Sensory Perception of an Oral Rehydration Solution during Exercise in the Heat

Prolonged exercise in the heat elicits a number of physiological changes as glycogen stores are low and water and electrolytes are lost through sweat. However, it is unclear whether these changes provoke an increase in liking of saltiness and, therefore, palatability of an oral rehydration solution (ORS). Twenty-seven recreationally active participants (n = 13 males; n = 14 females) completed sensory analysis of an ORS, a traditional sports drink (TS), and a flavored water placebo (PL) at rest and during 60 min (3 × 20-min bouts) of cycling exercise at 70% age-predicted maximum heart rate (HR_max) at 35.3 ± 1.4 °C and 41 ± 6% relative humidity. Before and after every 20 min of exercise, drinks were rated (using 20-mL beverage samples) based on liking of sweetness, liking of saltiness, thirst-quenching ability, and overall liking on a nine-point hedonic scale. Hydration status was assessed by changes in semi-nude body mass, saliva osmolality (S_Osm), and saliva total protein concentration (S_PC). After 60 min of exercise, participants lost 1.36 ± 0.39% (mean ± SD) of body mass and there were increases in S_Osm and S_PC. At all time points, liking of sweetness, saltiness, thirst-quenching ability, and overall liking was higher for the TS and PL compared to the ORS (p < 0.05). However, the saltiness liking and thirst-quenching ability of the ORS increased after 60 min of exercise compared to before exercise (p < 0.05). There was also a change in predictors of overall liking with pre-exercise ratings mostly determined by liking of sweetness, saltiness, and thirst-quenching ability (p < 0.001), whereas only liking of saltiness predicted overall liking post-exercise (R² = 0.751; p < 0.001). There appears to be a hedonic shift during exercise in which the perception of saltiness becomes the most important predictor of overall liking. This finding supports the potential use of an ORS as a valuable means of hydration during the latter stages of prolonged and/or intense exercise in the heat.     

Expecting yoghurt drinks to taste sweet or pleasant increases liking

This experiment studied the effect of cues on liking of yoghurt drinks. We examined how hedonic (degrees of like/dislike) and sensory (level of sweetness/saltiness) cues affected liking ratings. In the learning phase, thirty-nine participants learned to associate cues with yoghurt drinks. Cues were learned for mildly and highly salty and sweet yoghurts. Sweet yoghurts were used as liked, salty yoghurts as disliked stimuli. Half the participants associated the cues with yoghurt liking (i.e. hedonic cues), the other half with the sweetness or saltiness of the yoghurt drink (i.e. sensory cues). In the test phase a cue was presented to participants subliminally (20 ms) or supraliminally (500 ms) before they tasted and rated liking of one of three yoghurt drinks in each category. The three yoghurt drinks consisted of the trained samples and a new third drink situated approximately half-way in between. The cue-drink combination was either congruent (the cued drink was given) or incongruent (two degrees of incongruence). For sweet yoghurt drinks cue-following assimilation effects were found for the supraliminal but not the subliminal cue presentations. For salty yoghurts, no effects of cue were found. This indicates that the nature of the drinks itself plays a critical role in modulating assimilation.     

Glycemic response to carbohydrate and the effects of exercise and protein

ObjectiveThe purpose of this study was to investigate the effects of pre-exercise and protein coingestion on the glycemic response to carbohydrates.MethodsTwenty-one volunteers (13 males and 8 females) aged 22 y (± 3.8 y) participated in four trials in random order. These included: 1) glucose ingestion at rest (RG), 2) glucose and protein ingestion at rest (RGP), 3) glucose ingestion after exercise (EG), and 4) glucose and protein ingestion after exercise (EGP). Exercise consisted of 45 min of cycling at 60% of participants’ age-predicted maximum heart rate. Test drinks contained 50 g glucose or 50 g glucose with 20 g whey protein. Venous blood samples were taken at baseline and subsequently every 15 min for 2 h after drink consumption. Blood plasma was subsequently analyzed for glucose and insulin.ResultsPlasma glucose concentration was significantly lower in the RGP group than in the RG group at 30, 45, 60, and 75 min and in the EGP group than in the EG group at 30, 45, and 60 min (P < 0.05). Plasma insulin area under the curve was significantly higher in the RGP group than in the RG group and in than in the EGP group than in the EG group (P < 0.05). No significant effect of exercise was seen on glycemic or insulinemic responses.ConclusionsCoingestion of protein with carbohydrate reduces glycemic response and increases insulinemic response in healthy subjects, whereas pre-exercise seems to have no effect.     

