Effects of food bar chewing duration on the physiologic, metabolic, and perceptual responses to moderate-intensity running.

PURPOSE: Chewing duration can affect food particle size, gastric processing, and postprandial glycemia, but these effects have not been investigated with exercise. This study examined how the chewing duration of a food bar impacts glycemic and metabolic responses, gastrointestinal (GI) symptoms, psychological affect, and performance during endurance running. METHODS: This randomized, unblinded, crossover study had 15 males (35.2 ± 7.4 years, VO2peak: 56.1 ± 5.2 ml/kg/min) attend three laboratory visits. Visit 1 required a VO2peak test, 10 min familiarization run at 60% VO2peak, and familiarization time-to-exhaustion (TTE) test (10 min at 90% VO2peak, followed by TTE at 100% VO2peak). Visits 2 and 3 consisted of a 60 min run at 60% VO2peak, followed by TTE testing. Participants were fed 45 g of a bar (180 kcal, 4 g fat, 33 g carbohydrate, 3 g protein, 1 g fiber) in 9 g servings 30 min before running, and 27 g of bar in 9 g servings at three timepoints during the 60 min run. Participants consumed the servings in 20 (20CHEW) or 40 (40CHEW) masticatory cycles, at 1 chew/second. Outcomes included blood glucose, substrate use, GI symptoms, perceived exertion (RPE), overall feeling, and TTE. RESULTS: Post-prandial blood glucose, GI symptoms, and RPE increased over time, but there were no significant between-condition or condition-by-time effects. TTE showed no significant between-condition effect (20CHEW: 288 ± 133 s; 40CHEW: 335 ± 299 s; p = 0.240). Overall feeling demonstrated a time-by-condition effect (p = 0.006), suggesting possible better maintenance over time with 40CHEW. CONCLUSION: Cumulatively, the results suggest that extended chewing minimally impacts physiology, perceptions, and performance during 60 min moderate-intensity running.

The association of moderate-to-vigorous and light-intensity physical activity on static balance in middle-aged and older-aged adults.

BACKGROUND: Falls are the leading cause of injury among adults ≥ 65 years of age. Participation in physical activity (PA) is associated with improved balance, though it is impact in the middle-age population is not well understood. AIM: The purpose of the current study was to examine the influence of PA intensity on static balance in middle-aged and older aged individuals. METHODS: Included were middle-aged adults (40-64 years) and older adults (≥ 65 years) from the 2003-2004 years of the National Health and Nutrition Evaluation Survey. Light physical activity (LPA) and moderate-vigorous physical activity (MVPA) were collected via accelerometer and static balance via the Romberg Test of Standing Balance. RESULTS: No significant odds ratio relationship was found between MVPA or LPA and having good static balance in the middle-aged population; 1.04 (95% CI 0.95, 1.13) p = 0.427 and 1.05 (95% CI 0.97, 1.14) p = 0.182, respectively. Whereas, in older adults, every 60-min increase in LPA was significantly associated with 28% higher odds of good balance (95% CI 1.15, 1.41; p < 0.001), and every 10-min increase in MVPA with 25% higher odds of good balance (95% CI 1.08, 1.45; p = 0.006). DISCUSSION: LPA and MVPA were not associated with good static balance in middle-aged adults, but in older adults LPA was significantly associated with good static balance. CONCLUSION: A significant relationship is found between age and fall risk, which is a major concern in the aging population.

Ammonia Inhalation Does Not Increase Deadlift 1-Repetition Maximum in College-Aged Male and Female Weight Lifters.

