Sun-dried raisins are a cost-effective alternative to Sports Jelly Beans in prolonged cycling

The purpose of this study was to examine the effects of a natural carbohydrate (CHO) source in the form of sun-dried raisins (SDRs) vs. Sports Jelly Beans? (SJBs) on endurance performance in trained cyclists and triathletes. Ten healthy men (18-33 years) completed 1 water-only acclimatization exercise trial and 2 randomized exercise trials administered in a crossover fashion. Each trial consisted of a 120-minute constant-intensity glycogen depletion period followed by a 10-km time trial (TT). During each experimental trial, participants consumed isocaloric amounts of SDRs or SJBs in 20-minute intervals. Measurements included time to complete 10-km TT, power output during 10-km TT, blood glucose levels and respiratory exchange ratio during glycogen depletion period, rate of perceived exertion (RPE), 'flow' questionnaire responses, and a hedonic (i.e., pleasantness) sensory acceptance test. There were no significant differences in endurance performance for TT time (SDRs vs. SJBs, 17.3 ± 0.4 vs. 17.3 ± 0.4 seconds) or power (229.3 ± 13.0 vs. 232.0 ± 13.6 W), resting blood glucose levels (5.8 ± 04 mmol·L(-1) for SDRs and 5.4 ± 0.2 mmol·L(-1) for SJBs), RPE, or flow experiences between SDR and SJB trials. However, the mean sensory acceptance scores were significantly higher for the SDRs compared to the SJBs (50.7 ± 1.7 vs. 44.3 ± 2.7). Consuming SDRs or SJBs during 120 minutes of intense cycling results in similar subsequent TT performances and are equally effective in maintaining blood glucose levels during exercise. Therefore, SDRs are a natural, pleasant, cost-effective CHO alternative to commercial SJBs that can be used during moderate- to high-intensity endurance exercise.     

Single-leg cycle training is superior to double-leg cycling in improving the oxidative potential and metabolic profile of trained skeletal muscle

Single-leg cycling may enhance the peripheral adaptations of skeletal muscle to a greater extent than double-leg cycling. The purpose of the current study was to determine the influence of 3 wk of high-intensity single- and double-leg cycle training on markers of oxidative potential and muscle metabolism and exercise performance. In a crossover design, nine trained cyclists (78 ± 7 kg body wt, 59 ± 5 ml·kg(-1)·min(-1) maximal O(2) consumption) performed an incremental cycling test and a 16-km cycling time trial before and after 3 wk of double-leg and counterweighted single-leg cycle training (2 training sessions per week). Training involved three (double) or six (single) maximal 4-min intervals with 6 min of recovery. Mean power output during the single-leg intervals was more than half that during the double-leg intervals (198 ± 29 vs. 344 ± 38 W, P < 0.05). Skeletal muscle biopsy samples from the vastus lateralis revealed a training-induced increase in Thr(172)-phosphorylated 5'-AMP-activated protein kinase α-subunit for both groups (P < 0.05). However, the increase in cytochrome c oxidase subunits II and IV and GLUT-4 protein concentration was greater following single- than double-leg cycling (P < 0.05). Training-induced improvements in maximal O(2) consumption (3.9 ± 6.2% vs. 0.6 ± 3.6%) and time-trial performance (1.3 ± 0.5% vs. 2.3 ± 4.2%) were similar following both interventions. We conclude that short-term high-intensity single-leg cycle training can elicit greater enhancement in the metabolic and oxidative potential of skeletal muscle than traditional double-leg cycling. Single-leg cycling may therefore provide a valuable training stimulus for trained and clinical populations.     

