Effects of 2% Dehydration on Lactate Concentration During Constant-Load Cycling

Abstract

Green, JM, Miller, B, Simpson, J, Dubroc, D, Keyes, A, Neal, K, Gann, J, and Andre, T. Effects of 2% dehydration on lactate concentration during constant-load cycling. J Strength Cond Res 32(7): 2066-2071, 2018-The lactate [La] threshold (LT) can predict endurance performance potential. Dehydration may alter LT. This study examined effects of dehydration on [La] response during constant-load cycling. Recreationally fit (V[Combining Dot Above]O2peak = 48.7 ± 5.2 ml·kg·min) male participants (n = 9) completed 2 × 40-minute constant-load cycling trials; euhydrated (HYD) and after previous evening passive (water bath) dehydration (2% body weight, DEH) (HYD and DEH counterbalanced). Lactate, heart rate (HR), 10-point Omni ratings of perceived exertion (RPE), and rectal temperature (Trec) were measured after warm-up (WU) and at 10, 20, 30, and 40 minutes. Before cycling, urine specific gravity (USG) was measured and participants estimated perceived recovery status (PRS). Urine specific gravity DEH (1.027 ± 0.004) was significantly greater than HYD (1.013 ± 0.007). After WU, [La] was significantly greater (all time points) for DEH (∼4.1 mmol·L) vs. HYD (∼3.5 mmol·L) with similar results for HR (DEH: ∼167, HYD: ∼158 b·min). For DEH, RPE was significantly greater (∼1 unit) at 20, 30, and 40 minutes, and Trec was significantly greater at 30 and 40 minutes (∼0.4° C). DEH (vs. HYD) also resulted in significantly different resting HR (93 ± 6, vs. 85 ± 7 b·min), significantly greater session RPE (7.7 ± 1.1 vs. 5.3 ± 1.1), and significantly lower subjective feelings of recovery (PRS = 6.4 ± 2.9, vs. 9.0 ± 1.5). Current results indicate systematic changes in [La] and associated physiological responses result from previous day dehydration. Hydration status should be a concern in paradigms where [La] assessment is used.

Frequency and Prognostic Significance of Serum lactate in Children with Diabetic Ketoacidosis

“…Another study(10) reveled that lactate level was not significantly associated with length of hospital stay (p = 0.115) or the length of time to diabetic ketoacidosis resolution (p = 0.143).In the current study, there was a no significant difference between the serum lactate levels and different hydration states of the patients (p = 0.4). In disagreement with our study, another study(13) showed a strong relation between systematic changes in lactic acid and associated physiological responses resulting from previous day dehydration.…”

Effects of a 2-km Swim on Markers of Cycling Performance in Elite Age-Group Triathletes

“…Moquin and Mazzeo [19] observed a 12% decrease in power at lactate threshold after ~2.6% body mass loss via fluid restriction compared with a euhydrated state. Similarly, Green et al [24] observed that 2% dehydration increased HR and blood lactate during steady-state cycling compared to cycling in a euhydrated state. Kenefick et al [25] found that the lactate threshold occurred at a lower exercise intensity after 4% exercise-induced hypohydration.…”

A quasi-experimental examination of weight-reducing dehydration practices in collegiate male rowers

“…We found an earlier onset of lactate accumulation with increasing weight loss through fluid abstinence. Previous investigations in other athlete populations have found higher blood lactate at submaximal intensities with weight-reducing dehydration practices [ 40 , 41 ]. Nine recreationally fit males demonstrated elevated blood lactate at all time points during a constant-load cycle-ergometer task following a 2%BMC via a warm water bath the previous evening [ 40 ].…”

“…Previous investigations in other athlete populations have found higher blood lactate at submaximal intensities with weight-reducing dehydration practices [ 40 , 41 ]. Nine recreationally fit males demonstrated elevated blood lactate at all time points during a constant-load cycle-ergometer task following a 2%BMC via a warm water bath the previous evening [ 40 ]. Similarly, a study of intercollegiate wrestlers has demonstrated a lower treadmill velocity required to achieve the lactate threshold following exercise in a rubberized sweat suit [ 41 ].…”