Stimulus Level during Endurance Training: Effects on ...downloads.hindawi.com/journals/jsm/2018/3158949.pdf · training phases of varying intensity on endurance perfor- mance as well

Clinical StudyStimulus Level during Endurance Training Effects onLactate Kinetics in Untrained Men

Michael Tuttor 12 Simon von Stengel2 Michael Hettchen2 andWolfgang Kemmler 2

1German Rugby-Union Deutscher Rugby-Verband eV (DRV) Ferdinand-Wilhelm-Fricke-Weg 1030169 Hannover Rugby-Verband Germany2Institute of Medical Physics Friedrich-Alexander University Erlangen-Nurnberg Erlangen Henkestrasse 9191052 Erlangen Germany

Correspondence should be addressed to Michael Tuttor mtuttorrugby-verbandde

Received 20 June 2018 Revised 19 October 2018 Accepted 15 November 2018 Published 2 December 2018

Academic Editor Nancy J Rehrer

Copyright copy 2018 Michael Tuttor et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

BackgroundObjective Not only but particularly due to their time efficiency High-Intensity Interval Training (HIIT) is becomingincreasingly popular in fitness-oriented endurance sports The purpose of this study was to determine the effect of a HIIT runningprogram versus a Moderate Intensity Continuous Exercise (MICE) training running program (16 weeks each) on lactate kineticsin untrainedmalesMethods 65 healthy but untrainedmales (30-50 years BMI 272 plusmn 37kgm2) were randomly assigned to eitheran HIIT (n=33) or a waiting-controlMICE group (n=32) HIIT consisted of intervals and intense continuous running bouts ator above the individual anaerobic threshold (IANS 95-110 of IANS-HR) while MICE focused on continuous running at 70-825 IANS-HR Both programs were adjusted for ldquototal workloadrdquo Study endpoints were time to IANS and time from IANS tillldquotime to exhaustionrdquo (TTE) as assessed by stepwise treadmill test Results In both exercise groups time to reach IANS (MICE320 plusmn 160 s versus HIIT 198 plusmn 118 s) increased significantly (plt001) with the groups differing significantly (plt001) Time fromIANS until TTE was prolonged significantly among the HIIT group (27 plusmn 66s p=030) while among the MICE group a significantreduction of time from IANS until TTE (59 plusmn 109s p=017) was determined Between-group difference is significant (p=003) forthis parameter In both groups TTE increased significantly (HIIT 272 plusmn 177 versusMICE 290 plusmn 194 both plt001) at a similarlevel (p=279) Conclusion HIIT and MICE protocols when adjusted for total workload similarly increased running performancein untrained male subjects however the underlying mechanisms differ fundamentally Due to its effects on aerobic and anaerobicperformance improvement HIIT can be recommended for untrained individuals as a time-efficient alternative or complementarytrainingmethod toMICEHowever our protocol didnot confirm the general superiority ofHIIT versusMICEon the key enduranceparameter ldquotime to exhaustionrdquo that has been reported by other comparative exercise studies

1 Background

High-Intensity Interval Training (HIIT)methods are becom-ing increasingly popular in fitness-oriented endurance sportsnot least because of their time effectiveness and interestingnature [1 2] The method is basically characterized byintermittent loading phases of high to maximum stimulusintensity that alternate with ldquorecovery phasesrdquo of lower butnot necessarily low intensity

Studies with different groups have shown that HIIThas significant and in some cases significantly more favor-able effects on maximum oxygen consumption (VO

2max)

than the moderate-intensive continuous exercise (ldquomoderateintensity continuous exerciserdquo MICE) [3ndash7]

The present RUSH Study (Running Strengthens theHeart) [8] also confirmed the significant superiority ofHIIT on this aspect of endurance performance in untrainedmiddle-aged men However HIIT and MICE showed them-selves to be comparable in terms of endurance performancemeasured by treadmill level test as ldquotime to exhaustionrdquo

In addition to VO2max anaerobic capacity (ANC) and

running economy (RE) also make an important contributionto endurance performance [9] In fact as with Iaia et al[10] but unlike other similar studies [5 11ndash13] the RUSH

HindawiJournal of Sports MedicineVolume 2018 Article ID 3158949 10 pageshttpsdoiorg10115520183158949

2 Journal of Sports Medicine

Study showed a significantly more favorable development ofRE in MICE compared with the HIIT group Correspondingeffects on lactate kinetics as a central aspect of anaerobiccapacity were not observed in the present study but a positiveinfluence of HIIT on ANC especially for HIIT formats withhighmaximum stimulation and a load duration of between20 seconds and 5 minutesinterval was ascertained [3 9 1415] At this point at the latest it should be noted that severalintensity-oriented concepts are subsumed under the termHIIT which may lead to significantly different adaptationalreactions Buchheit and Laursen distinguish between severalHIIT formats [16] to which they assign different metabolicrelevance In addition to the classic HIIT of endurance-oriented sports [17] newHIIT concepts have been establishedunder the terms ldquoRepeated Sprint Interval Trainingrdquo (RST)and ldquoSprint Interval Trainingrdquo (SIT) which aremainly used inball sports [18 19] Without going into the different formatsHIIT is therefore to be seen as a relatively heterogeneousinterval training method the interval duration of whichvaries between approx 5 seconds and 8 minutes [15 20] Theapplicability of HIIT to the untrained is not uncontroversial[21 22]

Within the RUSH Study considering the status of ourtarget group (untrained healthy men 30-50 years predomi-nantly overweight) the load type (running) and the trainingobjective (10 km running competition) we regarded theexecution of a complex HIIT protocol including SIT andRST components as possibly too demanding so we limitedourselves mainly to interval training forms in the range ofge90 sec

Following the spiroergometric estimation of the perform-ance-determining endurance components ldquomaximum oxy-gen uptakerdquo and ldquowork economyrdquo [8] it is the aim of thispaper to evaluate the effects of HIIT versus MICE on aerobicand anaerobic ldquoefficiencyrdquo by means of lactate kineticsThe ldquoanaerobic thresholdrdquo (IANS) which is determined viathe ldquolactate performance testrdquo provides insights into themetabolism [23ndash25] Nevertheless after exceeding the IANSphysical activity is not accompanied by purely anaerobicenergy supply (product of the capacity of the cardiorespira-tory system to supply oxygen and the capacity of the skeletalmuscles to utilize oxygen [26]) (maximal amount of ATPresynthesis via anaerobic metabolism during a short durationmaximal exercise [27]) in the true sense of the word [25 28]In this article we equate the aerobic efficiency (AE) withthe performance range up to reaching IANS the anaerobicefficiency (ANE) with the performance range after reachingIANS up to the end of performance (TTE) Following thispremise we investigated the extent to which amoderate HIIT(in terms of stimulus intensity) compared withMICE leads toa ldquoshiftrdquo of the IANS and thus to training-induced metabolicadjustments In this context we are not aware of any otherstudy which has investigated this question in a comparabledesign with an untrained adult population and a sufficientnumber of test persons