Drinking while thirsty can lead to conditioned increases in consumption

A within-subject design was used to test whether repeatedly drinking a novel-flavoured and coloured drink while thirsty would influence subsequent liking for or consumption of that drink, compared to a different flavoured and coloured drink repeatedly consumed while less thirsty. Each participant was given 300 ml of one flavoured drink (H) after consuming a high salt meal (5.27 g of salt), and 300 ml of another flavoured drink (L) after consuming a low salt meal (1.27 g of salt). Participants had 4 sessions with each meal-type/drink combination, in an intermixed order. Pre- and post-training assessments of the drinks were conducted to determine the impact of the training regime on pleasantness and perceived thirst-quenching effect of the drinks. The final session included a choice test, and ad libitum access to the chosen drink, after either a high or low salt meal. In this final choice session, people drank almost twice as much H as L; however, there were no differential effects of past training on rated liking or choice. The increased consumption of H might reflect greater liking for H which was not detected by the rating scales; or it might reflect the learning of greater "conditioned thirst" in response to the flavour of H.     

Pre-Exercise Hyperhydration-Induced Bodyweight Gain Does Not Alter Prolonged Treadmill Running Time-Trial Performance in Warm Ambient Conditions

This study compared the effect of pre-exercise hyperhydration (PEH) and pre-exercise euhydration (PEE) upon treadmill running time-trial (TT) performance in the heat. Six highly trained runners or triathletes underwent two 18 km TT runs (~28 °C, 25%–30% RH) on a motorized treadmill, in a randomized, crossover fashion, while being euhydrated or after hyperhydration with 26 mL/kg bodyweight (BW) of a 130 mmol/L sodium solution. Subjects then ran four successive 4.5 km blocks alternating between 2.5 km at 1% and 2 km at 6% gradient, while drinking a total of 7 mL/kg BW of a 6% sports drink solution (Gatorade, USA). PEH increased BW by 1.00 ± 0.34 kg (P < 0.01) and, compared with PEE, reduced BW loss from 3.1% ± 0.3% (EUH) to 1.4% ± 0.4% (HYP) (P < 0.01) during exercise. Running TT time did not differ between groups (PEH: 85.6 ± 11.6 min; PEE: 85.3 ± 9.6 min, P = 0.82). Heart rate (5 ± 1 beats/min) and rectal (0.3 ± 0.1 °C) and body (0.2 ± 0.1 °C) temperatures of PEE were higher than those of PEH (P < 0.05). There was no significant difference in abdominal discomfort and perceived exertion or heat stress between groups. Our results suggest that pre-exercise sodium-induced hyperhydration of a magnitude of 1 L does not alter 80–90 min running TT performance under warm conditions in highly-trained runners drinking ~500 mL sports drink during exercise.     

Milk as an effective post-exercise rehydration drink

The effectiveness of low-fat milk, alone and with an additional 20 mmol/l NaCl, at restoring fluid balance after exercise-induced hypohydration was compared to a sports drink and water. After losing 1.8 (sd 0.1) % of their body mass during intermittent exercise in a warm environment, eleven subjects consumed a drink volume equivalent to 150 % of their sweat loss. Urine samples were collected before and for 5 h after exercise to assess fluid balance. Urine excretion over the recovery period did not change during the milk trials whereas there was a marked increase in output between 1 and 2 h after drinking water and the sports drink. Cumulative urine output was less after the milk drinks were consumed (611 (sd 207) and 550 (sd 141) ml for milk and milk with added sodium, respectively, compared to 1184 (sd 321) and 1205 (sd 142) ml for the water and sports drink; P < 0.001). Subjects remained in net positive fluid balance or euhydrated throughout the recovery period after drinking the milk drinks but returned to net negative fluid balance 1 h after drinking the other drinks. The results of the present study suggest that milk can be an effective post-exercise rehydration drink and can be considered for use after exercise by everyone except those individuals who have lactose intolerance.     

