Hemodynamic, ventilatory and gas exchange responses to exercise using a cycle ergometer and the incremental shuttle walk test in pregnant women.

BACKGROUND: Cardiovascular disease, including hypertension, in pregnant women is a leading cause of morbidity and mortality globally. The development of reference intervals for cardiovascular responses using exercising testing to measure oxygen utilisation (V̇O2) with cardiopulmonary exercise testing (CPET), and distances walked using the incremental shuttle walk test (ISWT), may be promising methods to assess and stratify pregnant women regarding their risk of adverse pregnancy outcomes, to encourage exercise during pregnancy, and to improve exercise prescriptions during pregnancy. We aimed to determine the reference intervals for V̇O2 at rest, anaerobic threshold (AT), and submaximal exercise using CPET, and the reference interval for the ISWT, to develop a correlation equitation that predicts submaximal V̇O2 from the distance walked in the ISWT, and to explore the relationship between hemoglobin (Hb) and ferritin concentration and V̇O2 at AT in women in second trimester. METHODS: After prospective IRB approval (HREC 15/23) and clinical trials registration (ANZCTR ACTRN12615000964516), and informed written consent, we conducted CPET and the ISWT according to international guidelines in a university associated tertiary referral obstetric and adult medicine hospital, in healthy pregnant women in second trimester (14 to 27 gestational weeks). Hemoglobin and ferritin concentrations were recorded from pathology results in the participants' medical records at the time of exercise testing. Adverse events were recorded. RESULTS: About 90 participants undertook CPET, 28 of which also completed the ISWT. The mean ± SD age and body mass index (BMI) were 32 ± 3.2 years, and 25 ± 2.7 kg/m2. Median (IQR) gestation was 23 (22-24) weeks. One in 4 women were 24 weeks or greater gestation. The reference intervals for V̇O2 at rest, AT, and submaximal exercise were 2.9 to 5.3, 8.1 to 20.7, and 14.1 to 30.5 mL/kg/min respectively. The reference interval for the ISWT was 218 to 1058 meters. The correlation equation to predict submaximal V̇O2 from the distance walked in the ISWT was submaximal V̇O2 (mL/kg/min) = 0.012*distance walked in ISWT (m) + 14.7 (95%CI slope 0.005-0.070, Pearson r = 0.5426 95%CI 0.2126-0.7615, P = .0029). Hemoglobin concentration was positively correlated with V̇O2 at AT (AT V̇O2 (mL/kg/min) = 0.08*Hb (g/L) + 4.9 (95%CI slope 0.0791-0.143, Pearson r = 0.2538 95%CI 0.049-0.438, P = .016). There was no linear association between ferritin and submaximal V̇O2 (Pearson r = 0.431 P = .697). There were no maternal or fetal complications. CONCLUSIONS: CPET and ISWT are safe and feasible in women in second trimester including those at or beyond 24 weeks gestation. We have established the reference interval for V̇O2 at rest, AT, and submaximal exercise by CPET, the reference interval for the distance walked for the ISWT, and a correlation equation to predict submaximal V̇O2 for use in clinical practice and research. Hemoglobin rather than ferritin is likely correlated with exercise capacity in pregnancy suggesting vigilance to correct lower hemoglobin levels may positively impact maternal health. CLINICAL TRIALS REGISTRY: The study was prospectively registered with the Australian and New Zealand Clinical Date of registration - 15/9/2015; Date of initial participant enrolment - 4/11/2015; Clinical trial identification number; ACTRN12615000964516; URL of the registration site - https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=369216.

An 8-week Forced-rate Aerobic Cycling Program Improves Cardiorespiratory Fitness in Persons With Chronic Stroke: A Randomized Controlled Trial.

