Influence of water-based exercise on energy intake, appetite, and appetite-related hormones in adults: A systematic review and meta-analysis.

Single bouts of land-based exercise suppress appetite and do not typically alter energy intake in the short-term, whereas it has been suggested that water-based exercise may evoke orexigenic effects. The primary aim was to systematically review the available literature investigating the influence of water-based exercise on energy intake in adults (PROSPERO ID number CRD42022314349). PubMed, Medline, Sport-Discus, Academic Search Complete, CINAHL and Public Health Database were searched for peer-reviewed articles published in English from 1900 to May 2022. Included studies implemented a water-based exercise intervention versus a control or comparator. Risk of bias was assessed using the revised Cochrane 'Risk of bias tool for randomised trials' (RoB 2.0). We identified eight acute (same day) exercise studies which met the inclusion criteria. Meta-analysis was performed using a fixed effects generic inverse variance method on energy intake (8 studies (water versus control), 5 studies (water versus land) and 2 studies (water at two different temperatures)). Appetite and appetite-related hormones are also examined but high heterogeneity did not allow a meta-analysis of these outcome measures. We identified one chronic exercise training study which met the inclusion criteria with findings discussed narratively. Meta-analysis revealed that a single bout of exercise in water increased ad-libitum energy intake compared to a non-exercise control (mean difference [95% CI]: 330 [118, 542] kJ, P = 0.002). No difference in ad libitum energy intake was identified between water and land-based exercise (78 [-176, 334] kJ, P = 0.55). Exercising in cold water (18-20 °C) increased energy intake to a greater extent than neutral water (27-33 °C) temperature (719 [222, 1215] kJ; P < 0.005). The one eligible 12-week study did not assess whether water-based exercise influenced energy intake but did find that cycling and swimming did not alter fasting plasma concentrations of total ghrelin, insulin, leptin or total PYY but contributed to body mass loss 87.3 (5.2) to 85.9 (5.0) kg and 88.9 (4.9) to 86.4 (4.5) kg (P < 0.05) respectively. To conclude, if body mass management is a person's primary focus, they should be mindful of the tendency to eat more in the hours after a water-based exercise session, particularly when the water temperature is cold (18-20 °C).

Effects of moderate to vigorous intensity cycling on appetite, ad libitum energy intake and appetite-related hormones in healthy South Asian and white European men.

Compensatory changes in appetite and energy intake do not appear to occur in the short-term after acute exercise; however, responses have not been compared in South Asians, a group at high risk of central obesity and type 2 diabetes, with white Europeans. This study examined appetite perceptions, energy intake and appetite-related hormones after moderate-to-vigorous intensity cycling in South Asian versus white European men. Fifteen South Asians (mean(SD) 29(8) years; 25.4(4.5) kg m-2) and fifteen white Europeans (33(10) years; 26.1(3.8) kg m-2) matched for age and body mass index completed two 7 h trials (control and exercise). Participants rested throughout both trials apart from completing 60 min cycling at 2-3 h in the exercise trial. A standardised breakfast was consumed at 0 h and an ad libitum buffet meal at 4 h. Appetite perceptions and appetite-related hormones were measured at predetermined intervals. Exercise suppressed acylated ghrelin (d = 0.19, P < 0.001) and increased total peptide YY (PYY) (d = 0.14, P = 0.004), insulin (d = 0.09, P = 0.046) and glucose concentrations (d = 0.31, P < 0.001) (main effect of trial), without stimulating compensatory increases in energy intakes in either group (group-by-trial interactions). South Asians exhibited lower absolute energy intake and higher insulin concentrations than white Europeans (main effect group d ≥ 0.63, P ≤ 0.003), whereas group-by-time interactions revealed lower acylated ghrelin concentrations at 3 and 4 h (d ≥ 0.75, P ≤ 0.038) and higher glucose concentrations at 0.75 and 2 h (d ≥ 0.67, P ≤ 0.008) in South Asian than white European men. These findings demonstrate that acute exercise induces a short-term energy deficit and similar appetite responses in South Asian and white European men.

