Two environmental symptoms questionnaires during 10 days of exercise-heat acclimation.

BACKGROUND: The purpose was to: 1) correlate and compare the long Environmental Symptoms Questionnaire (56-ESQ) with markers of heat acclimation; 2) compare the 56-ESQ with a modified version of the ESQ (14-ESQ) over a 10-d exercise heat acclimation protocol; 3) correlate both scales with physiological data; and 4) determine those questions most sensitive to heat acclimation responses to further refine the 14-ESQ. This is reported as a 12-question ESQ (12-ESQ), which was correlated with physiological data. METHODS: There were 10 non-trained, non-heat-acclimatized men (age 20 +/- 1 yr; height 184 +/- 8 cm; weight 81.7 +/- 12.2 kg; percent body fat 10.1 +/- 2.9%) who undertook 10 consecutive days of heat acclimation (walking at 5.6 km x h(-1), 5% grade, 90 min duration; 33 degrees C, 30-50% relative humidity). ESQ forms were completed on days 1, 4, 7, and 10 pre- and post-exercise. During exercise, rectal temperature (T(r)), heart rate (HR), and rating of perceived exertion (RPE) were recorded. RESULTS: Verification of heat acclimation was based on T(r) and HR, which were significantly lower on day 4 (38.11 +/- 0.25 degrees C, 143 +/- 13 bpm) vs. day 1 (38.46 +/- 0.47 degrees C, 158 +/- 17 bpm) and all subsequent days. All ESQ scales demonstrated a significant effect of time, supporting evidence of heat acclimation. The 56-, 14-, and 12-ESQ post-exercise scores were significantly correlated with HR (r2 = 0.424, 0.353, and 0.430, respectively). The 12-ESQ was correlated with T(r) (r2 = 0.400). DISCUSSION: The 12- and 14-ESQ tracked well with the 56-ESQ. All ESQs were able to track physiological variables and symptoms of heat stress. All ESQ forms may be used as an efficient method to indicate environmental heat stress and symptoms.

Mild dehydration affects mood in healthy young women.

Limited information is available regarding the effects of mild dehydration on cognitive function. Therefore, mild dehydration was produced by intermittent moderate exercise without hyperthermia and its effects on cognitive function of women were investigated. Twenty-five females (age 23.0 ± 0.6 y) participated in three 8-h, placebo-controlled experiments involving a different hydration state each day: exercise-induced dehydration with no diuretic (DN), exercise-induced dehydration plus diuretic (DD; furosemide, 40 mg), and euhydration (EU). Cognitive performance, mood, and symptoms of dehydration were assessed during each experiment, 3 times at rest and during each of 3 exercise sessions. The DN and DD trials in which a volunteer attained a ≥1% level of dehydration were pooled and compared to that volunteer's equivalent EU trials. Mean dehydration achieved during these DN and DD trials was -1.36 ± 0.16% of body mass. Significant adverse effects of dehydration were present at rest and during exercise for vigor-activity, fatigue-inertia, and total mood disturbance scores of the Profile of Mood States and for task difficulty, concentration, and headache as assessed by questionnaire. Most aspects of cognitive performance were not affected by dehydration. Serum osmolality, a marker of hydration, was greater in the mean of the dehydrated trials in which a ≥1% level of dehydration was achieved (P = 0.006) compared to EU. In conclusion, degraded mood, increased perception of task difficulty, lower concentration, and headache symptoms resulted from 1.36% dehydration in females. Increased emphasis on optimal hydration is warranted, especially during and after moderate exercise.

Nutritional, physiological, and perceptual responses during a summer ultraendurance cycling event.

