Figure 3.

HIIT increases RA skeletal muscle carnitine acetyltransferase enzyme activity in association with increased cardiorespiratory fitness and changes in CD4 + T cell oxidative function. Graphs show individual rheumatoid arthritis (RA) participant (subgroup n = 9) (A) cardiorespiratory fitness (relative VO₂; ml/kg/min), skeletal muscle (B) carnitine acetyltransferase (mCrAT) and (C) citrate synthase enzyme activity (μmol/min/g) before (Pre-HIIT) and after (Post-HIIT) high-intensity interval training (HIIT). (D) Graphs show individual RA participant protein expression of mitochondrial complexes II, III, and V and electron transfer flavoprotein (ETF) Pre-HIIT and Post-HIIT. (E) Scatter plot depicts relationship between percent change in RA mCrAT enzyme activity (y-axis) and percent change and percent change in relative peak VO₂ (ml/kg/min) (x-axis) following HIIT. (F) Scatter plot depicts relationship between percent change in RA mCrAT enzyme acitivity (y-axis) and percent change and percent change in peripheral CD4 + T cell ATP linked respiration (y-axis) following HIIT. *p < 0.05 for paired t-tests and Spearman correlations.