ASPO Abstracts
Exercise-induced changes in sleep quality and association with insulin resistance in breast cancer survivors
Category: Lifestyles Behavior, Energy Balance & Chemoprevention
Conference Year: 2020
Abstract Body:
Purpose Poor sleep quality affects nearly one third of breast cancer survivors and is associated
with greater breast cancer mortality. A detrimental effect of poor sleep quality is the
development of insulin resistance, the underlying pathophysiologic disruptor of metabolic
syndrome and type 2 diabetes. The purpose of this secondary analysis was to examine the
effects of a 16-week aerobic and resistance exercise intervention on sleep quality among breast
cancer survivors. We assessed whether exercise-induced changes in sleep quality were
associated with insulin resistance.
Methods Sedentary, overweight or obese (BMI>25.0 kg/m2) breast cancer survivors (Stage I-III)
were randomized to exercise (n=50) or usual care (n=50). The thrice weekly 16-week
intervention included supervised moderate-vigorous aerobic (65-85% maximum heart rate) and
resistance (65-85% 1-repetition maximum) exercise. Sleep quality was assessed by the
Pittsburgh Sleep Quality Index (PSQI). Insulin resistance was estimated using the homeostatic
model assessment of insulin resistance (HOMA-IR) calculated from fasting insulin and glucose
levels. Outcomes were measured at baseline and post-intervention (week 17). Within and
between group differences were assessed by paired t-tests and repeated measures ANOVA.
The association between changes in PSQI and HOMA-IR in the exercise group was computed
using Pearson correlation.
Results Participants were 52 ± 10.4 years old, overweight (54%), Hispanic (55%), and had
undergone a mastectomy (90%) and chemotherapy + radiation therapy (75%). At baseline,
65% of patients were considered poor sleepers. Adherence to the intervention was 95% and
post-intervention assessments were available on 98% of participants. Post-intervention, PSQI
global score improved significantly in the exercise group when compared to usual care (mean
between group difference -2.2; 95% CI -3.2 to -0.6). Change in PSQI was inversely associated
with change in HOMA-IR (r=-0.82; p<0.01) among the exercise group.
Conclusions An aerobic and resistance exercise intervention appears effective to improve sleep
quality in breast cancer survivors. Breast cancer survivors who experience exercise-induced
improvements in sleep quality may also experience improved insulin resistance.
Keywords: exercise, sleep quality, breast cancer survivors