Comparison of effects of two interval-training programmes on lactate and ventilatory thresholds

The Effects of Exercise Training on Plasma Volume Variations: A Systematic Review

The aim of this systematic review was to summarize the evidence on the acute and long-term effects of exercise training on PV, in both trained and untrained individuals and to examine associations between changes in %PVV and change in physical/physiological performance. Despite the status of participants and the exercise duration or intensity, all the acute studies reported a significant decrease of PV (effect size: 0.85<d<3.45, very large), and ranged between 7 and 19.9%. In untrained individuals, most of studies reported a significant increase of PV in response to different kind of training including endurance training and high intensity interval training (effect size: 0.19<d<3.52, small to very large), and ranged from 6.6 to 16%. However, in trained individuals the results are equivocal. We showed that acute exercise appears to induce a significant decrease of PV in both healthy untrained and trained individuals in response to several exercise modalities. Moreover, there is evidence that long-term exercise training induced a significant increase of PV in healthy untrained individuals. However, it seems that there is no consensus concerning the effect of long-term exercise training on PV in trained individuals.

Systematic Review and Meta-analysis of Blood Glucose Response to High-intensity Interval Exercise in Adults With Type 1 Diabetes

OBJECTIVES

Exercise-induced hyperglycemia is recognized in type 1 diabetes (T1D) clinical guidelines, but its association with high-intensity intermittent exercise (HIIE) in acute studies is inconsistent. In this meta-analysis, we examined the available evidence of blood glucose responses to HIIE in adults with T1D. The secondary, aim was to examine predictors of blood glucose responses to HIIE. We hypothesized that there would be no consistent effect on blood glucose from HIIE, unless examined in the context of participant prandial status.

METHODS

We conducted a literature search using key words related to T1D and HIIE. Studies were required to include at least 6 participants with T1D with a mean age >18 years, involve an HIIE intervention, and contain pre- and postexercise measures of blood glucose. Analyses of extracted data were performed using a general inverse variance statistical method with a random effects model and a weighted multiple regression.

RESULTS

Nineteen interventions from 15 reports were included in the analysis. A mean overall blood glucose decrease of -1.3 mmol/L (95% confidence interval [CI], -2.3 to -0.2 mmol/L) was found during exercise, albeit with high heterogeneity (I²=84%). When performed after an overnight fast, exercise increased blood glucose by +1.7 mmol/L (95% CI, 0.4 to 3.0 mmol/L), whereas postprandial exercise decreased blood glucose by -2.1 mmol/L (95% CI, -2.8 to -1.4 mmol/L), with a statistically significant difference between groups (p<0.0001). No associations with fitness (p=0.4), sex (p=0.4), age (p=0.9), exercise duration (p=0.9), or interval duration (p=0.2) were found.

CONCLUSION

The effect of HIIE on blood glucose is inconsistent, but partially explained by prandial status.

Interval training during concurrent training optimizes cardiorespiratory adaptations in women

Abstract This study compared the effects of using continuous and interval aerobic exercise during concurrent training on cardiorespiratory adaptations in women. Thirty-two participants were randomly assigned into one of the following groups: continuous running and resistance training (C-RUN, n = 10), interval running and resistance training (I-RUN, n = 11), or control group that performed resistance training only (RT, n = 11). Each group trained twice a week during 11 weeks. Oxygen uptake corresponding to the first ventilatory threshold (VO2VT1), second ventilatory threshold (VO2VT2) and maximal effort (VO2max) was measured in a maximal incremental test performed before and after training. Significant increases in VO2VT1, VO2VT2 and VO2max were observed in all training groups. VO2VT2 and VO2max presented time-group interactions, indicating that the magnitude of the increase in these variables was dependent on the training group (VO2VT2: C-Run = 6.6%, I-Run = 15.7%, RT = 1.7%; VO2max: C-Run = 7.2%, I-Run = 14.3%, RT = 2.7%). The effect size observed for post-training values comparing C-RUN and RT groups was d = 0.566 for VO2VT2 and d = 0.442 for VO2max. On the other hand, values of d = 0.949 for VO2VT2 and d = 1.189 for VO2max were verified between I-RUN and RT groups. In conclusion, the use of continuous and interval aerobic exercise during concurrent training improved different cardiorespiratory parameters in women, but in a greater magnitude when interval aerobic exercise was performed simultaneously to resistance training.