OBJECTIVE: To examine the cardiorespiratory effects of a forced-rate aerobic exercise (FE) intervention among individuals with chronic stroke compared with an upper extremity repetitive task practice (UE RTP) control group. DESIGN: Secondary analysis of data from a randomized controlled trial. SETTING: Research laboratory. PARTICIPANTS: Individuals with chronic stroke (N=60). INTERVENTIONS: Participants completed 24 sessions of FE followed by RTP (FE+RTP, N=30) or time matched RTP alone (N=30). The FE+RTP group was prescribed exercise at 60%-80% of heart rate reserve on a motorized stationary cycle ergometer for 45 minutes followed by 45 minutes of RTP. The control group completed 90 minutes of RTP. MAIN OUTCOME MEASURES: Metabolic exercise stress tests on a cycle ergometer were conducted at baseline and post-intervention. Outcomes included peak oxygen consumption (peak V̇o2) and anaerobic threshold (AT). RESULTS: Fifty participants completed the study intervention and pre/post stress tests. The FE+RTP group demonstrated significantly greater improvements in peak V̇o2 from 16.4±5.7 to 18.3±6.4 mL/min/kg compared with the RTP group (17.0±5.6 to 17.2±5.6 mL/min/kg, P=.020) and significantly greater improvements in AT from 10.3±2.8 to 11.5±3.6 mL/min/kg compared with the RTP group (10.8±3.9 to 10.4±3.2 mL/min/kg, P=.020). In analyzing predictors of post-intervention peak V̇o2, the multivariable linear regression model did not reveal a significant effect of age, sex, body mass index, or beta blocker usage. Similarly, bivariate linear regression models for the FE group only did not find any exercise variables (aerobic intensity, power, or cycling cadence) to be significant predictors of peak V̇o2. CONCLUSIONS: While the aerobic exercise intervention was integrated into rehabilitation to improve UE motor recovery, it was also effective in eliciting significant and meaningful improvements in cardiorespiratory fitness. This novel rehabilitation model may be an effective approach to improve motor and cardiorespiratory function in persons recovering from stroke.

The polymorphism T1470A of the SLC16A1 gene is associated with the lactate and ventilatory thresholds but not with fat oxidation capacity in young men.

PURPOSE: To examine the association of the single nucleotide polymorphism A1470T in the SLC16A1 gene with blood lactate accumulation during a graded exercise test and its associated metaboreflex. METHODS: Forty-six Latin-American men (Age: 27 ± 6 years; Body fat: 17.5 ± 4.7%) performed a graded exercise test on a treadmill for the assessment of maximal oxygen uptake (VO2max), lactate threshold (LT), ventilatory threshold (VT) and the exercise intensity corresponding to maximal fat oxidation rate (FATmax), via capillary blood samples and indirect calorimetry. Genomic DNA was extracted from a peripheral blood sample. Genotyping assay was carried out by real-time polymerase chain reaction to identify the A1470T polymorphism (rs1049434). RESULTS: Genotypes distribution were in Hardy-Weinberg equilibrium (X2 = 5.6, p > 0.05), observing allele frequencies of 0.47 and 0.53 for the A and T alleles, respectively. No difference in VO2max, body composition nor FATmax were observed across genotypes, whereas carriers of the TT genotype showed a higher LT (24.5 ± 2.2 vs. 15.6 ± 1.7 mL kg-1 min-1, p < 0.01) and VT in comparison to carriers of the AA + AT genotypes (32.5 ± 3.3 vs. 21.7 ± 1.5 mL kg-1 min-1, p < 0.01). Both, VO2max and the A1470T polymorphism were positively associated to the LT (R2 = 0.50, p < 0.01) and VT (R2 = 0.55, p < 0.01). Only VO2max was associated to FATmax (R2 = 0.39, p < 0.01). CONCLUSION: Independently of cardiorespiratory fitness, the A1470T polymorphism is associated to blood lactate accumulation and its associated ventilatory response during submaximal intensity exercise. However, the A1470 polymorphism does not influence fat oxidation capacity during exercise in young men.

Effect of Acute Altitude Exposure on Anaerobic Threshold Assessed by a Novel Electrocardiogram-Based Method.

