TNF and ankylosing spondylitis: Based upon the observations in cultured cells (Brunt et al., 2018), rodents (Chen et al., 2004), and patients with ankylosing spondylitis (Tarner et al., 2009) of reduced inflammation after exposure to heat stress, we further hypothesized that leg HT would reduce the plasma levels of interleukin 6 (IL‐6) and tumor necrosis factor alpha (TNF alpha).