Lactate Anaerobic Threshold Research Articles

Low-to-Moderate Correlations Between Repeated Sprint Ability and Aerobic Capacity: A Systematic Review and Meta-analysis

ABSTRACT This systematic review and meta-analysis aims to provide meta-analytic estimates of the relationships between repeated sprint ability (RSA) outputs (total sprint time [TST] and fatigue scores) and aerobic capacity indicators (V̇O2max, the covered distance in the endurance shuttle run test [SRTdistance], and the velocity at the anaerobic lactate threshold [ALTvelocity]). To identify potential studies for inclusion, a search strategy was implemented on MEDLINE (through PubMed) and Web of Science. The correlation coefficients between RSA outputs and aerobic capacity indicators were extracted from the individual studies to reveal a pooled correlation. After the identification of studies providing inclusion criteria, 45 studies consisting of 1,488 accumulated participants were included. Meta-analysis showed the positive moderate relationships between TST and V̇O2max (pooled r = 0.444, p < 0.001), TST and SRTdistance (pooled r = 0.465, p < 0.001), TST and ALTvelocity (pooled r = 0.527, p < 0.001), RSA fatigue score and V̇O2max (pooled r = 0.449, p < 0.001), and RSA fatigue score and ALTvelocity (pooled r = 0.460, p < 0.001), which showed a low positive relationship between RSA fatigue score and SRTdistance (pooled r = 0.305, p = 0.029). This study showed pooled correlations between RSA outputs and practical aerobic capacity indicators. However, contrary to popular belief that there were stronger relationships, these relationships were low to moderate.

MATH MODEL OF RUNNING INDEX FOR EVALUATION AND CONTROL OF SPECIFIC EFFICIENCY AND TRACING THE FATIGUE LEVEL IN LONG-DISTANCE RUNNING

The aim of this case study was to develop and verify a math model of running index (RI) for evaluation and control of specific efficiency and tracing the fatigue level in long-distance running. The suggested RI was modeled on the basis of polynomial function between the running velocity and the change in heart rate frequency (V=f(HR)). The method was designed in such a way that the influence of denivelation of the terrain was removed when calculating RI. The research was done among 19 highly qualified athletes competing in long-distance running events (16 men and 3 women), with a mean age of 28 years (SD±8), BMI 20 (SD±2), maximum oxygen consumption 67 ml/min/kg (SD ±5). The participants in the research were subjected to two lab and two terrain surveys. In a period of one week after the testing, RI was traced and calculated on the basis of the data taken from the major training loads. The model was verified only for the studied subjects - highly qualified competitors in long-distance running. RI was tested for validity through comparing the values obtained from the lab and terrain tests. The obtained results showed there was no significant difference between the values of RI measured during the lab testing and the terrain testing compared to the values of the velocity of ventilatory and lactate anaerobic threshold (VAnT). The results from this research revealed that the suggested method for calculation of the running index is more accurate than the previous ones. This manuscript discusses the possible implications of this new method for measurement of RI. Future scientific research is needed to prove its efficiency and applicability in sports.

Effect of Two Different Training Interventions on Cycling Performance in Mountain Bike Cross-Country Olympic Athletes.

To improve performance in endurance sports, it is important to include both high-intensity and low-intensity training, but there is neither a universally accepted practice nor clear scientific evidence that allows reliable statements about the predominance of a specific training method. This randomized controlled trial compared the effects of a polarized training model (POL) to a low-intensity training model (LIT) on physiological parameters and mountain bike cross-country Olympic (XCO) race performance in eighteen competitive XCO athletes (17.9 ± 3.6 years). The superiority of one of the two methods could not be shown in this study. The results did not show statistically significant differences between POL and LIT, as both interventions led to slight improvements. However, a small tendency toward better effects for POL was seen for cycling power output during the race (4.4% vs. –2.2%), at the 4 mmol/L (6.1% vs. 2.8%) and individual anaerobic lactate threshold (5.1% vs. 2.3%), and for maximal aerobic performance (4.4% vs. 2.6%), but not for maximal efforts lasting 10 to 300 s. Despite the lack of significant superiority in this and some other studies, many athletes and coaches prefer POL because it produces at least equivalent effects and requires less training time.

Comparison and Performance Validation of Calculated and Established Anaerobic Lactate Thresholds in Running.