The influence of different concentrations of flavanol chocolate bars under acute supplement conditions on exercise and performance.

OBJECTIVE: The purpose of this study was to assess the effects and acute dosage of different flavanol concentrations in a dark chocolate bar on physiological parameters during steady state (SS) and incremental exercise. METHODS: In a double-blind, randomised, crossover study, 15 healthy participants with a mean ± SD age of 30 ± 7 years; stature 176.8 ± 8.6 cm and body mass 80.3 ± 8.4 kg supplemented with high flavanol (HF) (1060 mg), moderate flavanol (MF) (746 mg), low flavanol (LF) (406 mg), or a control (CON) (88 mg) chocolate bar (~ 34 g), 2 h prior to 40 min of SS cycling (80% gas-exchange threshold) followed by an incremental test to volitional fatigue. During the SS cycle oxygen consumption ([Formula: see text]), respiratory exchange ratio (RER) and heart rate (HR) were continuously monitored. Plasma samples were collected prior to commencing exercise to determine nitrate (NO3-) and nitrite (NO2-) levels under each condition. RESULTS: There was no observed effect between flavanol concentrations on [Formula: see text], RER, and HR during SS cycling (P > 0.05). [Formula: see text], peak power, HR peak, and RER peak also did not significantly differ between conditions (P > 0.05). There was a small trend for higher plasma NO2- levels following higher flavanol concentration; however, this did not reach statistical significance (P > 0.05). CONCLUSION: Acute supplementation with cocoa of differing flavanol concentrations does not appear to have any effect on exercise and performance. It is plausible that longer flavanol supplementation periods might have greater accumulative effects and thus may potentially elicit a larger effect.

Effects of protein-carbohydrate supplementation on immunity and resistance training outcomes: a double-blind, randomized, controlled clinical trial.

PURPOSE: To examine the impact of ingesting hydrolyzed beef protein, whey protein, and carbohydrate on resistance training outcomes, body composition, muscle thickness, blood indices of health and salivary human neutrophil peptides (HNP1-3), as reference of humoral immunity followed an 8-week resistance training program in college athletes. METHODS: Twenty-seven recreationally physically active males and females (n = 9 per treatment) were randomly assigned to one of the three groups: hydrolyzed beef protein, whey protein, or non-protein isoenergetic carbohydrate. Treatment consisted of ingesting 20 g of supplement, mixed with orange juice, once a day immediately post-workout or before breakfast on non-training days. Measurements were performed pre- and post-intervention on total load (kg) lifted at the first and last workout, body composition (via plethysmography) vastus medialis thickness (mm) (via ultrasonography), and blood indices of health. Salivary HNP1-3 were determined before and after performing the first and last workout. RESULTS: Salivary concentration and secretion rates of the HNP1-3 decreased in the beef condition only from pre-first-workout (1.90 ± 0.83 µg/mL; 2.95 ± 2.83 µg/min, respectively) to pre-last-workout (0.92 ± 0.63 µg/mL, p = 0.025, d = 1.03; 0.76 ± 0.74 µg/min, p = 0.049, d = 0.95), and post-last-workout (0.95 ± 0.60 µg/mL, p = 0.032, d = 1.00; 0.59 ± 0.52 µg/min, p = 0.027, d = 1.02). No other significant differences between groups were observed. CONCLUSIONS: Supplementation with a carbohydrate-protein beverage may support resistance training outcomes in a comparable way as the ingestion of only carbohydrate. Furthermore, the ingestion of 20 g of hydrolyzed beef protein resulted in a decreased level and secretion rates of the HNP1-3 from baseline with no negative effect on blood indices of health.

Salivary and plasma cortisol and testosterone responses to interval and tempo runs and a bodyweight-only circuit session in endurance-trained men.