Hemodynamic Adaptations Induced by Short-Term Run Interval Training in College Students

Perceived lack of time is one of the most often cited barriers to exercise participation. High intensity interval training has become a popular training modality that incorporates intervals of maximal and low-intensity exercise with a time commitment usually shorter than 30 min. The purpose of this study was to examine the effects of short-term run interval training (RIT) on body composition (BC) and cardiorespiratory responses in undergraduate college students. Nineteen males (21.5 ± 1.6 years) were randomly assigned to a non-exercise control (CON, n = 10) or RIT (n = 9). Baseline measurements of systolic and diastolic blood pressure, resting heart rate (HRrest), double product (DP) and BC were obtained from both groups. VO_2max and running speed associated with VO_2peak (sVO_2peak) were then measured. RIT consisted of three running treadmill sessions per week over 4 weeks (intervals at 100% sVO_2peak, recovery periods at 40% sVO_2peak). There were no differences in post-training BC or VO₂max between groups (p > 0.05). HRrest (p = 0.006) and DP (p ≤ 0.001) were lower in the RIT group compared to CON at completion of the study. RIT lowered HRrest and DP in the absence of appreciable BC and VO_2max changes. Thereby, RIT could be an alternative model of training to diminish health-related risk factors in undergraduate college students.

Evidence of altered cardiac autonomic regulation in myalgic encephalomyelitis/chronic fatigue syndrome: A systematic review and meta-analysis

BACKGROUND

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex condition with no reliable diagnostic biomarkers. Studies have shown evidence of autonomic dysfunction in patients with ME/CFS, but results have been equivocal. Heart rate (HR) parameters can reflect changes in autonomic function in healthy individuals; however, this has not been thoroughly evaluated in ME/CFS.

METHODS

A systematic database search for case-control literature was performed. Meta-analysis was performed to determine differences in HR parameters between ME/CFS patients and controls.

RESULTS

Sixty-four articles were included in the systematic review. HR parameters assessed in ME/CFS patients and controls were grouped into ten categories: resting HR (RHR), maximal HR (HRmax), HR during submaximal exercise, HR response to head-up tilt testing (HRtilt), resting HR variability (HRVrest), HR variability during head-up tilt testing (HRVtilt), orthostatic HR response (HROR), HR during mental task(s) (HRmentaltask), daily average HR (HRdailyaverage), and HR recovery (HRR) Meta-analysis revealed RHR (MD ± 95% CI = 4.14 ± 1.38, P < .001), HRtilt (SMD ± 95% CI = 0.92 ± 0.24, P < .001), HROR (0.50 ± 0.27, P < .001), and the ratio of low frequency power to high frequency power of HRVrest (0.39 ± 0.22, P < .001) were higher in ME/CFS patients compared to controls, while HRmax (MD ± 95% CI = -13.81 ± 4.15, P < .001), HR at anaerobic threshold (SMD ± 95% CI = -0.44 ± 0.30, P = 0.005) and the high frequency portion of HRVrest (-0.34 ± 0.22, P = .002) were lower in ME/CFS patients.

CONCLUSIONS

The differences in HR parameters identified by the meta-analysis indicate that ME/CFS patients have altered autonomic cardiac regulation when compared to healthy controls. These alterations in HR parameters may be symptomatic of the condition.