Vigil, JN, Sabatini, PL, Hill, LC, Swain, DP, and Branch, JD. Ammonia inhalation does not increase deadlift 1-repetition maximum in college-aged male and female weight lifters. J Strength Cond Res 32(12): 3392-3397, 2018-Ammonia inhalant use by powerlifters and weight lifters is a prevalent practice with little research support for improved performance. The purpose of this study was to investigate the effects of ammonia as a stimulant on athletic performance during a deadlift 1-repetition maximum (1RM) absolute strength test. Subjects (men: n = 10, mean ± SD age = 21 ± 1 year, mass = 72.5 ± 6.8 kg; and women: n = 10, age = 22 ± 5 years, mass = 66.2 ± 8.1 kg) were required to have at least 2 years of resistance training experience while lacking a history of asthma, lightheadedness, fainting, anaphylaxis, sickle cell traits, and other respiratory disorders. After a baseline 1RM test, subjects were paired by 1RM performance and gender, then randomly assigned in a counterbalanced treatment order to control (water) or ammonia trials after a minimum 72-hour recovery period for another 1RM test involving attempts at 100.0, 102.5, 105.0, and 107.5% of the established 1RM value. Testing was then repeated after the minimum rest period for the remaining trial. Results revealed the expected gender main effect for absolute deadlift 1RM (93.0 ± 29.5 [women]; 152.0 ± 29.5 kg [men]; p < 0.001), but no trial main effect (p = 0.874) or gender by trial interaction effect (baseline = 93.0 ± 15.3, 151.8 ± 42.3 kg; water = 92.0 ± 12.5, 150.9 ± 37.8 kg; ammonia = 92.5 ± 16.4, 153.4 ± 37.9 kg) for women and men, respectively (p = 0.559). Within the limitations of this study, there is no support for the practice of ammonia inhalation to improve deadlift 1RM in training or competition.

C57BL/6 mice are resistant to joint degeneration induced by whole-body vibration.

OBJECTIVE: Whole-body vibration (WBV) platforms are commercially available devices that are used clinically to treat numerous musculoskeletal conditions based on their reported ability to increase bone mineral density and muscle strength. Despite widespread use, there is an alarming lack of understanding of the direct effects of WBV on joint health. Previous work by our lab demonstrated that repeated exposure to WBV using protocols that model those used clinically, induces intervertebral disc (IVD) degeneration and osteoarthritis-like damage in the knee of skeletally mature, male mice of a single outbred strain (CD-1). The present study examined whether exposure to WBV induces similar deleterious effects in a genetically different strain of mouse (C57BL/6). DESIGN: Male 10-week-old C57BL/6 mice were exposed to vertical sinusoidal WBV for 30 min/day, 5 days/week, for 4 or 8 weeks using previously reported protocols (45 Hz, 0.3 g peak acceleration). Following WBV, joint tissues were examined using histological analysis and gene expression was quantified using real-time PCR (qPCR). RESULTS: Our analyses show a lack of WBV-induced degeneration in either the knee or IVDs of C57BL/6 mice exposed to WBV for 4 or 8 weeks, in direct contrast to the WBV-induced damage previously reported by our lab in CD-1 mice. CONCLUSIONS: Together with previous studies from our group, the present study demonstrates that the effects of WBV on joint tissues vary in a strain-specific manner. These findings highlight the need to examine genetic or physiological differences that may underlie susceptibility to the deleterious effects of WBV on joint tissues.

Autonomic response to tactical pistol performance measured by heart rate variability.

This study evaluated changes in autonomic tone during a tactical pistol competition. At rest and during a match, heart rate variability (HRV) was examined in 28 healthy subjects. Heart rate variability time-domain variables (including interbeat interval [IBI]) and frequency-domain variables (low frequency [LF], high frequency [HF], total power [TP]) measured during shooting were subtracted from those measured during rest to produce Δs. The shooting task involved several, rapid tactical maneuvers. Raw time to completion and inaccurate shots (points down [PDs]) were recorded and combined to form a match score where lower values indicated superior shooting performance. Mean (±SD) raw time was 135.9 ± 34.1 seconds, PDs were 78 ± 34, and match score was 175.3 ± 39.8. Shooting decreased IBI (i.e., increased heart rate) and LF. ΔLF, ΔHF, and ΔTP were independent of ΔIBI. Raw time was significantly (p ≤ 0.05) correlated to shooting IBI (r = 0.404) and ΔIBI (r = -0.426). Points down were significantly correlated to ΔTP (r = 0.416) and ΔLF (r = 0.376). Match score was significantly correlated to ΔIBI (r = -0.458), ΔHF (r = 0.467), ΔLF (r = 0.377), and ΔTP (r = 0.451). In conclusion, individuals with a greater decrease in IBI (and thus heart rate) performed better by accomplishing the match faster. Individuals with less change in stress-related HRV measures (LF, HF, and TP) performed better through improved accuracy. Thus, HRV-derived sympathetic response is significantly related to shooting performance and should be used to assess marksmanship effectiveness under duress.

