Lipolysis, Substrate Metabolism, & Time Trial Performance In Cold Versus Thermo-neutral Environments In Trained Cyclists

Abstract

The degree to which temperature affects endurance performance and exercise metabolism in trained athletes is not fully known. PURPOSE: In the present study, we investigated the impact of cold and neutral environmental temperatures on subcutaneous abdominal adipose tissue (SCAAT) lipolysis and whole-body substrate oxidation during submaximal steady-state cycling in trained cyclists. Additionally, we assessed subsequent time trial (TT) performance. METHODS: Ten trained male cyclists (age = 22.80 ± 2.76 yr; height = 178.58 ± 5.65 cm; mass = 74.02 ± 10.95 kg; body fat = 18.35 ± 3.37%; peak oxygen consumption (VO2peak) = 60.60 ± 4.67 ml·kg-1·min-1; power output in Watts (W) at lactate threshold (LT) = 234.00 ± 35.00 W) participated in a randomized, crossover designed study that consisted of baseline testing to determine LT and VO2peak, two familiarization trials, and two experimental trials. The experimental trials consisted of 25 min of cycling at 70% LT, followed immediately by 25 min at 90% LT in either cold (3.06±1.78°C; 41.63±5.60%RH) or thermoneutral (19.43±0.98°C; 38.97±2.23%RH) conditions. Following a 15-min break, subjects then completed a 20kmthermoneutral room. SCAAT interstitial glycerol concentrations were measured in situ throughout the trial via the microdialysis technique. Two-way (group x time) repeated measures analysis of variance tests and student t-tests (where appropriate) were used to identify differences between measured variables with significance set at p ≤ 0.05. RESULTS: A significant time effect was observed for HR (p < 0.001), core temperature (p < 0.001), interstitial glycerol (p < 0.001), blood lactate (p < 0.028), carbohydrate oxidation (p < 0.0001), fat oxidation (p < 0.0001), and VO2 (p < 0.001). No significant differences were observed between conditions for any measured variable including TT performance (cold, 189.9±24.6 v. neutral, 187.5±27.4 W, p=0.858). CONCLUSION: SCAAT lipolysis increases during steady state exercise. However, metabolism and performance are not impacted by cold ambient conditions. This study was funded by the National Strength and Conditioning Association and Florida State University.