Metabolic and physiological effects of high intensity interval training in patients with knee osteoarthritis: A pilot and feasibility study

OBJECTIVE: To examine the feasibility of a 6-week high intensity interval training (HIIT) program in patients with symptomatic knee osteoarthritis (OA). A secondary aim was to evaluate the change in whole-body metabolism. DESIGN: In a single-arm intervention, 16 adults (mean age 59.9 yrs; BMI: 29.0 ± 4.3 kg/m(2); 77% female) with radiographically diagnosed knee OA (Kellgren-Lawrence [KLG]: 2–4) and moderate to severe pain score (≥6) from the Western Ontario and McMasters Universities Index (WOMAC) enrolled in a 6-week, twice weekly, supervised HIIT cycle ergometry intervention. The primary outcome was feasibility; secondary outcomes included change in peak oxygen consumption (VO(2)peak), WOMAC, and circulating biomarkers of metabolism. RESULTS: Feasibility was moderate; of the 21 participants screened by phone, 16 were enrolled; 13 completed pre- and post-testing. The average adherence rate (sessions completed/available) was >96%. VO(2)peak was significantly improved (mean ± SD: 2.6 ± 3.0 mL/min/kg; 95% CI [0.70–4.56]). Significant improvements in WOMAC (mean ± SD: −8.7 ± 12.5; CI: [18.9 to −2.80]), pain [-5.15 to −1.01], and function [-12.9 to −0.98] resulted. There was a significant reduction in concentrations of amino acids: methionine, phenylalanine, and tyrosine (p < 0.02 for all), with trends towards lower concentrations of serine (p = 0.08; [-20.66-1.18]) and greater aspartate/asparagine (p = 0.06; [-1.99-65.73].). Post-training acylcarnitine concentrations were reduced with training. CONCLUSIONS: In this cohort of overweight adults with symptomatic knee OA, 6-weeks of HIIT cycling showed excellent rates of retention and adherence with no adverse events, improved cardiorespiratory fitness and OA symptoms, in concert with metabolic alterations indicative of improved skeletal muscle energetics. TRIAL REGISTRATION NUMBER: clinicaltrials.gov: NCT03039452.