Background: Acute altitude has a relevant impact on exercise physiology and performance. Therefore, the positive impact on the performance level is utilized as a training strategy in professional as well as recreational athletes. However, ventilatory thresholds (VTs) and lactate thresholds (LTs), as established performance measures, cannot be easily assessed at high altitudes. Therefore, a noninvasive, reliable, and cost-effective method is needed to facilitate and monitor training management at high altitudes. High Alt Med Biol. 25:94-99, 2024. Methods: In a cross-sectional setting, a total of 14 healthy recreational athletes performed a graded cycling exercise test at sea level (Munich, Germany: 512 m/949 mbar) and high altitude (Zugspitze: 2,650 m/715 mbar). Anaerobic thresholds (ATs) were assessed using a novel method based on beat-to-beat repolarization instability (dT) detected by Frank-lead electrocardiogram (ECG) monitoring. The ECG-based ATs (ATdT°) were compared to routine LTs assessed according to Dickhuth and Mader. Results: After acute altitude exposure, a decrease in AT was detected using a novel ECG-based method (ATdT°: 159.80 ± 52.21 W vs. 134.66 ± 34.91 W). AtdT° levels correlated significantly with LTDickhuth and LTMader, at baseline (rDickhuth/AtdT° = 0.979; p < 0.001) (rMader/AtdT° = 0.943; p < 0.001), and at high altitude (rDickhuth/AtdT° = 0.969; p < 0.001) (rMader/AtdT° = 0.942; p < 0.001). Conclusion: Assessment of ATdT is a reliable method to detect performance alterations at altitude. This novel method may facilitate the training management of athletes at high altitudes.

Do freedivers and spearfishermen differ in local muscle oxygen saturation and anaerobic power?

BACKGROUND: Freediving is defined as an activity where athletes repetitively dive and are exposed to long efforts with limited oxygen consumption. Therefore, anaerobic features are expected to be an important facet of diving performance. This study aimed to investigate differences in anaerobic capacity and local muscle oxygenation in spearfisherman and freedivers. METHODS: The sample of participants included 17 male athletes (nine freedivers, and eight spearfishermen), with an average age of 37.0±8.8 years, training experience of 10.6±9.5 years, body mass of 82.5±9.5 kg and height of 184.2±5.7 cm. Anthropometric characteristics included: body mass, body height, seated height, and body fat percentage. Wingate anaerobic test was conducted, during which local muscle oxygenation was measured with a NIRS device (Moxy monitor). Wingate power outputs were measured (peak power [W/kg] and average power [W/kg]), together with muscle oxygenation variables (baseline oxygen saturation [%], desaturation slope [%/s], minimum oxygen saturation [%], half time recovery [s], and maximum oxygen saturation [%]). RESULTS: The differences were not obtained between freedivers and spearfisherman in power outputs (peak power (9.24±2.08 spearfisherman; 10.68±1.04 freedivers; P=0.14); average power (6.85±0.95 spearfisherman; 7.44±0.60 freedivers; P=0.15) and muscle oxygenation parameters. However, analysis of effect size showed a moderate effect in training experience (0.71), PP (0.89), AP (0.75), Desat slope mVLR (0.66), half time recovery mVLR (0.90). CONCLUSIONS: The non-existence of differences between freedivers and spearfishermen indicates similar training adaptations to the anaerobic demands. However, the results show relatively low anaerobic capacities of our divers that could serve as an incentive for the further development of these mechanisms.

Estimated standard values of aerobic capacity according to sex and age in a Japanese population: A scoping review.

Aerobic capacity is a fitness measure reflecting the ability to sustain whole-body physical activity as fast and long as possible. Identifying the distribution of aerobic capacity in a population may help estimate their health status. This study aimed to estimate standard values of aerobic capacity (peak oxygen uptake [Formula: see text] and anaerobic threshold [AT]/kg) for the Japanese population stratified by sex and age using a meta-analysis. Moreover, the comparison of the estimated standard values of the Japanese with those of other populations was performed as a supplementary analysis. We systematically searched original articles on aerobic capacity in the Japanese population using PubMed, Ichushi-Web, and Google Scholar. We meta-analysed [Formula: see text] (total: 78,714, men: 54,614, women: 24,100) and AT (total: 4,042, men: 1,961, women: 2,081) data of healthy Japanese from 21 articles by sex and age. We also searched, collected and meta-analysed data from other populations. Means and 95% confidence intervals were calculated. The estimated standard values of [Formula: see text] (mL/kg/min) for Japanese men and women aged 4-9, 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 years were 47.6, 51.2, 43.2, 37.2, 34.5, 31.7, 28.6, and 26.3, and 42.0, 43.2, 33.6, 30.6, 27.4, 25.6, 23.4, and 23.1, respectively. The AT/kg (mL/kg/min) for Japanese men and women aged 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 years were 21.1, 18.3, 16.8, 15.9, 15.8, and 15.2, and 17.4, 17.0, 15.7, 15.0, 14.5, and 14.2, respectively. Herein, we presented the estimated standard values of aerobic capacity according to sex and age in a Japanese population. In conclusion, aerobic capacity declines with ageing after 20-29 years of age. Additionally, aerobic capacity is lower in the Japanese population than in other populations across a wide range of age groups. Standard value estimation by meta-analysis can be conducted in any country or region and for public health purposes.