Background and Objectives: This study aimed to compare the calculated running velocity at the anaerobic lactate threshold (cLTAn), determined by a mathematical model for metabolic simulation, with two established threshold concepts (onset of blood lactate accumulation (OBLA; 4 mmol∙L−1) and modified maximal deviation method (mDmax)). Additionally, all threshold concepts were correlated with performance in different endurance running events. Materials and Methods: Ten sub-elite runners performed a 30 s sprint test on a cycle ergometer adjusted to an isokinetic mode set to a cadence of 120 rpm to determine maximal lactate production rate (VLamax), and a graded exercise test on a treadmill to determine maximal oxygen uptake (VO2max). Running velocities at OBLA, mDmax, and cLTAn were then compared with each other, and further correlated with running performance over various distances (3000 m, 5000 m, and 10,000 m). Results: The mean difference in cLTAn was −0.13 ± 0.43 m∙s−1 and −0.32 ± 0.39 m∙s−1 compared to mDmax (p = 0.49) and OBLA (p < 0.01), respectively. cLTAn indicated moderate to good concordance with the established threshold concepts (mDmax: ICC = 0.87, OBLA: ICC = 0.74). In comparison with other threshold concepts, cLTAn exhibited comparable correlations with the assessed running performances (cLTAn: r = 0.61–0.76, mDmax: r = 0.69–0.79, OBLA: r = 0.56–0.69). Conclusion: Our data show that cLTAn can be applied for determining endurance performance during running. Due to the consideration of individual physiological profiles, cLTAn offers a physiologically justified approach to assess an athlete’s endurance performance.

Four weeks of high-intensity interval training (HIIT) improve the cardiometabolic risk profile of overweight patients with type 1 diabetes mellitus (T1DM)

ABSTRACT This study investigated the effects of a four-week HIIT intervention on the cardiometabolic risk profile, liver fat content, insulin requirement, hypoglycaemia, physical fitness, and health-related quality of life in patients with T1DM. A supervised exercise intervention with baseline to follow-up comparison between overweight (BMI = 28.6 ± 2.1 kg/m2) and normal weight (BMI = 23.2 ± 1.40 kg/m2) T1DM patients was performed. Eleven overweight (age = 40.7 ± 14.3 years) and 11 normal weight (age = 42.2 ± 15.5 years) T1DM patients performed a four-week, low-volume, all-out cycling HIIT (4–6 bouts, work/relief ratio 1:1) twice weekly. HIIT lowered low-density lipoprotein and uric acid levels in overweight patients by up to 10.5% (vs. normal weight, p≤0.0312). HbA1c, high-density lipoprotein, and triglyceride levels did not change in any of the groups. Participants’ maximal exercise capacity and power output at individual anaerobic lactate threshold increased to an equal extend of up to 10% (p≤0.0002) in both groups. During the intervention, participants used fewer daily bolus insulin (−5.22 ± 12.80%) and less total units of insulin (−4.42 ± 10.20%, p≤0.023) compared to the pre-intervention period with no between-group difference. Overall, the average daily number of hypoglycaemias increased from 0.90 ± 0.56–1.08 ± 0.63 during the intervention (p = 0.033). SF-36 subscales showed higher scores after the intervention, with a significant improvement of “role limitations due to physical problems” (p<0.05) for both groups. We conclude that in T1DM, HIIT may exert beneficial effects on physical fitness, insulin requirement and health-related quality of life. Of note, beneficial HIIT effects on the cardiometabolic risk profile in T1DM may be larger in overweight T1DM patients.

Lactate response during acute exercise in cancer survivors undergoing exercise rehabilitation.