Whole-Body High-Intensity Interval Training Induce Similar Cardiorespiratory Adaptations Compared With Traditional High-Intensity Interval Training and Moderate-Intensity Continuous Training in Healthy Men

Schaun, GZ, Pinto, SS, Silva, MR, Dolinski, DB, and Alberton, CL. Sixteen weeks of whole-body high-intensity interval training induce similar cardiorespiratory responses compared with traditional high-intensity interval training and moderate-intensity continuous training in healthy men. J Strength Cond Res 32(10): 2730-2742, 2018-Low-volume high-intensity interval training (HIIT) protocols that use the body weight as resistance could be an interesting and inexpensive alternative to traditional ergometer-based high-intensity interval training (HIIT-T) and moderate-intensity continuous training (MICT). Therefore, our aim was to compare the effects of 16 weeks of whole-body HIIT (HIIT-WB), HIIT-T, and MICT on maximal oxygen uptake (V[Combining Dot Above]O2max), second ventilatory threshold (VT2), and running economy (RE) outcomes. Fifty-five healthy men (23.7 ± 0.7 years, 1.79 ± 0.01 m, 78.5 ± 1.7 kg) were randomized into 3 training groups (HIIT-T = 17; HIIT-WB = 19; MICT = 19) for 16 weeks (3× per week). The HIIT-T group performed eight 20-second bouts at 130% of the velocity associated to V[Combining Dot Above]O2max (vV[Combining Dot Above]O2max) interspersed by 10-second passive recovery on a treadmill, whereas HIIT-WB group performed the same protocol but used calisthenics exercises at an all-out intensity instead of treadmill running. Finally, MICT group exercised for 30 minutes at 90-95% of the heart rate (HR) associated to VT2. After the intervention, all groups improved V[Combining Dot Above]O2max, vV[Combining Dot Above]O2max, time to exhaustion (Tmax), VT2, velocity associated with VT2 (vVT2), and time to reach VT2 (tVT2) significantly (p < 0.05). Moreover, Tmax, vVT2, and tVT2 were greater after HIIT-T compared with HIIT-WB (p < 0.05), whereas oxygen uptake increased and HR decreased during the RE test in all groups (p < 0.05). Our results demonstrate that HIIT-WB can be as effective as traditional HIIT while also being time-efficient compared with MICT to improve health-related outcomes after 16 weeks of training. However, HIIT-T and MICT seem preferable to enhance performance-related outcomes compared with HIIT-WB.

Effects of Recovery Mode during High Intensity Interval Training on Glucoregulatory Hormones and Glucose Metabolism in Response to Maximal Exercise

Catecholamines [adrenaline (A) and noradrenaline (NA)] are known to stimulate glucose metabolism at rest and in response to maximal exercise. However, training and recovery mode can alter theses hormones. Thus our study aims to examine the effects of recovery mode during High-intensity Interval Training (HIIT) on glucoregulatory hormone responses to maximal exercise in young adults. Twenty-four male enrolled in this randomized study, assigned to: control group (eg, n=6), and two HIIT groups: intermittent exercise (30 s run/30 s recovery) with active (arg, n=9) or passive (prg, n=9) recovery, arg and prg performed HIIT 3 times weekly for 7 weeks. Before and after HIIT, participants undergo a Maximal Graded Test (MGT). Plasma catecholamines, glucose, insulin, growth hormone (Gh) and cortisol were determined at rest, at the end of MGT, after 10 and 30 min of recovery. After training V0_2max and Maximal Aerobic Velocity (MAV) increased significantly (p<0.05) in arg. After HIIT and in response to MGT plasma glucose increase significantly (p=0.008) lesser in arg compared to prg whereas insulin concentrations were similar. The glucose/insulin ratio was significantly lower at MGT end (p=0.033) only in arg after training. After HIIT, in response to MGT, plasma A, NA, cortisol and Gh concentrations were significantly higher only in arg (p<0.05). HIIT using active recovery is beneficial for aerobic fitness, plasma glucose and glucoregulatory hormones better than HIIT with passive recovery. These findings suggest that HIIT with active recovery may improve some metabolic and hormonal parameters in young adults.

