Individual Anaerobic Threshold Research Articles

Effect of Sugar- and Polyphenol-Rich, Diluted Cloudy Apple Juice on the Intestinal Barrier after Moderate Endurance Exercise and in Ultra-Marathon Runners

Background: Exercise and the consumption of sugars result in a dysfunction of the intestinal barrier (IB). Here, we determined the effect of sugar in a natural matrix on the intestinal barrier after moderate (A) and intensive endurance exercise (B). Method: The IB function was determined before (pre) and after running (post), and 120 and 180 min after consuming the drink by measuring serum endotoxin concentrations (lipopolysaccharides—LPS), IL-6, CD14, and i-FABP. In study A, nonspecifically trained participants (n = 24, males and females, age 26 ± 4) ran for one hour at 80% of their individual anaerobic threshold (IAT). After finishing, the runners consumed, in a crossover setup, either 500 mL of water, diluted cloudy apple juice (test drink), or an identical drink (placebo) without the fruit juice matrix (FJM). In study B, the participants (n = 30, males and females, age 50 ± 9) completed an ultra-marathon run, were divided into groups, and consumed one of the above-mentioned drinks. Results: Study A: Exercise resulted in a significant increase in serum LPS, i-FABP, and IL-6, which decreased fast after finishing. No impact of the different drinks on LPS i-FABP, or IL-6 could be observed, but there was an impact on CD14. Study B: The ultra-marathon resulted in a strong increase in serum LPS, which decreased fast after finishing in the water and test drink groups, but not in the placebo group. Conclusions: The consumed drinks did not affect the kinetics of IB regeneration after moderate exercise, but impacted CD14 serum concentrations, indicating possible beneficial effects of the FJM on the immune system. After an ultra-marathon, IB function regenerates very fast. The intake of sugar (placebo) seems to have had a negative impact on IB regeneration, which was diminished by the presence of the FJM.

Effects of Specific Bioactive Collagen Peptides in Combination with Concurrent Training on Running Performance and Indicators of Endurance Capacity in Men: A Randomized Controlled Trial

BackgroundFirst evidence indicates that the supplementation of specific collagen peptides (SCP) is associated with a significant improvement in running performance in physically active women; however, it is unclear if the same is true in males. The purpose of the present study was to investigate the effects of a concurrent training program including 60 min of continuous moderate intensity running training and 15 min of dynamic resistance training combined with supplementation of SCP on parameters of running performance in moderately trained males.MethodsIn a double-blind, placebo-controlled, randomized trial, participants performed a 12 weeks concurrent training and ingested 15 g of SCP [treatment group (TG)] or placebo [control group (CG)] daily. Before and after the intervention, running endurance performance was measured by a 1-h time trial on a running track. Velocity at the lactate threshold (VLT) and at the individual anaerobic threshold (VIAT) were assessed on a treadmill ergometer. Body composition was evaluated by bioelectrical impedance analysis.ResultsThirty-two men (28.4 ± 5.2 years) completed the study and were included in the analysis. After 12 weeks, TG had a statistically significant (p ≤ 0.05) higher increase in running distance (1727 ± 705 m) compared to the CG (1018 ± 976 m) in the time trial. VLT increased in the TG by 0.680 ± 1.27 km h−1 and slightly decreased by − 0.135 ± 0.978 km h−1 in the CG, resulting in statistically significant group differences (p ≤ 0.05). A significantly higher improvement in VIAT (p ≤ 0.05) was shown in the TG compared with the CG only (1.660 ± 1.022 km h−1 vs 0.606 ± 0.974 km h−1; p ≤ 0.01). Fat mass decreased (TG − 1.7 ± 1.6 kg; CG − 1.2 ± 2.0 kg) and fat free mass increased (TG 0.2 ± 1.2 kg; CG 0.5 ± 1.3 kg) in both groups with no significant group differences.ConclusionIn summary, supplementation with 15 g of SCP improved running performance in a 1-h time trial and enhanced indicators of endurance capacity at submaximal exercise intensities such as an increased velocity at the lactate as well as the anaerobic threshold more effectively than CT alone.Trial registration: ETK: 123/17; DRKS-ID: DRKS00015529 (Registered 07 November 2018—Retrospectively registered); https://drks.de/search/de/trial/DRKS00015529