The aim of this study was to examine the acute response to plasma and salivary cortisol and testosterone to three training protocols. Ten trained endurance athletes participated in three experimental trials, such as interval training (INT), tempo run (TEMP) and bodyweight-only circuit training (CIR), on separate days. Blood and saliva samples were collected pre- and 0, 15, 30 and 60 min post-exercise. Peak post-exercise salivary cortisol was higher than pre-exercise in all trials (P < 0.01). After INT, salivary cortisol remained elevated above pre-exercise than 60 min post-exercise. Salivary testosterone also increased post-exercise in all trials (P < 0.05). Plasma and salivary cortisol were correlated between individuals (r = 0.81, 0.73-0.88) and within individuals (r = 0.81, 0.73-0.87) (P < 0.01). Plasma and salivary testosterone was also correlated between (r = 0.57, 0.43-0.69) and within individuals (r = 0.60, 0.45-0.72), (P < 0.01). Peak cortisol and testosterone levels occurred simultaneously in plasma and saliva, but timing of post-exercise hormone peaks differed between trials and individuals. Further investigation is required to identify the mechanisms eliciting an increase in hormones in response to CIR. Furthermore, saliva is a valid alternative sampling technique for measurement of cortisol, although the complex, individual and situation dependent nature of the hormone response to acute exercise should be considered.

Effects of Interrupting Prolonged Sitting with Physical Activity Breaks on Blood Glucose, Insulin and Triacylglycerol Measures: A Systematic Review and Meta-analysis.

BACKGROUND: Physical activity (PA) breaks in sitting time might attenuate metabolic markers relevant to the prevention of type 2 diabetes. OBJECTIVES: The primary aim of this paper was to systematically review and meta-analyse trials that compared the effects of breaking up prolonged sitting with bouts of PA throughout the day (INT) versus continuous sitting (SIT) on glucose, insulin and triacylglycerol (TAG) measures. A second aim was to compare the effects of INT versus continuous exercise (EX) on glucose, insulin and TAG measures. METHODS: The review followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) recommendations. Eligibility criteria consisted of trials comparing INT vs. SIT or INT vs. one bout of EX before or after sitting, in participants aged 18 or above, who were classified as either metabolically healthy or impaired, but not with other major health conditions such as chronic obstructive pulmonary disease or peripheral arterial disease. RESULTS: A total of 42 studies were included in the overall review, whereas a total of 37 studies were included in the meta-analysis. There was a standardised mean difference (SMD) of - 0.54 (95% CI - 0.70, - 0.37, p = 0.00001) in favour of INT compared to SIT for glucose. With respect to insulin, there was an SMD of - 0.56 (95% CI - 0.74, - 0.38, p = 0.00001) in favour of INT. For TAG, there was an SMD of - 0.26 (95% CI - 0.44, - 0.09, p = 0.002) in favour of INT. Body mass index (BMI) was associated with glucose responses (ß = - 0.05, 95% CI - 0.09, - 0.01, p = 0.01), and insulin (ß = - 0.05, 95% CI - 0.10, - 0.006, p = 0.03), but not TAG (ß = 0.02, 95% CI - 0.02, 0.06, p = 0.37). When energy expenditure was matched, there was an SMD of - 0.26 (95% CI - 0.50, - 0.02, p = 0.03) in favour of INT for glucose, but no statistically significant SMDs for insulin, i.e. 0.35 (95% CI - 0.37, 1.07, p = 0.35), or TAG i.e. 0.08 (95% CI - 0.22, 0.37, p = 0.62). It is worth noting that there was possible publication bias for TAG outcomes when PA breaks were compared with sitting. CONCLUSION: The use of PA breaks during sitting moderately attenuated post-prandial glucose, insulin, and TAG, with greater glycaemic attenuation in people with higher BMI. There was a statistically significant small advantage for PA breaks over continuous exercise for attenuating glucose measures when exercise protocols were energy matched, but no statistically significant differences for insulin and TAG. PROSPERO Registration: CRD42017080982. PROSPERO REGISTRATION: CRD42017080982.

Salivary antimicrobial peptides (LL-37 and alpha-defensins HNP1-3), antimicrobial and IgA responses to prolonged exercise.

