Effect of Environmental Temperature on High-Intensity Intervals in Well-Trained Cyclists.

PURPOSE: To examine the effect of environmental temperature (TA) on performance and physiological responses (eg, body temperature, cardiopulmonary measures) during a high-intensity aerobic interval session. It was hypothesized that power output would be highest in the 13°C condition and lower in the 5°C, 22°C, and 35°C conditions. METHODS: Eleven well-trained cyclists randomly completed 4 interval sessions at 5°C, 13°C, 22°C, and 35°C (55% [13%] relative humidity), each involving five 4-min intervals interspersed with 5 min of recovery. During the intervals, power output, core temperature (TC), skin temperature, VO2, and heart rate were recorded. RESULTS: Mean session power output for 13°C (366 [32] W) was not higher than 5°C (363 [32] W; P = 1.00, effect size = 0.085), 22°C (364 [36] W; P = 1.00, effect size = 0.061), or 35°C (352 [31] W; P = .129, effect size = 0.441). The 5th interval of the 35°C condition had a lower power output compared with all other TA. TC was higher in 22°C compared with both 5°C and 13°C (P = .001). VO2 was not significantly different across TA (P = .187). Heart rate was higher in the 4th and 5th intervals of 35°C compared with 5°C and 13°C. CONCLUSIONS: This study demonstrates that while mean power outputs for intervals are similar across TA, hot TA (≥35°C) reduces interval power output later in a training session. Well-trained cyclists performing maximal high-intensity aerobic intervals can achieve near-optimal power output over a broader range of TA than previous literature would indicate.

Outcomes During Intended Fluoroscopy-free Ablation in Adults and Children.

Electroanatomic mapping (EAM) systems facilitate the elimination of fluoroscopy during electrophysiologic (EP) studies and ablations. The rate and predictors of fluoroscopy requirements while attempting fluoroscopy-free (FF) ablations are unclear. This study aimed (1) to investigate the rates of fluoroscopic use and acute success in patients initially referred for FF ablation and (2) to identify procedural characteristics associated with fluoroscopic use in patients in whom FF ablation was initially planned (IFF). We performed a retrospective review of all patients who underwent IFF EP study or ablation between 2010 and 2013. Patient and procedural characteristics were compared between those with successful FF procedures and those who subsequently required fluoroscopy during their procedure. An FF EP study with or without ablation was performed in 124 patients during 138 procedures for either supraventricular or idiopathic ventricular arrhythmias. Of the 138 procedures, 105 of them were performed without fluoroscopy. In the remaining 33 cases, fluoroscopy was used for an average of 1.21 minutes ± 1.18 minutes. Acute procedural success was achieved in 97% of both FF and fluoroscopy procedures. The primary reason for fluoroscopy use was as a guide for transseptal puncture. There were no significant differences between FF and fluoroscopy procedures with respect to catheter placement time or complication rate. In conclusion, in this single-center study of IFF procedures, despite careful case selection for IFF ablation, 24% of IFF cases ultimately required minimal fluoroscopy. Fluoroscopy and FF procedures had similar rates of procedural success and complications. Additional large prospective studies are required to further investigate the safety and efficacy of FF ablations.