Concepts of Lactate Metabolic Clearance Rate and Lactate Clamp for Metabolic Inquiry: A Mini-Review.

Lactate is known to play a central role in the link between glycolytic and mitochondrial oxidative metabolism, as well as to serve as a primary gluconeogenic precursor. Blood lactate concentration is sensitive to the metabolic state of tissues and organs as lactate rates of appearance and disposal/disappearance in the circulation rise and fall in response to physical exercise and other metabolic disturbances. The highest lactate flux rates have been measured during moderate intensity exercise in endurance-trained individuals who exhibit muscular and metabolic adaptations lending to superior oxidative capacity. In contrast, a diminished ability to utilize lactate is associated with poor metabolic fitness. Given these widespread implications in exercise performance and health, we discuss the concept of lactate metabolic clearance rate, which increases at the onset of exercise and, unlike flux rates, reaches a peak just below the power output associated with the maximal lactate steady state. The metabolic clearance rate is determined by both disposal rate and blood concentration, two parameters that are mutually interdependent and thus difficult to parse during steady state exercise studies. We review the evolution of the in vivo lactate clamp methodology to control blood lactate concentration and discuss its application in the investigation of whole-body lactate disposal capacities. In conclusion, we assert that the lactate clamp is a useful research methodology for examining lactate flux, in particular the factors that drive metabolic clearance rate.

Estimation of maximal lactate steady state using the sweat lactate sensor.

A simple, non-invasive algorithm for maximal lactate steady state (MLSS) assessment has not been developed. We examined whether MLSS can be estimated from the sweat lactate threshold (sLT) using a novel sweat lactate sensor for healthy adults, with consideration of their exercise habits. Fifteen adults representing diverse fitness levels were recruited. Participants with/without exercise habits were defined as trained/untrained, respectively. Constant-load testing for 30 min at 110%, 115%, 120%, and 125% of sLT intensity was performed to determine MLSS. The tissue oxygenation index (TOI) of the thigh was also monitored. MLSS was not fully estimated from sLT, with 110%, 115%, 120%, and 125% of sLT in one, four, three, and seven participants, respectively. The MLSS based on sLT was higher in the trained group as compared to the untrained group. A total of 80% of trained participants had an MLSS of 120% or higher, while 75% of untrained participants had an MLSS of 115% or lower based on sLT. Furthermore, compared to untrained participants, trained participants continued constant-load exercise even if their TOI decreased below the resting baseline (P < 0.01). MLSS was successfully estimated using sLT, with 120% or more in trained participants and 115% or less in untrained participants. This suggests that trained individuals can continue exercising despite decreases in oxygen saturation in lower extremity skeletal muscles.

Physiological and Energetic Demands During Still-Rings Routines of Elite Artistic Gymnasts.

PURPOSE: The aim of the study was to analyze physiological and energetic demands of elite gymnasts during still-rings routines (SRRs). METHODS: Eleven male gymnasts (mean [SD] 23.6 [3.9] y, 65.9 [5.6] kg, 171.1 [6.7] cm) performed a maximal graded exercise test and an individual SRR, during which respiratory gas and heart rate (HR) were measured using a mobile spiroergometer and a paired HR sensor. Metabolic energy and the energy contribution in terms of aerobic, anaerobic lactic, and anaerobic alactic were determined by oxygen uptake (VO2) during exercise, net lactate production, and the fast component of postexercise VO2 kinetics. RESULTS: Mean routine duration of the SRRs was 48.3 (4.5) seconds. VO2 and HR during SRRs were shown to be 86.9% (5.9%) and 91.0% (3.3%), respectively, of the maximal values measured during the graded exercise test. The anaerobic alactic, aerobic, and anaerobic lactic systems provided 50.9% (6.6%), 28.6% (4.8%), and 20.5% (5.2%), respectively, of the total energy required during SRRs. The energy contribution of the anaerobic lactic system correlated negatively with individual anaerobic threshold (r = -.715) and maximal VO2 (r = -.682). CONCLUSIONS: The anaerobic alactic system is the predominant energy source for ATP resynthesis during SRRs. The high relative VO2 and HR values reached during SRRs show that these routines strongly stress the cardiovascular system.