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

The aim of the study was to analyze physiological and energetic demands of elite gymnasts during still-rings routines (SRRs). 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. 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). The anaerobic alactic system is the predominant energy source for ATP resynthesis during SRRs. The high relative VO2 and HR values reached during SRRs showthat these routines strongly stress the cardiovascular system.

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

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. 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. 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). 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.

APRIMORAMENTO DA COORDENAÇÃo FÍSICA DOS NADADORES BASEADO NO TREINAMENTO DE RESISTÊNCIA ANAERÓBICA

ABSTRACT Introduction: Anaerobic exercise is a critical factor in swimming training. Coaches who monitor an athlete’s anaerobic capacity can use this tool to improve competitive performance. Objective: Analyze the effect of the anaerobic function test on swimmers’ training. Methods: We examined the anaerobic exercise capacity of swimmers the relationship between human body composition and anaerobic work capacity. For this purpose, 14 swimmers were selected by random sampling. Individual anaerobic threshold, serum testosterone and serum cortisol of the athletes at different periods were measured. Results: Individual anaerobic thresholds were significantly lower in male and female athletes after training. The difference was statistically significant (P&lt;0.05). The plasma testosterone/cortisol content of female swimmers after six weeks of anaerobic endurance training was significantly lower than the pre-training mean (P&lt;0.05). After six weeks of anaerobic endurance training, the plasma testosterone/cortisol content of the male swimmers was lower than that of the standard group (P&lt;0.05). Conclusion: The swimmers’ bodies were impacted after anaerobic endurance training. The importance of attention by the coach to consider the differences between male and female athletes when conducting dedicated anaerobic threshold training is emphasized. Level of evidence II; Therapeutic studies-investigating treatment outcomes .

Heart Rate Recovery (HRR) Is Not a Singular Predictor for Physical Fitness

For optimal recommendations in cardiovascular training for the general population, knowing the essential parameters for physical fitness is required. Heart rate recovery (HRR) is an easy-to-measure parameter and is discussed to derive the physical fitness of an individual subject. This study evaluates HRR as a potential physical fitness parameter for public health programs, as it is measured in every ergometry. In this retrospective cross-sectional study, we analyzed HRR regarding physical fitness (W/kg (IAT: individual anaerobic threshold)). In total, we analyzed 1234 performance protocols in cycle ergometry. Significance tests (p < 0.001) and multiple linear regression were performed. The analysis of HRR and weight-related performance showed a significant correlation with a moderate coefficient of determination (R2 = 0.250). The coefficient of determination increases from very weak correlation levels at 1 min post-workout towards weak to moderate levels of correlation at 5 min post-workout. In this study HRR and the weight-related performance at the IAT showed a significant correlation with a mean strength. Thus, a prediction or conclusion on physical performance based singularly on HRR decrease is not recommended. However, in preventive medicine, HRR should be measured and observed on a long-term basis, for analysis of vagal activity and to draw to inferences of mortality.

Effects of increasing physical load and fatigue on the biomechanics of elite cyclists

In this study, we propose to expand the research on the biomechanics of cycling, including changes caused by riding at different intensity levels and fatigue, similar to training or competition. Six well-trained, experienced male road cyclists (27.17 ± 3.89 years; 180.41 ± 5.31 cm; 75.23 ± 4.91 kg) with 8.3 ± 4.85 years of (professional) experience in road cycling underwent a lactate test, starting with 100 W and an increment of 20 W every 3 minutes until total exhaustion. Afterward, subjects drove an increment of 50 W every 3 minutes, starting again with 100 W and ending with 250 W (post-test). Changes in position were recorded via 2D video analysis. We found that with higher power output relative to the individual anaerobic threshold (IAT), the joint angles changed. No significant differences were present for the pre–post comparisons of the examined angles, which should map the influence of fatigue (p &gt; .05). Future research should try to observe cycling movement in more realistic settings, such as cycling-specific fatigue or during an outdoor ride, as the biomechanics under these conditions are of particularly high relevance for the athletes. Overall, the results suggest performing bike fitting more individually and in more realistic situations or setting.