Pre-Exercise Carbohydrate or Protein Ingestion Influences Substrate Oxidation but Not Performance or Hunger Compared with Cycling in the Fasted State

Nutritional intake can influence exercise metabolism and performance, but there is a lack of research comparing protein-rich pre-exercise meals with endurance exercise performed both in the fasted state and following a carbohydrate-rich breakfast. The purpose of this study was to determine the effects of three pre-exercise nutrition strategies on metabolism and exercise capacity during cycling. On three occasions, seventeen trained male cyclists (VO_2peak 62.2 ± 5.8 mL·kg⁻¹·min⁻¹, 31.2 ± 12.4 years, 74.8 ± 9.6 kg) performed twenty minutes of submaximal cycling (4 × 5 min stages at 60%, 80%, and 100% of ventilatory threshold (VT), and 20% of the difference between power at the VT and peak power), followed by 3 × 3 min intervals at 80% peak aerobic power and 3 × 3 min intervals at maximal effort, 30 min after consuming a carbohydrate-rich meal (CARB; 1 g/kg CHO), a protein-rich meal (PROTEIN; 0.45 g/kg protein + 0.24 g/kg fat), or water (FASTED), in a randomized and counter-balanced order. Fat oxidation was lower for CARB compared with FASTED at and below the VT, and compared with PROTEIN at 60% VT. There were no differences between trials for average power during high-intensity intervals (367 ± 51 W, p = 0.516). Oxidative stress (F₂-Isoprostanes), perceived exertion, and hunger were not different between trials. Overall, exercising in the overnight-fasted state increased fat oxidation during submaximal exercise compared with exercise following a CHO-rich breakfast, and pre-exercise protein ingestion allowed similarly high levels of fat oxidation. There were no differences in perceived exertion, hunger, or performance, and we provide novel data showing no influence of pre-exercise nutrition ingestion on exercise-induced oxidative stress.     

A comparison of bottle tops,teaspoons and WHO glucose-electrolyte packets for home made oral rehydration solutions in The Gambia

Three methods of preparation of oral rehydration solution were taught to Gambian mothers and the sodium concentration and osmolality of the solutions prepared were estimated. Most of the solutions made up using WHO glucose-electrolyte mix had a satisfactory sodium content (70 to 120 mmol/l) and osmolality (200 to 350 mosmoles/kg). Of the sugar and salt mixtures using a teaspoon as a measure, 17% were hypertonic (>120 mmol sodium/l) and 24% were hyperosmolar (>350 mosmol/kg). Nearly all the sugar and salt solutions prepared using a soft drink bottle top as a measure had sodium contents of 30–88 mmol/l and none was hyperosmolar. We suggest that wider trials of this simple, widely available measure are indicated.     

Acceptability of sodium-reduced research diets, including the Dietary Approaches To Stop Hypertension diet, among adults with prehypertension and stage 1 hypertension

OBJECTIVE: Examine the acceptability of sodium-reduced research diets. DESIGN: Randomized crossover trial of three sodium levels for 30 days each among participants randomly assigned to one of two dietary patterns. PARTICIPANTS/SETTING: Three hundred fifty-four adults with prehypertension or stage 1 hypertension who were participants in the Dietary Approaches to Stop Hypertension (DASH-Sodium) outpatient feeding trial. INTERVENTION: Participants received their assigned diet (control or DASH, rich in fruits, vegetables, and low-fat dairy products), each at three levels of sodium (higher, intermediate, and lower) corresponding to 3,500, 2,300, and 1,200 mg/day (150, 100, and 50 mmol/day) per 2,100 kcal. MAIN OUTCOME MEASURES: Nine-item questionnaire on liking and willingness to continue the assigned diet and its level of saltiness using a nine-point scale, ranging from one to nine. STATISTICAL ANALYSES PERFORMED: Generalized estimating equations to test participant ratings as a function of sodium level and diet while adjusting for site, feeding cohort, carryover effects, and ratings during run-in. RESULTS: Overall, participants rated the saltiness of the intermediate level sodium as most acceptable (DASH group: 5.5 for intermediate vs 4.5 and 4.4 for higher and lower sodium; control group: 5.7 for intermediate vs 4.9 and 4.7 for higher and lower sodium) and rated liking and willing to continue the DASH diet more than the control diet by about one point (ratings range from 5.6 to 6.6 for DASH diet and 5.2 to 6.1 for control diet). Small race differences were observed in sodium and diet acceptability. CONCLUSIONS: Both the intermediate and lower sodium levels of each diet are at least as acceptable as the higher sodium level in persons with or at risk for hypertension.     

