A Pilot Study of High-Intensity Interval Training in Older Adults with Treatment Naïve Chronic Lymphocytic Leukemia

Abstract

AbstractChronic lymphocytic leukemia (CLL) is the most common leukemia in the USA, affecting predominantly older adults. CLL is characterized by low physical fitness, reduced immunity, and increased risk of secondary malignancies and infections. One approach to improving physical fitness and immune functions is participation in a structured exercise program. The aims of this pilot study were to determine the feasibility and outcomes of 12-weeks of high-intensity interval training (HIIT) combined with muscle endurance-based resistance training on older adults with treatment naïve CLL. We enrolled eighteen participants with CLL aged 64.9 (9.1) years and assigned them to groups depending on distance lived from our fitness center. Ten participants (4M/6F) completed HIIT and six participants (4M/2F) completed a non-exercising control group (Controls). HIIT consisted of three 30-minute treadmill sessions/week plus two concurrent 30-minute strength training sessions/week. We confirmed feasibility if >70% of HIIT participants completed >75% of prescribed sessions and prescribed minutes, and if >80% of high-intensity intervals were at a heart rate corresponding to 80% of aerobic capacity [139 (19) bpm]. Other outcomes included aerobic capacity, muscle strength and endurance, and natural killer (NK) cell recognition and killing of tumor cells. Results are presented as Hedge’s G effect sizes (g), with 0.2, 0.5 and 0.8 representing small, medium and large effects, respectively. Feasibility was achieved, with HIIT completing 5.0 (0.2) sessions/week and 99 (3.6)% of prescribed minutes/week at 142 (19)bpm. Following HIIT, leg strength (g=2.52), chest strength (g=1.15) and seated row strength (g=3.07) were 35.4%, 56.1% and 39.5% higher, respectively, while aerobic capacity was 3.8% lower (g=0.49) than changes for Controls. Similarly, following HIIT, in vitro NK-cell cytolytic activity against the K562 cell line (g=1.43), OSU-CLL cell line (g=0.95), and autologous B-cells (g=1.30) were 20.3%, 3.0% and 14.6% higher, respectively, than changes for Controls. We demonstrate that 12-weeks of HIIT combined with muscle endurance-based resistance training is feasible in older adults with untreated CLL and that HIIT has a large effect on muscle strength and important components of immune function.