Prediction of Relevant Training Control Parameters at Individual Anaerobic Threshold without Blood Lactate Measurement.

BACKGROUND: Active exercise therapy plays an essential role in tackling the global burden of obesity. Optimizing recommendations in individual training therapy requires that the essential parameters heart rate HR(IAT) and work load (W/kg(IAT) at individual anaerobic threshold (IAT) are known. Performance diagnostics with blood lactate is one of the most established methods for these kinds of diagnostics, yet it is also time consuming and expensive. METHODS: To establish a regression model which allows HR(IAT) and (W/kg(IAT) to be predicted without measuring blood lactate, a total of 1234 performance protocols with blood lactate in cycle ergometry were analyzed. Multiple linear regression analyses were performed to predict the essential parameters (HR(IAT)) (W/kg(IAT)) by using routine parameters for ergometry without blood lactate. RESULTS: HR(IAT) can be predicted with an RMSE of 8.77 bpm (p < 0.001), R2 = 0.799 (|R| = 0.798) without performing blood lactate diagnostics during cycle ergometry. In addition, it is possible to predict W/kg(IAT) with an RMSE (root mean square error) of 0.241 W/kg (p < 0.001), R2 = 0.897 (|R| = 0.897). CONCLUSIONS: It is possible to predict essential parameters for training management without measuring blood lactate. This model can easily be used in preventive medicine and results in an inexpensive yet better training management of the general population, which is essential for public health.

The effect of acute heat exposure on the determination of exercise thresholds from ramp and step incremental exercise.

PURPOSE: The aim of this study was to examine how respiratory (RT) and lactate thresholds (LT) are affected by acute heat exposure in the two most commonly used incremental exercise test protocols (RAMP and STEP) for functional evaluation of aerobic fitness, exercise prescription and monitoring training intensities. METHODS: Eleven physically active male participants performed four incremental exercise tests, two RAMP (30 W·min-1) and two STEP (40 W·3 min-1), both in 18 °C (TEMP) and 36 °C (HOT) with 40% relative humidity to determine 2 RT and 16 LT, respectively. Distinction was made within LT, taking into account the individual lactate kinetics (LTIND) and fixed value lactate concentrations (LTFIX). RESULTS: A decrease in mean power output (PO) was observed in HOT at LT (-6.2 ± 1.9%), more specific LTIND (-5.4 ± 1.4%) and LTFIX (-7.5 ± 2.4%), compared to TEMP, however not at RT (-1.0 ± 2.7%). The individual PO difference in HOT compared to TEMP over all threshold methods ranged from -53 W to +26 W. Mean heart rate (HR) did not differ in LT, while it was increased at RT in HOT (+10 ± 8 bpm). CONCLUSION: This study showed that exercise thresholds were affected when ambient air temperature was increased. However, a considerable degree of variability in the sensitivity of the different threshold concepts to acute heat exposure was found and a large individual variation was noticed. Test design and procedures should be taken into account when interpreting exercise test outcomes.

Validation of a non-linear index of heart rate variability to determine aerobic and anaerobic thresholds during incremental cycling exercise in women.