On the basis of comparable changes in ldquoduration upto the end of performancerdquo in the present study [8] ourhypothesis was that (1) MICE leads to a higher increase inaerobic performance defined as time under load (TUL) until

the anaerobic threshold is reached while (2) HIIT leads toa stronger increase in anaerobic performance defined astime (TUL) between reaching the anaerobic threshold andaborting the physical activity (TTE)

2 Material and Methods

The Running Strengthens the Heart (RUSH) study was acontrolled intervention study using a randomized two-groupdesign We evaluated the effects of two 16-week runningtraining phases of varying intensity on endurance perfor-mance as well as on spirometric metabolic and cardiacparameters However we also implemented a waiting-controlgroup in order to estimate the overall effect of the exercisemethods Nevertheless in this article we specifically focuson the effects of a HIIT versus a MICE protocol on lactatekinetics in the stress test The study was conducted at theInstitute of Medical Physics of the Friedrich-Alexander Uni-versitat Erlangen-Nurnberg (FAU) The study protocol wasapproved by the Ethics Committee of the FAU (application4463) all study participants gave their written consent Thestudy is registered at wwwclinicaltrialsgov (NCT01406730)

21 Study Endpoints

211 Primary Endpoint

(i) Change of time under load (TUL) between reachingthe anaerobic threshold and the point at which theload is aborted (TTE)

212 Secondary Endpoints

(i) Change in the duration of time under load (TUL)until the anaerobic threshold (IANS) is reached

(ii) Change in the IANS speed(iii) Change in maximum lactate concentration at the end

of the load

22 Participants Figure 1 gives the participant flow of thestudy Men aged 30-50 years living in the area of Erlangen-Nurnberg (Germany) were contacted by personal mail Onehundred and twenty-one males responded and were assessedfor eligibility Following our main inclusion criteria of (a)male (b) 30-50 years old (c) untrained status for longerthan 2 years (ie le1 endurance exercise sessions le2 exercisesessionsweek in total) and the corresponding exclusioncriteria of (a) inflammatory diseases (b) pathological changesof the heart (c) medicationdiseases affecting cardiovascularsystem andor muscle (d) severe obesity (BodyMass Index gt35 kgm2) (e) very low physical capacity (lt100Watt3 min atbicycle ergometry) (f) more than 2 weeks of absence duringthe interventional period 97 men were invited to a meetingwith presentation of our study protocol Sixteen subjects wereunwilling to join the randomization procedure and quit thestudy before randomization Thus 81 subjects were randomlyassigned (computerized block randomization stratified forage) to two subgroups (a) high-intensity (interval) training

Journal of Sports Medicine 3

April - July 2011 Newspaper and radio advertisement in Nuremberg Erlangen Fuumlrth Forchheim

Total excluded by study protocol n=24

- Pathological changes of the heart n=2- Acute inflammatory diseases n=2- Medicationsdiseases of the cardiovascular system muscle n=5- Adipose (BMIgt35kgm2) n=2- 2 weeks absence during the intervention period n=7- Contraindications in connection with MRI assessment n=6

Aer telephone interview classified as suitable n=121

Invited to information conference n=97

Abandonment of participation in the study n=16

Randomized allocation (stratified by age) to test groups n=81

HIIT Running group n=40

HIIT bdquoLost to follow-upldquo n=7

HIIT Included in analysis n=33

Non-training waiting group n=41

Waiting group Lost to follow-upldquo n=0

Included in analysis n=41

MICE Running group n=39

MICE Lost to follow-upldquo n=7

MICE Included in analysis n=32

Figure 1 Flowchart of the ldquoRUSH Studyrdquo


Table 1 Baseline characteristics of subject groups 1However in five subjects each per group a plateau of oxygen consumption could not bedetermined

Characteristics HIIT (n=33) MICE (n=32)Age (Y) 439 plusmn 50 429 plusmn 51Height (cm) 1811 plusmn 70 1816 plusmn 53Weight (kg) 915 plusmn 140 895 plusmn 123Body fat () 254 plusmn 57 247 plusmn 62Lean body mass (kg) 682 plusmn 80 686 plusmn 73Energy Intake (kcald) 2595plusmn738 2737plusmn592Activity (Index) 28 plusmn 13 27 plusmn 12Activity (minweek) 322 plusmn 319 330 plusmn 363Rel VO

2max (mlkgmin)1 369 plusmn 56 393 plusmn 55

(HIIT) group and (b) waiting-control groupmoderate inten-sity continuous exercise (MICE) group (Figure 1)

Table 1 gives the baseline characteristics of the partici-pants Of importance variables that may have impacted ourresults did not vary between the groups

23 Measurement All examinations were carried out bythe same investigator in identical sequence on the samepremises at the same time (plusmn1 h) with the same test device(see below) The examiners were also forbidden to inquireabout the status (HIIT or waiting groupMICE) of the testpersons

231 Anthropometric Data Height (Holtain Ltd CrymychGB) and perimeter values (Prym Stollberg Germany) ofthe test persons were measured with calibrated instrumentsBody weight (in kg) total and regional fat-free body mass (inkg) and body fat (in ) were measured by means of mod-ern multifrequency bioimpedance measurement (BiospaceInbody-230 Seoul Korea) Intra Class Correlation (ICC test-retest) of total fat-free body mass as assessed by the Inbody-230 was 088 for a comparable cohort of men 30-50 years oldICC for percent body fat was comparably high (086)

232 Endurance Capacity and Lactate Diagnostics Theendurance capacity was measured by treadmill level test(Technogym Gambetolla Italy) up to the subjective loadAs objective loading criteria all tests carried out showed amaximum respiratory quotient of gt105 and an O

2breath

equivalent of gt30The initial load was selected depending on the individual

performance capability and was consistent (base and controlmeasurement) at 7 or 8 kmh for the individual test personto ensure a load duration of at least 9 minutes The treadmillincline was 1 every 3 minutes the speed was increased by1 kmh

Heart rate monitors (Polar RS-400 Kempele Finland)were used to continuously record the heart rateTheheart rateof the last 30 s of each exercise level was included in the dataanalysis

At the end of each exercise stage the blood lactateconcentration was determined The blood collection at theearlobe was carried out via 20 120583L end-to-end plastic capil-laries which was then expelled into 1mL reaction vessels for

analysis The diagnostic device used is based on enzymatic-amperometric chip-sensor technology (Biosen-5130 GemarCelle Germany)

233 Lactate Threshold Determination The individualanaerobic threshold (IANS) was determined as minimumlactate + 20mmoll as our research subject as well forgenerating a reference value within the framework oftraining planning It is quite similar to the model ofDickhuth et al [29] Speed heart rate (HR) and lactatevalues at this threshold were calculated using the softwareldquoThresholdrdquo (Wassermann Bayreuth Germany)