Change in VO2max and time trial performance in response to high-intensity interval training prescribed using ventilatory threshold

Completion of high-intensity interval training (HIIT) leads to significant increases in maximal oxygen uptake (VO_2max) and oxidative capacity. However, individual responses to HIIT have been identified as approximately 20-40% of individuals show no change in VO_2max, which may be due to the relatively homogeneous approach to implementing HIIT.

PURPOSE

This study tested the effects of HIIT prescribed using ventilatory threshold (VT) on changes in VO_2max and cycling performance.

METHODS

Fourteen active men and women (age and VO_2max = 27 ± 8 year and 38 ± 4 mL/kg/min) underwent nine sessions of HIIT, and 14 additional men and women (age and VO_2max = 22 ± 3 year and 40 ± 5 mL/kg/min) served as controls. Training was performed on a cycle ergometer at a work rate equal to 130%VT and consisted of eight to ten 1 min bouts interspersed with 75 s of recovery. At baseline and post-testing, they completed progressive cycling to exhaustion to determine VO_2max, and on a separate day, a 5 mile cycling time trial.

RESULTS

Compared to the control group, HIIT led to significant increases in VO_2max (6%, p = 0.007), cycling performance (2.5%, p = 0.003), and absolute VT (9 W, p = 0.005). However, only 57% of participants revealed meaningful increases in VO_2max and cycling performance in response to training, and two showed no change in either outcome.

CONCLUSIONS

A greater volume of HIIT may be needed to maximize the training response for all individuals.

Can anti-gravity running improve performance to the same degree as over-ground running?

This study examined the changes in running performance, maximal blood lactate concentrations and running kinematics between 85%BM anti-gravity (AG) running and normal over-ground (OG) running over an 8-week training period. Fifteen elite male developmental cricketers were assigned to either the AG or over-ground (CON) running group. The AG group (n = 7) ran twice a week on an AG treadmill and once per week over-ground. The CON group (n = 8) completed all sessions OG on grass. Both AG and OG training resulted in similar improvements in time trial and shuttle run performance. Maximal running performance showed moderate differences between the groups, however the AG condition resulted in less improvement. Large differences in maximal blood lactate concentrations existed with OG running resulting in greater improvements in blood lactate concentrations measured during maximal running. Moderate increases in stride length paired with moderate decreases in stride rate also resulted from AG training. The use of AG training to supplement regular OG training for performance should be used cautiously, as extended use over long periods of time could lead to altered stride mechanics and reduced blood lactate.

Is irisin the new player in exercise-induced adaptations or not? A 2017 update

Irisin is produced by a proteolytic cleavage of fibronectin type III domain-containing protein 5 (FNDC5) and has emerged as a potential mediator of exercise-induced energy metabolism. The purpose of this study was to review the results of studies that investigated irisin responses to acute and chronic exercise and provide an update. A comprehensive search in the databases of MEDLINE was performed (74 exercise studies). The focus of the analysis was on data concerning FNDC5 mRNA expression in skeletal muscle and circulating irisin concentration relatively to exercise mode, intensity, frequency and duration and the characteristics of the sample used. Circulating irisin levels may either not relate to FNDC5 transcription or expression of the later precedes irisin rise in the blood. Acute speed/strength and endurance exercise protocols represent potent stimuli for irisin release if they are characterized by adequate intensity and/or duration. There are no reports regarding irisin responses to field sport activities. Although animal studies suggest that irisin may also respond to systematic exercise training, the majority of human studies has produced contradictory results. Certain methodological issues need to be considered here such as the analytical assays used to measure irisin concentration in the circulation. Results may also be affected by subjects’ age, conditioning status and exercise intensity. The role of irisin as a moderator of energy metabolism during exercise remains to be seen.