A tendon graft weave using an acellular dermal matrix for repair of the Achilles tendon and other foot and ankle tendons.

Many techniques are available to repair tendon ruptures of the Achilles tendon as well as other foot and ankle tendons. The purpose of this article was to present a technique of tendon repair that is a combination of a tendon graft inlay with a Pulvertaft-type tendon weave using an acellular human dermal matrix graft with a resultant "strip and shoelace." A description of the technique, along with 3 case reports, is included. Tendon donor site morbidity problems associated with tendon transfer procedures are avoided by use of this dermal matrix weave. This procedure is felt to have enhanced strength with less bulk than soft tissue graft wrap procedures.

Functional performance following an ice bag application to the hamstrings.

This study examined the immediate and short-term (20 minute) effects of 3- and 10-minute ice bag applications to the hamstrings on functional performance as measured by the cocontraction test, shuttle run, and single-leg vertical jump. Forty-two (25 women, 17 men) recreational or collegiate athletes who were free of injury in the lower extremity 6 months before testing and who did not suffer from allergy to cryotherapy were included. Time to completion was measured in seconds for the cocontraction and the shuttle run test. Single-leg vertical jump was measured on the Vertec (Sports Imports, Columbus, Ohio) in centimeters. The 10-minute ice bag application reduced immediate post-application vertical jump performance and increased immediate post and 20-minute post shuttle run time (p

Adrenal cortical carcinoma metastatic to the breast.

A 56 year old woman was diagnosed with adrenal cortical carcinoma in May 2003, for which she underwent left radical adrenalectomy. Eight months later, in January 2004, she presented with a solitary, well delineated, left breast mass with central pleomorphic calcifications on mammographic examination. A diagnosis of metastatic adrenal cortical carcinoma was made on core biopsy. Subsequently, the patient underwent a lumpectomy of the mass, which confirmed the diagnosis. To our knowledge, this is the first case report of adrenal cortical carcinoma metastatic to the breast.

Response of T lymphocytes from previously infected calves to recombinant Cryptosporidium parvum P23 vaccine antigen.

We had previously demonstrated that a Type-1-like immune response involving interferon-gamma expression in lamina propria lymphocytes accompanied by IgG2 subclass fecal antibodies to Cryptosporidium parvum p23 emerged in gut mucosa of calves recovering from cryptosporidiosis. Because a recombinant p23 had been shown to protect calves from cryptosporidiosis when administered as a vaccine antigen to late gestation cattle, this study was undertaken to determine if the same vaccine antigen could induce a Type-1-like, in vitro response by T cells from calves that had recovered from C. parvum infection. We isolated peripheral blood mononuclear cells from calves that had been previously infected with C. parvum oocysts and incubated them in the presence or absence of the recombinant C. parvum p23 vaccine antigen. We used flow cytometry to simultaneously detect cells in cell cycle and identify the T cell subset containing cycling cells. We also used flow cytometry to identify interferon-gamma positive cells and 2-dimensional gel electrophoresis to profile proteins made by PBMC stimulated with the recombinant p23 vaccine antigen. The results demonstrated that CD4+ T lymphocytes proliferated and that interferon-gamma was synthesized by a subset of stimulated cells. Two-dimensional gel electrophoresis revealed the presence of several cytoplasmic proteins in a size range of approximately 25-80 kDa that were detected in p23-stimulated, but not in unstimulated, cytoplasmic samples. Together, the results show that the recombinant p23 vaccine antigen can stimulate a Type-1-like immune response by T cells from calves that have recovered from C. parvum infection.

A comparison of point-of-care instruments designed for monitoring oral anticoagulation with standard laboratory methods.