Neurophysiological Markers for Monitoring Exercise and Recovery Cycles in Endurance Sports.

The current study analyzes the suitability and reliability of selected neurophysiological and vegetative nervous system markers as biomarkers for exercise and recovery in endurance sport. Sixty-two healthy men and women, endurance trained and moderately trained, performed two identical acute endurance tests (running trial 1 and running trial 2) followed by a washout period of four weeks. Exercise protocol consisted of an acute running trial lasting 60 minutes. An intensity corresponding to 95% of the heart rate at individual anaerobic threshold for 40 minutes was followed by 20 minutes at 110%. At pre-exercise, post-exercise, three hours post-exercise and 24 hours post-exercise, experimental diagnostics on Brain-derived neurotrophic factor (BDNF), heart rate variability (HRV), Stroop Color and Word Test (SCWT), and Short-Form McGill Pain Questionnaire (SF-MPQ) were performed. Significant changes over time were found for all parameters (<i>p</i> &lt; .05). Furthermore, there was an approached statistical significance in the interaction between gender and training status in BDNF regulation (F₍₃₎ = 2.43; <i>p</i> = 0.06), while gender differences were found only for LF/HF-ratio (3hPoEx, F₍₃₎ = 3.40; <i>p</i> = 0.002). Regarding the reliability, poor ICC-values (&lt; 0.5) were found for BDNF, Stroop sensitivity and pNN50, while all other parameters showed moderate ICC-values (0.5-0.75). Plasma-BDNF, SCWT performance, pain perception and all HRV parameters are suitable exercise-sensitive markers after an acute endurance exercise. Moreover, pain perception, SCWT reaction time and all HRV parameters show a moderate reliability, others rather poor. In summary, a selected neurophysiological and vegetative marker panel can be used to determine exercise load and recovery in endurance sports, but its repeatability is limited due to its vaguely reliability.

Exercise-induced hypoalgesia (EIH) in response to different exercise intensities

PurposeAcute physical activity leads to exercise-induced hypoalgesia (EIH). The aim of this study was to investigate the effects of four different exercise intensities on EIH.Methods25 male (age: 24.7 ± 3.0) subjects underwent four different exercise sessions on a bicycle ergometer for 30 min each at 60, 80, 100, and 110% of the individual anaerobic threshold on separate days in a randomized crossover design. Before, as well as 5- and 45-min post-exercise, pain sensitivity was measured employing pain pressure thresholds (PPT) at the elbow, knee, and ankle joints as well as the sternum and forehead. Besides, conditioned pain modulation (CPM) was conducted using thermal test- and conditioned stimuli before, 5-, and 45-min post-exercise.ResultsA main time effect was observed regarding PPT at all landmarks except for the forehead with higher values observed 5 and 45 min post-exercise compared to the pre-values. Yet, no interaction effects occurred. CPM did not change in response to any of the intensities used.ConclusionEIH occurs 5 and 45 min after exercise regardless of the intensity used at the joints and sternum which might be explained by local pain-inhibiting pathways and probably to a limited degree by central mechanisms, as no hypoalgesia was observed at the forehead and no changes in CPM occurred.