Physiological responses during intermittent running exercise differ between outdoor and treadmill running

The aim of this study was to compare the physiological responses during 15 min of intermittent running consisting of 30 s of high-intensity running exercise at maximal aerobic velocity (MAV) interspersed with 30 s of passive recovery (30–30) performed outdoor versus on a motorized treadmill. Fifteen collegiate physically active males (age, 22 ± 1 years old; body mass, 66 ± 7 kg; stature, 176 ± 06 cm; weekly training volume, 5 ± 2 h·week−1), performed the Fitness Intermittent Test 45–15 to determine maximal oxygen uptake (V̇O2max) and MAV and then completed in random order 3 different training sessions consisting of a 30-s run/30-s rest on an outdoor athletic track (30–30 Track) at MAV; a 30-s run/30-s rest on a treadmill (30–30 Treadmill) at MAV; a 30-s run/30-s rest at MAV+15% (30–30 + 15% MAV Treadmill). Oxygen uptake (V̇O2), time above 90%V̇O2max (t90%V̇O2max), and rating of perceived exertion (RPE) were measured during each training session. We observed a statistical significant underestimation of V̇O2 (53.1 ± 5.4 mL·kg−1·min−1 vs 49.8 ± 6.7 mL·kg−1·min−1, –6.3%, P = 0.012), t90%V̇O2max (8.6% ± 11.5% vs 38.7% ± 32.5%, –77.8%, P = 0.008), RPE (11.4 ± 1.4 vs 16.5 ± 1.7, –31%, P < 0.0001) during the 30–30 Treadmill compared with the same training session performed on track. No statistical differences between 30–30 +15 % MAV Treadmill and 30–30 Track were observed. The present study demonstrates that a 15% increase in running velocity during a high-intensity intermittent treadmill training session is the optimal solution to reach the same physiological responses than an outdoor training session.

Does cumulating endurance training at the weekends impair training effectiveness?

BACKGROUND

Due to occupational restrictions many people's recreational endurance activities are confined to the weekends. We intended to clarify if cumulating the training load in such a way diminishes endurance gains.

DESIGN

We conducted a longitudinal study comparing training-induced changes within three independent samples.

METHODS

Thirty-eight healthy untrained participants (45+/-8 years, 80+/-18 kg; 172+/-9 cm) were stratified for endurance capacity and sex and randomly assigned to three groups: 'weekend warrior' (n=13, two sessions per week on consecutive days, 75 min each, intensity 90% of the anaerobic threshold; baseline lactate+1.5 mmol/l), regular training (n=12, five sessions per week, 30 min each, same intensity as weekend warrior), and control (n=13, no training). Training was conducted over 12 weeks and monitored by means of heart rate. Identical graded treadmill protocols before and after the training program served for exercise prescription and assessment of endurance effects.

RESULTS

VO2max improved similarly in weekend warrior (+3.4 ml/min per kg) and register training (+1.5 ml/min per kg; P=0.20 between groups). Compared with controls (-1.0 ml/min per kg) this effect was significant for weekend warriors (P<0.01) whereas there was only a tendency for the regular training group (P=0.10). In comparison with controls (mean decrease, 3 beats/min), the average heart rate during exercise decreased significantly by 11 beats/min (weekend warriors, P<0.01) and 9 beats/min (regular training, P<0.05). There was no significant difference, however, between the weekend warrior and regular training groups (P=0.99).

CONCLUSION

In a middle-aged population of healthy untrained subjects, cumulating the training load at the weekends does not lead to an impairment of endurance gains in comparison with a smoother training distribution.

The impact of work-matched interval training on V̇O2peak and V̇O2 kinetics: diminishing returns with increasing intensity

