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Objectives Human blood gas stability data is limited to small sample sizes and questionable statistical techniques. We sought to determine the stability of blood gases under room temperature and slushed iced conditions in patients using survival analyses. Methods Whole blood samples from ∼200 patients were stored in plastic syringes and kept at room temperature (22–24 °C) or in slushed ice (0.1–0.2 °C) before analysis. Arterial and venous pO2 (15–150 mmHg), pCO2 (16–72 mmHg), pH (6.73–7.52), and the CO-oximetry panel [total hemoglobin (5.4–19.3 g/dL), percentages of oxyhemoglobin (O2Hb%, 20–99%), carboxyhemoglobin (COHb, 0.1–5.4%) and methemoglobin (MetHb, 0.2–4.6%)], were measured over 5-time points. The Royal College of Pathologists of Australasia’s (RCPA’s) criteria determined analyte instability. Survival analyses identified storage times at which 5% of the samples for various analytes became unstable. Results COHb and MetHb were stable up to 3 h in slushed ice and at room temperature; pCO2, pH was stable at room temperature for about 60 min and 3 h in slushed ice. Slushed ice shortened the storage time before pO2 became unstable (from 40 to 20 min), and the instability increased when baseline pO2 was ≥60 mmHg. The storage time for pO2, pCO2, pH, and CO-oximetry, when measured together, were limited by the pO2. Conclusions When assessing pO2 in plastic syringes, samples kept in slushed ice harm their stability. For simplicity’s sake, the data support storage times for blood gas and CO-oximetry panels of up to 40 min at room temperature if following RCPA guidelines. more...

Background Data on the stability of whole blood electrolytes is limited to small sample sizes. We sought to determine the stability of whole blood electrolytes under room temperature and slushed iced conditions in human patients at a major hospital center. Methods Whole blood samples were obtained from 203 patients hospitalized for various pathophysiological conditions. Electrolyte concentrations of sodium, potassium [K+], ionized calcium, and chloride were measured at 5 different timepoints spanning 3 h. Samples were stored at room temperature (22–24 °C) or under slushed ice conditions (0.1–0.2 °C) before analysis. Results Under both conditions, sodium, ionized calcium, and chloride did not show a measurable change up to 109 min compared to baseline; however, the mean increase in [K+] over 138 min of storage in slushed ice was 0.0032 (0.0021 [5th percentile] to 0.0047 [95th percentile]) mmol/L/min (adjusted R2 = 0.62, P Conclusions Whole blood sodium, [K+], ionized calcium, and chloride concentrations remain stable for at least 109 min at room temperature. However, whole blood specimens stored in slushed ice for not more than 67 min exhibit a 5% probability that the [K+] concentration will increase by at least 0.3 mmol/L compared to baseline. The other analytes do not destabilize for up to 178 min of slushed ice storage. more...

While there is increasing evidence on the long-term risks associated with concussions, the association between hopelessness, suicidal ideation, suicidal planning, and suicidal attempts in high school aged adolescents has not yet been explored. The current study aims to estimate the association between concussions and suicidal behaviors in Utah high school students. We analyzed the 2013 Utah Youth Risk Behavior Survey (YRBS), a state, representative survey of 2,195 ninth through 12th grade high school students. Bivariate and multi-variate logistic regressions controlling for race/ethnicity, sex, grade, and alcohol use were conducted to evaluate the adjusted odds ratio (OR) and 95% confidence interval (CI) of suicidal behaviors comparing students exposed to one or more concussions with those unexposed. Students with self-reported concussion exposure had significantly greater odds of reporting feeling sad or hopeless (OR = 1.7; 95% CI 1.4, 2.2, suicidal ideations [adjusted odds ratio (AOR) = 2.0; 95% CI 1.4, 2.7], suicidal planning [AOR = 2.0; 95% CI 1.4, 2.8], and suicidal attempts [OR = 2.3; 95% CI 1.4, 3.7]) after controlling for grade, sex, race, and alcohol-use. Results from this study suggest that high school students who have had a concussion are more likely to report suicidal behaviors, compared with high school students who did not report a concussion. Given the results, concussion prevention education efforts in high schools are warranted. In addition, it is imperative to educate parents, teachers, and health professionals how to recognize a concussion and any possible mental health outcomes as a result. Future longitudinal research is needed to better understand temporality of this association. more...

Background Few reference equations exist for healthy adults of various races for pulmonary diffusing capacity for nitric oxide (DLNO). The purpose of this study was to collect pilot data to demonstrate that race-specific reference equations are needed for DLNO. Methods African Americans (blacks) were chosen as the comparative racial group. In 2016, a total of 59 healthy black subjects (27 males and 32 females) were recruited to perform a full battery of pulmonary function tests. In the development of DLNO reference equations, a white reference sample (randomly drawn from a population) matched to the black sample for sex, age, and height was used. Multiple linear regression equations for DLNO, alveolar volume (VA), and pulmonary diffusing capacity for carbon monoxide (DLCO) using a 5–6 s breath-hold were developed. Results Our models demonstrated that sex, age2, race, and height explained 71% of the variance in DLNO and DLCO, with race accounting for approximately 5–10% of the total variance. After normalizing for sex, age2, and height, blacks had a 12.4 and 3.9 mL/min/mmHg lower DLNO and DLCO, respectively, compared to whites. The lower diffusing capacity values in blacks are due, in part, to their 0.6 L lower VA (controlling for sex and height). Conclusion The results of this pilot data reveal small but important and statistically significant racial differences in DLNO and DLCO in adults. Future reference equations should account for racial differences. If these differences are not accounted for, then the risk of falsely diagnosing lung disease increase in blacks when using reference equations for whites. more...

