Introduction: Cold-induced changes in lactate kinetics are critically important for athletes, particularly those training and competing in the cold. Alterations in lactate production and/or clearance may result in altered blood lactate concentrations and calculated lactate threshold), which affects the exercise intensity that athletes can sustain during a race. The purpose of this study was to evaluate the effect of cold ambient temperature on lactate threshold with and without a preceding warm-up in female cyclists/triathletes. Methods: Seven well-trained female cyclists/triathletes (age: 37 ± 5.yrs; body mass: 60.08 ± 8.93kg; VO2peak :50.36 ± 3.04 ml·kg-1·min-1; peak power output: 261.43 ± 30.78W) participated in this study and completed five study visits: 1) baseline testing; 2) familiarization trial: 3) three experimental trials. The experimental visits consisted of: 1) thermoneutral temperature (20ºC, NEU); 2) cold temperature (0ºC) without an active warm-up (CNWU); 3) cold temperature (0ºC) with 25 min active warm-up (CWU). During each condition, participants performed a lactate threshold test followed by a time to exhaustion trial at 120% of the participant’s peak power output. Heart rate (HR), VO2, core temperature, skin temperature, blood lactate concentration, and rating of perceived exertion (RPE) were assessed throughout each trial. Magnitude based inferences were utilized to examine performance effects (interpreted with Hopkins’ effect sizes). Physiological and perceptual data was assessed via null-hypothesis testing. Data are presented as mean ± SD. Results: Power output at lactate threshold was 182.1 ± 26.4, 200.0 ± 22.6, and 192.9 ± 30.1 W for NEU, CNWU, and CWU, respectively. Power output at lactate threshold was 5.4 ± 2.6% lower in NEU vs. CWU (90% C. I= -10, 0.04; ES = -0.34). Power output at lactate threshold was 4.2 ± 2.7% higher in CNWU vs. CWU; this difference was likely trivial (90% C.I = -1.1, 9.8; ES = 0.25). Power output at lactate threshold in CNWU vs. NEU was 10.2 ± 2.6% greater and the effect was considered very likely small (90% C. I= 4.9, 15.8; ES= 0.59). At lactate threshold, there were no significant differences between groups in VO2, lactate concentration, heart rate or RPE (p = 0.487, 0.115, 0.841, and 0.87, respectively).There was an 11% increase in time to exhaustion at 120% peak power output VO2max between CNWU vs. CWU (73.14 ± 7.93 s, 64.86 ± 7.93 s; 90% C. I= -2.4, 26.5; ES =0.62, respectively) and this effect was likely small. Time to exhaustion was 7.8% longer in NEU condition compared to CWU (70.14 ± 10.45 s, 64.86 ± 7.93 s, 90% C. I= -6.2, 23.9; possibly small; ES =0.44, respectively). Lastly, CNWU vs. NEU had a possibly trivial (3%) increase in time to exhaustion (73.14 ± 7.93 s, 70.14 ± 10.45 s; 90% C.I =-9.1, 16.8; ES =0.18, respectively) Conclusion: These findings suggest that power output at lactate threshold and time to exhaustion at 120% of peak power output was greater and longer in CNWU compared to NEU in female cyclists/triathletes, likely resulting in a small change in performance. For female cyclists/triathletes exercising in the cold, it appears avoiding a 25 min active warm-up may improve performance at lactate threshold and time to exhaustion at 120% of peak power output. Therefore, athletes should consider the effect temperature has on lactate kinetics and determine appropriate training methods and race procedures necessary to optimize performance.