Despite the rapid growth of mass participation road cycling, little is known about the dietary, metabolic, and behavioral responses of ultraendurance cyclists. This investigation describes physiological responses, perceptual ratings, energy balance, and macronutrient intake of 42 men (mean ± SD; age, 38 ± 6 years; height, 179.7 ± 7.1 cm; body mass, 85.85 ± 14.79 kg) and 6 women (age, 41 ± 4 years; height, 168.0 ± 2.9 cm; body mass, 67.32 ± 7.21 kg) during a summer 164-km road cycling event. Measurements were recorded 1 day before, and on the Event Day (10.5 hours) at the start (0 km), at 2 aid stations (52 and 97 km), and at the finish line (164 km). The ambient temperature was >39.0° C during the final 2 hours of exercise. The mean finish times for men (9.1 ± 1.2 hours) and women (9.0 ± 0.2 hours) were similar, as were mean gastrointestinal temperature (TGI), 4 hydration biomarkers, and 5 perceptual (e.g., thermal, thirst, pain) ratings. Male cyclists consumed enough fluids on the Event Day (5.91 ± 2.38 L; 49% water) to maintain body mass within 0.76 kg, start to finish, despite a sweat loss of 1.13 ± 0.54 L·h(-1) and calculated energy expenditure of 3,115 kcal·10.5·h(-1). However, men voluntarily underconsumed food energy (deficit of 2,594 kcal, 10.9 MJ) and specific macronutrients (carbohydrates, 106 ± 48 g; protein, 8 ± 7 g; and sodium, 852 ± 531 mg) between 0530 and 1400 hours. Also, a few men exhibited extreme final values (i.e., urine specific gravity of 1.035-1.038, n = 5; body mass loss >4 kg, n = 2; T(GI), 39.4 and 40.2°C). We concluded that these findings provide information regarding energy consumption, macronutrient intake, hydration status, and the physiological stresses that are unique to ultraendurance exercise in a hot environment.

Effect of ambient temperature on caffeine ergogenicity during endurance exercise.

It is well established that caffeine ingestion during exercise enhances endurance performance. Conversely, the physiological and psychological strain that accompanies increased ambient temperature decreases endurance performance. Little is known about the interaction between environmental temperature and the effects of caffeine on performance. The purpose of this study was to compare the effects of ambient temperature (12 and 33°C) on caffeine ergogenicity during endurance cycling exercise. Eleven male cyclists (mean ± SD; age, 25 ± 6 years; [Formula: see text] 58.7 ± 2.9 ml kg(-1) min(-1)) completed four exercise trials in a randomized, double blind experimental design. After cycling continuously for 90 min (average 65 ± 7% [Formula: see text]) in either a warm (33 ± 1°C, 41 ± 5%rh) or cool (12 ± 1°C, 60 ± 7%rh) environment, subjects completed a 15-min performance trial (PT; based on total work accumulated). Subjects ingested 3 mg kg(-1) of encapsulated caffeine (CAF) or placebo (PLA) 60 min prior to and after 45 min of exercise. Throughout exercise, subjects ingested water so that at the end of exercise, independent of ambient temperature, their body mass was reduced 0.55 ± 0.67%. Two-way (temperature × treatment) repeated-measures ANOVA were conducted with alpha set at 0.05. Total work (kJ) during the PT was greater in 12°C than 33°C [P < 0.001, η(2) = 0.804, confidence interval (CI): 30.51-62.30]. When pooled, CAF increased performance versus PLA independent of temperature (P = 0.006, η(2) = 0.542 CI: 3.60-16.86). However, performance differences with CAF were not dependent on ambient temperature (i.e., non-significant interaction; P = 0.662). CAF versus PLA in 12 and 33°C resulted in few differences in other physiological variables. However, during exercise, rectal temperature (T (re)) increased in the warm environment (peak T (re); 33°C, 39.40 ± 0.45; 12°C, 38.79 ± 0.42°C; P < 0.05) but was not different in CAF versus PLA (P > 0.05). Increased ambient temperature had a detrimental effect on cycling performance in both the CAF and PLA conditions. CAF improved performance independent of environmental temperature. These findings suggest that caffeine at the dosage utilized (6 mg/kg body mass) is a, legal drug that provides an ergogenic benefit in 12 and 33°C.

Accumulation of 2H2O in plasma and eccrine sweat during exercise-heat stress.