Seasonal variation in heart rate variability in asthmatic children

Asthma is a "seasonal disease" with symptoms either aggravated by environmental changes during specific seasons or prevalent at certain times of the year for other reasons. We examined whether the heart rate variability (HRV) of asthmatic children changes by season. The HRV during a portion of one night (00:00-04:00) and day (12:00-16:00) and the entire 24h period (00:00-24:00) during each of the four seasons was analyzed. The data of 95 children with asthma and 106 healthy children, as controls, were assessed. In children with asthma during the 24h period, seasonal variation in the low-frequency (LF) band (0.04-0.15 Hz) and the high-frequency (HF) band (0.15-0.4 Hz) were detected (HF: F=6.81, p=.0003; LF: F=4.18, p= .008). The HF value in the summer was significantly higher than in autumn and spring (Scheffe test: autumn vs. summer, s = 4.46, p < .001: spring vs. summer, s = 2.86, p < .05), while the LF value in autumn was significantly lower than in summer (s = 3.42, p < .01). In the control group, no seasonal variation in HF, LF, or LF/HF was detected. The findings infer the HRV, a surrogate measure of autonomic nervous system function, of asthmatic children is more susceptible to seasonal changes brought about by either endogenous annual rhythms or environmental weather phenomena.     

四川梅花鹿的昼夜活动节律与时间分配

1987 年2 月至2000 年9 月, 用直接观察法在四川省铁布自然保护区中先后对287 只四川梅花鹿的昼夜活动节律和时间分配进行了2 934 h 的观察。四川梅花鹿的昼夜活动具有明显的活动与休息相间出现的节律, 晨昏和午夜是其活动的高峰期, 白昼活动强度较低以休息反刍为主。不同季节其昼夜活动节律有较大的变化。春、夏、秋、冬4 季每天单位时间的平均活动频率分别为: 55.29 ±32.97 %、46.42 ±37.24 %、48.21 ±35.80 %、47.75±32.21 % , 季节差异不明显( F = 0.32 < F_o.o1 ) 。昼夜年平均每天约有52.07 %的时间在活动, 其中白昼活动仅占5.28 % , 而晨昏和夜晚的活动占46.79 %。影响时间分配比例的因素为: 鹿的年龄、性别、繁殖状态、食物资源、天气状况、人为干扰等。     

Metabolic and cardioventilatory responses during a graded exercise test before and 24 h after a triathlon

Previous studies have reported respiratory, cardiac and muscle changes at rest in triathletes 24 h after completion of the event. To examine the effects of these changes on metabolic and cardioventilatory variables during exercise, eight male triathletes of mean age 21.1 (SD 2.5) years (range 17-26 years) performed an incremental cycle exercise test (IET) before (pre) and the day after (post) an official classic triathlon (1.5-km swimming, 40-km cycling and 10-km running). The IET was performed using an electromagnetic cycle ergometer. Ventilatory data were collected every minute using a breath-by-breath automated system and included minute ventilation (V(E)), oxygen uptake (VO2), carbon dioxide production (VCO2), respiratory exchange ratio, ventilatory equivalent for oxygen (V(E)/VO2) and for carbon dioxide (V(E)/VCO2), breathing frequency and tidal volume. Heart rate (HR) was monitored using an electrocardiogram. The oxygen pulse was calculated as VO2/HR. Arterialized blood was collected every 2 min throughout IET and the recovery period, and lactate concentration was measured using an enzymatic method. Maximal oxygen uptake (VO2max) was determined using conventional criteria. Ventilatory threshold (VT) was determined using the V-slope method formulated earlier. Cardioventilatory variables were studied during the test, at the point when the subject felt exhausted and during recovery. Results indicated no significant differences (P > 0.05) in VO2max [62.6 (SD 5.9) vs 64.6 (SD 4.8) ml x kg(-1) x min(-1)], VT [2368 (SD 258) vs 2477 (SD 352) ml x min(-1)] and time courses of VO2 between the pre- versus post-triathlon sessions. In contrast, the time courses of HR and blood lactate concentration reached significantly higher values (P < 0.05) in the pre-triathlon session. We concluded that these triathletes when tested 24 h after a classic triathlon displayed their pre-event aerobic exercise capacity, bud did not recover pretriathlon time courses in HR or blood lactate concentration.     