Test-retest reliability of lung diffusing capacity for nitric oxide during light to moderate intensity cycling exercise

This study examined test-retest reliability of single-breath lung diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) during exercise. Sixteen healthy subjects (age 20–67 years) performed DLNO-DLCO tests during light and moderate intensity cycling exercise at 50% and 80% of individual anaerobic threshold (IAT). Primary endpoint was DLNO at 80% IAT. Precision of DLNO, DLCO, and alveolar volume was quantified by within-subject standard deviation (SDws, measurement error) and intraclass correlation coefficients (ICC). Reproducibility was determined by SDws* 2.77. Overall, reliability was excellent for all outcomes. SDws and reproducibility for DLNO at 80% IAT were 4.6 and 12.7 mL.min−1.mmHg−1, and the ICC was 0.99 (95% confidence interval 0.98–0.99). Median breathlessness at 80% IAT was 4 (interquartile range 3–6) on a 0–10 scale. Our data suggest excellent reliability of single-breath DLNO during moderate intensity exercise, but perceived levels of breathlessness may limit its usefulness, especially at exercise intensities beyond IAT.

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.

Cardiovascular stress in football referees

Problem: As opposed to athletes, the cardiovascular strain of referees during a competition is neither systematically explored nor included in their cardiovascular screening programs. Methods: Twenty-one referees from the two upper Luxemburgish football divisions were monitored during and after a match with an ambulatory Holter electrocardiogram. The results were compared to a sports cardiological check-up including a maximal incremental test on the treadmill. Results: During the match, the referees evolved in average 17%, 32%, 34% and 17% in the “regenerative” (&lt;80% of the HR of individual anaerobic threshold, IAT), “extensive” (80 - 87.5% IAT), “intensive” (87.6 - 102.5% IAT) and “high intensive” (&gt;102.5% IAT) zones. During the match, the mean (154 ± 11 bpm, mean ±SD) and maximal HR (180 ± 10 bpm) were only slightly lower than at the IAT (161 ± 9 bpm) and the end of the treadmill test (183 ± 11 bpm), respectively. ECG only revealed minor arrhythmias both during Holter monitoring and ergometry on the treadmill, but a higher incidence of premature beats during the 1.5h of the match than during the 15.5h off-match period. One referee showing significant ST segment depressions during the match suffered from a sudden cardiac exercise-associated event two years later. Conclusion: Football referees experience significant cardiovascular strain. A systematic endurance training is indispensable for football referees. Regular health monitoring, including a maximal exercise test on a treadmill ergometer, should be recommended not only for athletes but also for football referees. Key Words: Sudden Death, Cardiovascular Risk, Cardiovascular Strain, Soccer

Cardiovascular-metabolic responses and oxygen uptake kinetics during kayak paddling in normobaric hypoxia in young flatwater kayakers

Background: The aim of the study was to evaluate response of cardiovascular, metabolic and oxygen consumption kinetics at kayak paddling exercise in the normoxic and normobaric environment. Material and Methods: Seven kayakers (age: 16±1.2 year; height: 165±8.3cm; body weight: 53±8kg; fat percentage: 17±4.4%; VO2max: 34.57±9.24 ml.kg-1.dk-1; Maximal La: 8.72±2.75 mM) with four years’ experience participated in the study. All subjects performed incremental maximal and sub-threshold constant load kayak paddling tests in normoxic and normobaric hypoxic conditions on different days. According to maximal tests results, the individual anaerobic threshold and VO2max values were determined. Results: VO2max, HRmax, peak power and maximal lactate values demonstrated statistical significant differences between the normobaric hypoxia and normoxic environment. The response of VO2max was found higher in the normoxic than the normobaric environment. Oxygen uptake kinetic was statistically (p&lt;0.05) faster, and O2 values were lower (p&lt;0.05) in the normoxic than the normobaric environment. Recovery kinetics was found to be statistically faster (p&lt;0.05) in the hypoxia than in the normoxia environment. Conclusions: The ATP supply in an anaerobic way was higher in the normoxic environment than in the normobaric environment, and lactate tolerance increased. Having faster oxygen uptake kinetics in the normoxic environment shows that the volume of oxygen deficit is lower. Faster recovery kinetics in normobaric hypoxia shows the positive effects of altitude on recovery.