The purpose of this research was to characterize the movement of ingested water through body fluids, during exercise-heat stress. Deuterium oxide ((2)H(2)O) accumulation in plasma and eccrine sweat was measured at two sites (back and forehead). The exercise of 14 males was controlled via cycle ergometry in a warm environment (60 min; 28.7 degrees C, 51%rh). Subjects consumed (2)H(2)O (0.15 mg kg(-1), 99.9% purity) mixed in flavored, non-caloric, colored water before exercise, then consumed 3.0 ml kg(-1) containing no (2)H(2)O every 15 min during exercise. We hypothesized that water transit from mouth to skin would occur before 15 min. (2)H(2)O appeared rapidly in both plasma and sweat (P < 0.05), within 10 min of water consumption. The ratio (2)H(2)O/H(2)O (D:H) was 47.3-55.0 times greater in plasma than in back sweat at minutes 10, 20, and 30 (DeltaD:H relative to baseline). At elapsed minute 20, the mean rate of deuterium accumulation (DeltaD:H min(-1)) in plasma was 14.9 and 23.7 times greater than in forehead and back sweat samples, respectively. Mean (+/-SE) whole-body sweat rate was 1.04 +/- 0.05 L h(-1) and subjects with the greatest whole-body sweat rate exhibited the greatest peak deuterium enrichment in sweat (r(2) = 0.87, exponential function); the peak (2)H(2)O enrichment in sweat was not proportional (P > 0.05) to body mass, volume of the deuterium dose, or total volume of fluid consumed. These findings clarify the time course of fluid movement from mouth to eccrine sweat glands, and demonstrate considerable differences of (2)H(2)O enrichment in plasma versus sweat.

Effect of quercetin supplementation on maximal oxygen uptake in men and women.

Quercetin is a naturally occurring flavonoid with anti-oxidant and anti-inflammatory properties. The effect of quercetin supplementation on maximal oxygen uptake (VO(2max)) is unknown. The purpose of this investigation was to test the effects of quercetin supplementation on VO(2max) in untrained, sedentary individuals. After baseline treadmill VO(2max) testing, 11 participants (5 males, 6 females) ingested either placebo or quercetin-supplemented (1000 mg x day(-1)) food bars in a randomized, double-blind, counterbalanced, crossover research design. The participants ingested food bars for six consecutive mornings (5 days). On the sixth morning, participants underwent repeat VO(2max) testing. After a 22 day wash-out, the participants repeated baseline VO(2max) testing, daily consumption of the opposite food bars, and post-supplementation VO(2max) testing. The condition x time interaction for VO(2max) was non-significant when expressed in absolute (litres x min(-1); P = 0.929) and relative (ml x kg(-1) x min(-1); P = 0.778) terms. These findings were similar when taking sex into account (P > 0.05). The mean difference in VO(2max) change from pre to post between groups (quercetin vs. placebo) was 0.139 ml x kg(-1) x min(-1) (P = 0.780). Other physiological measures also were similar between conditions (P > 0.05). In conclusion, 5 days of quercetin supplementation did not influence VO(2max) or related variables in sedentary men and women.

The effects of resistance training on road cycling performance among highly trained cyclists: a systematic review.

Highly trained cyclists may be hesitant to incorporate resistance training (RT) with their endurance training (ET) because of the mixed data regarding concurrent RT and ET (CT). The purpose of this review was to search the scientific body of literature for randomized controlled trials (RCTs) of CT on road cycling performance for highly trained cyclists. Key words (including cycling and strength training) were used to search relevant databases through September 2009 for literature related to CT. Randomized controlled trials were included if they scored > or =5 on the Physiotherapy Evidence Database scale. Five studies met the inclusion criteria: highly trained road cyclists (>7 h.wk or > 150 km.wk, with at least 6 months of training), outcome measure was cycling performance (time trial or time to exhaustion), and RT performed off-bike. Two of the 5 studies found no improvement in performance with CT, but these studies added RT on top of the athletes' existing ET. The 3 studies with improved cycling performance replaced a portion of the athletes' ET with RT, and 2 of the 3 studies included high-intensity explosive-type resistance exercises. Despite the limited research on CT for highly trained cyclists, it is likely that replacing a portion of a cyclist's ET with RT will result in improved time trial performance and maximal power.

Effect of caffeine on sport-specific endurance performance: a systematic review.