BACKGROUND: There are limited data on lactate stability in whole blood. The purpose of this study was to determine whole blood lactate stability at room temperature and in slushed ice conditions. METHODS: An equal number of arterial and venous samples were obtained from 202 subjects hospitalized for various pathophysiological conditions. Whole blood lactate concentration was measured over 5 different times spanning 80–90 min in a blood gas lab at a major hospital center. Samples were stored at room temperature (22–24°C) or in slushed ice conditions (0.1–0.2°C) before analysis. RESULTS: The mean increase in lactate concentration was 0.001 mmol/L/min in samples on slushed ice over 90 min. However, at room temperature conditions, the mean increase in lactate concentration was 0.008 mmol/L/min regardless of whether the sample was arterial or venous. An increase in whole blood lactate concentration of ≥ 0.4 mmol/L occured after 45 min at room temperature, with 5% of all whole blood specimens demonstrating a meaningful change at ≤ 20 min. The ≥ 0.4 mmol/L change in whole blood lactate is considered significant based on the College of American Pathologists instrument peer-group standards. CONCLUSIONS: Considering that a change in whole blood lactate concentration of ≥ 0.4 mmol/L is unacceptable instrument peer-group variation as defined by the College of American Pathologists, ice is no longer needed to stabilize whole blood lactate specimens when the draw time to analyze time is < 45 min. Samples remain stable even at 90 min when left on ice. more...

Pulmonary diffusing capacity for carbon monoxide (DLCO) has been an important pulmonary function test used since the 1950's. It measures the uptake of CO from the alveolar space into pulmonary capillary blood, following the same path as oxygen. It's used to evaluate/follow the progress of various lung diseases. In the eighties, a new test was developed similar to the DLCO test: pulmonary diffusing capacity for nitric oxide (DLNO). About 81-90% of the variance in DLNO is shared by DLCO in patients with cardiopulmonary disease and in healthy subjects. When DLNO is abnormally low, so is DLCO, and when DLNO is normal, so is DLCO (Kappa Statistic=0.69, n=251). The probability that DLNO and DLCO will be abnormally low when a cardiopulmonary disease is present (sensitivity) is 79% and 68%, respectively. The DLNO test avoids many technical issues associated with the measurement of DLCO: (1) DLNO is relatively unaffected by inspired oxygen concentration or ambient pressure, (2) DLNO is unaffected by carboxyhemoglobin, (3) DLNO is minimally affected by hemoglobin (Hb) concentration, thus correcting for Hb is not needed. (4) DLNO is more affected by lung volume compared to DLCO, thus DLNO divided by alveolar volume (KNO) is a better measure than KCO in those with restrictive lung disease, and (5) DLNO is a more stable measure over time compared to DLCO. Therefore, DLNO has several advantages over DLCO in the management of patients and could replace the DLCO test in most cases moving forward. more...

Pulmonary diffusing capacity for nitric oxide (DL,NO) and carbon monoxide (DL,CO) measured at rest (mL/min/mmHg) is strongly associated with aerobic capacity (cardiorespiratory fitness or peak oxygen uptake, VO2peak) measured in L/min. Data from healthy, non-obese individuals from various studies (n = 121 males and 81 females) were combined to examine this association. Subjects that were above the upper limit of normal (ULN, 97.5th percentile for age and sex and height) for DL,NO and DLCO had a higher median VO2peak compared to subjects below the ULN (Above the ULN = 4.2–4.5 L/min or 54–56 mL/kg/min; below the ULN = 3.0–3.2 L/min, 45–46 mL/kg/min, p more...

Burtch, AR, Ogle, BT, Sims, PA, Harms, CA, Symons, TB, Folz, RJ, and Zavorsky, GS. Controlled frequency breathing reduces inspiratory muscle fatigue. J Strength Cond Res 31(5): 1273-1281, 2017-Controlled frequency breathing (CFB) is a common swim training modality involving holding one's breath for approximately 7-10 strokes before taking another breath. We sought to examine the effects of CFB training on reducing respiratory muscle fatigue. Competitive college swimmers were randomly divided into either the CFB group that breathed every 7-10 strokes or a control group that breathed every 3-4 strokes. Twenty swimmers completed the study. The training intervention included 5-6 weeks (16 sessions) of 12 × 50-m repetitions with breathing 8-10 breaths per 50-m (control group) or 2-3 breaths per 50-m (CFB group). Inspiratory muscle fatigue was defined as the decrease in maximal inspiratory pressure (MIP) between rest and 46 seconds after a 200-yard freestyle swimming race (115 seconds [SD 7]). Aerobic capacity, pulmonary diffusing capacity, and running economy were also measured pre- and posttraining. Pooled results demonstrated a 12% decrease in MIP at 46 seconds post-race (-15 [SD 14] cm H2O, effect size = -0.48, p0.01). After 4 weeks of training, only the CFB group prevented a decline in MIP values before to 46 seconds after race (-2 [13] cm H2O, p0.05). However, swimming performance, aerobic capacity, pulmonary diffusing capacity, and running economy did not improve (p0.05) posttraining in either group. In conclusion, CFB training appears to prevent inspiratory muscle fatigue; yet, no difference was found in performance outcomes. more...

Background As pulmonary diffusing capacity is related to mortality risk and prognosis in patients with heart failure (HF), it is measured frequently. As such, it would be essential to know the week-to-week variability (reproducibility) of pulmonary diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO). This variability would let clinicians understand what a clinically measurable change in DLCO and DLNO would be in these patients. Methods On three different days spanning over ten weeks, 40 H F patients underwent testing for DLCO and DLNO. DLCO was determined after a 4 s and 10 s breath-hold maneuver, while DLNO was determined after a 4 s breath-hold maneuver. Results Forty heart failure patients (66 ± 10 years; BMI = 28.4 ± 4.6 kg∙m−2; 28 males), that were referred to our clinic were able to complete the protocol. DLCO (4 s breath-hold) and DLNO (4 s breath-hold) were 79 ± 19 % and 59 ± 14 % predicted, respectively. Fifty percent of patients (n = 20) were below the lower limit of normal (LLN, below the 5th percentile) for predicted DLCO (4 s), while 78 % of patients (n = 31) were below the LLN for predicted DLNO. All 16 patients that were below the LLN for DLCO were also below the LLN for DLNO. Over a ten week period, the reproducibility of DLNO (4 s) DLCO (4 s) and DLCO (10 s) was 18.9, 8.2, and 5.9 mL min mmHg-1, respectively. Conclusions The week-to-week fluctuation in DLNO (4 s), as a percentage, is less than DLCO (4 s) in patients with HF. The reproducibility of DLNO in patients with HF is like that of healthy subjects. more...