There are many factors in mucosal secretions that contribute to innate immunity and the 'first line of defence' at mucosal surfaces. Few studies, however, have investigated the effects of exercise on many of these 'defence' factors. The aim of the present study was to determine the acute effects of prolonged exercise on salivary levels of selected antimicrobial peptides (AMP) that have not yet been studied in response to exercise (HNP1-3 and LL-37) in addition to immunoglobulin A (IgA). A secondary objective was to assess the effects of exercise on saliva antibacterial capacity. Twelve active men exercised on a cycle ergometer for 2.5 h at approximately 60% of maximal oxygen uptake. Unstimulated whole saliva samples were obtained before and after exercise. There was a significant decrease (P < 0.05) in salivary IgA:osmolality ratio, following exercise, but IgA concentration and secretion rate were unaltered. Salivary HNP1-3 and LL-37 concentrations (P < 0.01 and P < 0.05, respectively), concentration:osmolality ratios (P < 0.01) and secretion rates (P < 0.01) all increased following exercise. Salivary antibacterial capacity (against E. coli) did not change. The increased concentration of AMPs in saliva may confer some benefit to the 'first line of defence' and could result from synergistic compensation within the mucosal immune system and/or airway inflammation and epithelial damage. Further study is required to determine the significance of such changes on the overall 'defence' capacity of saliva and how this influences the overall risk for infection.

Plasma Free Fatty Acids Metabolic Profile with LC-MS and Appetite-Related Hormones in South Asian and White European Men in Relation to Adiposity, Physical Activity and Cardiorespiratory Fitness: A Cross-Sectional Study.

South Asians have a greater cardiovascular disease (CVD) and type 2 diabetes (T2D) risk than white Europeans, but the mechanisms are poorly understood. This study examined ethnic differences in free fatty acids (FFAs) metabolic profile (assessed using liquid chromatography-mass spectrometry), appetite-related hormones and traditional CVD and T2D risk markers in blood samples collected from 16 South Asian and 16 white European men and explored associations with body composition, objectively-measured physical activity and cardiorespiratory fitness. South Asians exhibited higher concentrations of five FFAs (laurate, myristate, palmitate, linolenic, linoleate; p ≤ 0.040), lower acylated ghrelin (ES = 1.00, p = 0.008) and higher leptin (ES = 1.11, p = 0.004) than white Europeans; total peptide YY was similar between groups (p = 0.381). South Asians exhibited elevated fasting insulin, C-reactive protein, interleukin-6, triacylglycerol and ratio of total cholesterol to high-density lipoprotein cholesterol (HDL-C) and lower fasting HDL-C (all ES ≥ 0.74, p ≤ 0.053). Controlling for body fat percentage (assessed using air displacement plethysmography) attenuated these differences. Despite similar habitual moderate-to-vigorous physical activity (ES = 0.18, p = 0.675), V ˙ O2max was lower in South Asians (ES = 1.36, p = 0.001). Circulating FFAs in South Asians were positively correlated with body fat percentage (r2 = 0.92), body mass (r2 = 0.86) and AUC glucose (r2 = 0.89) whereas in white Europeans FFAs were negatively correlated with total step counts (r2 = 0.96). In conclusion, South Asians exhibited a different FFA profile, lower ghrelin, higher leptin, impaired CVD and T2D risk markers and lower cardiorespiratory fitness than white Europeans.

A multi-ingredient containing carbohydrate, proteins L-glutamine and L-carnitine attenuates fatigue perception with no effect on performance, muscle damage or immunity in soccer players.