24-hour pattern in lag time of response by firemen to calls for urgent medical aid

The aim of the study was to assess the group 24-h pattern of lag time (LT) in response by regular and volunteer firemen (RFM and VFM) to calls for medical help (CFMH), specifically calls for out-of-hospital cardiac arrest (OHCA). LT, duration in min between a CFMH and departure of service vehicle equipped with a semiautomated defibrillator and generally staffed with four well-trained and ready-to-go FM, represents the integrated duration of several processes, each with separate reaction and decision-making times. The exact time of each CFHM (in min, h, day, month, yr) was recorded electronically, and the exact departure time from the station of the responding FM vehicle was recorded by an on-duty FM. Overall, CFMH made up 53 ± 9% (SEM) of all emergencies calls for aid. To standardize the study methods, the reported findings are based on 568 CFMH specifically regarding OHCA that occurred during the 4-yr study span (January 2005 to December 2008). CFMH exhibited a 24-h pattern with a major peak at 10:00 h (mean ± SEM: n = 9.5 ± 1.6) and major trough at 01:00 h (n = 1.3 ± 0.3; t test, p??.05). In CFMH/h pooled time series, ANOVA-detected differences between the hourly means (p?相似文献   

Circadian phase, sleepiness, and light exposure assessment in night workers with and without shift work disorder

Most night workers are unable to adjust their circadian rhythms to the atypical hours of sleep and wake. Between 10% and 30% of shiftworkers report symptoms of excessive sleepiness and/or insomnia consistent with a diagnosis of shift work disorder (SWD). Difficulties in attaining appropriate shifts in circadian phase, in response to night work, may explain why some individuals develop SWD. In the present study, it was hypothesized that disturbances of sleep and wakefulness in shiftworkers are related to the degree of mismatch between their endogenous circadian rhythms and the night-work schedule of sleep during the day and wake activities at night. Five asymptomatic night workers (ANWs) (3 females; [mean ± SD] age: 39.2 ± 12.5 yrs; mean yrs on shift = 9.3) and five night workers meeting diagnostic criteria (International Classification of Sleep Disorders [ICSD]-2) for SWD (3 females; age: 35.6 ± 8.6 yrs; mean years on shift = 8.4) participated. All participants were admitted to the sleep center at 16:00 h, where they stayed in a dim light (<10 lux) private room for the study period of 25 consecutive hours. Saliva samples for melatonin assessment were collected at 30-min intervals. Circadian phase was determined from circadian rhythms of salivary melatonin onset (dim light melatonin onset, DLMO) calculated for each individual melatonin profile. Objective sleepiness was assessed using the multiple sleep latency test (MSLT; 13 trials, 2-h intervals starting at 17:00 h). A Mann-Whitney U test was used for evaluation of differences between groups. The DLMO in ANW group was 04:42 ± 3.25 h, whereas in the SWD group it was 20:42 ± 2.21 h (z = 2.4; p 相似文献   

Prior eccentric exercise reduces v[combining dot above]o2peak and ventilatory threshold but does not alter movement economy during cycling exercise

Exercise-induced muscle damage (EIMD) has been shown to reduce force production and result in delayed-onset soreness and pain in the damaged muscle(s). Cycling in the presence of EIMD reduces peak power output and time-trial performance. However, its effect on peak aerobic capacity has not been widely studied. The purpose of this study was to examine the impact of EIMD targeted specifically to the quadriceps muscle group on peak oxygen consumption (V[Combining Dot Above]O2peak) during cycling. Ten participants (4 men, 6 women) completed a V[Combining Dot Above]O2peak test on a cycle ergometer before and 48 hours after performing 24 eccentric contractions with their right and left quadriceps with a weight equal to 120% of 1-repetition maximal concentric strength (1RM). The EIMD was assessed using 1RM, and muscle soreness was assessed using a 100-mm visual analog scale. The presence of EIMD was confirmed by a 9% reduction in 1RM (p = 0.0001) and increased ratings of soreness from 2.4 ± 2.1 to 24.6 ± 10.8 mm (p = 0.001). The V[Combining Dot Above]O2peak was reduced from 46.2 ± 9.7 to 41.8 ± 10.7 ml·kg·min (10%; p = 0.01) with participants terminating exercise at lower heart rates 191 ± 9 vs. 186 ± 10 b·min (p = 0.02) and power output 248 ± 79 vs. 238 ± 81 W (p = 0.02) after EIMD. Additionally, ventilatory threshold decreased from 34.2 ± 7.8 to 30.5 ± 8.5 ml·kg·min (11%; p = 0.031). Despite the reduction in V[Combining Dot Above]O2peak, cycling economy (p = 0.17) did not differ pre-EIMD and post-EIMD. These findings indicate that EIMD reduced peak aerobic exercise capacity to an extent that could result in meaningful reductions in exercise performance. The reduction is likely attributable to a combination of reduced strength, earlier accumulation of lactic acid, and heightened muscle pain during exercise.     