Background There has been considerable debate as to whether sexual activity prior to an athletic event can affect physical performance. The goal of the study was to determine if sexual activity the evening before several physical performance tests affected the results compared to the same performance tests after five days of abstinence. Methods Ten, monogamous, married young men (28±7 years old, body mass index = 25.5±2.7 kg/m2) underwent a six-physical performance/balance/agility tests (forearm grip strength, balance, lateral movement, reaction time, anaerobic power, and maximal oxygen uptake) on three different days. The first day was a familiarization session, where the subjects familiarized themselves with the performance tests. Then, two randomized, single-blind mornings sessions occurred there was either no sexual intercourse on the five days prior to the tests (control condition) or sexual intercourse on the night before the tests (experimental condition) in a randomized counterbalanced, fashion. The six performance tests were performed in the same order for each of the three sessions. A paired-t-test was used to compare each fitness test between conditions. Results The results showed that sexual activity had no effect on any of the six physical performance tests. Conclusions This suggests that physical performance is unaffected by sexual activity within 24 hours prior to competition in young men. more...

Introduction The idea that sexual activity can affect athletic performance has been a matter of conjecture for the past several decades. Aim To provide preliminary data on whether sexual activity the evening before several physical exercise performance tests affects performance the next day. Methods Eight participants (mean age, 28 ± 5 years) underwent several physical exercise performance tests on 3 different mornings, under 3 conditions: (i) no sexual intercourse the night before the tests (control), (ii) sexual intercourse the night before the tests, and (iii) yoga the night before the tests (randomized, single-blinded). Main Outcome Measures Physical work capacity, lower body muscular power (standing vertical jump), upper body strength (handgrip strength), reaction time, and upper body musculoskeletal endurance (number of push-ups completed). Results All participants experienced orgasm through intercourse. The more pleasurable the orgasm, the lower the systolic blood pressure (SBP) on the day after intercourse (Spearman’s rho = -0.86; P = .007). For every 2% increase in the total orgasm score, SBP decreased by 1 mmHg. Intercourse lasted 13 minutes; mean heart rate (HR) and caloric expenditure ranged from 88 to 145 beats/minute and from 53 to 190 kcal, respectively. There were no significant differences in the physical working capacity that elicited an HR of 170 beats/minute, number of push-ups completed, vertical jump height, grip strength, or reaction time across the 3 conditions. Conclusion Orgasm through sexual activity on the night before physical exercise may reduce SBP; however, we were unable to demonstrate a statistically significant difference in physical exercise performance in any of the 3 conditions. more...

Background Alveolar-capillary membrane diffusing capacity for carbon monoxide (DMCO) and pulmonary capillary volume (Vcap) can be estimated by the multi-step Roughton and Foster (RF, original method from 1957) or the single-step NO–CO double diffusion technique (developed in the 1980s). The latter method implies inherent assumptions. We sought to determine which combination of the alveolar membrane diffusing capacity for nitric oxide (DMNO) to DMCO ratio, an specific conductance of the blood for NO (θNO) and CO (θCO) gave the lowest week-to-week variability in patients with heart failure. Methods 44 heart failure patients underwent DMCO and Vcap measurements on three occasions over a ten-week period using both RF and double dilution NO-CO techniques. Results When using the double diffusing method and applying θNO = infinity, the smallest week-to-week coefficient of variation for DMCO was 10 %. Conversely, the RF method derived DMCO had a much greater week-to-week variability (2x higher coefficient of variation) than the DMCO derived via the NO-CO double dilution technique. The DMCO derived from the double diffusion technique most closely matched the DMCO from the RF method when θNO = infinity and DMCO = DLNO/2.42. The Vcap measured week-to-week was unreliable regardless of the method or constants used. Conclusions In heart failure patients, the week-to-week DMCO variability was lowest when using the single-step NO-CO technique. DMCO obtained from double diffusion most closely matched the RF DMCO when DMCO/2.42 and θNO = infinity. Vcap estimation was unreliable with either method. more...

BACKGROUND: Waterpipe (hookah) smoking is a form of tobacco smoking that is noticeably increasing worldwide, particularly among young adults. A growing body of literature indicates that college students may not be as knowledgeable as they should be in making decisions about waterpipe smoking. PURPOSE: This study evaluated the prevalence, knowledge, and attitudes regarding waterpipe smoking use among college-based health-care students. METHODS: Two instruments were found to be appropriate to the study, and permission was obtained to modify usage in this specific study. Three hundred nineteen college-based health-care students were asked to participate and complete a questionnaire. Data were analyzed by using statistical software. RESULTS: Respondents used or tried waterpipe smoking before (n = 156 [49%]). Many respondents were able to identify health hazards that might result from waterpipe smoking, but 58% (n = 187) believed that cigarette smoking was more harmful than waterpipe smoking. Chi-square tests revealed significant differences between age groups (P = .029) and program of study (P = .01) but no differences among sex (P = .76), ethnicity (P = .19), or educational status (P = .65). CONCLUSIONS: This study showed that waterpipe smoking was common but not widespread among this group of health-care students. Their knowledge of the risks and health-related attitudes toward waterpipe smoking was lacking. Many had misinformation and misconceptions when comparing waterpipe smoking versus cigarette smoking. Further studies are needed to fully understand the reasons for waterpipe smoking among health-care students. Also, there is a need to offer educational campaigns that increase students9 knowledge and awareness as well as to correct misinformation that can lead to misguided beliefs and attitudes. more...

BACKGROUND: Prolonged endurance running may acutely reduce spirometric lung values. This study examined changes in spirometry before and immediately after prolonged endurance exercise (running and/or walking). Specifically, we examined potential factors that predict the presence of at least a 10% postexercise reduction in FEV1. METHODS: After institutional review board approval, recruitment occurred at a pre-race exposition, where informed consent was obtained. Pre-and post-race spirometry measurements were taken from 79 study subjects who competed in a half-marathon (n = 66) or a marathon (n = 13). Spirometry was performed 1–2 days before the marathon or half-marathon and 25 min after finish the race. RESULTS: We identified a subgroup of 23 subjects with a postexercise decrease in FEV1 of ≥10%. In this subgroup, the mean post-race values for FEV1, FVC, and peak expiratory flow were 19–24% lower than the pre-race values. In the 56 subjects with a change in FEV1 of 6%. There was no difference between the 2 groups in sex distribution or between subjects who completed the half-marathon or the full marathon. For every 1-y increase in age, the likelihood of developing a postexercise reduction in FEV1 of at least 10% decreased by nearly 10% (R2 = 0.15, P = .003). CONCLUSIONS: Exercise-induced bronchoconstriction (EIB) is the most probable explanation for the reduction in post-race FEV1. Prolonged endurance exercise reduced spirometric lung function by ∼20% in those with EIB. Age was the only predictor for EIB, and EIB did not affect the finish times among recreational runners and/or walkers. more...