234 Spirometry Open spirometry (Viasys ConshohockenUSA) was used to continuously determine the VO

2with

a breath-by-breath procedure The data of the last 30 s ofeach load level were included in the data analysis Runningeconomy (RE) was assessed before and after intervention forthe last 30 sec of the second stage of the test (530 to 600min)at identical running speed which was consistently kept belowthe anaerobic threshold Running Economy was calculatedusing VO

2lowast kgminus075lowastminminus1

VO2maxwas considered as a plateau of oxygen consump-tion defined as any 30 s period that was no more higher thanthe preceding 30 s period

235 QuestionnaireInfluencing FactorsNutrition Amongother things sociodemographic factors dietary habits ill-nesses health risk factors sports activities and physicalactivity were recorded via a validated questionnaire [30]A final questionnaire captured changes that could haveinfluenced our study endpoints (eg taking medication andsports activities)

At the beginning and end of the study the participantsrsquonutrition was recorded and evaluated via a 4-day nutritionprotocol (Nutri-Science Hausach Germany)

Figure 2 shows the design of the intervention Bothtraining groups trained 16 weeks based on individualizedtraining protocols These training plans which includedintensity extent density and frequency of stimulus wereanalyzed every 4 weeks to monitor the quantity and qualityof the training The stimulation level was specified by theHR For this purpose the participants were provided witha heart rate monitor (Polar RS 400 Kempele Finland) The


Figure 2 Study design of the RUSH Study

participantsrsquo heart rate monitors were randomly sampled(each training session (TS) 15-20 datasets) to assess compli-ance with the training guidelines The training volume wasgradually increased in both training groups by extendingthe time under load per training unit (TS) (from initial 30-35min up to 90minTS) and the number of weekly trainingunits During the first four weeks 2 TSweek and during thesecond four-week period 2 to 3 TSweek were completedAfter this initial phase with progressively increasing volumea nonlinear training protocol with 3-4 TSweek was imple-mented during the last 8 weeks of the intervention periodParticipants were required to participate in a supervised TSat least once a week and were free to participate in furtherjoint TS In total a maximum of 49 TS could have beencompleted during the intervention period The intensity ofthe stimulus was determined individually according to thethreshold concept described above by means of a trainingplan In order to measure the isolated influence of thestimulus intensity on our endpoints the duration of thetraining protocols (HIIT versus MICE) was adjusted suchthat the physical work became comparable (isocaloric)

24 Intervention Training Groups

241 High-Intensity Interval Training (HIIT) The stimulusintensity of the HIIT training varied mainly in the range of95-110 IANS-HR In addition to the interval method withan interval duration of 90 s-12min and a pause duration of1-3min (70-75 IANS-HR) continuous loads (25-45min)were also used in the IANS zone (threshold runs) In totalthe training components were distributed as follows

(1) Loads above the IANS (interval gt1025 of the IANS-HR) approx 40 of the total volume

(2) Loads in the range of the IANS (intervalcontinuousload 95-1025 of the IANS-HR) approx 35 of thetotal volume

(3) Low-intensive loads clearly below the IANS (70-75of the IANS-HR) approx 25 of the total volume

The training components of the ldquolow-intensiverdquo exercisezone consisted exclusively of the load contents ldquowarm-uprunningrdquo and ldquoactive breakrdquo as well as (in total two)regenerative training units

242 Moderate Intensity Continuous Exercise (MICE)Although the intensity of training varied somewhat moremarkedly (asymp 70-100 IANS-HR) than in the HIIT groupover the intervention period as a whole the trainingmethodological emphasis was in the range of 70-825 ofIANS-HR Training mainly entailed an extensive enduranceelement ie extensive ldquoFartlekrdquo (35-90min) and onlysporadic loads in the area of the IANS (especially to verifyit see above) Overall the training components weredistributed as follows

(1) Loads above the IANS (gt1025of the IANS-HR) 0of the total volume

(2) Loads in the area of the IANS (95-1025of the IANS-HR) 5 of the total volume

(3) Loads below the IANS (825-95 IANS-HR) 10 ofthe total volume

(4) Loads in the low-intensity range (70-825 IANS-HR) 85 total volume

Table 1 shows the base characteristics of the two traininggroups No significant intergroup differences were recordedfor the given parameters

25 Statistical Procedures The present study has a random-ized two-part design The calculation of the formal numberof cases of the study is based on what is probably the ldquomostcriticalrdquo endpoint of the study the end diastolic volumeof Heart-MRI measurement a quantity that is not furtheraddressed in this paper The calculated number of cases of40 persons per group generates a statistical power (120572 5) of96 based on the expected intergroup difference of 10 plusmn 12for the questions addressed Furthermore the hypothesescited above attribute this contribution primarily to the effectof stimulus intensity so that the control group data are nolonger taken into account here A ldquoCompleter Analysisrdquo wascarried out in which all persons (independently of theirldquocompliancerdquo) who participated in the control (ie 16 weekfollow-up) assessment were taken into account

After checking the normal distribution assumption bymeans of graphical (boxplot histogram) and statisticaltests (Shapiro Wilks-Test) and if necessary correspondinglog transformations of nonnormally distributed variables


Table 2 Training characteristicsHIIT versus MICE

Characteristics HIIT MICE PFrequency (TS16 weeks) 405 plusmn 54 403 plusmn 59 926Volume (min16 weeks) 2092 plusmn 298 2303 plusmn 352 012Work (kcal16 weeks) 28966 plusmn 5228 30479 plusmn 6566 317

Table 3 Results for the study endpoints Mean values standard deviations and mean difference between the groups with 95 confidenceinterval as well as significance values of the intergroup comparison and corresponding effect size (ES) Numerical value in parenthesesSignificance value of the change within the groups between base and final (16-week measurement)

HIIT MICE Absolute differenceMV (95-CI) p ES

d1015840MV plusmn SD MVplusmnSDTime to reach IANS [s]Baseline 482 plusmn 235 511 plusmn 264 ----- ----- -----16 weeks 680 plusmn 228 831 plusmn 268 ----- ----- -----Difference 198 plusmn 128 (p=001) 320 plusmn 140 (p=001) 122 (51 to 192) 0001 091Time from attainment of the IANS until load abort [s]Baseline 351 plusmn 144 392 plusmn 152 ----- ----- -----16 weeks 378 plusmn 147 333 plusmn 134 ----- ----- -----Difference 27 plusmn 66 (p=030) -59 plusmn 109 (p=011) 86 (34 to 136) 0003 095

changes within the groups were analyzed bymeans of a T-testfor dependent samples Intergroup differences between HIITand MICE were calculated by independent (Welch) T-Testsbased on absolute differences within the groups betweenbaseline and 16-week follow-up adjusted for baseline data Asignificance level of 5 was set All data were analyzed withSPSS version 220 (SPSS INC Chicago USA)

