A randomized trial on the feasibility of high-intensity interval training during chemotherapy in young breast cancer patients
Question
Can HIIT be successfully implemented during chemotherapy in young breast cancer patients, and what are its exploratory effects on body composition and handgrip strength?
Summary
This randomized open-label trial tested whether supervised HIIT could be delivered during neoadjuvant chemotherapy in young women with breast cancer. Forty women aged 18-40 were randomized to supervised HIIT plus chemotherapy or chemotherapy plus physical-activity guidance. HIIT was performed twice weekly for 6 months in small supervised groups, progressed from 75% HRmax to 80%-90% HRmax, and used multiple cardio stations. Feasibility was high among the HIIT group: retention was 94.74%, the 18 retained participants attended all training sessions, and no training-related adverse events were observed. Exploratory outcomes showed preservation of affected-side handgrip strength versus decline in controls, while between-group body-composition differences were not significant.
Methodology
- Young women aged 18-40 with breast cancer undergoing neoadjuvant chemotherapy.
- 40 participants.
- Circuit cardio machines: treadmill, elliptical bike, cycle ergometer, rowing machine, endurance stepper.
- Work intervals: 1:15 at up to 75% HRmax in month 1; 1:30, 1:45, then 2:00 at 80%-90% HRmax over months 2-6.
- Recovery: 4 minutes active walking between sets.
- Intensity: 75% HRmax progressing to 80%-90% HRmax; HRmax calculated as 220 minus age.
- Approximately 40 minutes including warm-up and stretching/relaxation.
- Twice weekly supervised, plus one instructed 45-minute individual aerobic session weekly.
- 6 months.
- Open-label, parallel, randomized quantitative superiority trial.
- HIIT feasibility, Training-related adverse events, Body composition, and Handgrip strength were tracked.
Outcomes
HIIT retention
18 of 19 HIIT participants completed the intervention, exceeding the prespecified 80% retention threshold.
Retention 94.74%, 95% CI 99.07%-75.36%.
HIIT adherence
All 18 retained HIIT participants attended all training sessions, exceeding the prespecified 70% adherence threshold.
Adherence 100%, 95% CI 100%-82.41%.
Training-related adverse events
No adverse events related to physical training were observed in the HIIT group.
Body composition
HIIT participants had within-group increases in weight and muscle mass and a BMI decrease, but adjusted between-group body-composition outcomes were not significantly different.
HIIT within-group weight p=0.0271, muscle mass p=0.0041, BMI p=0.0232; between-group ANCOVA p=0.375 for weight, p=0.509 for BMI, p=0.058 for muscle mass, p=0.811 for fat mass.
Affected-side handgrip strength
Control affected-side handgrip declined after chemotherapy while HIIT affected-side handgrip was preserved, yielding a significant adjusted between-group difference.
Control 28.9 to 27.9 kg, p=0.0109; HIIT 32.1 to 32.1 kg, p=0.9333; between-group difference 1.2 kg, 95% CI 0.2-2.2, ANCOVA p=0.025.
Unaffected-side handgrip strength
No significant between-group difference was found for unaffected-side handgrip in the primary analysis.
Between-group difference 0.4 kg, 95% CI -0.4 to 1.3, ANCOVA p=0.312.
Insights
- In selected young chemotherapy patients, supervised HIIT can achieve high retention and attendance when sessions are flexible and professionally monitored.
- A progressive first-month skill/safety phase before harder intervals is a useful clinical programming pattern.
- For consumer translation, this evidence should be used for clinical-context education rather than direct workout prescription.
Limitations
- Intensity adherence was not verified throughout every session or work bout.
- Control group had higher weekly steps than HIIT group.
- Control group may have undertaken additional unsupervised activity.
- Participants were young, women only, ECOG 0-1, and relatively fit.
- Specialized supervised clinical setting limits generalizability.
- Physical activity monitor has accuracy limitations.
Safety
- No physical-training-related adverse events were observed in the HIIT group.
- Safety monitoring included heart-rate chest strap and symptom checks for nausea, dizziness, persisting muscle pain, and joint pain.
- One HIIT participant missed post-intervention assessment due to ongoing infection, not reported as training-related.