Despite the close link between asthma and obesity, there are no studies that have evaluated the sensory and physiological responses to exercise in obese asthmatics. We recently demonstrated that normal weight asthmatics with well controlled disease have preserved cardiorespiratory and sensory responses to exercise relative to non-asthmatic controls. However, these similarities may not hold true in patients with combined obesity and asthma. Accordingly, we sought to determine if combined asthma and obesity was associated with deleterious effects on cardiorespiratory fitness, exercise performance, dyspnoea, and physiological responses to exercise. Fourteen well-controlled obese asthmatics and fourteen age-matched normal weight asthmatics performed routine spirometry and underwent an incremental cardiopulmonary cycle test to assess the ventilatory, pulmonary gas exchange, cardiovascular, and sensory responses to exercise. Groups were well matched for age, height, spirometry, and asthma control. Obese asthmatics had a significantly greater body mass index (33 ± 3 vs. 23 ± 1 kg/m(2), p < 0.001) and lower self-reported activity levels by 47 % relative to normal weight asthmatics (p < 0.05). Obese asthmatics had a significantly lower maximal oxygen uptake (VO(2)) (82 ± 14 vs. 92 ± 10 %predicted) and work rate (75 ± 8 vs. 89 ± 13 %predicted) relative to normal weight asthmatics (p < 0.05). The anaerobic threshold occurred at a lower VO(2) in obese asthmatics vs. normal weight asthmatics (54 ± 15 vs. 66 ± 16 %predicted, p < 0.05). Ventilatory responses were superimposed throughout exercise with no evidence of a ventilatory limitation in either group. Cardiovascular responses were normal in both groups. Dyspnoea responses were similar but the obese asthmatics experienced greater leg fatigue ratings at submaximal work rates. In conclusion, obese individuals with well controlled asthma have reduced cardiorespiratory fitness and greater leg fatigue ratings relative to normal weight asthmatics. The relatively reduced cardiorespiratory fitness and exercise performance in obese compared to normal weight asthmatics is most likely driven by their more sedentary lifestyle and resultant deconditioning rather than due to respiratory factors. more...

Ginger possesses analgesic and pharmacological properties mimicking non-steroidal antiinflammatory drugs. We aimed to determine if ginger supplementation is efficacious for attenuating muscle damage and delayed onset muscle soreness (DOMS) following high-intensity resistance exercise. Following a 5-day supplementation period of placebo or 4 g ginger (randomized groups), 20 non-weight trained participants performed a high-intensity elbow flexor eccentric exercise protocol to induce muscle damage. Markers associated with muscle damage and DOMS were repeatedly measured before supplementation and for 4 days following the exercise protocol. Repeated measures analysis of variance revealed one repetition maximum lift decreased significantly 24 h post-exercise in both groups (p more...

BACKGROUND Observational research has linked altitude to concussion risk, but the physiologic and epidemiologic bases for this association remain questionable. METHODS We performed a retrospective cohort study by analyzing four seasons of National Football League data from a widely used database (Concussion Watch) to determine if previous claims that altitude ≥196 m reduced concussion risk were replicable and whether an arbitrary predictor variable (animal vs. non-animal team logo) was related to concussion risk. Relative risk (RR) and 95% confidence intervals (95% CIs) were computed. RESULTS The previous association with altitude was reproduced for earlier seasons, but not replicable for recent seasons (RR = 0.92 [95% CI = 0.70, 1.22]). Across four combined seasons, "higher altitude" (RR = 0.78 [0.64, 0.96]) and animal logo (RR = 0.75 [0.63, 0.89]) were similarly associated with reduced concussion risk. CONCLUSIONS Inconsistent epidemiologic effects, combined with weak physiologic rationale, suggest links between altitude and concussion are coincidental. Interdisciplinary critique of concussion research is necessary to ensure that marketing claims and clinical recommendations are scientifically justified.See video abstract at, http://links.lww.com/EDE/B234. more...

Citrulline has been proposed as an ergogenic aid, leading to an interest in watermelon given its high citrulline concentration. The aim of this study was to determine the effects of a single, pre-exercise dose of l-citrulline, watermelon juice, or a placebo on the total maximum number of repetitions completed over 5 sets, time to exhaustion, maximal oxygen consumption (VO2max), anaerobic threshold, and flow-mediated vasodilation. A randomised double-blind within-participants study design was used to examine these effects among 22 participants (n = 11 males). Supplementation included either a 7.5% sucrose drink containing 6 g of l-citrulline, 710 mL of watermelon juice (~1.0 g citrulline), or a 7.5% sucrose placebo drink. Supplementation was administered 1 or 2 h before exercise testing to investigate a timing effect. There was no significant effect between the three supplements for the total number of repetitions, time to exhaustion, VO2max, anaerobic threshold, or flow-mediated vasodilation. There was also no interaction observed relative to gender or supplement timing (P 0.05). A single dose of l-citrulline or watermelon juice as a pre-exercise supplement appears to be ineffective in improving exercise performance; however, greater doses of l-citrulline have been shown to be safe and are currently left unexamined. more...

The aim of this study was to examine the effect of active versus passive recovery on 6 repeated Wingate tests (30-s all-out cycling sprints on a Velotron ergometer).Fifteen healthy participants aged 29 (SD = 8) years old (body mass index = 23 [3] kg/m(2)) participated in 3 sprint interval training sessions separated by 3 to 7 days between each session during a period of 1 month. The 1st visit was familiarization to 6 cycling sprints; the 2nd and 3rd visits involved a warm-up followed by 6 30-s cycling sprints. Each sprint was followed by 4 min of passive (resting still on the ergometer) or active recovery (pedaling at 1.1 W/kg). The same recovery was used within each visit, and recovery type was randomized between visits.Active recovery resulted in a 0.6 W/kg lower peak power output in the second sprint (95% confidence interval [CI] [ - 0.2, - 0.8 W/kg], effect size = 0.50, p .01) and a 0.4 W/kg greater average power output in the 5th and 6th sprints (95% CI [+0.2,+0.6 W/kg], effect size = 0.50, p .01) compared with passive recovery. There was little difference between fatigue index, total work, or accumulated work between the 2 recovery conditions.Passive recovery is beneficial when only 2 sprints are completed, whereas active recovery better maintains average power output compared with passive recovery when several sprints are performed sequentially (partial eta squared between conditions for multiple sprints = .38). more...