3 Results

Thirty-three (33) participants of the HIIT (83) and 32participants of the MICE group (80) were included in thefinal analysis Nine persons discontinued the study becauseof injuries or orthopaedic problems (HIIT n=4 versusMICEn=5) In eight cases this was related to running trainingThree persons (HIIT n=2 versus MICE n=1) fell ill andwere no longer available for follow-up measurements Onesubject in each of the training groups discontinued trainingfor undisclosed reasons Two subjects of the controlwaitinggroup lost interest in further study participation even beforethe start of the MICE training period

31 Training Characteristics Table 2 shows the trainingfrequency training volume and work done over the inter-vention period of both training groups Due to the higherstimulus intensity of the HIIT group the physical ldquoworkrdquowas comparable despite different training duration and sametraining frequency

Both training groups carried out the training sessionsin accordance with the protocol as far as possible Theattendance rate for the HIIT group was 83 plusmn 11 (405 plusmn 54TS 27 to 49 TS) the corresponding rate for the MICE groupwas 82 plusmn 12 (403plusmn 59 TS 25 to 48 TS) (Table 2)The 4-weektraining sessions also showed no significant longitudinalchanges or differences between the groups with regard to

the attendance rate It was noticeable that the HIIT grouppreferred not to carry out the few intensive continuous powerunits (n=9) in the anaerobic threshold rangewith the plannedtraining frequency (56 execution rate) while in the MICEgroup there was no tendency to favor the implementation ofany particular training content

4 Study Outcome

In both groups the duration until load abort increasedcomparable (p= 297) and significantly (plt001) by 226 plusmn 120s (MICE) and 261 plusmn 143 s respectively

The significant (plt 001) increase in the time to reachIANS (TULIANS) in both training groups was more pro-nounced in the MICE group with an increase of 320 plusmn 140seconds (plt001) than in the HIIT group 198 plusmn 128 secondsIn the HIIT group the time from reaching IANS until loadabort (IANSTTE) increased significantly (p=030) by 27plusmn 66s whereas in theMICE group a significant (p=011) reductionof 59 plusmn 109 s was observed The difference between thesubgroups was significant (p=003)

Our hypothesis (1) can thus be confirmed Our assess-ment of hypothesis (2) regarding the exclusive effects of HIITon an increase in ANE is also verified by the study results(Table 3)

Speed at the IANS increased significantly in both groupsHowever the improvement was significantly higher in theMICE group than in the HIIT group A slight nonsignificantincrease in the maximum lactate concentration was recordedfor both training groups No differences between the groupswere recorded with tending higher lactate values in the HIITgroup (Table 4)

Not addressed in this article however potentially impor-tant in the interpretation of the results running economy(RE) nonsignificantly increased (30 plusmn 103 p=148) in the


Table 4 Results for the secondary endpoints ldquovelocity at anaerobic thresholdrdquo and ldquomaximum lactaterdquo Mean values standard deviationsand mean difference between the groups with 95 confidence interval as well as significance values of the intergroup comparison andcorresponding effect size (ES) Numerical value in parentheses significance value of the change within the groups between base and final(16-week measurement)

HIIT MICE Absolutedifference MV

(95-CI)p ES

MV plusmn SD MV plusmn SD d1015840

Speed at IANS [kmh]Baseline 968 plusmn 124 972 plusmn 147 ----- ----- -----16 weeks 1077 plusmn 133 1150 plusmn 144 ----- ----- -----Difference 110 plusmn 065 (p=001) 178 plusmn 083 (p=001) 069 (032 to 107) 001 91Maximum lactate (mmoll)Baseline 791 plusmn 222 764 plusmn 175 ----- ----- -----16 weeks 833 plusmn 208 772 plusmn 147 ----- ----- -----Difference 042 plusmn 127 (p=067) 008 plusmn 090 (p=616) 034 (-21 to 89) 222 31

HIIT group and significantly decline (-57 plusmn 93 p=005) inthe MICE group Differences between the two groups weresignificant (p=003)

41 Confounding Variables Weight and skeletal muscle masschanged relevantly with significant differences between thetraining groups (weight HIIT minus13 plusmn 25 versus MICEminus28 plusmn 27 p=028) (skeletal muscle mass HIIT +05 plusmn23 versus MICE minus13 plusmn 20 p=002) No significantchanges in lifestyle diet physical activity or exercise wererecorded during the intervention periodThe outcome effectsare therefore primarily attributable to the intervention

5 Discussion

The intention of this article was to investigate a relativelymoderate HIIT format [16] which is suitable for novicerunners with regard to the training effect on aerobic andanaerobic performance as compared withMICE training Forbetter comparability both training methods were ldquoadjustedrdquowith respect to the workload an approach that led torelatively long HIIT intervals despite high intensity In sum-mary both training methods led to a comparable significantincrease in endurance performance (TUL HIIT 272 plusmn 177versus MICE 290 plusmn 194) defined as time to load abortionbut by significantly different paths AlthoughHIIT andMICEshow significant improvements in aerobic performance (AE)defined as ldquotime to reach IANSrdquo (Table 3) or a significantldquoshift to the rightrdquo of IANS (Table 4) both values showsignificantly better results for the MICE group This findingthat a HIIT is able to have a significant but less favorableeffect on AE than MICE is at odds with the findings ofseveral studies [9 14 31] In contrast (only) HIIT inducesan increase of the anaerobic performance (ANE) definedas TUL between reaching the IANS and end of load Inessence this corresponds to the improvement inAE andANEdemonstrated by Tabata et al [6] and others [9 14 15 32]by a HIIT Since spiroergometry data or other parameterson the topic are usually available (see above) however theclassification of our results should be viewed with care

The HIIT stress protocol and the patient samples of theaforementioned (HIIT) interventions differ from the protocolpresented here so that a cautious interpretation seems all themore appropriate Nevertheless the available knowledge isfavorable

That HIIT causes an increase in the performance of fixedlactate values among trained persons [5 33] or at the ldquoLTthresholdrdquo among athletes [34] mainly supports our result ofHIIT raising the IANS in the case of untrained persons

In general however the interpretation of workout-induced lactate thresholdmodifications is always difficult andwe consider it plausible that stimulation level and extent of aworkout have different effects on the threshold of untrainedpersons compared with athletes [15]

Moreover the lack of standardization in threshold deter-mination is always critical The large number of existingthreshold concepts inconsistent ldquostress protocolsrdquo their inad-equate description and the nonexistent terminology stan-dards in the field of medicine and sports science do notpermit a clear evaluation of the study situation and thusmakeit difficult to classify the study results [23 35]