We investigated the effects of ingesting a multi-ingredient (53 g carbohydrate, 14.5 g whey protein, 5 g glutamine, 1.5 g L-carnitine-L-tartrate) supplement, carbohydrate only, or placebo on intermittent performance, perception of fatigue, immunity, and functional and metabolic markers of recovery. Sixteen amateur soccer players ingested their respective treatments before, during and after performing a 90-min intermittent repeated sprint test. Primary outcomes included time for a 90-min intermittent repeated sprint test (IRS) followed by eleven 15 m sprints. Measurements included creatine kinase, myoglobin, interleukine-6, Neutrophil; Lymphocytes and Monocyte before (pre), immediately after (post), 1 h and 24 h after exercise testing period. Overall, time for the IRS and 15 m sprints was not different between treatments. However, the perception of fatigue was attenuated (P<0.001) for the multi-ingredient (15.9±1.4) vs. placebo (17.8±1.4) but not for the carbohydrate (17.0±1.9) condition. Several changes in immune/inflammatory indices were noted as creatine kinase peaked at 24 h while Interleukin-6 and myoglobin increased both immediately after and at 1 h compared with baseline (P<0.05) for all three conditions. However, Myoglobin (P<0.05) was lower 1 h post-exercise for the multi-ingredient (241.8±142.6 ng·ml(-1)) and CHO (265.4±187.8 ng·ml(-1)) vs. placebo (518.6±255.2 ng·ml(-1)). Carbohydrate also elicited lower neutrophil concentrations vs. multi-ingredient (3.9±1.5 10(9)/L vs. 4.9±1.8 10(9)/L, P = 0.016) and a reduced (P<0.05) monocytes count (0.36±0.09 10(9)/L) compared to both multi-ingredient (0.42±0.09 10(9)/L) and placebo (0.42±0.12 10(9)/L). In conclusion, multi-ingredient and carbohydrate supplements did not improve intermittent performance, inflammatory or immune function. However, both treatments did attenuate serum myoglobin, while only carbohydrate blunted post-exercise leukocytosis.

Effects of a carbohydrate and caffeine gel on intermittent sprint performance in recreationally trained males.

We investigated the effects of ingesting carbohydrate gels with and without caffeine on a ~90-minute, four blocks intermittent sprint test (IST), in 12 recreationally trained male athletes. Using a cross-over design, one 70 ml dose of gel containing either 25 g of carbohydrate with (CHOCAF) or without (CHO) 100 mg of caffeine, or a non-caloric placebo (PL) was ingested on three occasions: one hour before, immediately prior to and during the IST. Blood glucose, rating of perceived exertion (RPE) and fatigue index (FI) were analysed. Glucose showed significantly higher values for both CHOCAF and CHO at the first (p=0.005 and p=0.000, respectively), second (p=0.009 and 0.008, respectively) and third (p=0.003 and 0.001, respectively) blocks when compared with PL, while only CHOCAF was significantly different to PL (p=0.002) at the fourth block. CHOCAF showed an improved FI (mean 5.0, s =1.7) compared with CHO (mean 7.6, s =2.6; p=0.006) and PL (mean 7.4, s =2.4; p=0.005), a significantly lower RPE (mean 14.2, s =2) compared with PL (mean 15.3, s =2; p=0.003) and a trend in respect of CHO (mean 14.9, s =2.3; p=0.056) after the third block. In conclusion, ingesting CHOCAF one hour before, prior to and during an IST is effective at transiently reducing fatigue and RPE whilst maintaining higher glucose levels at the final stages of the exercise.

Immunoendocrine responses of male spinal cord injured athletes to 1-hour self-paced exercise: pilot study.

This study examined the effect of a 1 h, self-paced handcycling time trial on blood leukocytes, mucosal immunity, and markers of stress in paraplegic athletes. Nine male paraplegic athletes (spinal injury level thoracic 4-lumbar 2) performed 1 h of handcycling exercise on a standard 400 m athletics track. Heart rate (HR) was measured continuously during exercise, and a retrospective rating of perceived exertion (RPE) was obtained immediately after. Venous blood and saliva samples were collected immediately before exercise (Pre-Ex), after exercise (End-Ex), and 1 h postexercise (1-h Post). The athletes completed mean +/- standard error of mean 22.4 +/- 1.1 km cycling at HR 165 +/- 2 beats/min, RPE 15 +/- 1, and blood lactate 7.9 +/- 2.5 mmol/L. Total leukocytes increased 72% and neutrophils increased 74% End-Ex; both remained elevated at 1-h Post (both p < 0.05). Lymphocytes increased 53% and natural killer cells increased 175% End-Ex (both p < 0.05), but returned to near baseline levels 1-h Post. Increases (p < 0.05) were observed End-Ex in alpha-amylase activity (p < 0.05), which returned to baseline at 1-h Post, but there was no significant change in saliva flow rate, salivary immunoglobulin A, or cortisol. These data confirm that 1 h of handcycling exercise elevated circulating leukocytes but had a minimal effect on mucosal immunity. These changes appear to be associated with alpha-amylase rather than cortisol.