Our study compared point-of-care (POC) device monitoring with traditional clinical laboratory methods device of patients on oral anticoagulant therapy. The POC devices used in the study were Coumatrak, CoaguChek, CoaguChek Plus, Thrombolytic Assessment System (TAS) PT-One, TAS PTNC, TAS PT, Hemachron Jr. Signature, ProTime Microcoagulation System, and Medtronics ACT II. The clinical laboratory method used thromboplastins with different ISI values: Innovin and Thromboplastin C Plus (TPC). All POC INRs showed strong correlation with both laboratory methods, with correlation coefficients of >0.900. All POC methods demonstrated a significant (p <0.05) difference in INR values, except the TAS PTNC and ACT II INRs (p: 0.12 and 0.71 respectively) when compared with Innovin INRs. All POC INRs were significantly different from TPC generated INRs (p <0.05). Comparisons of the POC INRs to the group mean of the POC methods, show higher correlation (R>0.93), but there were still significant (p<0.05) differences noted between the POC group INR mean and CoaguChek Plus, ACT II, TAS PT-One, TAS PTNC, and Hemachron Jr Signature INRs. These data indicate that POC INR biases exist between laboratory methods and POC devices. Until a suitable whole blood INR standardization method is available, we conclude that clinicians using point-of-care anticoagulation monitoring should be aware of differences between POC and parent laboratory values.

Perturbation of cell cycle regulators in Peyronie's disease.

Peyronie's disease is a fibromatosis of the tunica albuginea, characterized by development of a plaque consisting primarily of collagen. It has been suggested that trauma to the erect penis is the inciting event. More recent research has focused on the cellular events leading to the dysregulated wound healing and plaque formation. Previous work has shown chromosomal aneusomies and this combined with an increased S-phase in plaque derived cell cultures suggests a perturbation in the cell cycle in this condition. The p53 protein has been shown to be an important cell cycle regulator and pro-apoptotic factor. Aberrant p53 function leading to cell immortalization and proliferation has been implicated in several human malignancies. We hypothesized that abnormal p53 function may explain the high proliferative ability of fibroblasts derived from Peyronie's plaques. This study was undertaken to study the presence and function of p53 and its downstream elements (p21, mdm-2) in Peyronie's disease cell cultures. Plaque-derived fibroblasts have been established in culture and characterized. These cells and control neonatal foreskin fibroblasts were subjected to 5 Gy of gamma radiation to induce DNA damage. After fixation, antibodies to p53 and its transcriptional elements were used to stain irradiated and non-irradiated cells and levels of p53, p21 and mdm-2 were quantified using combined immunofluorescence and flow cytometry. Non-irradiated plaque fibroblasts demonstrated the presence of p53, p21 and mdm-2 at baseline. In control foreskin fibroblasts no p53 or mdm-2 were detectable at baseline. In irradiated foreskin-derived cells significant changes in all elements were demonstrated indicating a fully functional p53 pathway and cell cycle checkpoint system in these cells. In contrast, plaque-derived cells showed no such alterations in levels of cell cycle regulators following irradiation. This is highly suggestive of an aberration of the p53 pathway in plaque-derived fibroblasts. Peyronie's plaque-derived fibroblasts demonstrated stabilization and defunctionalization of p53 protein combined with appropriate responses of its transcriptional elements. These findings may explain the high cell proliferation rates in these cells and suggests a role for perturbation of the p53 pathway in the pathogenesis of Peyronie's disease.

Twelve weeks of endurance exercise training does not affect iron status measures in women.

