Feasibility, Safety, and Preliminary Efficacy of Very Low-Volume Interval Training in Advanced Cancer Patients
Question
Is a 12-week, very low-volume HIIT protocol feasible and safe for advanced cancer patients, including with respect to acute immune responses, and does it show preliminary efficacy for cardiorespiratory fitness, fatigue, quality of life, and related physiological outcomes compared with sham exercise?
Summary
This 12-week randomized pilot study tested a very low-volume cycle-ergometer HIIT protocol in adults with UICC stage III or IV cancer receiving anticancer therapy. Compared with a sham light-mobilization program, LOW-HIIT had low attrition, high attendance, achieved the intended heart-rate intensity, produced no serious exercise-related adverse events, and improved cardiorespiratory fitness, fatigue, physical functioning, and social functioning.
Methodology
- Adults with UICC stage III or IV advanced cancer and ongoing anticancer therapy.
- 27 participants.
- Electronically braked cycle ergometer.
- Work intervals: 1 minute at 80%-95% HRpeak.
- Recovery: 1 minute low-intensity recovery.
- Intensity: Weeks 1-4: 80%-85% HRpeak; weeks 5-8: 85%-90% HRpeak; weeks 9-12: 90%-95% HRpeak.
- 14 minutes total: 2-minute warm-up, 5 x 1-minute intervals with 1-minute recoveries, 3-minute cooldown.
- 2 sessions per week with at least 1 rest day between sessions.
- 12 weeks.
- 12-week randomized, sham-intervention controlled pre-post feasibility pilot study
- Attrition and attendance, Adverse events, Protocol fidelity, and VO2peak were tracked.
Outcomes
Feasibility
LOW-HIIT met predefined feasibility criteria with 8% attrition and 92.5% +/- 9.7% attendance.
Predefined acceptable thresholds were attrition <=25% and attendance >=80%.
Safety
LOW-HIIT was not associated with serious adverse events, severe muscle soreness, clinically relevant creatine kinase disturbances, increased infection susceptibility, or biochemical signs of acute immunosuppression.
Protocol fidelity
The prescribed minimum interval intensity was consistently reached, with mean interval heart rate 93% +/- 7% HRpeak.
Average whole-session heart rate was 79% +/- 4% HRpeak.
Relative VO2peak
LOW-HIIT increased relative VO2peak by 3.0 mL/kg/min, while SHAM had no significant change.
Group-time interaction P=0.001; LOW-HIIT post hoc change 95% CI 1.8 to 4.0 mL/kg/min, P<0.001.
Ventilatory threshold
LOW-HIIT increased ventilatory threshold by 2.5 mL/kg/min.
Group-time interaction P<0.010; LOW-HIIT post hoc 95% CI 1.2 to 3.8 mL/kg/min, P<0.001.
Fatigue and quality of life
LOW-HIIT improved FACIT fatigue score, physical functioning, and social functioning; SHAM showed no significant self-reported outcome changes.
FACIT +7 points, 95% CI 1 to 13, P=0.010; physical functioning +8 points, 95% CI 1 to 15, P=0.022; social functioning +28 points, 95% CI 12 to 44, P=0.001.
Acute immune response
Blood-cell concentrations rose and fell after exercise without dropping below baseline; NK-cell degranulation increased 60 minutes postexercise and NK-cell composition shifted toward CD56dim cells immediately postexercise.
No statistically significant differences in leukocyte, lymphocyte, neutrophil, or monocyte concentrations across four time points.
Insights
- A very short supervised HIIT session with only 5 minutes of hard work can be feasible in a medically screened, vulnerable clinical population.
- Heart-rate-monitored progression can verify that clinical participants actually reach target HIIT intensity.
- For high-risk populations, low volume and strong supervision are central parts of the protocol, not incidental details.
- Time-efficient HIIT may help address perceived barriers such as lack of time, fatigue, uncertainty about how to exercise, and lack of support.
Limitations
- Initial feasibility pilot with relatively small sample size.
- Acute immune-marker responses were assessed only once after 6 weeks.
- The intervention took place in a highly controlled and supervised clinical setting.
- Recruitment rate could not be meaningfully evaluated.
- Long-term effects on disease prognosis, survival, and tumor biology remain unknown.
- Main-text data do not provide detailed values for all minor adverse events listed in supplement.
Safety
- No serious adverse events occurred during training sessions in either group.
- Minor adverse events and physical complaints were recorded, but most complaints occurred shortly after chemotherapy and were considered unrelated to the exercise interventions.
- No severe muscle soreness or clinically relevant creatine kinase disturbances were observed.
- The authors caution that safe use outside well-controlled clinical settings requires further evaluation and medical clarification.