Does erythrocyte infusion improve 3.2-km run performance at high altitude?

The effects of autologous erythrocyte infusion on improving exercise performance at high altitude have not previously been studied. The effects of erythrocyte infusion on 3.2-km (2-mile) run performance were evaluated during 3 days (HA3) and 14 days (HA14) exposure to high altitude (4300 m) in erythrocyte-infused (ER) and control (CON) subjects that were initially matched (P>0.05; n = 8 in each group) for age, body size and aerobic fitness. After sea-level runs (SL; 50 m), unacclimated-male subjects received either 700 ml of saline and autologous erythrocytes (42% hematocrit; ER) or saline alone (CON). The 3.2-km run times (min:s) did not differ (P>0.05) between groups at SL [mean (SEM) ER, 13:14 (00:19); CON, 13:39 (00:32)] or during HA3 [ER, 19:02 (00:18); CON, 19:44 (00:43)] and HA14 [ER, 17:44 (00:27); CON, 18:45 (00:55)] but times were slower (P<0.05) when comparing HA3 or HA14 to SL. Heart rates (HR) did not differ between groups at SL [ER, 188 (3) beats x min(-1); CON, 191 (3) beats x min(-1)], or during HA3 [ER, 170 (4) beats x min(-1); CON, 178 (4) beats x min(-1)] and HA14 [ER, 162 (6) beats x min(-1); CON, 169 (5) beats x min(-1)], but HR were lower (P<0.05) when comparing HA3 or HA14 to SL. Ratings of perceived exertion (local, central, and overall ratings) did not differ between groups at SL, HA3 or HA14, but local ratings were higher (P<0.05) at HA3 and HA14 compared to SL, and overall ratings were higher for HA3 than SL. Analysis of covariance (adjusted for SL group run times) revealed (min:s) 00:14 (HA3) and 00:28 (HA14) mean improvement tendencies (P>0.05) for ER compared to CON. Thus, no significant improvements in 3.2-km run performance were associated with erythrocyte infusion, although the ER group showed a tendency to run slightly faster at high altitude.     

Higher prevalence of exercise-associated hyponatremia in triple iron ultra-triathletes than reported for ironman triathletes

"In a recent study of male and female ultra-marathoners in a 161-km ultra-marathon, the prevalence of exercise-associated hyponatremia (EAH) was higher than reported for marathoners. Regarding triathletes, the prevalence of EAH has been investigated in Ironman triathletes, but not in Triple Iron ultra-triathletes. The aim of this study was to investigate the prevalence of EAH in male ultra-triathletes competing in a Triple Iron ultra-triathlon over 11.4 km swimming, 540 km cycling, and 126.6 km running. Changes in body mass, fat mass, skeletal muscle mass, total body water, haematocrit, plasma volume, plasma sodium concentration ([Na ? ]) and urine specific gravity were determined in 31 male athletes with (means ± standard deviation) 42.1 ± 8.1 years of age, 77.0 ± 7.0 kg body mass, 1.78 ± 0.06 m body height and a BMI of 24.3 ± 1.7 kg/m2 in the 'Triple Iron Triathlon Germany'. Of the 31 finishers, eight athletes (26%) developed asymptomatic EAH. Body mass, fat mass, skeletal muscle mass, and haematocrit decreased, plasma volume increased ( P < 0.05), plasma [Na ?], total body water and urine specific gravity remained stable. The decrease in body mass was related to both the decrease in fat mass and skeletal muscle mass ( P < 0.05), but was not related to overall race time, the change in plasma [Na ? ], post-race plasma [Na ? ], or urine specific gravity. The prevalence of EAH was higher in these Triple Iron ultra-triathletes compared to existing reports on Ironman triathletes. Body fluid homeostasis remained stable in these ultra-triathletes although body mass decreased."     