Electrically assisted mountain biking: Riding faster, higher, farther in natural mountain systems

The number of people riding mountain bikes (MTBs) with electrical assistance (eMTB) is growing rapidly, creating a substantial switch from conventional mountain biking to electrically assisted mountain biking. Electrical support has the potential to alter riding behaviour on mountain bikes, associated with a change in destination choice and physiological demand. Hence, this study conducted test rides with 10 sport science students riding on conventional and electrically assisted mountain bikes with the purpose to examine how electrical assistance affects the spatio-temporal riding parameters mean speed, total distance, total climb and surface type. In addition, we recorded the physiological parameter heart rate and calculated the energy expenditure when riding conventional MTBs and eMTBs. We found higher speed associated with longer distance and elevated climb on eMTBs, combined with a higher percentage in the use of singletrails. At the same time, participants riding mountain bikes with electrical assistance showed lower heart rates and lower energy expenditure. Moreover, our results indicate that e-assisted participants are able to reach higher altitudes despite a lower endurance performance. Accordingly, the increasing use of eMTBs is leading to an augmentation of the movement capacity of people in natural mountain areas and thus, promoting physical activity and nature experiences on the one hand. However, a higher number of people in sensitive natural systems is also related to increasing risks for flora and fauna, particularly when riding gets “faster - higher – farther”. Informing people about the risks to increase awareness and promote appropriate behaviour in combination with the setting of a proper trail management, is of crucial importance to successfully merge recreation and nature protection in mountain systems. This study reveals clear differences in riding behaviour, trail choice and physiological response when riding conventional mountainbikes and mountainbikes with electrical assistance in mountain systems. With electrical assistance allowing less restricted access to physically demanding terrain, an increasing number of mountain bikers may reach sensitive ecosystems in high altitudes. To minimise ecological consequences such as vegetation damage and disturbance of wildlife, it is vital to adequately adjust management solutions. Our results highlight the need for clear regulations and informing of people, translating into a considerate and sustainable behaviour and trail choice and hence the prevention of conflicts with nature conservation and human stakeholders like recreationists or farmers. • Riding mountain bikes with electrical support implicates higher mean speed and a strong tendency to ride higher and farther. • The proportion of riding on singletrails is higher when using electrically-assisted mountain bikes. • On eMTBs, less physical energy is demanded and less time is spent above the individual anaerobic threshold. • People with eMTBs are able to reach higher altitudes despite a lower endurance performance.

Do exist gender differences in skin temperature of lower limbs following exercise test in male and female cross-country skiers?

The aim of study was to assess the skin temperature changes over selected muscles zones of the lower limbs following an exercise performed at similar relative external workload in 10 male and 6 female high-trained cross-country skiers. The first stage of experiment involved preliminary exercise to determine individual oxygen uptake VO2max and anaerobic threshold. The second stage experimental exercise consisted of 60 min running on treadmill with 80% of determined VO2max Thermographic imaging of lower limbs was performed, before, immediately after exercise and during recovery. Physiological parameters: VO2, MET—metabolic energy equivalent, heart rate and internal temperature were assessed at rest and at the end of exercise, respectively. Infrared thermography showed that at rest the skin temperature over lower limb muscles was significantly higher in men than in women. In response to exercise an increase in skin temperature over the studied muscles was significantly higher in women than men. Since was no significant difference in skin temperature in men and women after exercise. Before the test, no physiological parameter was significantly different in women and men. Exercise test reveled significant differences between men and women in some physiological parameters such as VO2 and MET. Our study showed that there are significant differences in lower limbs skin temperature between male and female at rest but not at the end of exercise test. Women in comparison with men had a greater increase in skin temperature in response to exercise and a persistence of elevated temperature over muscles of lower limbs after exercise.