Fluid availability of sports drinks differing in carbohydrate type and concentration

Plasma D2O-accumulation profiles (qualitative indices of fluid-absorption rates) were determined in eight subjects after ingestion of 275 mL of five D2O-labeled beverages: a water placebo (W), 6% maltodextrin (6% M), and three solutions containing a 6%, 8%, and 10% glucose-fructose mix (6% GF, 8% GF, and 10% GF). Except for W all beverages contained 20 mmol sodium/L and 3 mmol potassium/L. No differences in plasma D2O accumulation were found. Plasma glucose increased at 20 and 30 min after ingestion of the carbohydrate drinks and returned to baseline (6% GF and 6% M) or below (8% GF and 10% GF) by 60 min. Insulin responded similarly and, except for a slightly lower value at 30 min for 6% GF, no differences were detected. It appears that fluids in drinks containing less than or equal to 8-10% carbohydrate (simple sugars or maltodextrins) are made available for dilution in body fluids at similar rates and should be similar in replenishing body fluids lost in sweat during exercise.     

Carbohydrate and glutamine supplementation modulates the Th1/Th2 balance after exercise performed at a simulated altitude of 4500 m

ObjectiveThe aim of this study was to evaluate the effect of carbohydrate or glutamine supplementation, or a combination of the two, on the immune system and inflammatory parameters after exercise in simulated hypoxic conditions at 4500 m.MethodsNine men underwent three sessions of exercise at 70% VO2_peak until exhaustion as follows: 1) hypoxia with a placebo; 2) hypoxia with 8% maltodextrin (200 mL/20 min) during exercise and for 2 h after; and 3) hypoxia after 6 d of glutamine supplementation (20 g/d) and supplementation with 8% maltodextrin (200 mL/20 min) during exercise and for 2 h after. All procedures were randomized and double blind. Blood was collected at rest, immediately before exercise, after the completion of exercise, and 2 h after recovery. Glutamine, cortisol, cytokines, glucose, heat shock protein-70, and erythropoietin were measured in serum, and the cytokine production from lymphocytes was measured.ResultsErythropoietin and interleukin (IL)-6 increased after exercise in the hypoxia group compared with baseline. IL-6 was higher in the hypoxia group than pre-exercise after exercise and after 2 h recovery. Cortisol did not change, whereas glucose was elevated post-exercise in the three groups compared with baseline and pre-exercise. Glutamine increased in the hypoxia + carbohydrate + glutamine group after exercise compared with baseline. Heat shock protein-70 increased post-exercise compared with baseline and pre-exercise and after recovery compared with pre-exercise, in the hypoxia + carbohydrate group. No difference was observed in IL-2 and IL-6 production from lymphocytes. IL-4 was reduced in the supplemented groups.ConclusionCarbohydrate or glutamine supplementation shifts the T helper (Th)1/Th2 balance toward Th1 responses after exercise at a simulated altitude of 4500 m. The nutritional strategies increased in IL-6, suggesting an important anti-inflammatory effect.     

A randomized cross-over study of the metabolic and hormonal responses following two preoperative conditioning drinks

Objective

Preoperative conditioning with carbohydrate-based drinks attenuates postoperative insulin resistance and leads to clinical benefits. The use of metabolic conditioning agents such as glutamine and antioxidants, in addition to carbohydrate, may benefit patients undergoing major surgery, because glutamine and antioxidant supplementation have been shown to improve gastrointestinal perfusion, immune function, morbidity, and gluco-metabolic control in critically ill patients. We investigated the postprandial responses after ingestion of a clear carbohydrate drink (CCD) containing 50 g of carbohydrate (preOp, Nutricia, Trowbridge, UK) and that of another drink containing 50 g of carbohydrate, 15 g of glutamine, and antioxidants (ONS; Fresenius Kabi, Bad Homburg, Germany).