Studies highlight the usage of non-linear time series analysis of heart rate variability (HRV) using the short-term scaling exponent alpha1 of Detrended Fluctuation Analysis (DFA-alpha1) during exercise to determine aerobic and anaerobic thresholds. The present study aims to further verify this approach in women. Gas exchange and HRV data were collected from 26 female participants with different activity levels. Oxygen uptake (VO2) and heart rate (HR) at first (VT1) and second ventilatory thresholds (VT2) were compared with DFA-alpha1-based thresholds 0.75 (HRVT1) and 0.50 (HRVT2). Results: VO2 at VT1 and VT2 were 25.2 ml/kg/min (± 2.8) and 31.5 ml/kg/min (± 3.6) compared with 26.5 ml/kg/min (± 4.0) and 31.9 ml/kg/min (± 4.5) for HRVT1 and HRVT2, respectively (ICC3,1 = 0.77, 0.84; r = 0.81, 0.86, p < 0.001). The mean HR at VT1 was 147 bpm (± 15.6) and 167 bpm (± 12.7) for VT2, compared with 152 bpm (± 15.5) and 166 bpm (± 13.2) for HRVT1 and HRVT2, respectively (ICC3,1 = 0.87, 0.90; r = 0.87, 0.90, p < 0.001). Bland-Altman analysis for VT1 vs. HRVT1 showed a mean difference of - 1.3 ml/kg/min (± 2.4; LoA: 3.3, - 6.0 ml/kg/min) for VO2 and of - 4.7 bpm (± 7.8; LoA: 10.6, - 20.0 bpm) for HR. VT2 vs. HRVT2 showed a mean difference of - 0.4 ml/kg/min (± 2.3; LoA: 4.1, - 4.9 ml/kg/min) for VO2 and 0.5 bpm (± 5.7; LoA: 11.8, - 10.8 bpm) for HR. DFA-alpha1-based thresholds showed good agreement with traditionally used thresholds and could be used as an alternative approach for marking organismic transition zones for intensity distribution in women.

9/3-Minute Running Critical Power Test: Mechanical Threshold Location With Respect to Ventilatory Thresholds and Maximum Oxygen Uptake.

PURPOSE: The critical power (CP) concept has been extended from cycling to the running field with the development of wearable monitoring tools. Particularly, the Stryd running power meter and its 9/3-minute CP test is very popular in the running community. Locating this mechanical threshold according to the physiological landmarks would help to define each boundary and intensity domain in the running field. Thus, this study aimed to determine the CP location concerning anaerobic threshold, respiratory compensation point (RCP), and maximum oxygen uptake (VO2max). METHOD: A group of 15 high-caliber athletes performed the 9/3-minute Stryd CP test and a graded exercise test in 2 different testing sessions. RESULTS: Anaerobic threshold, RCP, and CP were located at 73% (5.41%), 86.82% (3.85%), and 88.71% (5.84%) of VO2max, respectively, with a VO2max of 66.3 (7.20) mL/kg/min. No significant differences were obtained between CP and RCP in any of its units (ie, in watts per kilogram and milliliters per kilogram per minute; P ≥ .184). CONCLUSIONS: CP and RCP represent the same boundary in high-caliber athletes. These results suggest that coaches and athletes can determine the metabolic perturbance threshold that CP and RCP represent in an easy and accessible way.

The Impact of Four High-Altitude Training Camps on the Aerobic Capacity of a Short Track PyeongChang 2018 Olympian: A Case Study.

This study characterizes high-altitude training camps and their effect on the aerobic capacity of a Polish national team member (M.W.), who was a participant in the PyeongChang 2018 Winter Olympic Games (body weight: 59.6 kg, body height: 161.0 cm, fat mass: 10.9 kg and 18.3% of fat tissue, fat-free mass: 48.7 kg, muscle mass: 46.3 kg, and BMI = 23.0 kg/m2). The tests were conducted in the periods from April 2018 to September 2018 and April 2019 to September 2019 (period of general and special preparation). The study evaluated aerobic and anaerobic capacity determined by laboratory tests, a cardiopulmonary graded exercise test to exhaustion performed on a cycle ergometer (CPET), and the Wingate anaerobic test. Based on the research, training in hypobaric conditions translated into significant improvements in the skater's exercise capacity recorded after participating in the Olympic Winter Games in Korea (February 2018). In the analyzed period (2018-2019), there was a significant increase in key parameters of aerobic fitness such as anaerobic threshold power output (AT-PO) [W]-223; power output POmax [W]-299 and AT-PO [W/kg]-3.50; (POmax) [W/kg]-4.69; and AT-VO2 [mL/kg/min]-51.3; VO2max [mL/kg/min]-61.0. The athlete showed high-exercise-induced adaptations and improvements in the aerobic metabolic potential after two seasons, in which four training camps were held in altitude conditions.