The effects of ionized and nonionized compression garments on sprint and endurance cycling

ABSTRACT: Burden, RJ and Glaister, M. The effects of ionized and nonionized compression garments on sprint and endurance cycling. J Strength Cond Res 26(10): 2837-2843, 2012-The aim of this study was to examine the effects of ionized and nonionized compression tights on sprint and endurance cycling performance. Using a randomized, blind, crossover design, 10 well-trained male athletes (age: 34.6 ± 6.8 years, height: 1.80 ± 0.05 m, body mass: 82.2 ± 10.4 kg, V[Combining Dot Above]O2max: 50.86 ± 6.81 ml·kg·min) performed 3 sprint trials (30-second sprint at 150% of the power output required to elicit V[Combining Dot Above]O2max [pV[Combining Dot Above]O2max] + 3 minutes recovery at 40% pV[Combining Dot Above]O2max + 30-second Wingate test + 3 minutes recovery at 40% pV[Combining Dot Above]O2max) and 3 endurance trials (30 minutes at 60% pV[Combining Dot Above]O2max + 5 minutes stationary recovery + 10-km time trial) wearing nonionized compression tights, ionized compression tights, or standard running tights (control). There was no significant effect of garment type on key Wingate measures of peak power (grand mean: 1,164 ± 219 W, p = 0.812), mean power (grand mean: 716 ± 68 W, p = 0.800), or fatigue (grand mean: 66.5 ± 6.9%, p = 0.106). There was an effect of garment type on blood lactate in the sprint and the endurance trials (p < 0.05), although post hoc tests only detected a significant difference between the control and the nonionized conditions in the endurance trial (mean difference: 0.55 mmol·L, 95% likely range: 0.1-1.1 mmol·L). Relative to control, oxygen uptake (p = 0.703), heart rate (p = 0.774), and time trial performance (grand mean: 14.77 ± 0.74 minutes, p = 0.790) were unaffected by either type of compression garment during endurance cycling. Despite widespread use in sport, neither ionized nor nonionized compression tights had any significant effect on sprint or endurance cycling performance.     

Fructose addition to a glucose supplement modifies perceived exertion during strength and endurance exercise

The addition of fructose (F) to a glucose (G) supplement may modify the metabolic response during exercise; however, its effect on perceived exertion (PE) and its influence on postprandial metabolism have not been jointly studied in different types of exercise. This study sought to assess the acute effects of F addition to a G supplement on PE and on the postprandial metabolic response during a single bout of either strength exercise (SE) or endurance exercise (EE). Twenty physically trained men ingested an oral dose of G or GF 15 minutes before starting a 30-minute session of SE (10 sets of 10 repetitions of half squat) or EE (cycling). The combination resulted in 4 randomized interventions in a crossover design in which all subjects performed all experimental conditions: G + SE, GF + SE, G + EE, and GF + SE. Perceived exertion, heart rate (HR), G, insulin, lactate, and urinary catecholamine levels were measured before exercise, during the exercise, and during acute recovery. Perceived exertion during exercise was lower for GF than for G during SE and EE (mean ± SD; 8.95 ± 0.62 vs. 9.26 ± 0.65, p < 0.05 and 7.47 ± 0.84 vs. 7.74 ± 0.93, p < 0.05, respectively). The glycemic peak in GF + SE was lower than in G + SE (p < 0.05), and there was a second peak during recovery (p < 0.05), whereas in EE, no difference in blood G levels was noted between G and GF supplements. Moreover, HR, urinary adrenalin, and noradrenalin were lower in GF than in G (p < 0.05), though only for EE. The results showed that PE is positively affected by GF supplementation for both SE and EE and thus may be a useful dietary strategy for helping to achieve higher training loads.     