Endurance athletes often ingest caffeine because of its reported ergogenic properties. Although there are a vast number of studies quantifying caffeine's effects, many research studies measure endurance performance using a time-to-exhaustion test (subjects exercise at a fixed intensity to volitional exhaustion). Time-to-exhaustion as a performance measure is not ideal because of the high degree of measurement variability between and within subjects. Also, we are unaware of any endurance sports in which individuals win by going a longer distance or for a longer amount of time than their competitors. Measuring performance with a time-trial test (set distance or time with best effort) has high reproducibility and is more applicable to sport. Therefore, the purpose of this review was to critically and objectively evaluate studies that have examined the effect of caffeine on time-trial endurance (>5 minutes) performance. A literature search revealed 21 studies with a total of 33 identifiable caffeine treatments that measured endurance performance with a time-trial component. Each study was objectively analyzed with the Physiotherapy Evidence Database (PEDro) scale. The mean PEDro rating was 9.3 out of 10, indicating a high quality of research in this topic area. The mean improvement in performance with caffeine ingestion was 3.2 +/- 4.3%; however, this improvement was highly variable between studies (-0.3 to 17.3%). The high degree of variability may be dependent on a number of factors including ingestion timing, ingestion mode/vehicle, and subject habituation. Further research should seek to identify individual factors that mediate the large range of improvements observed with caffeine ingestion. In conclusion, caffeine ingestion can be an effective ergogenic aid for endurance athletes when taken before and/or during exercise in moderate quantities (3-6 mg.kg body mass). Abstaining from caffeine at least 7 days before use will give the greatest chance of optimizing the ergogenic effect.

The effects of resistance training on endurance distance running performance among highly trained runners: a systematic review.

The current perception among highly competitive endurance runners is that concurrent resistance and endurance training (CT) will improve running performance despite the limited research in this area. The purpose of this review was to search the body of scientific literature for original research addressing the effects of CT on distance running performance in highly competitive endurance runners. Specific key words (including running, strength training, performance, and endurance) were used to search relevant databases through April 2007 for literature related to CT. Original research was reviewed using the Physiotherapy Evidence Database (PEDro) scale. Five studies met inclusion criteria: highly trained runners (>or= 30 mile x wk(-1) or >or= 5 d x wk(-1)), CT intervention for a period >or= 6 weeks, performance distance between 3K and 42.2K, and a PEDro scale score >or= 5 (out of 10). Exclusion criteria were prepubertal children and elderly populations. Four of the five studies employed sport-specific, explosive resistance training, whereas one study used traditional heavy weight resistance training. Two of the five studies measured 2.9% improved performance (3K and 5K), and all five studies measured 4.6% improved running economy (RE; range = 3-8.1%). After critically reviewing the literature for the impact of CT on high-level runners, we conclude that resistance training likely has a positive effect on endurance running performance or RE. The short duration and wide range of exercises implemented are of concern, but coaches should not hesitate to implement a well-planned, periodized CT program for their endurance runners.

Novel hydration assessment techniques employing thirst and a water intake challenge in healthy men.

Exploring novel hydration indices is important because no human biomarker has been shown to be incontrovertibly valid in all life situations. The present investigation was designed to identify inexpensive, nontechnical methods to use when self-assessing hydration status. This investigation evaluated the validity and efficacy of 2 novel techniques (i.e., thirst sensation and urine volume) to assess hydration state of 29 active men (mean ± SD; age, 23 ± 4 years; body mass, 76.02 ± 11.94 kg) at rest. Eight combinations of 4 water challenges (4.8, 9.3, 11.0, or 14 mL·kg(-1)) and 2 hydration states (mildly hypohydrated (HY), -2.0%; euhydrated (EU), -0.2% body mass) were employed. First, thirst was linearly related to body water loss, and ratings of thirst distinguished HY from EU (p < 0.001) subsequent to 19 h of controlled food and fluid intake. Second, measurements of urine volume 60 min after consuming a water bolus (11.0 or 14 mL·kg(-1)) were strongly and inversely correlated with entering hydration state, assessed by urine specific gravity (r(2) = 0.76, p < 0.0001) and urine osmolality (r(2) = 0.77, p < 0.0001). We concluded that healthy men can employ simple measurements of morning thirst sensation and urine volume to identify the presence of mild hypohydration and to guide fluid replacement. These 2 techniques are relevant because HY (-2% body mass) is the approximate threshold for the onset of thirst, reduced endurance exercise performance, and decrements of working memory and mood.

