# A pilot study of high-intensity interval training in older adults with treatment naive chronic lymphocytic leukemia

PMID: 34848750
Journal: Scientific Reports
Published: 2021 Nov 30
Authors: MacDonald G, Sitlinger A, Deal MA, Hanson ED, Ferraro S, Pieper CF, Weinberg JB, Brander DM, Bartlett DB

## Question

Is 12 weeks of supervised HIIT combined with muscle endurance resistance training feasible and associated with physical fitness and immune-function changes in older adults with treatment naive chronic lymphocytic leukemia?

## Summary

In a small nonrandomized pilot study of older adults with untreated chronic lymphocytic leukemia, 12 weeks of supervised treadmill HIIT plus resistance training was feasible, achieved high adherence, caused no exercise-session adverse events, and was associated with larger strength and immune-cell function changes than non-exercising controls. Aerobic fitness did not clearly improve more than control.

## Population

- Adults with stable treatment naive chronic lymphocytic leukemia who completed the 12-week study.
- Sample size: 16
- Age: Mean 64.9 years; range 49-79 years
- Sex: 8 men and 8 women
- Fitness level: Low-to-moderate baseline fitness in a clinical older adult sample
- Health status: Treatment naive chronic lymphocytic leukemia

## Methodology

- Two-arm quasi-experimental pilot study
- 12 weeks
- Duke University supervised exercise facility and clinical/laboratory testing
- Controlled study design.

## Protocol

- Treadmill HIIT plus resistance training.
- Modality: Treadmill walking intervals plus leg press, chest press, and seated row.
- Work intervals: 60-90 s high-intensity intervals after acclimation.
- Recovery: 60-90 s active recovery.
- Sets or repetitions: Interval count adjusted to make 30 min aerobic sessions; resistance sets to as many reps as possible at 70% 1RM.
- Intensity: 80-90% VO2 reserve/peak for high intervals; 50-60% for recovery.
- Session duration: 30 min HIIT; two sessions/week also included 30 min resistance training.
- Frequency: 3 HIIT sessions/week and 2 resistance sessions/week.
- Program length: 12 weeks.
- Progression: 3-6 acclimation sessions; treadmill gradient increased to achieve heart-rate target; resistance load increased 2-5 kg after 20 or more reps.
- Non-exercising control.
- Intensity: Continue daily activities and avoid structured exercise programs.
- Program length: 12 weeks.

## Outcomes

### Feasibility
Status: improved
HIIT completers met feasibility, fidelity, and compliance criteria with 99% prescribed minutes completed.

5.0 +/- 0.2 sessions/week; 99 +/- 3.6% prescribed minutes; 100% completed >80% high-intensity intervals at prescribed HR.

### Strength
Status: improved
Leg press, chest press, and seated row strength increased more in HIIT than control.

HIIT vs control: leg +35.4%, g=2.52; chest +56.1%, g=1.15; seated row +39.5%, g=3.07.

### Aerobic capacity
Status: mixed
HIIT did not outperform control for aerobic capacity.

Post-HIIT aerobic capacity was 3.8% lower than controls; g=0.49. Authors noted HIIT increased about 5.3% while controls increased about 10.3%.

### NK function
Status: improved
NK-cell cytolytic activity and cytotoxic protein expression were higher after HIIT versus control.

K562 +20.3%, g=1.43; OSU-CLL +3.0%, g=0.95; autologous B-cells +14.6%, g=1.30; granzyme B g=1.56.

## Practical Insights

- For selected older clinical users, walking HIIT can be delivered by raising treadmill grade while keeping speed at walking pace.
- High adherence in this study depended on supervision, screening, flexible scheduling, and symptom-aware load changes.
- This study should not be used to claim that HIIT improves aerobic capacity more than usual activity in CLL.

## Limitations

- Small pilot sample
- Nonrandomized allocation by travel distance
- Combined HIIT and resistance training prevents isolating the active ingredient
- Participants were screened and may not represent the broader CLL population with higher comorbidity burden
- No p-values were reported because of recruitment bias
- Possible control contamination

## Safety And Adherence

- No adverse events were recorded during exercise sessions.
- All HIIT participants reported minor muscle soreness early in training, considered a normal reaction.
- Arm edema, knee pain, upper respiratory infection, groin tenderness, and mild foot pain each led to brief rescheduling and reduced load until resolved within less than 1 week.
- One participant had dizziness and nausea more than 3 h after baseline CPET and went to the emergency department; clinicians deemed CPET not causal and allowed study continuation.
- The sample was screened to exclude abnormal CPET cardiac findings, absolute exercise contraindications, orthopedic limitations, diabetes, COPD, and uncontrolled hypertension.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/34848750/) (pubmed)
- [DOI](https://doi.org/10.1038/s41598-021-02352-6) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8633014/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.