OBJECTIVE: This study examined the effects of 12 weeks of endurance exercise training on iron status measures in previously inactive women and compared the effects of weight-bearing endurance exercise training and non-weight-bearing endurance exercise on iron status measures. DESIGN: Randomized, experimental study. SUBJECTS: Thirty-one healthy, inactive women (aged 23 to 43 years) with apparently normal iron stores (serum ferritin concentration > or = 20 micrograms/L) were recruited from the local area by newspaper advertisements and campus mailings. Twenty-one subjects completed the study (mean +/- standard deviation for age = 32 +/- 5 years, for body mass index = 23.1 +/- 4.9, and for maximum oxygen consumption [VO2max] = 33.8 +/- 6.3 mL/kg per minute). INTERVENTION: Subjects were randomly assigned to one of three groups: an inactive control group, a walking/running group, or a cycling group. Subjects in the two exercise groups trained three to four times per week at 80% VO2max for 12 weeks. Exercise training sessions were monitored and energy expenditure increased from 150 kcal per session (week 1) to 375 kcal per session (weeks 9 to 12). Subjects in the inactive control group were instructed to maintain their normal activity patterns for the duration of the study. All subjects were instructed to maintain their normal dietary habits. MAIN OUTCOME MEASURES: Serum ferritin concentration, serum iron concentration, percentage saturation of transferrin, total iron-binding capacity, serum haptoglobin concentration, and other selected hematologic variables were measured at baseline and at weeks 2, 4, 8, and 12. STATISTICAL ANALYSES: Repeated measures analysis of variance was used to examine group x time interactions in changes in iron status measures. Statistical significance was reached at P < .05. RESULTS: Analysis of variance indicated that serum ferritin concentration did not change significantly (P = .59) during the 12 weeks in the walking/running group (mean +/- standard deviation from 41.28 +/- 14.22 to 27.41 +/- 9.74 micrograms/L) or the cycling group (from 65.81 +/- 37.62 to 41.06 +/- 26.38 micrograms/L) compared with the control group (from 47.55 +/- 15.87 to 31.56 +/- 10.57 micrograms/L). Values for serum iron, total iron-binding capacity, percentage saturation of transferrin, and haptoglobin also did not change significantly (P > .30) in the walking/running or cycling groups compared with the control group. APPLICATIONS/CONCLUSIONS: Results of this study suggest that participation in 12 weeks of moderate-intensity endurance exercise training (walking/running or cycling) is not associated with negative effects on selected measures of iron status in healthy, previously untrained women with normal iron stores (serum ferritin > or = 20 micrograms/L).

Training for endurance sport.

1) An endurance athlete's performance level is determined largely by three physiological variables: maximal aerobic power, lactate threshold, and economy. Training strategies should be directed toward improvement of these factors. 2) Successful endurance training programs typically include an individually constructed combination of three major training strategies. These are long duration, moderate intensity training; moderate duration, high intensity training; and short duration, very high intensity training. 3) Endurance training involves a large daily expenditure of energy, and much of this energy is derived from catabolism of carbohydrates. Accordingly, it is essential that the endurance athlete's diet be rich in complex carbohydrates and provide the total amount of energy needed to maintain energy balance.

Physiological effects of constant versus variable power during endurance cycling.

PURPOSE: Previous theoretical research found that varying power slightly to counter external conditions may result in improved performance during cycling time trialing, but it is not known whether such power variations result in added physiological stress. Thus, the purpose of this study was to determine whether variable power (VP) cycling produced greater physiological stress than constant power (CP) cycling of the same mean intensity. METHODS: Eight trained male cyclists (age 28 +/- 2 yr, mass 74.4 +/- 2.3 kg, VO2max 4.24 +/- 0.13 L x min(-1), weekly training 277 +/- 44 km) performed three 1-h ergometer trials. The first trial was performed at a self-paced maximal effort. The mean power from that trial was used to determine the power for the CP trial (constant effort at mean power) and the VP trial (alternating +/- 5% of mean power every 5 min). RESULTS: No differences were found between the CP and VP trials in mean VO2 (CP 3.33 +/- 0.11 L x min(-1), VP 3.26 +/- 0.12 L x min(-1)), mean heart rate (CP 158 +/- 3 min(-1), VP 159 +/- 3 min(-1)), mean blood lactate concentration (CP 4.2 +/- 0.7 mM, VP 4.3 +/- 0.7 mM), or mean RPE (CP 13.9 +/- 0.4, VP 14.1 +/- 0.4). CONCLUSION: Therefore, during a strenuous 1-h effort (78% of VO2max), subjects experienced no additional physiological stress by varying power +/- 5% compared with that during a constant power effort.

Blood pressure responses to acute static and dynamic exercise in three racial groups.