Eleven days of moderate exercise and heat exposure induces acclimation without significant HSP70 and apoptosis responses of lymphocytes in college-aged males.

The purpose of this study was to assess whether a lymphocyte heat shock response and altered heat tolerance to ex vivo heat shock is evident during acclimation. We aimed to use flow cytometry to assess the CD3(+)CD4(+) T lymphocyte cell subset. We further aimed to induce acclimation using moderately stressful daily exercise-heat exposures to achieve acclimation. Eleven healthy males underwent 11 days of heat acclimation. Subjects walked for 90 min (50 ± 8% VO(2max)) on a treadmill (3.5 mph, 5% grade), in an environmental chamber (33°C, 30-50% relative humidity). Rectal temperature (°C), heart rate (in beats per minute), rating of perceived exertion , thermal ratings, hydration state, and sweat rate were measured during exercise and recovery. On days 1, 4, 7, 10, and 11, peripheral blood mononuclear cells were isolated from pre- and post-exercise blood samples. Intracellular and surface HSP70 (SPA-820PE, Stressgen, Assay Designs), and annexin V (ab14085, Abcam Inc.), as a marker of early apoptosis, were measured on CD3(+) and CD4(+) (sc-70624, sc-70670, Santa Cruz Biotechnology) gated lymphocytes. On day 10, subjects experienced 28 h of sleep loss. Heat acclimation was verified with decreased post-exercise rectal temperature, heart rate, and increased sweat rate on day 11, versus day 1. Heat acclimation was achieved in the absence of significant changes in intracellular HSP70 mean fluorescence intensity and percent of HSP70(+) lymphocytes during acclimation. Furthermore, there was no increased cellular heat tolerance during secondary ex vivo heat shock of the lymphocytes acquired from subjects during acclimation. There was no effect of a mild sleep loss on any variable. We conclude that our protocol successfully induced physiological acclimation without induction of cellular heat shock responses in lymphocytes and that added mild sleep loss is not sufficient to induce a heat shock response.

Effect of various carbohydrate-electrolyte fluids on cycling performance and maximal voluntary contraction.

The purpose of this study was to compare the effects of a carbohydrate-electrolyte plus caffeine, carnitine, taurine, and B vitamins solution (CE+) and a carbohydrate-electrolyte-only solution (CE) vs. a placebo solution (PLA) on cycling performance and maximal voluntary contraction (MVC). In a randomized, double-blind, crossover, repeated-measures design, 14 male cyclists (M +/- SD age 27 +/- 6 yr, VO2max 60.4 +/- 6.8 ml x kg-1 x min(-1)) cycled for 120 min submaximally (alternating 61% +/- 5% and 75% +/- 5% VO2max) and then completed a 15-min performance trial (PT). Participants ingested CE+, CE, or PLA before (6 ml/kg) and every 15 min during exercise (3 ml/kg). MVC was measured as a single-leg isometric extension (70 degree knee flexion) before (pre) and after (post) exercise. Rating of perceived exertion (RPE) was measured throughout. Total work accumulated (KJ) during PT was greater (p < .05) in CE+ (233 +/- 34) than PLA (205 +/- 52) but not in CE (225 +/- 39) vs. PLA. MVC (N) declined (p < .001) from pre to post in PLA (988 +/- 213 to 851 +/- 191) and CE (970 +/- 172 to 870 +/- 163) but not in CE+ (953 +/- 171 to 904 +/- 208). At Minutes 60, 90, 105, and 120 RPE was lower in CE+ (14 +/- 2, 14 +/- 2, 12 +/- 1, 15 +/- 2) than in PLA (14 +/- 2, 15 +/- 2, 14 +/- 2, 16 +/- 2; p < .001). CE+ resulted in greater total work than PLA. CE+, but not PLA or CE, attenuated pre-to-post MVC declines. Performance increases during CE+ may have been influenced by lower RPE and greater preservation of leg strength during exercise in part as a result of the hypothesized effects of CE+ on the central nervous system and skeletal muscle.