September 2017 - Volume 49 - Issue 9

  • L. Bruce Gladden, PhD, FACSM
  • 0195-9131
  • 1530-0315
  • 12 issues / year
  • 6/81 in Sports Sciences
  • 4.141
​​​​​​​​​​​​​​​​​​​​​​I am excited to direct your attention to three unique studies in this month's journal. First, Jamil et al. studied primary human tendon fibroblasts in cell culture, specifically investigating the effects of angiopoietin-like 4 (ANGPTL4), a substance found in numerous tissues in humans and secreted from cells. In fact, plasma levels of ANGPTL4 rise during exercise, potentially influencing a variety of processes including lipid metabolism and angiogenesis. In the current study, Jamil et al. conducted a gene array experiment to probe the impact of ANGPTL4 on tendon fibroblasts (tenocytes). Tenocyte proliferation and migration pathways were extensively influenced by ANGPTL4 at the mRNA level. Follow-up experiments found that proliferation and migration of tenocytes were indeed significantly impacted as was cell adhesion. In addition, the proliferative response of tenocytes to cyclic strain was dependent on ANGPTL4, highlighting its potential importance in the response of tendon to exercise.

In our second highlight, Connell et al. explored the individual contributions of dopamine and norepinephrine to fatigue-related impairments in oculomotor control. Their group has recently discovered that fatiguing cycle exercise (skeletal motor system) can reduce the velocity of rapid eye movements (oculomotor system). The phenomenon appears to be brain-based, demonstrating that central fatigue may influence independent motor control systems. Presently, Connell et al. show that this phenomenon cannot be accounted for by changes in visual perception or attention. Hypothesizing the cause to be an imbalance in high-turnover neurotransmitters (catecholamines), in two drug interventions, they demonstrated that increasing availability of brain catecholamines can prevent oculomotor fatigue. Eye movement velocity is a potential index of central fatigue, but more importantly, slower eye movements may have serious implications for situations in which physical activity and rapid acquisition of visual information are essential for human performance and safety.

Our third feature is a case study of swimming-induced pulmonary edema (SIPE). SIPE is a mysterious condition that often affects extremely fit individuals. Direct measurements have shown that susceptible individuals have higher than normal pulmonary artery and pulmonary artery wedge pressures during exercise in cold water, and that sildenafil can reduce these pressures. Sildenafil was selected for the initial study due to its known effects on pulmonary hypertension, absence of negative inotropy and minimal systemic effects. In Martina et al.'s current case report, an enthusiastic triathlete who had previously suffered at least five episodes of SIPE, experienced no recurrences (out of at least 20 triathlons) while taking 50 mg sildenafil prior to the start of the swim. ​


L. Bruce Gladden

School of Kinesiology
Auburn University