Considering the change in the maximum lactate con-centration at the time of load abort the HIIT group showsa partial increase (p=067) with no significant difference tothe MICE group where there is no significant change inthis value The data of the available literature are ratherinconsistent in this respect while Sperlich et al [36] andStoggl et al [37] reported significant HIT-induced lactatechanges Helgerud et al [5] reported no significant changesafter two different HIIT formats The same applies to MICEprotocols for which Sperlich et al [36] reported a reductionafter moderate-intensive high-volume training with 9-11-year-old performance swimmers

As a representative parameter of cardiorespiratory fitnessVO2max is the usually applied performance parameter in the

research field [5 38ndash40]There is no question that endurancecapacity manifests itself in VO

2max However it arises not

only from the VO2max but also from the determinants dis-

cussed here which come to light with a view to the submax-imal load situation (see above) Last but not least despite the


comparable increase in TUL significantly higher VO2max

absolute values were achieved through HIIT compared withMICE [8] Based on our results for the optimization of REby MICE [8] we assumed that the observed effects are alsorepresented in lactate kinetics The available results go someway to confirming this The spirometric variation of the RE isalso revealed to some extent in the correspondingly modifiedlactate threshold With an increase of 320 plusmn 160 seconds(versusHIIT 198plusmn 128 seconds)MICEhas amore significant(plt001) effect on the IANS (as a presumed expression ofeconomic metabolic processes in the submaximum loadrange) than HIIT Nevertheless the spirometry data of thepresent study also show a significant decrease in RE by HIITalthough the training method also achieved an increase inAE to a highly significant extent An increase in lactate-determined AE obviously does not necessarily mean animproved RE Here the term ldquoeconomisation effectrdquo mustalso be considered in a differentiated way Conversely aneconomisation of the submaximal metabolic process doesnot have to be accompanied by an increase in IANS It isalso conceivable that within the measuring range of the REdetermined spirometrically (the RE was determined on thebasis of the following calculation VO

2(ml x kg ndash 075 x

minminus1) [41] of the last 30 s of the second load stage (530 to600min)) an improved ANE leads to the load process beingunable to proceed so economically since the metabolism istrained to maximize performance per se Accordingly weconclude that the main adjustment takes place in the respec-tive main load areas As our measurements also show bothtypes of training can improve the athletic performance of theuntrained determined by the TUL comparably effectively(p=297) With regard to their effectiveness in improving thephysical performance of untrained subjects the results are inline with the current state of research [9 32 42]

Targeted measures must always be based on a target-group-oriented weighting of all the variables In this senseour training protocol was less intensive and should also beable to be carried out independently in the field

A HIIT protocol can be described with up to ninevariables the exercise as such the respective intensity andduration of the work and rest interval the number ofrepetitions and series and the duration and intensity of theseries breaks [16 19]

We were convinced that untrained sports beginnersshould avoid extremely high intensities as this would alsoreduce susceptibility to injury at lower levels of stress (cfspecial features and limitations-point (d))This topic was alsoaddressed by Lunt et al [43] As the authors show successand implementation of the HIIT study training protocolsare governed by different rules ldquoin real liferdquo In overweightadults only a very small improvement of the VO

2max

could be achieved Adherence was low and minor traininginjuries occurred Foster et al [32] observe a decrease in theldquojoyrdquo of HIIT among the untrained subjects over an 8-weekintervention period However to conclude that there is anacceptance problem with the HIIT method in the case ofuntrained persons would disregard further current research

results because it has also been shown that untrained personsprefer HIIT as a training variant [1 44]

Themain strengths of our study are (a) unlike many otherstudies [7 11 13 32 45] it offers a sufficiently high sample sizeand long duration of intervention which makes it possible toidentify clinically relevant differences (b) regular monitoringand adjustment of the load specifications via HR (c) atraining protocol that can be easily and safely incorporatedin the training routine (d) the controlled randomized designwith waitingcontrol group (e) the recording of relevantparameters of endurance capacity and its determinantsand (f) the consistent recording of covariates (medicationdiseases nutritional behavior lifestyle and training)

Particular features and limitations of our study are as fol-lows (a) The lack of a specific recording of the ANE eg vialdquoWingate-Anaerobic-Testrdquo as well as the fine adjustment ofthe IANS via maxLassMLSS-Test This could not be achievedfor economic reasons (b) In addition the determinationof ventilatory thresholds would contribute to the additionalverification of the available results and would provide furtherplausibility Thus the working group ldquocardiopulmonary exer-cise testingrdquo also calls for a combination of both diagnosticmethods in the sense of better and more precise diagnostics[25] (c) The delayed execution of the training protocols(Figure 2) Here it is possible that seasonal changes in physicalactivity may affect our results However the data for thisparameter at base and at the end of the study do not indicateany change (d) The relatively high drop-out rate (20) dueto training-induced injuries and discomfort (comparable inHIIT and MICE) (e) The only random checking of the givenstimulation level by reading out the heart rate monitorsIn this respect it is possible that the implementation ofthe stimulus level was not always in accordance with theprotocol (f) From a purely statistical point of view applyingthe intention-to-treat principle would be preferable to ourldquoCompleterrdquo approach Furthermore the formal case numbercalculation was carried out with a (cardiac) parameter whichwas not the subject of the present study

6 Conclusion

In summary it can be concluded that an increase in theAE of metabolism can be induced by both MICE and HIITMetabolic processes are optimized mainly in the most fre-quently trained area ie in the main requirement area Hightraining stimuli can contribute to performance improvementin a time-efficient way and address different physiologicaladaptations depending on the level of stimulation To ourknowledge HIIT can optimally represent the complementarycomponent to MICE or HIIT regimes and depending on theobjective it can contribute to the efficient optimization ofperformance Depending on the intention of the athlete aneasy-to-implement extended MICE protocol could also bethe preferred training option in terms of increasing energyconsumption Considering that MICE exceeds our HIITprogram by only 55 minutes in terms of average trainingtimeTS this is a conceivable approach Another desirableeffect was the best possible transfer of our intervention mea-sures into everyday training and the increase in compliance


beyond the end of the intervention Researching this in afollow-up study would be beneficial and worthwhile in termsof a more comprehensive understanding of the potentiallong-term effects of high-intensity training methods

Abbreviations

AE Aerobic efficiencyANE Anaerobic efficiencyANC Anaerobic capacityCm CentimeterHIIT High-Intensity Interval TrainingHR Heart rateIANS Anaerobic thresholdKg KilogramMICE Moderate intensity continuous exerciseMin Minutemmoll Millimole per literRE Running economyRST Repeated Sprint Interval TrainingS SecondSIT Sprint Interval TrainingTS Training sessionTTE Time to exhaustionTUL Time under loadVO2max Maximum oxygen consumption

Data Availability

The anonymized data used to support the findings of thisstudy are available from the corresponding author uponrequest

Conflicts of Interest

Michael Tuttor Simon von Stengel Michael Hettchen andWolfgang Kemmler declare no conflicts of interest