e23047 Background: Cancerous cells express a markedly different metabolic profile characterized by lactate production even when oxygen is plentiful. Lactate accumulation is a common marker for energy production and utilization, yet it is currently unclear how blood lactate responds during acute exercise to volitional fatigue in individuals with cancer and how this response is modified with exercise-based rehabilitation. The purpose of the current study is to assess the effect of an acute exercise bout to volitional fatigue on lactate accumulation before and after an exercise-based rehabilitation program for cancer survivors. Methods: 33 cancer survivors (female, n = 18; male, n = 15) were recruited to participate in a 12-week exercise-based rehabilitation program. All participants performed an initial assessment of physiological parameters, including blood lactate accumulation (LA) during a progressive treadmill protocol to volitional fatigue. LA was quantified every 2 minutes during treadmill testing via finger stick. The exercise intervention consisted of one hour sessions, three days per week, and included cardiovascular endurance, muscular strength, balance, and flexibility exercises. After 12 weeks of rehabilitation, participants completed a follow-up evaluation of physiological parameters. Results: There was a significant increase in LA at volitional fatigue after 12 weeks of training (Initial: 6.17 ± 2.61 mM, Post 12 Weeks: 7.26 ± 2.10 mM; p = 0.04), with no significant difference in resting blood lactate. The workload at which anaerobic lactate threshold presented was significantly increased after 12 weeks (Initial: 5.87 ± 1.59 METs, Post 12 weeks: 7.35 ± 1.85 METs; p = 0.02). Conclusions: Cancer survivors respond to acute exercise to volitional fatigue in a manner similar to healthy controls. Furthermore, similar to the response observed in healthy populations, cancer survivors exhibited an increase in lactate threshold and an increase in peak lactate accumulation at volitional fatigue after completing an exercise-based rehabilitation program. Thus, although many cancerous cells have a unique glycolytic profile, this does not appear to influence training-induced adaptations in blood lactate.

Agreement among Six Methods of Predicting the Anaerobic Lactate Threshold in Elite Cross-Country Skiers

Agreement among Six Methods of Predicting the Anaerobic Lactate Threshold in Elite Cross-Country Skiers

Running economy and energy cost of running with backpacks.

Running is a popular recreational activity and additional weight is often carried in backpacks on longer runs. Our aim was to examine running economy and other physiological parameters while running with a 1-kg and 3-kg backpack at different submaximal running velocities. Ten male recreational runners (age 25±4.2 years, VO2peak 60.5±3.1 mL/kg/min) performed runs on a motorized treadmill of 5 minutes durations at three different submaximal speeds of 70, 80 and 90% of anaerobic lactate threshold (LT) without additional weight, and carrying a 1-kg and 3-kg backpack. Oxygen consumption, heart rate, lactate and RPE were measured and analyzed. Oxygen consumption, energy cost of running and heart rate increased significantly while running with a backpack weighing 3 kg compared to running without additional weight at 80% of speed at lactate threshold (sLT) (P=0.026, P=0.009 and P=0.003) and at 90% sLT (P<0.001, P=0.001, and P=0.001). Running with a 1-kg backpack showed a significant increase in heart rate at 80% sLT (P=0.008) and a significant increase in oxygen consumption and heart rate at 90% sLT (P=0.045 and P=0.007) compared to running without additional weight. Also running at 70% sLT running economy and cardiovascular effort increased with weighted backpack running compared to running without additional weight, however these increases did not reach statistical significance. Running economy deteriorates and cardiovascular effort increases while running with additional backpack weight especially at higher submaximal running speeds. Backpack weight should therefore be kept to a minimum.

Active Recovery After High-Intensity Interval-Training Does Not Attenuate Training Adaptation.

Objective: High-intensity interval training (HIIT) can be extremely demanding and can consequently produce high blood lactate levels. Previous studies have shown that lactate is a potent metabolic stimulus, which is important for adaptation. Active recovery (ACT) after intensive exercise, however, enhances blood lactate removal in comparison with passive recovery (PAS) and, consequently, may attenuate endurance performance improvements. Therefore, the aim of this study was to examine the influence of regular ACT on training adaptations during a HIIT mesocycle.Methods: Twenty-six well-trained male intermittent sport athletes (age: 23.5 ± 2.5 years; O2max: 55.36 ± 3.69 ml min kg-1) participated in a randomized controlled trial consisting of 4 weeks of a running-based HIIT mesocycle with a total of 12 HIIT sessions. After each training session, participants completed 15 min of either moderate jogging (ACT) or PAS. Subjects were matched to the ACT or PAS groups according to age and performance. Before the HIIT program and 1 week after the last training session, the athletes performed a progressive incremental exercise test on a motor-driven treadmill to determine O2max, maximum running velocity (vmax), the running velocity at which O2max occurs (vO2max), and anaerobic lactate threshold (AT). Furthermore, repeated sprint ability (RSA) were determined.Results: In the whole group the HIIT mesocycle induced significant or small to moderate changes in vmax (p < 0.001, effect size [ES] = 0.65,), vO2max (p < 0.001, ES = 0.62), and AT (p < 0.001, ES = 0.56) compared with the values before the intervention. O2max and RSA remained unchanged throughout the study. In addition, no significant differences in the changes were noted in any of the parameters between ACT and PAS except for AT (p < 0.05, ES = 0.57).Conclusion: Regular use of individualized ACT did not attenuate training adaptations during a HIIT mesocycle compared to PAS. Interestingly, we found that the ACT group obtained a significantly higher AT following the training program compared to the PAS group. This could be because ACT allows a continuation of the training at a low intensity and may activate specific adaptive mechanisms that are not triggered during PAS.

