Of the 252 women initially approached and screened, 119 women were eligible to participate. Detailed information of individuals who did not participate is described elsewhere.18
Major reasons for refusal included not interested, not eligible, or too busy. No significant differences were found in any demographic variables between participants who completed and dropped out of the study.18
As shown in , 44.1% of the participants were classified as exercisers at T1. No differences were found at any time point in demographic and clinical/treatment characteristics between exercisers and nonexercisers. At T1, participants were asked if they were involved in a regular exercise program. A significantly higher number of participants in the exerciser group responded “yes” to this question (P<0.005). This pattern continued at T2 and T3. No difference was found in the proportion of exercisers and nonexercisers who received RT after their initial course of CTX.
Differences in Demographic and Clinical Characteristics across Time between Exercisers and Nonexercisers
Frequency, Duration, and Intensity of Exercise Dose at Three Time Points
In the total sample, in terms of frequency of exercise dose, more than 80% of the sample exercised more than three times a week. The frequency of exercise decreased to twice a week during cancer treatment (T2), and then it increased to three times a week after completion of cancer treatment (T3) ().
a. Frequency of exercise behavior per week, over time for the entire sample
In terms of duration of exercise per session at T1, about 80% of the sample exercised for more than 20 minutes per session and approximately 36% did more than 45 minutes per session. At T2, similar percentages were reported for duration, and more than 45 minutes per session was still the highest percentage. At T3, about 90% of the sample exercised more than 20 minutes per session, and 37% exercised 31 to 45 minutes per session ().
The intensity rating of “somewhat hard” had the highest percentage among all of the participants at all three time points (54% to 64%). At T1 and T2, a similar pattern was found, with 30% of the sample at the “fairly light” level and 52% at the “somewhat hard” level of intensity. At T3, the rate increased to 64% of the sample exercising at the “somewhat hard” intensity level ().
As to the mode or type of aerobic exercise, various types of aerobic exercise were reported: walking (72%–88%), bicycling (14%–26%), jogging (8.5%–16.5%), and swimming (6%–16%). Walking was the most popular mode of aerobic exercise in the total sample at all three time points. Approximately 50% of the participants at each time point (44% to 57%), were involved in additional “other” types of exercise on a regular basis during the study period. These various “other” exercises included aerobic exercises, the elliptical trainer, the Stairmaster®, or a combination of aerobic exercise with yoga.
As a total sample, a one group t-test was used to evaluate each of the exercise dose characteristics against the minimum criteria of ACS recommendations (three times per week, 20 minutes per session, and moderate intensity). The study participants exercised significantly more frequently (P ≤0.019) and longer (P < 0.0005) than the recommended levels (more than three times per week per week, 20 minutes per session), but less than the recommended level regarding intensity (“moderate”). They exercised significantly less hard at T1 and T2 (P <0.0005). No significant differences in intensity were found at T3 (P = 0.48).
A description of exercise doses of the exercisers and nonexercisers at each time point is shown in . The majority of the exercisers exercised more than three times a week, for more than 30 minutes per session, at a moderate intensity level at each time point. The majority of nonexercisers exercised twice a week, less than 20 minutes per session, and at a mild intensity level at each time point.
Differences over time in exercise behaviors between exercisers and nonexercisers
Comparison of Symptom Severity Between Exercisers and Nonexercisers
At T1, the exercisers had significantly lower total fatigue scores and lower behavioral and sensory fatigue subscale scores than the nonexercisers (P
= 0.037, 0.018, 0.04; respectively) (). The exercisers reported significantly lower depression scores than the nonexercisers (P
=0.038). However, the depression scores for both groups were lower than the cutoff score of 16 for being at risk for depression.52
No significant statistical differences in sleep disturbance or pain (P
= 0.49, 0.88, respectively) were found between exercisers and nonexercisers. In both groups, the mean sleep disturbance score was above the cutoff of ≥ 43 for a clinically significant level of sleep disturbance.48
Differences over time in fatigue, depression, sleep disturbance and pain between exercisers and nonexercisers
At T2, the exercisers reported significantly lower cognitive/mood fatigue subscale scores than the nonexercisers (P = 0.047). The exercisers had significantly lower depression scores than the nonexercisers (P =0.047) and both groups’ depression scores were lower than the cutoff score of 16. No significant differences were found in sleep disturbance (P = 0.28) and pain (P = 0.91) scores between the exercisers and nonexercisers.
At T3, no significant differences were found in any symptom severity scores between the two groups. Participants in both groups reported mild fatigue, pain, and sleep disturbance at each time point but were not at risk for depression at any of the three time points.