High-intensity interval training (HIIT) improves peak oxygen uptake (V̇O2peak) and oxygen uptake (V̇O2) kinetics, however, it is unknown whether an optimal intensity of HIIT exists for eliciting improvements in these measures of whole-body oxidative metabolism. The purpose of this study was to (i) investigate the effect of interval intensity on training-induced adaptations in V̇O2peak and V̇O2 kinetics, and (ii) examine the impact of interval intensity on the frequency of nonresponders in V̇O2peak. Thirty-six healthy men and women completed 3 weeks of cycle ergometer HIIT, consisting of intervals targeting 80% (LO), 115% (MID), or 150% (HI) of peak aerobic power. Total work performed per training session was matched across groups. A main effect of training (p < 0.05) and a significant interaction effect was observed for V̇O2peak, with the change in V̇O2peak being greater (p < 0.05) in the MID group than the LO group; however, no differences were observed between the HI group and either the MID or LO groups (ΔV̇O2peak; LO, 2.7 ± 0.7 mL·kg–1·min–1; MID, 5.8 ± 0.7; HI, 4.2 ± 1.0). The greatest proportion of responders was observed in the MID group (LO, 8/12; MID, 12/13; HI, 9/11). A nonsignificant relationship (p = 0.26; r2 = 0.04) was found between the changes in V̇O2peak and τV̇O2. These results suggest that training at intensities around V̇O2peak may represent a threshold intensity above which further increases in training intensity provide no additional adaptive benefit. The dissociation between changes in V̇O2peak and V̇O2 kinetics also reflects the different underlying mechanisms regulating these adaptations.

The Effect of Training Intensity on VO2max in Young Healthy Adults: A Meta-Regression and Meta-Analysis

Exercise training at a variety of intensities increases maximal oxygen uptake (VO₂max), the strongest predictor of cardiovascular and all-cause mortality. The purpose of the present study was to perform a systematic review, meta-regression and meta-analysis of available literature to determine if a dose-response relationship exists between exercise intensity and training-induced increases in VO₂max in young healthy adults. Twenty-eight studies involving human participants (Mean age: 23±1 yr; Mean VO₂max: 3.4±0.8 l·min^-1) were included in the meta-regression with exercise training intensity, session dose, baseline VO₂max, and total training volume used as covariates. These studies were also divided into 3 tertiles based on intensity (tertile 1: ~60-70%; 2: ~80-92.5%; 3: ~100-250%VO₂max), for comparison using separate meta-analyses. The fixed and random effects meta-regression models examining training intensity, session dose, baseline VO₂max and total training volume was non-significant (Q4=1.36; p=0.85; R²=0.05). There was no significant difference between tertiles in mean change in VO₂max (tertile 1:+0.29±0.15 l/min, ES (effect size) =0.77; 2:+0.26±0.10 l/min, ES=0.68; 3:+0.35±0.17 l/min, ES=0.80), despite significant (p<0.05) reductions in session dose and total training volume as training intensity increased. These data suggest that exercise training intensity has no effect on the magnitude of training-induced increases in maximal oxygen uptake in young healthy human participants, but similar adaptations can be achieved in low training doses at higher exercise intensities than higher training doses of lower intensity (endurance training).

VO2max trainability and high intensity interval training in humans: a meta-analysis

Endurance exercise training studies frequently show modest changes in VO₂max with training and very limited responses in some subjects. By contrast, studies using interval training (IT) or combined IT and continuous training (CT) have reported mean increases in VO₂max of up to ∼1.0 L · min⁻¹. This raises questions about the role of exercise intensity and the trainability of VO₂max. To address this topic we analyzed IT and IT/CT studies published in English from 1965–2012. Inclusion criteria were: 1)≥3 healthy sedentary/recreationally active humans <45 yrs old, 2) training duration 6–13 weeks, 3) ≥3 days/week, 4) ≥10 minutes of high intensity work, 5) ≥1∶1 work/rest ratio, and 6) results reported as mean ± SD or SE, ranges of change, or individual data. Due to heterogeneity (I² value of 70), statistical synthesis of the data used a random effects model. The summary statistic of interest was the change in VO₂max. A total of 334 subjects (120 women) from 37 studies were identified. Participants were grouped into 40 distinct training groups, so the unit of analysis was 40 rather than 37. An increase in VO₂max of 0.51 L ·min⁻¹ (95% CI: 0.43 to 0.60 L · min⁻¹) was observed. A subset of 9 studies, with 72 subjects, that featured longer intervals showed even larger (∼0.8–0.9 L · min⁻¹) changes in VO₂max with evidence of a marked response in all subjects. These results suggest that ideas about trainability and VO₂max should be further evaluated with standardized IT or IT/CT training programs.