Acknowledgments

We would like to thank the Institute for Medical PhysicsUniversity of Erlangen-Nurnberg and the ldquoStadtler StiftungNurnbergrdquo that supported the RUSH project This publica-tion is part of the doctoral work for the title ldquoDr rer humbiolrdquo

References

[1] J D Bartlett G L Close D P M MacLaren W Gregson BDrust and J P Morton ldquoHigh-intensity interval running isperceived to be more enjoyable than moderate-intensity con-tinuous exercise implications for exercise adherencerdquo Journalof Sports Sciences vol 29 no 6 pp 547ndash553 2011

[2] K M Heinrich P M Patel J L OrsquoNeal and B S HeinrichldquoHigh-intensity compared to moderate-intensity training forexercise initiation enjoyment adherence and intentions Anintervention studyrdquo BMC Public Health vol 14 no 1 2014

[3] A J R CochranM E Percival S Tricarico et al ldquoIntermittentand continuous high-intensity exercise training induce similar

acute but different chronic muscle adaptationsrdquo ExperimentalPhysiology vol 99 no 5 pp 782ndash791 2014

[4] M J Haykowsky M P Timmons C Kruger M McNeely DA Taylor and A M Clark ldquoMeta-analysis of aerobic intervaltraining on exercise capacity and systolic function in patientswith heart failure and reduced ejection fractionsrdquo AmericanJournal of Cardiology vol 111 no 10 pp 1466ndash1469 2013

[5] J Helgerud K Hoydal and E Wang ldquoAerobic high-intensityintervals improve V∙O2max more than moderate trainingrdquoMedicine amp Science in Sports amp Exercise vol 39 no 4 pp 665ndash671 2007

[6] I Tabata K NishimuraM Kouzaki et al ldquoEffects of moderate-intensity endurance and high-intensity intermittent training onanaerobic capacity and VO

2maxrdquoMedicine amp Science in Sports

amp Exercise vol 28 no 10 pp 1327ndash1330 1996[7] A E Tjoslashnna S J Lee Oslash Rognmo et al ldquoAerobic interval

training versus continuousmoderate exercise as a treatment forthe metabolic syndrome a pilot studyrdquo Circulation vol 118 no4 pp 346ndash354 2008

[8] W Kemmler M Tutor M Lell et al ldquoEinfluss hoher vsniedriger Reizintensitat auf die Ausdauerleistungsfahigkeituntrainierter Manner ndash die RUSH-Studierdquo Deutsche Zeitschriftfur Sportmedizin vol 65 pp 120ndash125 2014

[9] P B Laursen ldquoTraining for intense exercise performance High-intensity or high-volume trainingrdquo Scandinavian Journal ofMedicine amp Science in Sports vol 20 no 2 pp 1ndash10 2010

[10] F M Iaia M Thomassen H Kolding et al ldquoReduced volumebut increased training intensity elevatesmuscleNa+-K+pumpalpha1-subunit andNHE1 expression as well as short-termworkcapacity in humanrdquoAmerican Journal of Physiology-RegulatoryIntegrative and Comparative Physiology vol 294 no 3 ppR966ndashR974 2008

[11] K A Burgomaster K R Howarth S M Phillips et al ldquoSimilarmetabolic adaptations during exercise after low volume sprintinterval and traditional endurance training in humansrdquo TheJournal of Physiology vol 586 no 1 pp 151ndash160 2008

[12] D O Eddy K L Sparks and D A Adelizi ldquoThe effects ofcontinuous and interval training in women andmenrdquoEuropeanJournal of Applied Physiology vol 37 no 2 pp 83ndash92 1977

[13] B R McKay D H Paterson and J M Kowalchuk ldquoEffectof short-term high-intensity interval training vs continuoustraining on O2 uptake kinetics muscle deoxygenation andexercise performancerdquo Journal of Applied Physiology vol 107no 1 pp 128ndash138 2009

[14] M J Gibala J P Little M van Essen et al ldquoShort-termsprint interval versus traditional endurance training similarinitial adaptations in human skeletal muscle and exerciseperformancerdquoThe Journal of Physiology vol 575 no 3 pp 901ndash911 2006

[15] P B Laursen and D G Jenkins ldquoThe scientific basis for high-intensity interval training Optimising training programmesand maximising performance in highly trained enduranceathletesrdquo Sports Medicine vol 32 no 1 pp 53ndash73 2002

[16] M Buchheit and P B Laursen ldquoHigh-intensity interval train-ing solutions to the programming puzzle part I cardiopul-monary emphasisrdquo Sports Medicine vol 43 no 5 pp 313ndash3382013

[17] V L Billat ldquoInterval training for performance A scientific andempirical practice Special recommendations for middle- andlong-distance running Part II Anaerobic interval trainingrdquoSports Medicine vol 31 no 2 pp 75ndash90 2001


[18] D Bishop O Girard and A Mendez-Villanueva ldquoRepeated-sprint ability part II Recommendations for trainingrdquo SportsMedicine vol 41 no 9 pp 741ndash756 2011

[19] M Buchheit and P B Laursen ldquoHigh-intensity interval train-ing solutions to the programming puzzle Part II Anaerobicenergy neuromuscular load and practical applicationsrdquo SportsMedicine vol 43 no 10 pp 927ndash954 2013

[20] F M Iaia and J Bangsbo ldquoSpeed endurance training is a pow-erful stimulus for physiological adaptations and performanceimprovements of athletesrdquo Scandinavian Journal of Medicine ampScience in Sports vol 20 no 2 pp 11ndash23 2010

[21] T A Astorino and J S Thum ldquoResponse Commentary Whysprint interval training is inappropriate for a largely sedentarypopulationrdquo Frontiers in Psychology vol 7 p 746 2016

[22] M E Jung J P Little and A M Batterham ldquoCommentaryWhy sprint interval training is inappropriate for a largelysedentary populationrdquo Frontiers in Psychology vol 6 p 19992015

[23] H Heck ldquo30 Jahre Laktatschwellen - was bleibt zu tunrdquoDeutsche Zeitschrift fur Sportmedizin vol 59 p 5 2008

[24] K Svedahl and B R MacIntosh ldquoAnaerobic threshold theconcept and methods of measurementrdquo Canadian Journal ofApplied Physiology vol 28 no 2 pp 299ndash323 2003

[25] M Westhoff K H Ruhle A Greiwing et al ldquoPositionalpaper of the Germanworking group ldquocardiopulmonary exercisetestingordquo to ventilatory and metabolic (lactate) thresholdsrdquoDeutsche Medizinische Wochenschrift vol 138 no 6 pp 275ndash280 2013

[26] ACSM ACSMrsquos Guidelines for Exercise Testing and PrescriptionLippincotte Williams amp Wilkins Philadelphia Penn USA2013

[27] S Green ldquoA definition and systems view of anaerobic capacityrdquoEuropean Journal of Applied Physiology vol 69 no 2 pp 168ndash173 1994