Seasonality in foraging behaviour of Constrictotermes cyphergaster (Termitidae, Nasutitermitinae) in the Caatinga of Northeastern Brazil

The foraging activity of Constrictotermes cyphergaster was investigated in the Caatinga of Northeast Brazil. Eight colonies were monitored for seven days, during both dry and wet seasons. Foraging activity occurred in exposed columns at night, generally between 22:00 and 05:00 h. During the wet season, foraging activity was significantly higher, with one bout every 1.6 ± 0.2 days, than the dry season, when foraging bouts were performed every 1.9 ± 0.3 days. Foraging activity throughout the study colonies presented high temporal synchronization. In both seasons, foraging was negatively correlated with air temperature and positively correlated with humidity. The foraging trails were often re-utilized and ranged from 1 to 18.5 meters in length. No difference between seasons in the area potentially utilized by the study colonies was observed. Approximately 51000 individuals participated in the foraging bout during the dry season, whereas some 87000 individuals participated in the foraging bout during the wet season. This corresponds to 43 and 74% of the estimated total nest population for the dry and wet seasons respectively. The average ratio soldiers:workers during foraging was 1:1.2 in the dry season and 1:2 in the wet season. The higher frequency and number of individuals foraging during the wet season in the present study are likely to be a strategy from C. cyphergaster to store energy reserves to be utilized during the dry season. Received 28 November 2005; revised 29 May 2006 and 16 August 2006; accepted 1 September 2006.     

Comparison of systemic cytokine responses after a long distance triathlon and a 100-km run: relationship to metabolic and inflammatory processes

Suggested mechanisms for the systemic, circulating cytokinemia observed during heavy physical exertion include inflammation and energy demand. We compared cytokine levels and examined the underlying physiological mechanisms between a long-distance triathlon and a 100-km run, two endurance races of similar duration but characterized by differences in muscle strain. Blood samples were collected from 12 triathletes (34.8 +/- 1.4 yr) and 11 runners (42.4 +/- 2.2 yr) the day before and at the end of races (T1, R1), and 24 h and 7 days post-race (R2, R3). At R1, significant race-related differences were observed, with greater increases in plasma levels of interleukins (IL)-6, IL-1ra, and IL-10 in the triathletes than in the runners, while levels of the chemokine IL-8 increased solely in the runners (P < 0.05, P < 0.05, P < 0.01, and P < 0.001, respectively). At R1, free fatty acid (FFA) levels were 119% higher in the triathletes than in the runners, who were the most liable to muscle damage in view of increased levels of the muscle-specific enzyme, creatine kinase (CK), loss of muscle flexibility and decreased physical performance. At R1, levels of heat shock protein (HSP)72 increased in the two groups but were 173% higher in the runners. For the two groups, all parameters had returned to pre-race levels by seven days post-race. Positive correlations were noted between IL-6 and FFA in the triathletes and between IL-8 and CK and HSP72 in the runners. The differences between cytokine responses after a long distance triathlon and a 100-km run suggested that IL-6 and IL-8 could be employed as respective markers of the intensity of the muscular activity required for substrate availability and vascular inflammation.     

Diurnal variation in Wingate-test performance and associated electromyographic parameters

The present study was designed to evaluate time-of-day effects on electromyographic (EMG) activity changes during a short-term intense cycling exercise. In a randomized order, 22 male subjects were asked to perform a 30-s Wingate test against a constant braking load of 0.087?kg·kg(-1) body mass during two experimental sessions, which were set up either at 07:00 or 17:00?h. During the test, peak power (P(peak)), mean power (P(mean)), fatigue index (FI; % of decrease in power output throughout the 30 s), and evolution of power output (5-s span) throughout the exercise were analyzed. Surface EMG activity was recorded in both the vastus lateralis and vastus medialis muscles throughout the test and analyzed over a 5-s span. The root mean square (RMS) and mean power frequency (MPF) of EMG were calculated. Neuromuscular efficiency (NME) was estimated from the ratio of power to RMS. Resting core temperature, P(peak), P(mean), and FI were significantly higher (p?相似文献   

Insulin glargine maintains equivalent glycemic control and better lipometabolic control than NPH insulin in type 1 diabetes patients who missed a meal.