Running Interval Training and Estimated Plasma-Volume Variation

The effect of endurance interval training (IT) on hematocrit (Ht), hemoglobin (Hb), and estimated plasma-volume variation (PVV) in response to maximal exercise was studied in 15 male subjects (21.1 ± 1.1 y; control group n = 6, and training group, n = 9). The training group participated in interval training 3 times a week for 7 wk. A maximal graded test (GXT) was performed to determine maximal aerobic power (MAP) and maximal aerobic speed (MAS) both before and after the training program. To determine Ht, Hb concentration, and lactate concentrations, blood was collected at rest, at the end of GXT, and after 10 and 30 min of recovery. MAP and MAS increased significantly (P < .05) after training only in training group. Hematocrit determined at rest was significantly lower in the training group than in the control group after the training period (P < .05). IT induced a significant increase of estimated PVV at rest for training group (P < .05), whereas there were no changes for control group. Hence, significant relationships were observed after training between PVV determined at the end of the maximal test and MAS (r = .60, P < .05) and MAP (r = .76, P < .05) only for training group. In conclusion, 7 wk of IT led to a significant increase in plasma volume that possibly contributed to the observed increase of aerobic fitness (MAP and MAS).

Effects of recovery mode (active vs. passive) on performance during a short high-intensity interval training program: a longitudinal study

The aim of this longitudinal study was to compare two recovery modes (active vs. passive) during a seven-week high-intensity interval training program (SWHITP) aimed to improve maximal oxygen uptake ([Formula: see text]), maximal aerobic velocity (MAV), time to exhaustion (t lim) and time spent at a high percentage of [Formula: see text], i.e., above 90 % (t90 [Formula: see text]) and 95 % (t95 [Formula: see text]) of [Formula: see text]. Twenty-four adults were randomly assigned to a control group that did not train (CG, n = 6) and two training groups: intermittent exercise (30 s exercise/30 s recovery) with active (IEA, n = 9) or passive recovery (IEP, n = 9). Before and after seven weeks with (IEA and IEP) or without (CG) high-intensity interval training (HIT) program, all subjects performed a maximal graded test to determine their [Formula: see text] and MAV. Subsequently only the subjects of IEA and IEP groups carried out an intermittent exercise test consisting of repeating as long as possible 30 s intensive runs at 105 % of MAV alternating with 30 s active recovery at 50 % of MAV (IEA) or 30 s passive recovery (IEP). Within IEA and IEP, mean t lim and MAV significantly increased between the onset and the end of the SWHITP and no significant difference was found in t90 VO2max and t95 VO2max. Furthermore, before and after the SWHITP, passive recovery allowed a longer t lim for a similar time spent at a high percentage of VO2max. Finally, within IEA, but not in IEP, mean VO2max increased significantly between the onset and the end of the SWHITP both in absolute (p < 0.01) and relative values (p < 0.05). In conclusion, our results showed a significant increase in VO2max after a SWHITP with active recovery in spite of the fact that t lim was significantly longer (more than twice longer) with respect to passive recovery.

Extremely low volume, whole-body aerobic-resistance training improves aerobic fitness and muscular endurance in females

The current study evaluated changes in aerobic fitness and muscular endurance following endurance training and very low volume, whole-body, high-intensity, interval-style aerobic-resistance training. Subjects' enjoyment and implementation intentions were also examined prior to and following training. Subjects (22 recreationally active females (20.3 ± 1.4 years)) completed 4 weeks of exercise training 4 days per week consisting of either 30 min of endurance treadmill training (~85% maximal heart rate; n = 7) or whole-body aerobic-resistance training involving one set of 8 × 20 s of a single exercise (burpees, jumping jacks, mountain climbers, or squat thrusts) separated by 10 s of rest per session (n = 7). A third group was assigned to a nontraining control group (n = 8). Following training, [Formula: see text]O(2peak) was increased in both the endurance (~7%) and interval (~8%) groups (p < 0.05), whereas muscle endurance was improved (p < 0.05) in the interval group (leg extensions, +40%; chest presses, +207%; sit-ups, +64%; push-ups, +135%; and back extensions, +75%). Perceived enjoyment of, and intentions to engage in, very low volume, high-intensity, whole-body interval exercise were both increased following training (p < 0.05). No significant changes were observed for any variable in the control (nontraining) group. These data demonstrate that although improvements in cardiovascular fitness are induced by both endurance and extremely low volume interval-style training, whole-body aerobic-resistance training imparted addition benefit in the form of improved skeletal muscle endurance.