Creatine supplementation with specific view to exercise/sports performance: an update.

Creatine is one of the most popular and widely researched natural supplements. The majority of studies have focused on the effects of creatine monohydrate on performance and health; however, many other forms of creatine exist and are commercially available in the sports nutrition/supplement market. Regardless of the form, supplementation with creatine has regularly shown to increase strength, fat free mass, and muscle morphology with concurrent heavy resistance training more than resistance training alone. Creatine may be of benefit in other modes of exercise such as high-intensity sprints or endurance training. However, it appears that the effects of creatine diminish as the length of time spent exercising increases. Even though not all individuals respond similarly to creatine supplementation, it is generally accepted that its supplementation increases creatine storage and promotes a faster regeneration of adenosine triphosphate between high intensity exercises. These improved outcomes will increase performance and promote greater training adaptations. More recent research suggests that creatine supplementation in amounts of 0.1 g/kg of body weight combined with resistance training improves training adaptations at a cellular and sub-cellular level. Finally, although presently ingesting creatine as an oral supplement is considered safe and ethical, the perception of safety cannot be guaranteed, especially when administered for long period of time to different populations (athletes, sedentary, patient, active, young or elderly).

Regular dark chocolate consumption's reduction of oxidative stress and increase of free-fatty-acid mobilization in response to prolonged cycling.

This study investigated the effects of regular consumption of dark chocolate (DC), rich in cocoa polyphenols, on plasma metabolites, hormones, and markers of oxidative stress after prolonged exhaustive exercise. Twenty active men cycled at 60% maximal oxygen uptake (VO2max) for 1.5 hr, with the intensity increased to 90% VO2max for a 30-s period every 10 min, followed by a ride to exhaustion at 90% VO2max. In the 2 wk before exercise participants consumed 40 g of DC or an isocarbohydrate-fat control cocoa liquor-free chocolate (CON) twice daily and once 2 hr before exercise in a randomized, counterbalanced, crossover design. Venous blood samples were taken immediately before exercise, postexercise (fixed duration), postexhaustion, and after 1 hr of recovery. F2-isoprostanes were significantly lower (post hoc tests: p < .001) at exhaustion and after 1 hr of recovery with DC. Oxidized low-density lipoproteins were significantly lower with DC (p < .001) both before and after exercise and at exhaustion. DC was also associated with ~21% greater rises in free fatty acids during exercise (main effect: p < .05). Changes in circulating glucose, insulin, glucagon, cortisol, and interleukin (IL)-6, IL-10, and IL-1ra were unaffected by treatment. Time to exhaustion at 90% VO2max was not significantly different between trials (398 ± 204 and 374 ± 194 s for DC and CON, respectively). These results suggest that regular DC intake is associated with reduced oxidative-stress markers and increased mobilization of free fatty acids after exercise but has no observed effect on exercise performance.

Influence of a fed or fasted state on the s-IgA response to prolonged cycling in active men and women.