Our goal was to investigate blood glucose and lipometabolism control in type 1 diabetes patients who missed breakfast and the accompanying insulin injection of NPH insulin (NPH) or insulin glargine (glargine) as part of a basal-bolus regimen. This was a multi-center, open-label, controlled study in adults (> or =18 years) with HbA (1c)< or =11.5% on insulin therapy with NPH as basal insulin. Patients were randomized to receive prandial insulin plus either bedtime glargine (n=28) or NPH (n=32). Insulin was titrated to target fasting blood glucose levels 80-130 mg/dl at 06:00-07:00. Patients had no intake of insulin or food between 22:00 and 12:00 the next day. The change in blood glucose levels (07:00-11:00) was similar (27.5 mg/dl vs. 35.4 mg/dl), but the mean blood glucose level was higher with glargine vs. NPH at 22:00 (158.2 mg/dl vs. 130.2 mg/dl). During the period without insulin or food intake, blood glucose decreased with glargine (-25.8 mg/dl) and increased with NPH (+9.1 mg/dl; p=0.0284). Nonesterified fatty acid (07:00 and 09:00-12:00) and beta-hydroxybutyrate (07:00 and 10:00-12:00) levels were lower with glargine vs. NPH (both p<0.05). For patients who miss a morning meal, glargine is associated with maintained glycemic and lipometabolic control compared with NPH insulin.     

Examining the influence of hydration status on physiological responses and running speed during trail running in the heat with controlled exercise intensity

The purpose of this study was to determine the effects of dehydration at a controlled relative intensity on physiological responses and trail running speed. Using a randomized, controlled crossover design in a field setting, 14 male and female competitive, endurance runners aged 30 ± 10.4 years completed 2 (hydrated [HY] and dehydrated [DHY]) submaximal trail runs in a warm environment. For each trial, the subjects ran 3 laps (4 km per lap) on trails with 4-minute rests between laps. The DHY were fluid restricted 22 hours before the trial and during the run. The HY arrived euhydrated and were given water during rest breaks. The subjects ran at a moderate pace matched between trials by providing pacing feedback via heart rate (HR) throughout the second trial. Gastrointestinal temperature (T(GI)), HR, running time, and ratings of perceived exertion (RPE) were monitored. Percent body mass (BM) losses were significantly greater for DHY pretrial (-1.65 ± 1.34%) than for HY (-0.03 ± 1.28%; p < 0.001). Posttrial, DHY BM losses (-3.64 ± 1.33%) were higher than those for HY (-1.38 ± 1.43%; p < 0.001). A significant main effect of T(GI) (p = 0.009) was found with DHY having higher T(GI) postrun (DHY: 39.09 ± 0.45°C, HY: 38.71 ± 0.45°C; p = 0.030), 10 minutes post (DHY: 38.85 ± 0.48°C, HY: 38.46 ± 0.46°C; p = 0.009) and 30 minutes post (DHY: 38.18 ± 0.41°C, HY: 37.60 ± 0.25°C; p = 0.000). The DHY had slower run times after lap 2 (p = 0.019) and lap 3 (p = 0.025). The DHY subjects completed the 12-km run 99 seconds slower than the HY (p = 0.027) subjects did. The RPE in DHY was slightly higher than that in HY immediately postrun (p = 0.055). Controlling relative intensity in hypohydrated runners resulted in slower run times, greater perceived effort, and elevated T(GI), which is clinically meaningful for athletes using HR as a gauge for exercise effort and performance.     

Influence of Menstrual Cycle Phase and Oral Contraceptive Use on the Time-of-Day Effect on Maximal Anaerobic Power

This study was designed to analyse the time-of-day effect in maximal anaerobic power, and the influence of menstrual cycle phase and oral contraceptive use on any diurnal effect. Diurnal variations in maximal cycling power were studied in 11 eumenorrheic women and 10 women using monophasic oral contraceptives. Subjects were tested at 09:00, 14:00 and 18:00 hours, assigned randomly on separate days, in the mid-follicular or pseudo-follicular phase (days 7, 8, 9) and in the mid-luteal or pseudo-luteal phase (days 19, 20, 21) of the menstrual cycle. The order of test sessions was randomly assigned. Body mass was measured before, and rectal temperature after, a standardized 15-min warm-up. Maximal cycling power (Pc) was determined by a force-velocity test. Rectal temperature significantly increased from morning (09:00) to afternoon (14:00 and 18:00) in follicular and luteal phases for eumenorrheic subjects, and in days 7–9 and days 19–21 for contraceptive users (p < 0.05). No significant interaction effects (time of day × group × cycle phase) were observed for rectal temperature. In eumenorrheic subjects, Pc increased significantly from 09:00 to afternoon during the follicular phase (P < 0.05). In contrast, no significant time-of-day effects were observed during the luteal phase in eumenorrheic subjects, and at any cycle phase in contraceptive users. Analysis of variance failed to reveal any significant interaction effects for Pc. This study suggested that the time-of-day effect on maximal anaerobic power could be damped during the luteal phase of eumenorrheic women or at any cycle phase by oral contraceptive use.     