Effects of single bouts of different endurance exercises with different intensities on microRNA biomarkers with and without blood flow restriction: a three-arm, randomized crossover trial

PurposePhysical activity is associated with altered levels of circulating microRNAs (ci-miRNAs). Changes in miRNA expression have great potential to modulate biological pathways of skeletal muscle hypertrophy and metabolism. This study was designed to determine whether the profile of ci-miRNAs is altered after different approaches of endurance exercise.MethodsEighteen healthy volunteers (aged 24 ± 3 years) participated this three-arm, randomized-balanced crossover study. Each arm was a single bout of treadmill-based acute endurance exercise at (1) 100% of the individual anaerobic threshold (IANS), (2) at 80% of the IANS and (3) at 80% of the IANS with blood flow restriction (BFR). Load-associated outcomes (fatigue, feeling, heart rate, and exhaustion) as well as acute effects (circulating miRNA patterns and lactate) were determined.ResultsAll training interventions increased the lactate concentration (LC) and heart rate (HR) (p < 0.001). The high-intensity intervention (HI) resulted in a higher LC than both lower intensity protocols (p < 0.001). The low-intensity blood flow restriction (LI-BFR) protocol led to a higher HR and higher LC than the low-intensity (LI) protocol without BFR (p = 0.037 and p = 0.003). The level of miR-142-5p and miR-197-3p were up-regulated in both interventions without BFR (p < 0.05). After LI exercise, the expression of miR-342-3p was up-regulated (p = 0.038). In LI-BFR, the level of miR-342-3p and miR-424-5p was confirmed to be up-regulated (p < 0.05). Three miRNAs and LC show a significant negative correlation (miR-99a-5p, p = 0.011, r = − 0.343/miR-199a-3p, p = 0.045, r = − 0.274/miR-125b-5p, p = 0.026, r = − 0.302). Two partial correlations (intervention partialized) showed a systematic impact of the type of exercise (LI-BFR vs. HI) (miR-99a-59: r = − 0.280/miR-199a-3p: r = − 0.293).ConclusionMiRNA expression patterns differ according to type of activity. We concluded that not only the intensity of the exercise (LC) is decisive for the release of circulating miRNAs—as essential is the type of training and the oxygen supply.

Effects of face masks on performance and cardiorespiratory response in well-trained athletes

BackgroundDuring the COVID-19 pandemic, compulsory masks became an integral part of outdoor sports such as jogging in crowded areas (e.g. city parks) as well as indoor sports in gyms and sports centers. This study, therefore, aimed to investigate the effects of medical face masks on performance and cardiorespiratory parameters in athletes.MethodsIn a randomized, cross-over design, 16 well-trained athletes (age 27 ± 7 years, peak oxygen consumption 56.2 ± 5.6 ml kg−1 min−1, maximum performance 5.1 ± 0.5 Watt kg−1) underwent three stepwise incremental exercise tests to exhaustion without mask (NM), with surgical mask (SM) and FFP2 mask (FFP2). Cardiorespiratory and metabolic responses were monitored by spiroergometry and blood lactate (BLa) testing throughout the tests.ResultsThere was a large effect of masks on performance with a significant reduction of maximum performance with SM (355 ± 41 Watt) and FFP2 (364 ± 43 Watt) compared to NM (377 ± 40 Watt), respectively (p < 0.001; ηp2 = 0.50). A large interaction effect with a reduction of both oxygen consumption (p < 0.001; ηp2 = 0.34) and minute ventilation (p < 0.001; ηp2 = 0.39) was observed. At the termination of the test with SM 11 of 16 subjects reported acute dyspnea from the suction of the wet and deformed mask. No difference in performance was observed at the individual anaerobic threshold (p = 0.90).ConclusionBoth SM and to a lesser extent FFP2 were associated with reduced maximum performance, minute ventilation, and oxygen consumption. For strenuous anaerobic exercise, an FFP2 mask may be preferred over an SM.