Methods

Twelve overnight-fasted healthy male subjects ingested one of the drinks in a randomized, double-blinded, cross-over manner, after which blood was sampled for 360 min for measurement of glucose, insulin, glucagon, non-esterified fatty acids, β-hydroxybutyrate and glutamine.

Results

The means ± standard errors for age and body mass index of participants were 21 ± 0.9 y and 23.2 ± 0.5 kg/m². After CCD ingestion, glucose and insulin concentrations peaked within 40 min (8.4 ± 0.4 mmol/L and 43.9 ± 3.8 mIU/L, respectively) and returned to baseline at 80 min (glucose 4.9 ± 0.3 mmol/L) and 140 min (insulin 5.5 ± 0.5 mIU/L). After ONS ingestion, peak glucose and insulin concentrations occurred within 40 min but were of a lower magnitude (6.6 ± 0.1 mmol/L and 29.6 ± 2.9 mIU/L, respectively). Glucose concentrations after ONS were higher than after CCD at 100 min.

Conclusion

Peak insulin and glucose concentrations were higher after CCD ingestion; in contrast, responses after ONS ingestion were “blunted” and prolonged.     

Is thirst associated with disability in hospital inpatients?

Objectives: The study aimed to determine what factors prevent patients from drinking in hospital. It also investigated whether thirst is associated with disability and how patients obtain drinks.
Methods: Structured interviews with patients and staff were carried out using the Office of Population Censuses and Surveys (OPCS) disability instrument to measure patient's disability. The study took place in an oncology, orthopaedic and general medical ward in three Cardiff hospitals, with 50 patients studied on each ward (150 patients in total). The main outcome measures were thirst score, ease of reaching drinks, waiting before asking for assistance, availability of drinks and help to drink, and disability score.
Results: Fifty-two per cent ( n = 78) of the sample were more thirsty than usual since admission.
Thirty-seven per cent ( n = 56) were not able to drink as often as they needed to. For these patients the causes included: inability to reach the drink (89%) reluctance to ask for help to drink (45%), unavailability of drinks (32%) and unavailability of help to drink (29%). Of the patients who needed help to drink, 94% ( n = 33) waited before asking for help, and 91% did so because they did not want to trouble busy staff. Significant associations were found between thirst and various aspects of disability (locomotion, reaching and stretching, dexterity, personal care and continence).
Conclusion: Thirst was common in the sample of inpatients interviewed. Many patients were unable to drink as often as they needed. Inability to reach drinks, reluctance to ask busy staff for help and unavailability of drinks or help to drink were the main reasons for this. Thirst was associated with disability. No causal relationship was proved, but disabled dependant patients rely on the availability of drinks within reach and help to drink. Lack of these provisions may be important factors contributing to thirst in disabled inpatients.     

Impact of beverage acceptability on fluid intake during exercise

These two studies investigated the impact of beverage acceptability on voluntary fluid intake during exercise and the subsequent impact of exercise on the perception and liking of beverages. In Experiment 1, 49 triathletes and runners first tasted an array of 10 commercially available flavors of a 6% carbohydrate-electrolyte drink (CE) and water (W) to determine the most-acceptable flavor (M) and least-acceptable flavor (L) for each subject. Subjects were subsequently given M, L, or W ad libitum during 180 min of exercise. Drink acceptability was again measured after 90 and 180 min of exercise. Drink intake was measured at 15-min intervals. Intake of M was significantly greater than L and W throughout the first 75 min and significantly greater than W throughout the entire exercise period. In Experiment 2, subjects were given M+W, or L+W, in a two-bottle procedure. Voluntary intake of M and L exceeded W by 318% and 233%, respectively. An unexpected finding was a strong interaction between drink acceptability and exercise state. The acceptability of L increased substantially from sedentary to exercise conditions. These data demonstrated that the flavored, sweetened beverages used in this study, substantially increased voluntary fluid intake over W.     