Circulating micrornas as potential biomarkers of aerobic exercise capacity

Purpose microRNAs (miRs) are crucial intracellular mediators of various biological processes, also affecting the cardiovascular system. Recently, it has been shown that miRs circulate extracellularly in the bloodstream and that such circulating miRs change in response to physical activity. Therefore, the purpose of the current study was to investigate heart/muscle specific and inflammation related miRs in plasma of individuals before, directly after, and 24 h after a marathon run and to analyze their relation to conventional biochemical, cardiovascular, and performance indexes. Male endurance athletes (n =14) were recruited for the study after performing a battery of cardiac functional tests. Blood samples were collected before, directly after, and 24 h after a public marathon run. miR-1, miR-133, miR-206, miR-499, miR-208b, miR-21, and miR-155 were measured using individual Taqman assays and normalized to Caenorhabditis elegans miR-39 (cel-39) spike-in control. Moreover, soluble cardiac, inflammatory, and muscle damage markers were determined. As a result, skeletal- and heart muscle-specific miRs showed a significant increase after the marathon. The strongest increase was observed for miR-206. Twenty-four hours after the run, only miR-499 and miR-208b were returned to preexercise levels, whereas the others were still enhanced. In contrast, miR-21 and -155 were not affected by exercise. miR-1, -133a, and -206 correlated to aerobic performance parameters such as maximum oxygen uptake (V̇o2max) and running speed at individual anaerobic lactate threshold (VIAS). miR-1 showed a moderate negative correlation with fractional shortening, whereas miR-133a was positively related to the thickness of intraventricular septum. None of the miRs correlated with cardiac injury markers such as troponin T, troponin I, and pro-brain natriuretic peptide. In conclusion, these findings suggest a potential role for muscle- and heart-specific miRs in cardiovascular adaptation processes after endurance exercise. Moreover, the specific correlation of miR-1, -133a, and -206 to performance parameters indicated their potential role as biomarkers of aerobic capacity.

P11: Higher levels of endogenous nitrite are associated with superior vascular function and lactate anaerobic threshold in athletes

Background Nitrate and nitrite as oxidative derivates of nitric oxide have been suggested to both modulate and reflect exercise capacity in humans. The failure to increase endogenous nitrite has been related to decreased maximum exercise capacity, while a diet rich in nitrate improved exercise performance. The modulation of nitrate/nitrite levels has furthermore been related to an improvement of vascular functions. It remains unresolved to date whether baseline endogenous levels are associated with a superior vascular function and if this is also related to an improved exercise capacity. Objective To determine whether higher baseline nitrite levels are associated with a superior vascular function and whether this also relates to an advantage in exercise capacity as measured by lactate anaerobic threshold (LAT). Methods 12 male athletes with an average age of 25 ± 2 years, a body weight of 79 ± 4 kg, a height of 185 ± 5 cm and trained 5 ± 1 times per week (means ± SD) were enrolled in this study. Each participant reported twice to the testing facility ( n = 22 observations). Blood was drawn from the left cubital vein and the resulting plasma was used to determine the circulating levels of nitrate and nitrite via HPLC (ENO-20). 15 min later, vascular function was assessed on the contralateral arm (brachial artery) by measuring flow-mediated vasodilation (FMD) using a 12 MHz ultrasound probe. Participants were hereafter asked to complete a stepwise ergometric test starting at 100 W with increasing workloads (+50 W) every 5 min on a stationary bicycle ergometer (Lode Excalibur Sport). Blood was drawn from the ear lope and used to determine the levels of lactate at the end of each incremental steP Heart rate was measured continuously and the LAT (4 mM) in relation to heart rate was calculated using non-linear regression models. Results Baseline plasma nitrite levels correlated with LATs ( r = 0.65; p = 0.001, n = 22) and with endothelial function as assessed by FMD ( r = 0.71; p = 0.0002). Cor-relation coefficients from both testing days did not differ. Multiple linear regressions showed that base-line plasma nitrite level but not endothelial function was an independent predictor of exercise capacity. No such correlations were determined for plasma nitrate levels. Conclusion Higher baseline levels of nitrite are associated with a superior vascular function and lactate anerobic threshold. Disclosure M.T. was supported by a scholarship from the Deutsche Herzstiftung (German Heart Foundation), M.K. and T.R. were supported by grants from the German Research Foundation (DFG).