Sildenafil improves cardiac output and exercise performance during acute hypoxia, but not normoxia.

Sildenafil causes pulmonary vasodilation, thus potentially reducing impairments of hypoxia-induced pulmonary hypertension on exercise performance at altitude. The purpose of this study was to determine the effects of sildenafil during normoxic and hypoxic exercise. We hypothesized that 1) sildenafil would have no significant effects on normoxic exercise, and 2) sildenafil would improve cardiac output, arterial oxygen saturation (SaO2), and performance during hypoxic exercise. Ten trained men performed one practice and three experimental trials at sea level (SL) and simulated high altitude (HA) of 3,874 m. Each cycling test consisted of a set-work-rate portion (55% work capacity: 1 h SL, 30 min HA) followed immediately by a time trial (10 km SL, 6 km HA). Double-blinded capsules (placebo, 50, or 100 mg) were taken 1 h before exercise in a randomly counterbalanced order. For HA, subjects also began breathing hypoxic gas (12.8% oxygen) 1 h before exercise. At SL, sildenafil had no effects on any cardiovascular or performance measures. At HA, sildenafil increased stroke volume (measured by impedance cardiography), cardiac output, and SaO2 during set-work-rate exercise. Sildenafil lowered 6-km time-trial time by 15% (P<0.05). SaO2 was also higher during the time trial (P<0.05) in response to sildenafil, despite higher work rates. Post hoc analyses revealed two subject groups, sildenafil responders and nonresponders, who improved time-trial performance by 39% (P<0.05) and 1.0%, respectively. No dose-response effects were observed. During cycling exercise in acute hypoxia, sildenafil can greatly improve cardiovascular function, SaO2, and performance for certain individuals.     

The construct and longitudinal validity of the basketball exercise simulation test

The purpose of this study was to assess the validity of the recently developed Basketball Exercise Simulation Test (BEST). Ten semiprofessional (age, 22.7 ± 6.1 years; height, 189.6 ± 9.5 cm; weight, 86.5 ± 18.7 kg; % body fat, 14.7 ± 3.5%) and 10 recreational (age, 26.6 ± 4.0 years; height, 185.9 ± 7.9 cm; weight, 92.6 ± 8.4 kg; % body fat, 23.8 ± 6.3%) male basketball players volunteered for the study. The participants completed a Yo-Yo Intermittent Recovery Test (Yo-Yo IRT) and BEST trial midway through the playing season. Eight participants (semiprofessional, n = 4; recreational, n = 4) completed an additional Yo-Yo IRT and BEST trial at the end of the playing season. Performance measures from the BEST included sprint decrement (%), mean sprint and circuit time (seconds), and total distance covered (m). Construct validity was calculated using Student's unpaired t-tests to identify the differences in Yo-Yo IRT and BEST performances between playing levels. Longitudinal validity was determined based on the relationship between changes (%) in Yo-Yo IRT1 and BEST performances across the season. Semiprofessional players performed significantly (p < 0.01) better in the Yo-Yo IRT (1,283 ± 62 vs. 636 ± 297 m) and BEST (mean sprint time: 1.45 ± 0.01 vs. 1.65 ± 0.03 seconds; mean circuit time: 18.98 ± 1.79 vs. 22.72 ± 2.01 seconds; sprint decrement: 8.54 ± 0.15 vs. 15.38 ± 0.27%) compared with recreational players. For the group as a whole, a strong relationship was evident between the changes in BEST sprint decrement and changes in Yo-Yo IRT performance (R = -0.815, p = 0.014) across the season. In conclusion, the BEST displayed both discriminative and longitudinal validities and provides a novel match-specific fitness test for basketball players.