PURPOSE: African Americans have a higher incidence of hypertension than other racial groups. Furthermore, some research suggests that normotensive individuals who exhibit exaggerated blood pressure (BP) responses to exercise may be at risk for future hypertension. This study sought to determine whether normotensive African Americans exhibited exaggerated BP responses to static exercise or dynamic exercise relative to Caucasian Americans and Asian Americans. METHODS: Thirty normotensive subjects participated from each of the three racial groups (15 men and 15 women). Subjects held 30% of maximal voluntary contraction (right knee extension) for 3 min, and BP was recorded during the 3rd min. On a separate occasion, subjects cycled for six min at a power equivalent to 70% of VO2 reserve, and BP was recorded during the 6th min. RESULTS: Static exercise produced large, significant increases in both systolic and diastolic BP (35 +/- 1.5 and 29 +/- 1.3 mm Hg, respectively). Dynamic exercise produced large, significant increases in systolic BP (51 +/- 1.6 mm Hg) and moderate, yet significant, increases in diastolic BP (8 +/- 1.0 mm Hg). There were no significant differences between racial groups in BP response to either static exercise or dynamic exercise. However, during dynamic exercise, men had a higher systolic BP response than did women. CONCLUSIONS: African Americans who are normotensive at rest do not exhibit a greater BP response to static exercise or dynamic exercise than do Caucasian Americans or Asian Americans.

Validation of a new method for estimating VO2max based on VO2 reserve.

PURPOSE: The American College of Sports Medicine's (ACSM) preferred method for estimating maximal oxygen consumption (VO2max) has been shown to overestimate VO2max, possibly due to the short length of the cycle ergometry stages. This study validates a new method that uses a final 6-min stage and that estimates VO2max from the relationship between heart rate reserve (HRR) and VO2 reserve. METHODS: A cycle ergometry protocol was designed to elicit 65-75% HRR in the fifth and sixth minutes of the final stage. Maximal workload was estimated by dividing the workload of the final stage by %HRR. VO2max was then estimated using the ACSM metabolic equation for cycling. After the 6-min stage was completed, an incremental test to maximal effort was used to measure actual VO2max. Forty-nine subjects completed a pilot study using one protocol to reach the 6-min stage, and 50 additional subjects completed a modified protocol. RESULTS: The pilot study obtained a valid estimate of VO2max (r = 0.91, SEE = 3.4 mL x min(-1) x kg-1) with no over- or underestimation (mean estimated VO2max = 35.3 mL x min(-1) x kg(-1), mean measured VO2max = 36.1 mL x min(-1) x kg(-1)), but the average %HRR achieved in the 6-min stage was 78%, with several subjects attaining heart rates considered too high for submaximal fitness testing. The second study also obtained a valid estimate of VO2max (r = 0.89, SEE = 4.0 mL x min(-1) x kg(-1)) with no over- or underestimation (mean estimated VO2max = 36.7 mL x min(-1) x kg(-1), mean measured VO2max = 36.9 mL x min(-1) x kg(-1), and the average %HRR achieved in the 6-min stage was 64%. CONCLUSIONS: A new method for estimating VO2max from submaximal cycling based on VO2 reserve has been found to be valid and more accurate than previous methods.

Relationship between % heart rate reserve and % VO2 reserve in treadmill exercise.

For exercise prescription purposes, it is often assumed that % heart rate reserve (%HRR) provides equivalent intensities to %VO2max. However, a recent study from this laboratory demonstrated that during cycling exercise %HRR is not equivalent to %VO2max, but is instead equivalent to a percentage of the difference between resting and maximal VO2, i.e., % VO2reserve (%VO2R). The current study examined these relationships during treadmill exercise. Fifty adults performed Bruce protocol treadmill tests to exhaustion. For each subject, data obtained at rest, at the end of each stage, and at maximum were used to determine linear regressions of %HRR versus %VO2max, and of %HRR versus %VO2R. For %HRR versus %VO2max the mean intercept and slope were -6.1+/-0.7 and 1.10+/-0.01, respectively, with a mean r of 0.990+/-0.002. For %HRR versus %VO2R, the mean intercept and slope were 1.5+/-0.6 and 1.03+/-0.01, respectively, with a mean r of 0.990+/-0.002. Both regressions differed statistically from the line of identity (i.e., intercept of 0 and slope of 1). However, the regression of %HRR versus %VO2R was significantly closer (P < 0.001 ) to the line of identity than was the regression of %HRR versus %VO2max. We conclude that %HRR should be considered as an indicator of %VO2R, not %VO2max, when prescribing treadmill exercise, as was previously concluded for cycling exercise.