This study investigated the effect of a fed or fasted state on the salivary immunoglobulin A (s-IgA) response to prolonged cycling. Using a randomized, crossover design, 16 active adults (8 men and 8 women) performed 2 hr of cycling on a stationary ergometer at 65% of maximal oxygen uptake on 1 occasion after an overnight fast (FAST) and on another occasion 2 hr after consuming a 2.2-MJ high-carbohydrate meal (FED). Timed, unstimulated whole saliva samples were collected immediately before ingestion of the meal, immediately preexercise, 5 min before cessation of exercise, immediately postexercise, and 1 hr postexercise. The samples were analyzed for s-IgA concentration, osmolality, and cortisol, and saliva flow rates were determined to calculate s-IgA secretion rate. Saliva flow rate decreased by 50% during exercise (p < .05), and s-IgA concentration increased by 42% (p < .05), but s-IgA secretion rate remained unchanged. There was a 37% reduction in s-IgA:osmolality postexercise (p < .05), and salivary cortisol increased by 68% (p < .05). There was no effect of FED vs. FAST on these salivary responses. The s-IgA concentration, secretion rate, and osmolality were found to be significantly lower in women than in men throughout the exercise protocol (p < .05); however, there was no difference between genders in saliva flow rate, s-IgA:osmolality ratio, or cortisol. These data demonstrate that a fed or fasted state 2 hr before exercise does not influence resting s-IgA or the response to prolonged cycling. Furthermore, these results show lower levels of s-IgA and osmolality in women than in men at rest.

Effects of exercise intensity on salivary antimicrobial proteins and markers of stress in active men.

In the present study, we assessed the effects of exercise intensity on salivary immunoglobulin A (s-IgA) and salivary lysozyme (s-Lys) and examined how these responses were associated with salivary markers of adrenal activation. Using a randomized design, 10 healthy active men participated in three experimental cycling trials: 50% maximal oxygen uptake (VO2max), 75%VO2max, and an incremental test to exhaustion. The durations of the trials were the same as for a preliminary incremental test to exhaustion (22.3 min, sx = 0.8). Timed, unstimulated saliva samples were collected before exercise, immediately after exercise, and 1 h after exercise. In the incremental exhaustion trial, the secretion rates of both s-IgA and s-Lys were increased. An increase in s-Lys secretion rate was also observed at 75%VO2max. No significant changes in saliva flow rate were observed in any trial. Cycling at 75%VOmax and to exhaustion increased the secretion of alpha-amylase and chromogranin A immediately after exercise; higher cortisol values at 75%VO2max and in the incremental exhaustion trial compared with 50%VO2max were observed 1 h immediately after exercise only. These findings suggest that short-duration, high-intensity exercise increases the secretion rate of s-IgA and s-Lys despite no change in the saliva flow rate. These effects appear to be associated with changes in sympathetic activity and not the hypothalamic - pituitary - adrenal axis.

Caffeine improves physical and cognitive performance during exhaustive exercise.

UNLABELLED: Caffeine is thought to act as a central stimulant and to have effects on physical, cognitive, and psychomotor functioning. PURPOSE: To examine the effects of ingesting a performance bar, containing caffeine, before and during cycling exercise on physical and cognitive performance. METHODS: Twenty-four well-trained cyclists consumed the products [a performance bar containing 45 g of carbohydrate and 100 mg of caffeine (CAF), an isocaloric noncaffeine performance bar (CHO), or 300 mL of placebo beverage (BEV)] immediately before performing a 2.5-h exercise at 60% VO2max followed by a time to exhaustion trial (T2EX) at 75% VO2max. Additional products were taken after 55 and 115 min of exercise. Cognitive function measures (computerized Stroop and Rapid Visual Information Processing tests) were performed before exercise and while cycling after 70 and 140 min of exercise and again 5 min after completing the T2EX ride. RESULTS: Participants were significantly faster after CAF when compared with CHO on both the computerized complex information processing tests, particularly after 140 min and after the T2EX ride (P < 0.001). On the BEV trial, performance was significantly slower than after both other treatments (P < 0.0001). There were no speed-accuracy tradeoffs (P > 0.10). T2EX was longer after CAF consumption compared with both CHO and BEV trials (P < 0.05), and T2EX was longer after CHO than after BEV (P < 0.05). No differences were found in the ratings of perceived exertion, mean heart rate, and relative exercise intensity (% VO2max; P > 0.05). CONCLUSION: Caffeine in a performance bar can significantly improve endurance performance and complex cognitive ability during and after exercise. These effects may be salient for sports performance in which concentration plays a major role.