Aerobic and Anaerobic Performances in Tethered Swimming

The purpose of this study was to investigate whether the critical force (CritF) and anaerobic impulse capacity (AIC) - estimated by tethered swimming - reflect the aerobic and anaerobic performance of swimmers. 12 swimmers performed incremental test in tethered swimming to determine lactate anaerobic threshold (AnTLAC), maximal oxygen uptake ( ˙VO2MAX) and force associated with the ˙VO2MAX (i ˙VO2MAX). The swimmers performed 4 exhaustive (tlim) exercise bouts (100, 110, 120 and 130% i ˙VO2MAX) to compute the CritF and AIC (F vs. 1/tlim model); a 30-s all-out tethered swimming bout to determine their anaerobic fitness (ANF); 100, 200, and 400-m time-trials to determine the swimming performance. CritF (57.09±11.77 N) did not differ from AnTLAC (53.96±11.52 N, (P>0.05) but was significantly lower than i ˙VO2MAX (71.02±8.36 N). In addition, CritF presented significant correlation with AnTLAC (r=0.76; P<0.05) and i ˙VO2MAX (r=0.74; P<0.05). On the other hand, AIC (286.19±54.91 N.s) and ANF (116.10±13.66 N) were significantly correlated (r=0.81, p<0.05). In addition, CritF and AIC presented significant correlations with all time-trials. In summary, this study demonstrates that CritF and AIC can be used to evaluate AnTLAC and ANF and to predict 100, 200, and 400-m free swimming.

Maximal lactate steady-state and anaerobic thresholds from different methods in cyclists

The lactate anaerobic threshold (AT) determined during an incremental test has been used generally to estimate the maximal lactate steady-state intensity (MLSSint) in several sports. Furthermore, this index could be useful to predict the time-trial cycling performance and also to prescribe training intensity to enhance aerobic capacity. The aim of this study was to compare three different AT estimations with actual MLSSint in trained cyclists. Fourteen trained cyclists participated in this study. They had previously performed a maximal incremental cycling test (35 W increments each 3 min) in a laboratory followed by three to five visits to measure the MLSSint (30-min tests). Blood lactate concentration ([La]), oxygen uptake ([Vdot]O2), and heart rate (HR) were measured during all tests. Based on the incremental test, we calculated three ATs using different proposed methods: AT1-intensity corresponds to fixed [La]; AT2-minimum equivalent of the blood lactate-power output relationship plus 1.5 mmol·L−1; AT3-power output of the stage antecedent to the second lactate increase of at least 0.5 mmol·L−1 above the previous values, where the second increase was greater than the first. The MLSSint was determined for each participant as the highest power output that could be maintained with [La] fluctuating less than 1 mmol·L−1 during the final 20 min of the steady-state tests. ANOVA with repeated measures was used to compare physiological variables in the different methods. The relationship between the MLSSint and the power output of AT1, AT2, and AT3 was analysed using Pearson product-moment correlation coefficients. In addition, we calculated the bias and limits of agreement between the three different methods with actual MLSSint. The mean±s values of power output related to MLSSint, AT1, AT2, and AT3 were 247±33 W, 258±39 W, 248±35 W, and 230±36 W, respectively. The results showed that AT3 underestimated (P <0.05) the MLSSint for most of the participants and provided lower mean values compared with AT1 and AT2. Furthermore, AT2 seems to be more accurate to estimate MLSSint than other methods here verified when we analysed the mean values, correlation coefficient (r = 0.94), and Bland-Altman limits of agreement (± 9.5%). The AT1 also provided good prediction values, although it presented with a trend to overestimate MLSSint. Therefore, considering the methods analysed in the current study and the importance of this submaximal aerobic index to flat time-trials and prolonged uphill cycling performance, the AT2 method could be used with good accuracy by coaches and athletes.

