the impact of a mixed exercise program (MXEP) to improve physical capacity and decrease sedentary behavior time (SBT) in older adults during cancer treatment.

METHODS

Fourteen participants (68.8 ± 3.4 years) completed 12 weeks of a mixed exercise program (MEXP) (n = 6) or stretching (n = 8) while they were under cancer treatment. Five tests of the Senior Fitness Test (Chair Stand, 8-Foot Up & Go, Arm Curl, Sit & Reach, 6 min Walk Test), two maximal strength tests (leg press and handgrip) and a Global Physical Capacity Score (GPCS) were used to assess physical capacity. For the amount of SBT (min/day), we used question 1 of the Physical Activity Scale for the Elderly.

RESULTS

Both groups presented significant pre- vs post-intervention differences for the Chair Stand, Arm Curl, 6 min Walk Tests and also GPCS. Nevertheless, this difference was significantly greater in the MEXP group only for the Chair Stand Test (4.3 ± 2.2 vs 1.0 ± 1.3 reps; p = 0.01) and the GPCS (4.0 ± 0.6 vs 1.5 ± 2.3 points; p = 0.047). A tend to display a greater decrease in SBT (- 295 ± 241 min/week vs - 11 ± 290 min/week; p = 0.079) was observed in favor of MEXP.

CONCLUSION

A 12-week mixed exercise program led to significant improvements in physical capacity and may reduce SBT.

Minimal effect of walking before dinner on glycemic responses in type 2 diabetes: outcomes from the multi-site E-PAraDiGM study

AIM

To examine the effect of walking before dinner on 24-h glycemic control in individuals with type 2 diabetes using the standardized multi-site Exercise-Physical Activity and Diabetes Glucose Monitoring (E-PAraDiGM) Protocol.

METHODS

Eighty participants were studied under two conditions (exercise vs. non-exercise control) separated by 72 h in a randomized crossover design. Each condition lasted 2 days during which standardized meals were provided. Exercise consisted of 50 min of treadmill walking at 5.0 km/h before the evening meal, while control involved 50 min of sitting. The primary outcome measure was mean glucose during the 24-h period following exercise (or sitting) measured by continuous glucose monitoring.

RESULTS

Of the 80 participants who were initially randomized, 73 completed both exercise and control. Sixty-three participants [29 males, 34 females; age = 64 ± 8 years, body mass index = 30.5 ± 6.5 kg/m² and HbA1c = 51 ± 8 mmol/mol (6.8 ± 0.7%), mean ± SD] complied with the standardized diets and had complete continuous glucose monitoring data. Exercise did not affect mean 24-h glucose compared to control (0.03 mmol/L; 95% CI - 0.17, 0.22, P = 0.778) but individual differences between conditions ranged from - 2.8 to +1.8 mmol/L. Exercise did not affect fasting glucose, postprandial glucose or glucose variability. Glucose concentrations measured by continuous glucose monitoring were reduced during the 50 min of walking in exercise compared to sitting in control (- 1.56 mmol/L; 95% CI - 2.18, - 0.95, p < 0.001).

CONCLUSION

Contrary to previous acute exercise studies, 50 min of walking before dinner in the E-PAraDiGM protocol did not affect 24-h glucose profiles. However, highly heterogeneous responses to exercise were observed.

TRIAL REGISTRATION

NCT02834689.

Long-term exercise training and soy isoflavones to improve quality of life and climacteric symptoms

OBJECTIVE

To verify the efficacy of phytoestrogen supplementation combined with aerobic and resistance training on the improvement of climacteric symptoms and health-related quality of life (HRQoL) in postmenopausal women.

METHODS

From a pool of women who had participated in a 1-year intervention study and were randomly assigned to either exercise + phytoestrogen (EX + PHY) or exercise + placebo (EX + PL), a total of 31 healthy but overweight women (mean age 59.2 ± 4.8 years, body mass index 29.1 ± 3.5 kg/m2) finished the study (EX + PHY, n = 15; EX + PL, n = 16). All the following variables were measured before, after 6 months and after 12 months of intervention: body composition (fat and lean body mass, DXA), HRQoL (SF-36 questionnaire: physical and mental component summaries and subscales; and the 10-item Perceived Stress Scale questionnaire), climacteric symptoms (Kupperman Index questionnaire).

RESULTS

After 1 year of intervention, physical functioning (p = 0.003), role-emotional (p = 0.031), vitality (p = 0.007), and global health (p < 0.001) were significantly and similarly increased in both groups. Regarding climacteric symptoms, an improvement in the Kupperman index total score (p = 0.015) was observed.

CONCLUSION

Our results demonstrate that adding phytoestrogens to exercise training does not provide the additive effect for HRQoL in postmenopausal and overweight women. Moreover, exercise and phytoestrogen may interfere in the improvement of climacteric symptoms in the long term.