New Findings What is the central question of this study? Alveolar–capillary membrane conductance for nitric oxide (measured as lung diffusion of NO; DLNO) is not thought to be improved with regular exercise training in adult humans. The purpose was to examine the effect of regular exercise training on DLNO in unfit adult women. What is the main finding and its importance? Women performing moderate-intensity physical activity (4–6 metabolic equivalent tasks, or METS, 800 kcal week−1, for 6 weeks) can improve DLNO to a similar extent compared to women performing vigorous-intensity physical activity (>6 METS, 700 kcal week−1, for 6 weeks); however, the magnitude of improvement in DLNO will probably be small and physiologically questionable. This demonstrates that interval training may not provide additional improvements in DLNO compared with moderate-intensity physical activity. The purpose of the study was to determine whether short-term high-intensity aerobic interval training improves resting pulmonary diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO). Twenty-eight sedentary women [mean (SD) age 32 (11) years, body mass index 24.3 (5.7) kg m−2] were randomly assigned to either a self-directed moderate-intensity physical activity (n = 14) group or a supervised high-intensity aerobic interval training group (n = 14). The moderate physical activity group and the aerobic interval training group increased weekly physical activity energy expenditure by 800 and 1600 kcal week−1, respectively. After 6 weeks, aerobic capacity increased to a similar exent in both groups (mean improvement 8%, effect size 0.39). The DLNO, but not DLCO, increased to a similar extent in both groups, by 4% or 3.0 (5.7) [95% confidence interval 0.8, 5.2] ml min−1 mmHg−1 m−2 from pre- to post-training (effect size 0.27). There was no correlation between the change in aerobic capacity and the change in DLNO (P > 0.05) or between the change in aerobic capacity and the change in total weekly physical activity energy expenditure (P > 0.05). Interval training does not provide additional improvements in DLNO or aerobic capacity compared with self-directed moderate-intensity physical activity (4–6 metabolic equivalent tasks, 800 kcal week−1, for 6 weeks) in unfit women. Despite the slight improvement in both DLNO and aerobic capacity, true meaningful physiological changes in these parameters remain questionable. more...

Respiratory muscle fatigue can negatively impact athletic performance, but swimming has beneficial effects on the respiratory system and may reduce susceptibility to fatigue. Limiting breath frequency during swimming further stresses the respiratory system through hypercapnia and mechanical loading and may lead to appreciable improvements in respiratory muscle strength. This study assessed the effects of controlled-frequency breath (CFB) swimming on pulmonary function. Eighteen subjects (10 men), average (standard deviation) age 25 (6) years, body mass index 24.4 (3.7) kg/m2, underwent baseline testing to assess pulmonary function, running economy, aerobic capacity, and swimming performance. Subjects were then randomized to either CFB or stroke-matched (SM) condition. Subjects completed 12 training sessions, in which CFB subjects took two breaths per length and SM subjects took seven. Post-training, maximum expiratory pressure improved by 11% (15) for all 18 subjects (P more...

We measured the distance 112 patients walked in 6 min, as well as their peak oxygen consumption pedalling a bicycle, week before scheduled resection of benign or malignant colorectal disease. The distance walked correlated with peak oxygen consumption, the former 'accounting' for about half the variation in the latter, r² 0.52 (95% CI 0.38-0.64), p < 0.0001. In the first postoperative month, 42/112 patients experienced a complication. In multivariate analysis, complications were less likely with longer walking distances and increasing age: the odds ratio (95% CI) reduced to 0.995 (0.990-0.999) for each metre distance, and to 0.96 (0.93-0.99) with each year of age, p = 0.025 and p = 0.018, respectively. The distance walked in 6 min before surgery can provide prognostic information when cardiopulmonary exercise testing is unavailable. more...

Study Objective Because alkalinization of the renal tubules can theoretically protect against the mechanisms of acute kidney injury, we sought to determine whether a sodium bicarbonate infusion can prevent acute kidney injury after cardiac surgery. Design Prospective, randomized, double-blind, controlled trial. Setting Cardiac surgery service in a community hospital. Patients Ninety-two patients with stage 3 or higher chronic kidney disease who underwent cardiac surgery using cardiopulmonary bypass. Intervention Forty-eight patients received a perioperative intravenous infusion of 0.9% sodium chloride 154 mEq/L, and 44 patients received an infusion of sodium bicarbonate infusion 150 mEq/L in 5% dextrose solution; the infusions were started 1 hour preoperatively and continued for 6 hours after cardiopulmonary bypass. Measurements and Main Results The primary outcome was the development of any stage of acute kidney injury within 5 days after surgery as defined by the Acute Kidney Injury Network criteria. No statistically significant difference in the primary outcome was noted between the two groups: 32% in the bicarbonate group versus 42% in the sodium chloride group (p=0.12). Likewise, no significant differences in the 30-day hospital mortality rate or other adverse outcomes were noted between the two groups. Conclusion A perioperative infusion of sodium bicarbonate did not reduce the rate of acute kidney injury or adverse outcomes in patients with chronic kidney disease who underwent cardiac surgery. more...

The first aim of this study was to determine the age group at which marathon performance declines in top male and female runners and to compare that to the runners of average ability. Another aim of this of this study was to examine the age-related yearly decline in marathon performance between age group winners and the average marathon finisher. Data from the New York (NYC), Boston, and Chicago marathons from 2001-2016 were analyzed. Age, sex, and location were used in multiple linear regression models to determine the rate of decline in marathon times. Winners of each age group were assessed in 5-year increments from 16 through 74 years old (n = 47 per age group). The fastest times were between 25-34 years old, with overall champion males at 28.3 years old, and overall champion females at 30.8 years old (p = 0.004). At 35 years of age up to 74 years of age, female age group winners had a faster yearly decline in marathon finishing times compared to male age group winners, irrespective of marathon location [women = (min:sec) 2:33 per year, n = 336; men = 2:06 per year, n = 373, p < 0.01]. The median times between each age group only slowed beginning at 50 years old, thereafter the decline was similar between both men and women (women = 2:36, n = 140; men = 2:57, n = 150, p = 0.11). The median times were fastest at Boston and similar between Chicago and NYC. In conclusion, the rate of decline at 35 years old up to 74 years old is roughly linear (adjusted r2 = 0.88, p < 0.001) with female age group winners demonstrating 27 s per year greater decline per year compared to male age group winners. more...

to the editor: We thank those who presented their perspectives ([1][1]) to our Viewpoint ([8][2]). Although Stacey and Bailey introduced interesting ideas regarding hypoxia and brain volume, none of the commentaries challenged our central argument that the altitudes examined are too low to induce a more...

