The impact of high-intensity interval exercise training on NK-cell function and circulating myokines for breast cancer prevention among women at high risk for breast cancer
Question
Does 12 weeks of HIIT change resting NK-cell function and circulating myokines more than MICT or usual care in postmenopausal women with obesity at heightened breast-cancer risk?
Summary
In postmenopausal women with overweight or obesity at elevated breast-cancer risk, 12 weeks of supervised treadmill HIIT did not significantly change resting NK-cell function or circulating myokines compared with moderate continuous training or usual care. The parent trial reported high adherence and compliance, and this paper notes HIIT improved fitness more than comparison groups in prior reporting.
Methodology
- Postmenopausal women with overweight or obesity at heightened breast-cancer risk.
- 33 participants.
- Treadmill aerobic exercise.
- Work intervals: Four 4-min intervals at 90-100% peak HR.
- Recovery: 3-min active recovery at 50-70% peak HR after each high-intensity interval.
- Intensity: 90-100% peak HR.
- 33 min.
- 3 sessions/week.
- 12 weeks.
- Randomized controlled trial secondary biomarker analysis
- NK-cell function, Myokines, and Cardiorespiratory fitness were tracked.
Outcomes
NK-cell function
No significant within- or between-group changes were observed for NK-cell function variables.
Unadjusted and adjusted models p>0.05 for group changes.
Myokines
No significant between-group changes were observed for circulating myokines.
Change from baseline was not significantly different between groups in unadjusted or adjusted models.
Fitness correlations
Lower baseline fitness was associated with larger improvements in selected NK-cell function markers in the total sample.
Specific lysis r=-0.43, p=0.02; hemacytotoxicity r=-0.46, p=0.01.
Feasibility
The parent trial reported high adherence and protocol compliance for exercise groups.
Adherence 90% HIIT and 89% MICT; compliance 100% to both protocols.
Insights
- A supervised 4 x 4 min treadmill HIIT format can be feasible for a carefully screened older female clinical-prevention population.
- This paper should not be used to claim resting NK-cell or myokine improvements from HIIT.
- For high-risk users, translate the protocol only with screening, heart-rate monitoring, and conservative supervision assumptions.
Limitations
- Small sample size
- Biomarker-focused secondary analysis
- Blood collection timing after last workout varied
- Only one cell line was used for NK-cell assays
- Detailed eligibility, progression, attrition, and adverse-event data were reported elsewhere rather than in this paper
Safety
- This article did not report adverse events or injuries.
- Exercise sessions were supervised in a cancer prevention center and prescribed using individualized peak-HR zones.
- The parent trial was described as having low attrition, high adherence, and 100% compliance to HIIT and MICT protocols.