Mitochondrial Abnormalities in Patients with HIV-HCV Co-infection as Compared to Patients with HCV Mono-infection

Introduction: Mitochondrial dysfunction is a classic complication of HIV infection and its treatment and has also been reported in hepatitis C virus (HCV)–infected patients. Little is known about interactions between both viruses on mitochondrial metabolism. Methods: We performed a cross-sectional study of HCV-infected patients who underwent liver biopsy as part of their routine care. Mitochondrial function was assessed by (a) liver morphological (histology) and functional (spectro-photometry) studies, and (b) serum lactate kinetics, oxygen uptake, and anaerobic threshold measurement during standardized incremental exercise. Three predefined groups of patients were compared. Results: Thirty-eight HCV-infected patients were included: 13 not HIV infected (group 1), 7 with HIV co-infection and low nucleoside reverse transcriptase inhibitor (NRTI) exposure (none over the last 2 years; group 2), and 18 with HIV co-infection and high NRTI exposure (group 3). On liver biopsies, respiratory chain complex IV activity was impaired, at 5 (2–7) nmol/min/mg substrates in group 1, 5 (3–8) in group 2, and 8 (2–13) in group 3 (normal values, 20–56). Maximal power output was diminished and anaerobic threshold occurred earlier in HIV-infected patients, regardless of NRTI exposure. Conclusion: HCV has deleterious effects on liver mitochondrial metabolism, notably on respiratory chain complex IV. No significant interaction with HIV was observed.

Value of the Application of the Heart Rate Performance Curve in Sports

The heart rate performance curve (HRPC) has been shown to be nonlinearly related to work load. This phenomenon has been used to determine a deflection point and to be related to the lactate anaerobic threshold. The original method was heavily criticized, and the method was challenged by several authors. However, some authors also demonstrated a high value for this method's application in various sports conditions. Unfortunately, the HRPC was shown to be not uniform and three different patterns were found. Basic investigations have shown a dependence of the HR-deflection on beta1-receptor sensitivity, which gave a plausible explanation of the phenomenon. Important details regarding the testing protocol and the method of turn point determination are given in this review. As a conclusion, we may state that based on numerous studies the method is plausible and valid to determine aerobic exercise performance in various laboratory ergometer and specific sports-related field conditions. Standard protocol conditions adjusted to the exercise performance level of subjects and a computer-supported determination of turn points are necessary to obtain reliable results. Large-scale investigations to validate the heart rate turn point with maximal lactate steady state are still needed. However, from the available literature, the application of this noninvasive method can be recommended to determine aerobic exercise performance in various sports. This noninvasive test is easy to perform repeatedly, which gives interesting possibilities for the monitoring of training adaptation in the short term, such as altitude training or specific taper forms.

An internet-delivered exercise intervention for workplace health promotion in overweight sedentary employees: A randomized trial

Objective To evaluate the effect of structured vs. non-structured internet-delivered exercise recommendations on aerobic exercise capacity and cardiovascular risk profile in overweight sedentary employees. Methods 140 employees of an automobile company (11% female, median age 48 years (range 25–60), BMI 29.0 kg/m 2 (25.0–34.8)) were randomized in a 3:2 ratio to an intervention group receiving structured exercise schedules or a control group choosing workouts individually via an interactive website. The 12-week intervention took place in Munich, Germany, during summer 2008. Main outcome measure was performance at the lactate anaerobic threshold ( P AT/kg) during ergometry. Results 77 participants completed the study. The intervention group ( n = 50) improved significantly in P AT/kg ((mean (SD)) 1.68 (0.31) vs. 1.81 (0.33) W/kg; p = 0.002), VO 2peak (3.21 (0.63) vs. 3.35 (0.74) L/min; p = 0.04), and waist circumference (100.5 (7.9) vs. 98.0 (7.8) cm; p = 0.001). The control group ( n = 27) improved significantly in P AT/kg (1.59 (0.38) vs. 1.80 (0.49); p < 0.001) and waist circumference (101.9 (8.7) vs. 98.3 (8.5) cm; p < 0.001), but not in VO 2peak. No significant between group differences in these outcome measures were noted. Conclusion Structured, internet-delivered exercise recommendations are not superior to internet-delivered non-structured exercise recommendations in a workplace setting. Both lifestyle intervention strategies are, however, limited by high dropout rates.