Effect of Eleutherococcus senticosus on submaximal and maximal exercise performance.

We investigated the effect of Eleutherococcus senticosus Maxim L (ESML) on performance during submaximal and maximal aerobic exercise. Twenty highly trained distance runners randomly assigned in matched pairs to either an experimental (ESML) or placebo (PL) group, participated in an 8-wk double-blind study during which they completed five trails of a 10-min treadmill run at their 10 km (10K) race pace and a maximal treadmill test (T(max)). Following a baseline trail, ESML and PL consumed, respectively, 3.4 ml of ESML extract or placebo daily for 6 wk. Subjects were tested every 2 wk during supplementation and 2 wk following withdrawal. Heart rate (HR), oxygen consumption (VO2), expired minute volume (VE), ventilatory equivalent for oxygen (VE/VO2), respiratory exchange ratio (RER), and rating of perceived exertion (RPE) were measured during the 10K and T(max) tests. Resting, post-10K and post-T(max) blood samples were analyzed for serum lactate. No significant differences were observed between ESML and PL for: HR, VO2, VE, VE/VO2, RER, or RPE; T(max) time to exhaustion; or serum lactate. The data do not support an ergogenic effect of ESML supplementation on selected metabolic, performance, or psychologic parameters associated with submaximal and maximal aerobic exercise tasks.

Red cell volume and [erythropoietin] responses during exposure to simulated microgravity.

In order to test the hypothesis that normal gravity is an important influence on human serum [Erythropoietin] ([Epo]), the hematologic response to 16 d of 6 degrees head-down tilt (HDT, n = 6 men) was compared with 16 d of normal gravity exposure (CON, n = 7 men). Prior to bed rest, CON and HDT subjects, respectively, were similar in the following characteristics (mean +/- SD): age = 40 +/- 3, 39 +/- 6 yr; height = 181 +/- 5, 182 +/- 6 cm; weight = 88.5 +/- 11.3, 81.7 +/- 12.0 kg; maximal oxygen consumption in supine 6 degrees head-down tilt position (VO2max) = 2.63 +/- 0.38, 2.67 +/- 0.52 L.min-1; hematocrit = (Hct) 41.6 +/- 2.4, 43.0 +/- 3.4%; hemoglobin ([Hb]) = 15.1 +/- 1.0, 14.5 +/- 1.0 g.100 ml-1; plasma volume (PV) = 3829 +/- 857, 3768 +/- 512 ml; and [Epo] = 11.6 +/- 2.9, 10.0 +/- 6.2 mU.ml-1. Calculated red cell volume (RCV) was greater in HDT than CON (2845 +/- 410 vs. 2139 +/- 253 ml, p < 0.05) at baseline. Decreases in PV (-15%, 580 ml, p < 0.05) and an insignificant decrease in RCV (-12%, 354 ml, p = 0.07) were observed in the HDT group, with a concurrent 6% increase in [Hb] (p < 0.05). PV, RCV and [Hb] remained unchanged in the CON group. [Epo] remained unchanged during HDT (12.2 +/- 3.2; 10.8 +/- 3.8; 11.2 +/- 3.1; 11.2 +/- 2.6 mU.ml-1 for HDT days 1, 2, 8 and 16, respectively). There was no difference between CON and HDT groups in [Epo] before or during HDT. It was concluded that the insignificant change (-12%) in RCV observed during HDT was insufficient to stimulate an increase in [Epo], probably because the content of oxygen in arterial blood remained unaffected. The observation that [Epo] remained unchanged despite this loss of RCV during HDT also suggests a possible decrease in the responsiveness of the erythropoietic system to [Epo].