In recent years, various studies have attempted to understand human evolution by examining relationships between athletic performance or physical fitness and facial attractiveness. Over a wide range of five homogeneous groups (n = 327), there is an approximate 3% shared variance between facial attractiveness and athletic performance or physical fitness (95% CI = 0.5-8%, p = 0.002). Further, studies relating human performance and attractiveness often have major methodological limitations that limit their generalizability. Thus, despite statistical significance, the association between facial attractiveness and human performance has questionable biological importance. Here, we present a critique of these studies and provide recommendations to improve the quality of future research in this realm. more...

The purpose of this study determined if oral supplementation of Protandim® (a nutraceutical) for 90 days improved 5-km running performance and reduced serum thiobarbituric acid-reacting substances (TBARS) at rest, an indicator of oxidative stress. Secondary objectives were to measure whole blood superoxide dismutase (SOD), glutathione (GSH), and glutathione peroxidase (GPX), at rest and 10 minutes after completion of the race before and after supplementation as well as quality of life. In a double-blind, randomized, placebo controlled trial, 38 runners [mean (SD) = 34 (7) yrs; BMI = 22 (2) kg/m2] received either 90 days of Protandim® [1 pill a day, n = 19)] or placebo (n = 19). Randomization was done in blocks of two controlling for sex and 5-km baseline performance. A 5-km race was performed at baseline and after 90 days of supplementation, with blood samples taken before and 10-min after each race. Fasting blood samples were acquired at baseline, after 30, 60, and 90 days of supplementation. TBARS, SOD, GPX, and GSH were assayed in an out-of-state accredited lab. Running performance was not altered by Protandim® or placebo [20.3 (2.1) minutes, with an -8 (33) seconds change in 5-km time regardless of group]. There was no change in TBARS, SOD, or GPX (at rest) after three months of Protandim® supplementation compared to placebo. However, in a subgroup ≥ 35 years of age, there was a 2-fold higher increase in SOD in those taking Protandim® for three months compared to those on placebo (p = 0.038). The mean post-race change in TBARS (compared to pre-race) increased by about 20% in half of the subjects, but was not altered between groups, even after three months of supplementation. Quality of life was also not different between the two conditions. In conclusion, Protandim® did not (1) alter 5-km running time, (2) lower TBARS at rest (3) raise antioxidant enzyme concentrations compared to placebo (with exception of SOD in those ≥ 35 years old) or, (4) affect quality of life compared to placebo. Trial Registration: ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT02172625","term_id":"NCT02172625"}}NCT02172625 more...

recent studies claim that the incidence of sports-related concussions may be reduced ([16][1], [25][2]) at “higher altitudes.” The proposed mechanism of protection is rooted in the “tighter fit” theory, such that altitude exposure causes the brain to swell, which leaves less room for it to more...

The present study examined the relationship between urine specific gravity (Usg), body mass (BM) and bioelectrical impedance determined variables [total body water (TBW), per cent TBW and impedance values] before and after a marathon (n = 25 men; 10 women). A significant reduction in BM (pre: 71.2 ± 12.4 kg; post: 69.6 ± 12.0 kg; p 0.001) and an increase in Usg (pre: 1.009 ± 0.007; post: 1.018 ± 0.009; p 0.001) was observed post-race. TBW was not significantly decreased (pre: 42.7 ± 8.0 kg; post: 42.4 ± 7.7 kg) while per cent TBW significantly increased post-race (pre: 60.0 ± 3.9%; post: 60.8 ± 3.8%; p 0.001). Impedance values were significantly greater post-race (pre: 3288 ± 482; post: 3416 ± 492 Ω; p 0.001). There was no correlation between the change in Usg and the change in BM or any of the bioelectrical impedance determined variables. On average, BM, Usg and impedance values appear to express changes in hydration; however, the observed changes among these variables for a given individual appear to be inconsistent with one another. more...

Background. Abdominal surgery represents a physiologic stress and is associated with a period of recovery during which functional capacity is often diminished. ‘‘Prehabilitation’’ is a program to increase functional capacity in anticipation of an upcoming stressor. We reported recently the results of a randomized trial comparing 2 prehabilitation programs before colorectal surgery (stationary cycling plus weight training versus a recommendation to increase walking coupled with breathing exercises); however, adherence to the programs was low. The objectives of this study were to estimate: (1) the extent to which physical function could be improved with either prehabilitation program and identify variables associated with response; and (2) the impact of change in preoperative function on postoperative recovery. Methods. This study involved a reanalysis of data arising from a randomized trial. The primary outcome measure was functional walking capacity measured by the Six-Minute Walk Test; secondary outcomes were anxiety, depression, health-related quality of life, and complications (Clavien classification). Multiple linear regression was used to estimate the extent to which key variables predicted change in functional walking capacity over the prehabilitation and follow-up periods. Results. We included 95 people who completed the prehabilitation phase (median, 38 days; interquartile range, 22–60), and 75 who were also evaluated postoperatively (mean, 9 weeks). During prehabilitation, 33% improved their physical function, 38% stayed within 20 m of their baseline score, and 29% deteriorated. Among those who improved, mental health, vitality, self-perceived health, and peak exercise capacity also increased significantly. Women were less likely to improve; low baseline walking capacity, anxiety, and the belief that fitness aids recovery were associated with improvements during prehabilitation. In the postoperative phase, the patients who had improved during prehabilitation were also more likely to have recovered to their baseline walking capacity than those with no change or deterioration (77% vs 59% and 32%; P = .0007). Patients who deteriorated were at greater risk of complications requiring reoperation and/or intensive care management. Significant predictors of poorer recovery included deterioration during prehabilitation, age >75 years, high anxiety, complications requiring intervention, and timing of follow-up assessment. Conclusion. In a group of patients undergoing scheduled colorectal surgery, meaningful changes in functional capacity can be achieved over several weeks of prehabilitation. Patients and those who care for them, especially those with poor physical capacity, should consider a prehabilitation regimen to enhance functional exercise capacity before colectomy. (Surgery 2011;150:505-14.) more...

