Chris P. Repka

Oxidative Stress and Fitness Changes in Cancer Patients after Exercise Training.

INTRODUCTION The purpose of this study was to determine the effect of an exercise intervention (EX) on muscular strength, cardiorespiratory fitness (CRF), and oxidative stress in cancer survivors compared with a nonexercising cancer control group (CON). METHODS Fifteen cancer patients and seven age-matched individuals with no history of cancer (NC) participated in this study. A blood draw and assessments of muscular strength and CRF were administered to cancer survivors within 6 wk of completing radiation or chemotherapy, and again 10 wk later. Eight cancer patients completed a 10-wk supervised exercise intervention, whereas seven continued standard care. Baseline oxidative stress was compared between cancer patients and the NC group. Changes in plasma protein carbonyls, 8-OHdG, and Trolox equivalent antioxidant capacity were compared between groups using repeated-measures ANOVA, and correlations between fitness and oxidative stress changes were evaluated. RESULTS Baseline antioxidant capacity was significantly lower, and plasma protein carbonyls were significantly higher in cancer patients compared with NC (P = 0.001). EX had a significant increase in antioxidant capacity (P < 0.001) and decrease in protein carbonyls (P = 0.023), whereas CON did not. Improvements in composite arm (41%, P = 0.002) and leg strength (34%, P = 0.008), isometric handgrip strength (11%, P = 0.015), and V˙O2peak (16%, P = 0.018) were significant in EX but not in CON. 8-OHdG changes were significantly correlated with changes in V˙O2peak (r = -0.89, P < 0.001), arm strength (r = -0.67, P = 0.004), and leg strength (r = -0.56, P = 0.019). CONCLUSION A whole-body exercise intervention for cancer survivors may be an effective method of concurrently increasing muscular strength, CRF, and antioxidant capacity while decreasing markers of oxidative stress.

Comparison of posture and balance in cancer survivors and age-matched controls

Background: The combination of peripheral neuropathy and other treatment‐associated side effects is likely related to an increased incidence of falls in cancer survivors. The purpose of this study was to quantify differences in postural stability between healthy age‐matched controls and cancer survivors. Methods: Quiet standing under four conditions (eyes open/closed, rigid/compliant surface) was assessed in 34 cancer survivors (2 males, 32 females; age: 54(13) yrs., height: 1.62(0.07) m; mass: 78.5(19.5) kg) and 34 age‐matched controls (5 males, 29 females; age: 54(15) yrs.; height: 1.62(0.08) m; mass: 72.8(21.1) kg). Center of pressure data were collected for 30 s and the trajectories were analyzed (100 Hz). Three‐factor (group*surface*vision) mixed model MANOVAs with repeated measures were used to determine the effect of vision and surface on postural steadiness between groups. Findings: Cancer survivors exhibited larger mediolateral root‐mean square distance and velocity of the center of pressure, as well as increased 95% confidence ellipse area (P < 0.01) when compared with their age‐matched counterparts. For example, when removing visual input, cancer survivors had an average increase in 95% confidence ellipse area of 91.8 mm2 while standing on a rigid surface compared to a 68.6 mm2 increase for the control group. No frequency‐based center of pressure measures differed between groups. Interpretation: Cancer survivors exhibit decreased postural steadiness when compared with age‐matched controls. For cancer survivors undergoing rehabilitation focused on existing balance deficits, a small subset of the center of pressure measures presented here can be used to track progress throughout the intervention and potentially mitigate fall risk. HighlightsCancer survivors exhibit less postural steadiness than age‐matched controls.Center of pressure based measures change with varied vision and surface conditions.A subset of center of pressure metrics can adequately assess postural stability.Only time‐domain measures found differences between cancer survivors and controls.Time‐domain measures may be more useful when quantifying postural deficits.

Effects of an Exercise Intervention on Cancer-Related Fatigue and Its Relationship to Markers of Oxidative Stress:

Background: Although the underlying mechanisms of cancer-related fatigue (CRF) are not fully characterized, treatment-associated oxidative stress may play a role. The purpose of this study was to determine the effect of an exercise intervention on the relationship between CRF and oxidative stress. Methods: Upon cessation of radiation or chemotherapy, 8 cancer patients participated in a 10-week exercise intervention (EX), while 7 continued standard care (CON). Blood draws and fatigue questionnaires were administered to cancer patients before and after the intervention as well as to 7 age-matched individuals with no cancer history. Changes in plasma 8-hydroxy-deoxyguanosine (8-OHdG), protein carbonyls, antioxidant capacity, and fatigue were compared between groups. Correlations between CRF and oxidative stress were evaluated. Results: Mean total fatigue scores decreased significantly (5.0 ± 2.2 to 2.6 ± 1.5, P < .05) in EX, but not in CON. Antioxidant capacity significantly increased (+41%; P < .05) and protein carbonyls significantly decreased (−36%; P < .05) in EX, but not in CON. Increases in antioxidant capacity were significantly correlated with reductions in affective (r = −.49), sensory (r = −.47), and cognitive fatigue (r = −.58). Changes in total (r = .46) and affective (r = .47) fatigue exhibited significant correlations with changes in 8-OHdG over time, while behavioral (r = .46) and sensory (r = .47) fatigue changes were significantly correlated with protein carbonyls. Conclusions: Oxidative stress may be implicated in CRF, while improved antioxidant capacity following an exercise intervention may play a role in mitigating CRF in cancer survivors.