Effect of caffeine-deprivation on liking for a non-caffeinated drink

Liking for a novel non-caffeinated drink decreases when regular caffeine consumers are exposed repeatedly to that drink when caffeine-deprived; however, this dislike is not manifest if people are subsequently tested when not caffeine-deprived (Yeomans et al., 2000a). The present study investigated the basis for this effect, and in particular, whether the decrease in liking observed is specific to the drink flavour experienced during caffeine-deprivation. Twenty-four caffeine consumers evaluated five novel drinks (fruit teas) at pre-training. For each person, the drink with the median liking score was subsequently consumed mid-morning after 12 h caffeine-deprivation on four non-consecutive training days. Rated pleasantness of this drink decreased significantly over these four training days. Subjects subsequently re-evaluated all five drinks on a test day when half the consumers were given 100mg caffeine two hours prior to testing, with the remainder receiving placebo. The group who remained deprived continued to express depressed liking for the exposed (target) drink, compared to their pre-training rating of that drink. In contrast, rated pleasantness was not depressed compared to pre-training ratings in the group who had received caffeine prior to testing. Rated pleasantness of the four unexposed drinks was equivalent to pre-training ratings, for both groups, suggesting that the effect of exposure on ratings of the target drink was specific to that drink. As expected, there was some evidence of improved mood in the group receiving caffeine on the test day; but as it was only ratings of the target drink that differed across groups, the group difference cannot be attributed to general effects of mood on use of the rating scale. These data suggest that the reversal of acquired changes in liking for drinks when consumers are changed from a caffeine-deprived to an undeprived condition is best explained in terms of state-dependent learning, that is specific to the drink experienced during caffeine-deprivation.     

Taste responses to saltiness among hypertensive subjects under different therapeutic regimens

Dietary sodium restriction is increasingly regarded as important in the prevention and treatment of essential hypertension. However, low-sodium diets are frequently considered unpalatable and therefore unfeasible. The objectives of this study were to determine (a) whether hypertensives, treated and untreated, differ in saltiness taste perception from age-matched normotensive controls and (b) whether sodium reduction can be accomplished by substituting another taste stimulus without reducing apparent saltiness and palatability. Subjects included 72 hypertensives, 44 to 69 years old, divided among three treatment groups; 25 age-matched normotensive controls; and an additional 21 normotensives, 20 to 43 years old, to provide an age continuum for evaluating age effects. Taste responses were measured in terms of saltiness intensity and preference using tomato juice varying systematically in sodium chloride and citric acid content. No significant differences were found between normotensives and hypertensives. No significant effects were associated with blood pressure status, therapeutic regimen, age, sex, race, or anthropometric measurements. Both sodium chloride and citric acid were main effects for saltiness, allowing a trade-off between salt and acid. Addition of citric acid permitted 50% reduction of sodium content in tomato juice without disturbing palatability criteria. Results provide a model for modifying other processed foods.     

Exercise and energy intake in overweight,sedentary individuals

Exercise expends energy, but without dietary intervention, exercise does not appear to produce substantial weight loss. The present study examined whether overweight, sedentary individuals increase their energy intake after moderate intensity exercise, particularly in the presence of negative mood. A repeated measures design was used where overweight, sedentary individuals (N = 65) completed, in counterbalanced order, two conditions: 3 min of exercise (Active) and 3 min of sedentary activity (Sedentary) during one session. Snack foods were presented 10 min after each activity. Mixed-effects regression modeling revealed no significant effect of Active versus Sedentary condition on energy intake. However, moderational analyses revealed that change in negative mood interacted with condition to predict energy intake, such that participants who reported increased negative mood during exercise consumed more calories in the Active compared to the Sedentary condition. That a short bout of exercise resulted in mood deterioration and increased energy intake for some overweight, sedentary individuals is concerning. Further research examining behavioral and physiological mechanisms of mood deterioration and caloric overcompensation following exercise in overweight, sedentary individuals is warranted.     