[28] G Antonutto and P E Di Prampero ldquoThe concept of lactatethreshold A short reviewrdquo The Journal of Sports Medicine andPhysical Fitness vol 35 no 1 pp 6ndash12 1995

[29] H H Dickhuth M Huonker T Munzel et al ldquoIndividualanaerobic threshold for evaluation of competitive athletes andpatients with left ventricular dysfunctionrdquo in Advances inErgometry T G Bachl and H Lollgen Eds pp 173ndash179Springer Berlin Germany New York NY USA 1991

[30] W Kemmler J Weineck W A Kalender and K EngelkeldquoThe effect of habitual physical activity non-athletic exercisemuscle strength andVO2max on bonemineral density is ratherlow in early postmenopausal osteopenic womenrdquo Journal ofMusculoskeletal andNeuronal Interactions vol 4 no 3 pp 325ndash334 2004

[31] M J Gibala J B Gillen and M E Percival ldquoPhysiologicaland health-related adaptations to low-volume interval traininginfluences of nutrition and sexrdquo Sports Medicine vol 44supplement 2 pp S127ndashS137 2014

[32] C V Farland J Schuette C Foster et al ldquoThe Effects ofHigh Intensity Interval Training versus Steady State Training onAerobic and Anaerobic CapacityrdquoMedicine amp Science in Sportsamp Exercise vol 14 pp 747ndash755 2015

[33] K A Burgomaster G J F Heigenhauser and M J GibalaldquoEffect of short-term sprint interval training on human skeletalmuscle carbohydratemetabolism during exercise and time-trialperformancerdquo Journal of Applied Physiology vol 100 no 6 pp2041ndash2047 2006

[34] N J Nı Cheilleachair A J Harrison and G D WarringtonldquoHIIT enhances endurance performance and aerobic charac-teristics more than high-volume training in trained rowersrdquoJournal of Sports Sciences vol 35 no 11 pp 1052ndash1058 2017

[35] PWahlW Bloch and JMester ldquoModerne Betrachtungsweisendes Laktats Laktat ein uber- schatztes und zugleich unter-schatztesMolekulrdquo Swiss Sports amp Exercise Medicine vol 57 pp101ndash107 2014

[36] B Sperlich C Zinner I Heilemann P-L Kjendlie H-CHolm-berg and J Mester ldquoHigh-intensity interval training improvesVO2peak maximal lactate accumulation time trial andcompetition performance in 9-11-year-old swimmersrdquo Euro-pean Journal of Applied Physiology vol 110 no 5 pp 1029ndash10362010

[37] T L Stoggl and G Bjorklund ldquoHigh Intensity Interval TrainingLeads to Greater Improvements in Acute Heart Rate Recoveryand Anaerobic Power as High Volume Low Intensity TrainingrdquoFrontiers in Physiology vol 8 p 562 2017

[38] G Huang C A Gibson Z V Tran and W H OsnessldquoControlled endurance exercise training and VO

2119898119886119909changes

in older adults a meta-analysisrdquo Preventive Cardiology vol 8no 4 pp 217ndash225 2005

[39] ZMilanovic G Sporis andMWeston ldquoEffectiveness of High-Intensity Interval Training (HIT) and Continuous EnduranceTraining for VO2max Improvements A Systematic Review andMeta-Analysis of ControlledTrialsrdquo SportsMedicine vol 45 no10 pp 1469ndash1481 2015

[40] B H Roxburgh P B Nolan R M Weatherwax and L CDalleck ldquoIs moderate intensity exercise training combined withhigh intensity interval training more effective at improving car-diorespiratory fitness than moderate intensity exercise trainingalonerdquo Journal of Sports Science andMedicine vol 13 no 3 pp702ndash707 2014

[41] J Helgerud ldquoMaximal oxygen uptake anaerobic thresholdand running economy in women and men with similar per-formances level in marathonsrdquo European Journal of AppliedPhysiology vol 68 no 2 pp 155ndash161 1994

[42] N F Sculthorpe P Herbert and F Grace ldquoOne session of high-intensity interval training (HIIT) every 5 days improvesmusclepower but not static balance in lifelong sedentary ageingmen Arandomized controlled trialrdquo Medicine (United States) vol 96no 6 Article ID e6040 2017

[43] H Lunt NDraperH CMarshall et al ldquoHigh intensity intervaltraining in a real world setting A randomized controlled fea-sibility study in overweight inactive adults measuring changein maximal oxygen uptakerdquo PLoS ONE vol 9 no 1 p e832562014

[44] J S Thum G Parsons T Whittle and T A Astorino ldquoHigh-intensity interval training elicits higher enjoyment than mod-erate intensity continuous exerciserdquo PLoS ONE vol 12 no 1Article ID e0166299 2017

[45] A W Midgley and L R Mc Naughton ldquoTime at or nearVO2max during continuous and intermittent running Areview with special reference to considerations for the optimi-sation of training protocols to elicit the longest time at or nearVO2maxrdquo The Journal of Sports Medicine and Physical Fitnessvol 46 pp 1ndash14 2006

Stem Cells International

Hindawiwwwhindawicom Volume 2018


MEDIATORSINFLAMMATION

of

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Immunology ResearchHindawiwwwhindawicom Volume 2018

Journal of

ObesityJournal of



Computational and Mathematical Methods in Medicine


Behavioural Neurology

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Research and TreatmentAIDS


Gastroenterology Research and Practice


Parkinsonrsquos Disease

Evidence-Based Complementary andAlternative Medicine

Volume 2018Hindawiwwwhindawicom

Submit your manuscripts atwwwhindawicom


Study showed a significantly more favorable development ofRE in MICE compared with the HIIT group Correspondingeffects on lactate kinetics as a central aspect of anaerobiccapacity were not observed in the present study but a positiveinfluence of HIIT on ANC especially for HIIT formats withhighmaximum stimulation and a load duration of between20 seconds and 5 minutesinterval was ascertained [3 9 1415] At this point at the latest it should be noted that severalintensity-oriented concepts are subsumed under the termHIIT which may lead to significantly different adaptationalreactions Buchheit and Laursen distinguish between severalHIIT formats [16] to which they assign different metabolicrelevance In addition to the classic HIIT of endurance-oriented sports [17] newHIIT concepts have been establishedunder the terms ldquoRepeated Sprint Interval Trainingrdquo (RST)and ldquoSprint Interval Trainingrdquo (SIT) which aremainly used inball sports [18 19] Without going into the different formatsHIIT is therefore to be seen as a relatively heterogeneousinterval training method the interval duration of whichvaries between approx 5 seconds and 8 minutes [15 20] Theapplicability of HIIT to the untrained is not uncontroversial[21 22]