Attentive Processes and Blood Lactate in the Sambo.

BACKGROUND: Sambo is a martial art and combat sport that originated in the Soviet Union. There are two main stiles, Sport Sambo and Combat Sambo which resembles modern mixed martial arts. Very little literature is available about physiological aspects of Sambo and, in particular, on the possible effects on cognitive domains. The purpose of the present research was to determine if there is a correlation between a blood lactate increase and the intensity and/or selectivity of attentions. METHODS: Sixteen male athletes practicing Sambo for at least 5 years participated voluntarily in the study. Each athlete had to sustain, with an interval of one week, both a Sport Sambo match and a Combat Sambo match, each lasting 5 min. Blood lactate levels as well as attentive capacities were evaluated at three different times: at rest, i.e., 5 min before the start of the session (pre), at end of the session and 15 min after its conclusion. Reaction time protocol was used to evaluate the intensity of attention, whereas divided attention was assessed for analyzing the selectivity of attention together with errors and omissions. RESULTS: Concerning Sport Sambo, blood lactate was 1.66 mmol/L (±0.55 SD) before the session, reached a mean value of 3.40 mmol/L (±0.45 SD) at the end of the session (end) and returned to values similar to initial ones (a mean value of 1.98 mmol/L (±0.37 SD) after 15 min (15-end). None of the attentive parameters examined, showed statistically significant differences. Conversely, for Combat Sambo, it was found a significant increase in blood lactate levels that went from 1.66 mmol/L (±0.55 SD) before the session (pre), to 4.76 mmol/L (±0.60 SD) at the end (end) and then back to values similar to those observed before the session 15 min after its conclusion (15-end), i.e., 1.97 mmol/L (±0.37 SD); however, after a Combat Sambo session increases in blood lactate were associated with significant worsening of attentional mechanisms. CONCLUSIONS: In conclusion, in all the participants, the worsening of attentional mechanisms was observed only after the Combat Sambo session in which blood lactate values exceeded 4 mmol/L. This figure, also known as the Onset of Blood Lactate Accumulation (OBLA), is commonly used to determine the anaerobic threshold.

Is the Tyme Wear Smart Shirt Reliable and Valid at Detecting Personalized Ventilatory Thresholds in Recreationally Active Individuals?

The aim of this study was to determine the extent to which the Tyme Wear smart shirt is as reliable and valid in detecting personalized ventilatory thresholds when compared to the Parvo Medics TrueOne 2400. In this validation study, 19 subjects were recruited to conduct two graded exercise test (GXT) trials. Each GXT trial was separated by 7 to 10 days of rest. During the GXT, gas exchange and heart rate data were collected by the TrueOne 2400 (TRUE) in addition to the ventilation data collected by the Tyme Wear smart shirt (S-PRED). Gas exchange data from TRUE were used to detect ventilatory threshold 1 (VT1) and ventilatory threshold 2 (VT2). TRUE and S-PRED VT1 and VT2 were compared to determine the reliability and validity of the smart shirt. Of the 19 subjects, data from 15 subjects were used during analysis. S-PRED exhibited excellent (intraclass correlation coefficient-CC > 0.90) reliability for detection of VT1 and VT2 utilizing time point and workload and moderate (0.90 > ICC > 0.75) reliability utilizing heart rate. TRUE exhibited excellent reliability for detection of VT1 and VT2 utilizing time point, workload, and heart rate. When compared to TRUE, S-PRED appears to underestimate the VT1 workload (p > 0.05) across both trials and heart rate (p < 0.05) for trial 1. However, S-PRED appears to underestimate VT2 workload (p < 0.05) and heart rate (p < 0.05) across both trials. The result from this study suggests that the Tyme Wear smart shirt is less valid but is comparable in reliability when compared to the gold standard. Moreover, despite the underestimation of S-PRED VT1 and VT2, the S-PRED-detected personalized ventilatory thresholds provide an adequate training workload for most individuals. In conclusion, the Tyme Wear smart shirt provides easily accessible testing to establish threshold-guided training zones but does not devalue the long-standing laboratory equivalent.