Dissociation of performance parameters at the IAT requires specific exercise recommendations for depressed patients

Aerobic exercise training is considered an adequate complementary treatment strategy for major depressive disorder (MDD). However, there is a need for comparative methodological investigations to determine the appropriate exercise intensity for these patients. The study compared submaximal exercise intensity determination with those derived from maximal parameters such as percentages of heart rate reserve (HRR), maximal heart rate (HR(max)) and peak oxygen uptake (VO(2peak)) of patients and controls. An exhaustive incremental bicycle exercise test was completed by 15 female MDD patients and matched controls. The individual anaerobic lactate threshold (IAT) as a gold standard to determine individual aerobic exercise intensity was assessed according to Stegmann and coworkers. Exercise intensities at 70 and 85% of HR(max), 70 and 85% of HRR and 50 to 80% of VO(2peak) were compared to the IAT. Patients suffering from MDD switched earlier to anaerobic metabolism than matched healthy controls. But interestingly, the level of self-rated perceived exertion, concentration of lactate, respiratory exchange ratio and heart rate at the IAT level revealed no significant difference between both groups. Due to a growing number of clinical aerobic exercise treatments in depressive disorders exercise intensities >70% of (a) HR(max), (b) HRR, (c) VO(2peak) should be amended by the IAT and Borg scale measurements to avoid over challenging as well as increased anaerobic metabolism.

Total Protein of Whole Saliva as a Biomarker of Anaerobic Threshold

Saliva provides a convenient and noninvasive matrix for assessing specific physiological parameters, including some biomarkers of exercise. We investigated whether the total protein concentration of whole saliva (TPWS) would reflect the anaerobic threshold during an incremental exercise test. After a warm-up period, 13 nonsmoking men performed a maximum incremental exercise on a cycle ergometer. Blood and stimulated saliva were collected during the test. The TPWS anaerobic threshold (PAT) was determined using the Dmax method. The PAT was correlated with the blood lactate anaerobic threshold (AT; r = .93, p < .05). No significant difference (p = .16) was observed between PAT and AT. Thus, TPWS provides a convenient and noninvasive matrix for determining the anaerobic threshold during incremental exercise tests.

The influence of ambient temperature on power at anaerobic threshold determined based on blood lactate concentration and myoelectric signals

To compare the mechanical power and physiological parameters in males at the lactate (LAAT) and integrated electromyographic (IEMGAT) anaerobic thresholds during exercise testing at 23 degrees C, 31 degrees C and 37 degrees C. Fifteen men aged 21.9+/-1.80 years performed an incremental exercise test on a cycle ergometer at pedal frequency of 60 rpm. The test began at the power output of 120 W which was increased by 30 W every 3 min. Heart rate, oxygen uptake, carbon dioxide in expired air and minute ventilation were monitored. Venous blood samples were collected at 30 s before termination of each 3-min stage of test to determine the lactate anaerobic threshold. IEMGAT for vastus lateralis (VL) and rectus femoris (RF) muscles were regarded as the inflection point at which a non-linear increase in IEMGAT occurred. IEMGAT for VL and RF were similar for all the three temperatures. IEMGAT (VL and RF) correlated closely with LAAT at ambient temperatures of 23 degrees C (r = 0.91), 31 degrees C (r = 0.96) and 37 degrees C (r = 0.97). Repeated measures analysis of variance (ANOVA) revealed that the mechanical power at LAAT and IEMGAT was higher at 23 degrees C (202+/-26.5 W vs. 205+/-22.9 W) than at 31 degrees C (186+/-20.2 W vs. 186.2+/-20.2 W) and 37 degrees C (175.5+/-25.2 W vs. 175.3+/-20.0 W) for LAAT and IEMGAT respectively (p < 0.01). Higher ambient temperature induced a decrease in the mechanical power at which the anaerobic threshold occurred. The high correlation between LAAT and IEMGAT (r = 0.91-0.97) indicated that IEMGAT can be used as a practical and reliable, non-invasive method for assessment of the anaerobic threshold.

Commentary on Point-Counterpoint

This letter is in response to the Point:Counterpoint series “Positive effects of intermittent hypoxia (live high:train low) on exercise performance are/are not mediated primarily by augmented red cell volume that appeared in the November issue (vol. 99: 2053–2058, 2005; doi: 10.1152/japplphysiol