Within the RUSH Study considering the status of ourtarget group (untrained healthy men 30-50 years predomi-nantly overweight) the load type (running) and the trainingobjective (10 km running competition) we regarded theexecution of a complex HIIT protocol including SIT andRST components as possibly too demanding so we limitedourselves mainly to interval training forms in the range ofge90 sec

Following the spiroergometric estimation of the perform-ance-determining endurance components ldquomaximum oxy-gen uptakerdquo and ldquowork economyrdquo [8] it is the aim of thispaper to evaluate the effects of HIIT versus MICE on aerobicand anaerobic ldquoefficiencyrdquo by means of lactate kineticsThe ldquoanaerobic thresholdrdquo (IANS) which is determined viathe ldquolactate performance testrdquo provides insights into themetabolism [23ndash25] Nevertheless after exceeding the IANSphysical activity is not accompanied by purely anaerobicenergy supply (product of the capacity of the cardiorespira-tory system to supply oxygen and the capacity of the skeletalmuscles to utilize oxygen [26]) (maximal amount of ATPresynthesis via anaerobic metabolism during a short durationmaximal exercise [27]) in the true sense of the word [25 28]In this article we equate the aerobic efficiency (AE) withthe performance range up to reaching IANS the anaerobicefficiency (ANE) with the performance range after reachingIANS up to the end of performance (TTE) Following thispremise we investigated the extent to which amoderate HIIT(in terms of stimulus intensity) compared withMICE leads toa ldquoshiftrdquo of the IANS and thus to training-induced metabolicadjustments In this context we are not aware of any otherstudy which has investigated this question in a comparabledesign with an untrained adult population and a sufficientnumber of test persons

On the basis of comparable changes in ldquoduration upto the end of performancerdquo in the present study [8] ourhypothesis was that (1) MICE leads to a higher increase inaerobic performance defined as time under load (TUL) until

the anaerobic threshold is reached while (2) HIIT leads toa stronger increase in anaerobic performance defined astime (TUL) between reaching the anaerobic threshold andaborting the physical activity (TTE)

2 Material and Methods

The Running Strengthens the Heart (RUSH) study was acontrolled intervention study using a randomized two-groupdesign We evaluated the effects of two 16-week runningtraining phases of varying intensity on endurance perfor-mance as well as on spirometric metabolic and cardiacparameters However we also implemented a waiting-controlgroup in order to estimate the overall effect of the exercisemethods Nevertheless in this article we specifically focuson the effects of a HIIT versus a MICE protocol on lactatekinetics in the stress test The study was conducted at theInstitute of Medical Physics of the Friedrich-Alexander Uni-versitat Erlangen-Nurnberg (FAU) The study protocol wasapproved by the Ethics Committee of the FAU (application4463) all study participants gave their written consent Thestudy is registered at wwwclinicaltrialsgov (NCT01406730)

21 Study Endpoints

211 Primary Endpoint

(i) Change of time under load (TUL) between reachingthe anaerobic threshold and the point at which theload is aborted (TTE)

212 Secondary Endpoints

(i) Change in the duration of time under load (TUL)until the anaerobic threshold (IANS) is reached

(ii) Change in the IANS speed(iii) Change in maximum lactate concentration at the end

of the load

22 Participants Figure 1 gives the participant flow of thestudy Men aged 30-50 years living in the area of Erlangen-Nurnberg (Germany) were contacted by personal mail Onehundred and twenty-one males responded and were assessedfor eligibility Following our main inclusion criteria of (a)male (b) 30-50 years old (c) untrained status for longerthan 2 years (ie le1 endurance exercise sessions le2 exercisesessionsweek in total) and the corresponding exclusioncriteria of (a) inflammatory diseases (b) pathological changesof the heart (c) medicationdiseases affecting cardiovascularsystem andor muscle (d) severe obesity (BodyMass Index gt35 kgm2) (e) very low physical capacity (lt100Watt3 min atbicycle ergometry) (f) more than 2 weeks of absence duringthe interventional period 97 men were invited to a meetingwith presentation of our study protocol Sixteen subjects wereunwilling to join the randomization procedure and quit thestudy before randomization Thus 81 subjects were randomlyassigned (computerized block randomization stratified forage) to two subgroups (a) high-intensity (interval) training




























2breath








2with































3 Results





4 Study Outcome









(95-CI)p ES





5 Discussion




















2max





6 Conclusion




Abbreviations


Data Availability




Acknowledgments


References











































2119898119886119909changes













of




Disease Markers



OncologyJournal of





PPAR Research



Volume 2018


Journal of

ObesityJournal of














































2breath








2with































3 Results





4 Study Outcome









(95-CI)p ES





5 Discussion




















2max





6 Conclusion




Abbreviations


Data Availability




Acknowledgments


References











































2119898119886119909changes













of




Disease Markers



OncologyJournal of





PPAR Research



Volume 2018


Journal of

ObesityJournal of




























2breath








2with































3 Results





4 Study Outcome









(95-CI)p ES





5 Discussion




















2max





6 Conclusion




Abbreviations


Data Availability




Acknowledgments


References











































2119898119886119909changes













of




Disease Markers



OncologyJournal of





PPAR Research



Volume 2018


Journal of

ObesityJournal of











































3 Results





4 Study Outcome









(95-CI)p ES





5 Discussion




















2max





6 Conclusion




Abbreviations


Data Availability




Acknowledgments


References











































2119898119886119909changes













of




Disease Markers



OncologyJournal of





PPAR Research



Volume 2018


Journal of

ObesityJournal of


























3 Results





4 Study Outcome









(95-CI)p ES





5 Discussion




















2max





6 Conclusion




Abbreviations


Data Availability




Acknowledgments


References











































2119898119886119909changes













of




Disease Markers



OncologyJournal of





PPAR Research



Volume 2018


Journal of

ObesityJournal of






















(95-CI)p ES





5 Discussion




















2max





6 Conclusion




Abbreviations


Data Availability




Acknowledgments


References











































2119898119886119909changes













of




Disease Markers



OncologyJournal of





PPAR Research



Volume 2018


Journal of

ObesityJournal of



























2max





6 Conclusion




Abbreviations


Data Availability




Acknowledgments


References











































2119898119886119909changes













of




Disease Markers



OncologyJournal of





PPAR Research



Volume 2018


Journal of

ObesityJournal of





















Abbreviations


Data Availability




Acknowledgments


References











































2119898119886119909changes













of




Disease Markers



OncologyJournal of





PPAR Research



Volume 2018


Journal of

ObesityJournal of









































2119898119886119909changes













of




Disease Markers



OncologyJournal of





PPAR Research



Volume 2018


Journal of

ObesityJournal of























of




Disease Markers



OncologyJournal of





PPAR Research



Volume 2018


Journal of

ObesityJournal of



















Documents

Stimulus Level during Endurance Training: Effects on ...downloads.hindawi.com/journals/jsm/2018/3158949.pdf · training phases of varying intensity on endurance perfor- mance as well