Determination of Second Lactate Threshold Using Near-infrared Spectroscopy in Elite Cyclists.

The use of near-infrared spectroscopy could be an interesting alternative to other invasive or expensive methods to estimate the second lactate threshold. Our objective was to compare the intensities of the muscle oxygen saturation breakpoint obtained with the Humon Hex and the second lactate threshold in elite cyclists. Ninety cyclists performed a maximal graded exercise test. Blood capillary lactate was obtained at the end of steps and muscle oxygenation was continuously monitored. There were no differences (p>0.05) between muscle oxygen oxygenation breakpoint and second lactate threshold neither in power nor in heart rate, nor when these values were relativized as a percentage of maximal aerobic power or maximum heart rate. There were also no differences when men and women were studied separately. Both methods showed a highly correlation in power (r=0.914), percentage of maximal aerobic power (r=0.752), heart rate (r=0.955), and percentage of maximum heart rate (r=0.903). Bland-Altman resulted in a mean difference of 0.05±0.27 W·kg-1, 0.91±4.93%, 0.63±3.25 bpm, and 0.32±1.69% for power, percentage of maximal aerobic power, heart rate and percentage of maximum heart rate respectively. These findings suggest that Humon may be a non-invasive and low-cost alternative to estimate the second lactate threshold intensity in elite cyclists.

Identification of Non-Invasive Exercise Thresholds: Methods, Strategies, and an Online App.

During incremental exercise, two thresholds may be identified from standard gas exchange and ventilatory measurements. The first signifies the onset of blood lactate accumulation (the lactate threshold, LT) and the second the onset of metabolic acidosis (the respiratory compensation point, RCP). The ability to explain why these thresholds occur and how they are identified, non-invasively, from pulmonary gas exchange and ventilatory variables is fundamental to the field of exercise physiology and requisite to the understanding of core concepts including exercise intensity, assessment, prescription, and performance. This review is intended as a unique and comprehensive theoretical and practical resource for instructors, clinicians, researchers, lab technicians, and students at both undergraduate and graduate levels to facilitate the teaching, comprehension, and proper non-invasive identification of exercise thresholds. Specific objectives are to: (1) explain the underlying physiology that produces the LT and RCP; (2) introduce the classic non-invasive measurements by which these thresholds are identified by connecting variable profiles to underlying physiological behaviour; (3) discuss common issues that can obscure threshold detection and strategies to identify and mitigate these challenges; and (4) introduce an online resource to facilitate learning and standard practices. Specific examples of exercise gas exchange and ventilatory data are provided throughout to illustrate these concepts and a novel online application tool designed specifically to identify the estimated LT (θLT) and RCP is introduced. This application is a unique platform for learners to practice skills on real exercise data and for anyone to analyze incremental exercise data for the purpose of identifying θLT and RCP.

A Personal Biography of a Physiological Misnomer: The Anaerobic Threshold.

In 1973 Wasserman, Whipp, Koyal, and Beaver published a groundbreaking study titled "Anaerobic threshold and respiratory gas analysis during exercise". At that time, respiratory gas analysis and laboratory computers had evolved such that more advanced respiratory exercise physiology studies were possible. The initial publications from this group on the onset of anaerobic metabolism in cardiac patients, the first breath-by-breath VO2 system, the first description of the anaerobic threshold, and then later new methods to detect the anaerobic threshold have been and continue to be highly cited. In fact, their 1973 anaerobic threshold paper is the sixth and their 1986 paper is the second most cited paper ever published in the Journal of Applied Physiology. The anaerobic threshold concept has also generated>5500 publications with the rates increasing over time. The publication of two papers that help to refute the "anaerobic" explanation for this phenomenon had no effect on the rates of citations of the original anaerobic threshold papers or the number of anaerobic threshold papers published since. Thus, despite now substantial evidence refuting the proposed anaerobic mechanisms underlying this phenomenon, these papers continue to be highly influential in the discipline of exercise physiology and, perhaps even more explicitly, clinical exercise physiology.