Several versions of exercise guidelines for pregnancy have been published, the latest 9 years ago. These guidelines recommend 30 minutes or more of moderate exercise on most if not all days of the week for pregnant women in the absence of medical or obstetric complications. However, moderate-intensity exercise was not defined. In addition, the specific weekly energy expenditure of physical activity was not suggested. Recent research has determined that, compared with less vigorous activities, exercise intensity that reaches at least 60% of the heart rate reserve during pregnancy while gradually increasing physical-activity energy expenditure reduces the risk of gestational diabetes. To achieve the minimum expenditure of 16 metabolic equivalent task-h/wk, one could walk at 2 miles/h for 6.4 h/wk (2.5 metabolic equivalent task-hours, light intensity) or, preferably, exercise on a stationary bicycle for 2.7 h/wk (6 to 7 metabolic equivalent task-hours, vigorous intensity). To achieve the target expenditure of 28 metabolic equivalent task-hours per week, one could walk at 2.0 miles/h for 11.2 h/wk (2.5 metabolic equivalent task-hours, light intensity) or, preferably, exercise on a stationary bicycle for 4.7 h/wk (6 to 7 metabolic equivalent task-hours, vigorous intensity). The more vigorous the exercise, the less total exercise time is required. Light muscle strengthening performed during the second and third trimesters of pregnancy has minimal effect on newborn body size and overall health. On the basis of this and other information, updated recommendations for exercise in pregnancy are suggested. more...

Measurement error is a common problem in several fields of research such as medicine, physiology, and exercise science. The standard deviation of repeated measurements on the same person is the measurement error. One way of presenting measurement error is called the repeatability, which is 2.77 multiplied by the within subject standard deviation. In this article, the two different repeatabilities obtained from two different protocols or “tests” are statistically compared. Briefly, the squared differences between protocols are natural log transformed to achieve normality and compared with a paired t-test. The natural log transformation guarantees that the squared differences follow a normal distribution. When more than two repeatabilities are compared from more than two protocols or “tests,” repeated-measures ANOVA comparing the log transformation of the squared differences is used. When comparing repeatabilities between protocols and between different magnitudes of measurement, repeated-measures ANOVA com... more...

Background ‘Prehabilitation’ is an intervention to enhance functional capacity in anticipation of a forthcoming physiological stressor. In patients scheduled for colorectal surgery, the extent to which a structured prehabilitation regimen of stationary cycling and strengthening optimized recovery of functional walking capacity after surgery was compared with a simpler regimen of walking and breathing exercises. Methods Some 112 patients (mean(s.d.) age 60(16) years) were randomized to either the structured bike and strengthening regimen (bike/strengthening group, 58 patients) or the simpler walking and breathing regimen (walk/breathing group, 54 patients). Randomization was done at the surgical planning visit; the mean time to surgery available for prehabilitation was 52 days; follow-up was for approximately 10 weeks after surgery. Results There were no differences between the groups in mean functional walking capacity over the prehabilitation period or at postoperative follow-up. The proportion showing an improvement in walking capacity was greater in the walk/breathing group than in the bike/strengthening group at the end of the prehabilitation period (47 versus 22 per cent respectively; P = 0·051) and after surgery (41 versus 11 per cent; P = 0·019). Conclusion There was an unexpected benefit from the recommendation to increase walking and breathing, as designed for the control group. Adherence to recommendations was low. An examination of prehabilitation ‘responders’ would add valuable information. Registration number: NCT00227526 (http://www.clinicaltrials.gov). more...

This paper reviews the scientific evidence for the safety of carbon monoxide (CO) and nitric oxide (NO) inhalation to measure pulmonary diffusing capacity (DL(CO) and DL(NO)) in pregnant women and their fetuses. In eight earlier studies, 650 pregnant women had DL(CO) measurements performed at various times during pregnancy, with a minimum of two to four tests per session. Both pregnant subjects that were healthy and those with medical complications were tested. No study reported adverse maternal, fetal, or neonatal outcomes from the CO inhalation in association with measuring DL(CO). Eleven pregnant women, chiefly with pulmonary hypertension, and 1105 pre-term neonates, mostly with respiratory failure, were administered various dosages of NO (5-80ppm for 4 weeks continuously in pregnant women, and 1-20ppm for 15min to 3 weeks for the neonates). NO treatment was found to be an effective therapy for pregnant women with pulmonary hypertension. In neonates with respiratory failure and pulmonary hypertension, NO therapy improved oxygenation and survival and has been associated with only minor, transient adverse effects. In conclusion, maternal carboxyhemoglobin ([Hb(CO)]) levels can safely increase to 5% per testing session when the dose-exposure limit is 0.3% CO inhalation for more...

Morbidly obese men may have poorer pulmonary gas exchange compared to morbidly obese women (see Zavorsky et al., Chest 131:362-367, 2007). The purpose was to compare pulmonary gas exchange in morbidly obese men and women at rest and throughout exercise.Twenty-five women (age=38+/-10 years, 164+/-7 cm, body mass index or BMI = 51+/-7 kg/m(2), peak oxygen consumption or VO(2peak)=2.0+/-0.4 l/min) and 17 men (age=43+/-9 years, 178+/-7 cm, BMI=50+/-10 kg/m(2), VO(2peak)=2.6+/-0.8 l/min) were recruited to perform a graded exercise test on a cycle ergometer with temperature-corrected arterial blood-gas samples taken at rest and every minute of exercise, including peak exercise.At rest, women were 98% predicted for pulmonary diffusion compared to 88% predicted in men. At rest, women had better pulmonary gas exchange compared to the men which was related to women having a lower waist-to-hip ratio (WHR; p0.01). Only 20% of the subjects had an excessive alveolar-to-arterial oxygen partial pressure difference (or=25 mmHg) at peak exercise, but 75% of the subjects showed inadequate compensatory hyperventilation at peak exercise (arterial carbon dioxide pressure35 mmHg), and both were not different between genders.At rest, morbidly obese men have poorer pulmonary gas exchange and pulmonary diffusion compared to morbidly obese women. The better gas exchange in women is related to the lower WHR in the women. During exercise, few subjects showed disturbances in pulmonary gas exchange despite demonstrating poor compensatory hyperventilation at peak exercise. more...