Comparison of maximal lactate steady state with anaerobic threshold determined by various methods based on graded exercise test with 3-minute stages in elite cyclists

BackgroundThe maximal lactate steady state (MLSS) is defined as the highest workload that can be maintained for a longer period of time without continued blood lactate (LA) accumulation. MLSS is one of the physiological indicators of aerobic performance. However, determination of MLSS requires the performance of a series of constant-intensity tests during multiple laboratory visits. Therefore, attempts are made to determine MLSS indirectly by means of anaerobic threshold (AT) evaluated during a single graded exercise test (GXT) until volitional exhaustion. The aim of our study was to verify whether AT determined by maximal deviation (Dmax), modified maximal deviation (ModDmax), baseline LA concentration + 1 mmol/l (+ 1 mmol/l), individual anaerobic threshold (IAT), onset of blood lactate accumulation (OBLA4mmol/l) and V-slope methods based on GXT with 3-min stages provide valid estimates of MLSS in elite cyclists.MethodsTwelve elite male cyclists (71.3 ± 3.6 ml/kg/min) completed GXT (the increase by 40 W every 3 min) to establish the AT (by Dmax, ModDmax, + 1 mmol/l, IAT, OBLA4mmol/l and V-slope methods). Next, a series of 30-min constant-load tests to determine MLSS was performed. Agreement between the MLSS and workload (WR) at AT was evaluated using the Bland–Altman method.ResultsThe analysis revealed a very high (rs > 0.90, p < 0.001) correlation between WRMLSS and WRDmax and WRIAT. The other AT methods were highly (rs > 0.70) correlated with MLSS except for OBLA4mmol/l (rs = 0.67). The Bland-Altman analysis revealed the highest agreement with MLSS for the Dmax, IAT and + 1 mmol/l methods. Mean difference between WRMLSS and WRDmax, WRIAT and WR+1mmol/l was 1.7 ± 3.9 W, 4.3 ± 7.9 W and 6.7 ± 17.2 W, respectively. Furthermore, the WRDmax and WRIAT had the lowest limits of agreement with the WRMLSS. The ModDmax and OBLA4mmol/l methods overestimated MLSS by 31.7 ± 18.5 W and 43.3 ± 17.8 W, respectively. The V-slope method underestimated MLSS by 36.2 ± 10.9 W.ConclusionsThe AT determined by Dmax and IAT methods based on the cycling GXT with 3-min stages provides a high agreement with the MLSS in elite cyclists. Despite the high correlation with MLSS and low mean difference, the AT determined by + 1 mmol/l method may highly overestimate or underestimate MLSS in individual subjects. The individual MLSS cannot be properly estimated by V-slope, ModDmax and OBLA4mmol/l methods.

Endurance Capacities in Professional Soccer Players: Are Performance Profiles Position Specific?

The aim of this study was to investigate position-specific endurance performance of soccer players. 136 professional players competing in the 1st and 2nd division in Germany were divided into the positional groups goalkeepers (GK), central defenders (CD), wingers (WI), central midfielders (CM), and forwards (FW). All players performed an incremental treadmill test with blood lactate sampling until exhaustion with the following endurance parameters being obtained: Fixed aerobic threshold (v2mmol/l), fixed anaerobic threshold (v4mmol/l), individual aerobic threshold (vLT), individual anaerobic threshold (vIAT), and maximum velocity (vmax). Results revealed significant differences between GK and all outfield playing positions for all endurance parameters (p ≤ 0.03; ES 0.87–2.19). No significant differences among outfield playing positions were evident for any of the parameters. However, trends were found in favor of the CM compared to the WI (p = 0.11; ES = 0.68) and the FW (p = 0.06; ES = 0.47) relating to vLT as well as in favor of the CM compared to the WI (p = 0.10; ES = 0.56) relating to vIAT. Findings suggest that goalkeepers possess the lowest endurance capacity compared to other playing positions. While outfield players in general showed similar endurance performance, CM seem to possess the highest aerobic capacity of all positions as indicated by all lactate-based thresholds, however, with only small to moderate ES. These findings could lead one to question the appropriateness of current endurance training regimes to prepare all players adequately for their positional match-running demands. Indeed, endurance training of players should be specific to their match-running demands. However, it remains unknown to what extent these demands are position or player specific.

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.