Levels and patterns of sedentary behavior in men and women with intellectual disability

BackgroundThere are limited data on the levels and patterns of sedentary behavior (SB) among U.S. adults with ID.ObjectiveTo examine SB levels and patterns in U.S. adults with ID and how these differ between sexes, age-groups, and week vs. weekend days.MethodsFifty-two adults with ID (25 men; age 45 ± 14 years) wore a hip accelerometer (wGT3X-BT; Actigraph) during the waking hours for 7 days. We determined total sedentary time, percent of wear time spent sedentary bouts ≥1, ≥10, ≥30, and ≥60 min, and breaks in sedentary time for bouts ≥10 min. We examined differences in SB variables as a function of sex, age-group by median split (≤48 vs. >48 years), and day of the week.ResultsTotal sedentary time was 514 ± 139 min · day^?1 accumulated in bouts 1–30 min and did not differ between sexes or age-groups. Bouts ≥1 min across days were longer for men than women and longer during weekend days than weekdays (p < 0.05). The number of bouts ≥1 min was greater during weekdays than weekend days (p < 0.05). Bouts ≥60 min were longer for men than women (p < 0.05). The duration of sedentary breaks was longer during weekdays than weekend days (p < 0.001). There were no differences between age-groups.ConclusionsAdults with ID spend a large portion of the day in SB primarily of short bouts. Despite small differences, SB levels and patterns were similar for men and women with ID and across age-groups throughout the week.     

Blood glucose and meal patterns in time-blinded males, after aspartame, carbohydrate, and fat consumption, in relation to sweetness perception

In a study of the impact of aspartame, fat, and carbohydrate on appetite, we monitored blood glucose continuously for 431 (SE 16) min. Ten healthy males (19-31 years) participated in three time-blinded visits. As blood glucose was monitored, appetite ratings were scored at randomized times. On the first meal initiation, volunteers consumed one of three isovolumetric drinks (aspartame, 1 MJ simple carbohydrate, and 1 MJ high-fat; randomized order). High-fat and high-carbohydrate foods were available ad libitum subsequently. Blood glucose patterns following the carbohydrate drink (+1.78 (SE 0.28) mmol/l in 38 (SE 3) min) and high-fat drink (+0.83 (SE 0.28) mmol/l in 49 (SE 6) min) were predictive of the next intermeal interval (R 0.64 and R 0.97 respectively). Aspartame ingestion was followed by blood glucose declines (40% of subjects), increases (20%), or stability (40%). These patterns were related to the volunteers' perception of sweetness of the drink (R 0.81, P = 0.014), and were predictive of subsequent intakes (R -0.71, P = 0.048). For all drinks combined, declines in blood glucose and meal initiation were significantly associated (chi 2 16.8, P < 0.001), the duration of blood glucose responses and intermeal intervals correlated significantly (R 0.715, P = 0.0001), and sweetness perception correlated negatively with hunger suppression (R -0.471, P = 0.015). Effects of fat, carbohydrate, and aspartame on meal initiation, meal size, and intermeal interval relate to blood glucose patterns. Varied blood glucose responses after aspartame support the controversy over its effects, and may relate to sweetness perception.     

Exercise and lipoprotein metabolism in women

Exercise is not regarded as a major risk factor for ischaemic heart disease (IHD). Nevertheless, physically active individuals have a lower risk than their sedentary counterparts, possibly because of favourable modifications of lipoprotein metabolism. In particular, endurance-trained men and women have markedly higher concentrations of high-density lipoprotein cholesterol than sedentary controls. Although the results of exercise intervention studies are less consistent than cross-sectional observations, many do show an increase in high density lipoprotein cholesterol with training. However, most studies have involved high-intensity exercise, usually running, and adherence to these sort of training regimens is poor. Exercise will only influence the risk of IHD in the population if the amount and type of exercise needed to confer benefit is attractive and attainable to large numbers of people. Consequently, there is a need to examine the potential of more socially acceptable, low-intensity exercise to influence risk factors for IHD. In a study at Loughborough University 42 women (mean age 44.9 years) were studied for one year. Twenty-eight followed a programme of brisk walking, whilst 16 acted as controls. After 12 months the walkers showed an 11% increase in maximal oxygen uptake (Mean±s.e.m.) (26.7±-0.7 ml/kg/min cf . 29.7±0.8 ml/kg/min, P<0.01) but no change in body mass or the sum of four skinfolds. Plasma total cholesterol was not significantly different at 12 months for either group but walkers showed a 27% increase in plasma high-density lipoprotein cholesterol (1.17 ± 0.08 mmol/l cf . 1.49±0.06 mmol/l, P<0.01). Brisk walking was therefore a sufficient exercise stimulus to improve fitness and influence lipoprotein metabolism in these previously sedentary, middle-aged women.