Morbidly obese individuals may have poor compensatory hyperventilation during exercise. The objective was to examine pulmonary gas exchange and the compensatory hyperventilatory response during exercise pre- and post-weight reduction surgery in obese subjects.Fifteen patients (age=39+/-8 years, body mass index=47+/-6 kg/m2), with an excess weight of 69+/-17 kg, were recruited. Pulmonary function at rest was assessed and arterial-blood gases were sampled at rest and all levels of exercise pre- and 10+/-3 weeks postsurgery.There was a loss of excess weight 21+/-6 kg (p0.01). Waist and hip circumference decreased by 13+/-9 and 8+/-7 cm, respectively (p0.01). Prior to surgery, there was no compensatory hyperventilation between rest and peak exercise as arterial PCO2 (PaCO2) remained unchanged (37+/-3 mm Hg). However, postsurgery, there was compensatory hyperventilation as PaCO2 decreased to 33+/-2 mm Hg at peak exercise (p0.01), with no change in peak oxygen consumption (VO2peak in L/min). Multiple linear regression revealed that the restored ventilatory response to exercise was most strongly associated with the reduction in overall fat mass (adjusted r2=0.25; p=0.03). Total weight loss of 21 kg induces adequate compensatory hyperventilation that begins to show at about 50% of VO2peak, resulting in improved gas exchange at moderate to peak exercise intensities.Improvement in compensatory hyperventilation is most closely related to loss in overall fat mass. more...

Our objective was to create reference values for single-breath DLNO based on a sample of non-smoking healthy males and females using a short breath-hold time. The sample included 130 individuals varied in age (18-85 yr), height (149-190 cm), and weight (49.4-102.6 kg). The subjects performed single-breath-hold maneuvers at rest inhaling 41 +/- 6 ppm NO and a standard diffusion mixture. The breath-hold time was 5.5 +/ -0.6 s. Multiple linear regression with backward elimination of the independent variables age, weight, gender, and either measured lung volume (called alveolar volume or VA) or height revealed specific prediction equations for DLNO. Inserting VA instead of height into the regression equation determined how much of an abnormality of DLNO was due to gas exchange versus low lung volume. The predicted DLNO adjusted for lung volume (ml/min/mmHg) = DLNO = 73.1 + 17.26 x (VA)+17.56 x (gender) - 1.0 x (age). The predicted DLNO unadjusted for lung volume (ml/min/mmHg) = -20.1 + 1.167 x (height)+31.81 x (gender) - 1.21 x (age). For gender, 1 = males, 0 = females; VA = liters; height = cm. Age, gender and VA (lung volume) were the best predictors of DLNO and DLCO. Weight was not a good independent predictor of DLNO or DLCO. When normalizing for height and age, women have 650 ml lower forced vital capacity, 660 ml lower VA, and a 6 and 32 ml/min/mmHg lower DLCO and DLNO, respectively, compared to men. Normalizing for lung volume and age, women have, on average, a 3.2 and 18 ml/min/mmHg lower DLCO and DLNO, respectively, compared to men. more...

This study was designed to compare differences in pulmonary gas exchange at rest and at peak exercise in two groups of women: (1) physically active, non-obese women and (2) women with morbid obesity. Fourteen morbidly obese women (body mass index or BMI = 49 ± 7 kg/m2; peak oxygen consumption or V ˙ O 2 peak = 14 ± 2 ml/ ( kg min ) ) and 14 physically active non-obese women (BMI = 22 ± 2 kg/m2; V ˙ O 2 peak = 50 ± 6 ml/ ( kg min ) ) performed an incremental, ramped exercise test to exhaustion on a cycle ergometer. Arterial blood was sampled at rest and at peak exercise. At rest, the alveolar to arterial oxygen partial pressure difference was 3× higher in the obese women (14 ± 10 mmHg) compared to non-obese women (5 ± 4 mmHg). Arterial carbon dioxide pressure ( P a C O 2 ) was identical in both groups at rest (37 ± 4 mmHg). Only the non-obese women showed a decrease in P a C O 2 rest to peak exercise (−5 ± 3 mmHg). The slope between heart rate and V ˙ O 2 during exercise was higher in the morbidly obese compared to non-obese women indicating that for the same absolute increase in V ˙ O 2 a larger increase in heart rate is needed, demonstrating poorer cardiac efficiency in obese women. In conclusion, morbidly obese women have poorer exercise capacity, cardiac efficiency, and compensatory hyperventilation at peak exercise, and poorer gas exchange at rest compared to physically active, non-obese women. more...

When monitoring nitric oxide diffusing capacity (DL NO ) in patients, it is necessary to distinguish natural biological variation from a real change in alveolar-membrane conductance. The short-term variability of single-breath DL NO has not been established. The aim was to determine the short-term variability DL NO in healthy subjects. Twelve healthy subjects performed single-breath hold diffusing capacity tests at rest over a 2-month period (eight separate sessions with 8 ± 3 days between each session). Each subject inhaled 41 ± 4 ppm NO and a standard diffusion mixture. DL NO , which is a multiple of the membrane diffusing capacity for carbon monoxide (Dm CO ), as well as carbon monoxide diffusing capacity (DL CO ) and pulmonary capillary blood volume ( V c ) remained unaltered over the 2-month period ( P > 0.05). Reproducibility (calculated as 2.77 multiplied by the within-subject standard deviation) over eight sessions was 20, 5 and 8 mL min −1 mmHg −1 for DL NO , DL CO and Dm CO , respectively, and 19 mL for V c (when Dm CO = DL NO /2.42). DL NO , DL CO , Dm CO and V c remain unchanged over a period of 2 months. Since the inter-session variability is 20, 5 and 8 mL min −1 mmHg −1 for DL NO , DL CO and Dm CO , and 19 mL for V c , a meaningful change should equal or exceed those values. While there is a small chance that week-to-week variation can also be partly due to mild pathophysiological changes, any differences that are below the reproducibility values are likely to be natural biological variation or technical variation of the equipment, rather than true physiological change. more...