Blood Lactate Diagnostics in Exercise Testing and Training

A link between lactate and muscular exercise was seen already more than 200 years ago. The blood lactate concentration (BLC) is sensitive to changes in exercise intensity and duration. Multiple BLC threshold concepts define different points on the BLC power curve during various tests with increasing power (INCP). The INCP test results are affected by the increase in power over time. The maximal lactate steady state (MLSS) is measured during a series of prolonged constant power (CP) tests. It detects the highest aerobic power without metabolic energy from continuing net lactate production, which is usually sustainable for 30 to 60 min. BLC threshold and MLSS power are highly correlated with the maximum aerobic power and athletic endurance performance. The idea that training at threshold intensity is particularly effective has no evidence. Three BLC-orientated intensity domains have been established: (1) training up to an intensity at which the BLC clearly exceeds resting BLC, light- and moderate-intensity training focusing on active regeneration or high-volume endurance training (Intensity < Threshold); (2) heavy endurance training at work rates up to MLSS intensity (Threshold ≤ Intensity ≤ MLSS); and (3) severe exercise intensity training between MLSS and maximum oxygen uptake intensity mostly organized as interval and tempo work (Intensity > MLSS). High-performance endurance athletes combining very high training volume with high aerobic power dedicate 70 to 90% of their training to intensity domain 1 (Intensity < Threshold) in order to keep glycogen homeostasis within sustainable limits.

The effects of four weeks of creatine supplementation and high-intensity interval training on cardiorespiratory fitness: a randomized controlled trial

Background

High-intensity interval training has been shown to be a time-efficient way to induce physiological adaptations similar to those of traditional endurance training. Creatine supplementation may enhance high-intensity interval training, leading to even greater physiological adaptations. The purpose of this study was to determine the effects of high-intensity interval training (HIIT) and creatine supplementation on cardiorespiratory fitness and endurance performance (maximal oxygen consumption (VO_2PEAK), time-to-exhaustion (VO_2PEAKTTE), ventilatory threshold (VT), and total work done (TWD)) in college-aged men.

Methods

Forty-three recreationally active men completed a graded exercise test to determine VO_2PEAK, VO_2PEAKTTE, and VT. In addition, participants completed a time to exhaustion (TTE) ride at 110% of the maximum workload reached during the graded exercise test to determine TWD (TTE (sec) × W = J). Following testing, participants were randomly assigned to one of three groups: creatine (creatine citrate) (Cr; n = 16), placebo (PL; n = 17), or control (n = 10) groups. The Cr and PL groups completed four weeks of HIIT prior to post-testing.

Results

Significant improvements in VO_2PEAK and VO_2PEAKTTE occurred in both training groups. Only the Cr group significantly improved VT (16% vs. 10% improvement in PL). No changes occurred in TWD in any group.

Conclusion

In conclusion, HIIT is an effective and time-efficient way to improve maximal endurance performance. The addition of Cr improved VT, but did not increase TWD. Therefore, 10 g of Cr per day for five days per week for four weeks does not seem to further augment maximal oxygen consumption, greater than HIIT alone; however, Cr supplementation may improve submaximal exercise performance.

Effects of beta-alanine supplementation and high-intensity interval training on endurance performance and body composition in men; a double-blind trial

Background

Intermittent bouts of high-intensity exercise result in diminished stores of energy substrates, followed by an accumulation of metabolites, promoting chronic physiological adaptations. In addition, β-alanine has been accepted has an effective physiological hydrogen ion (H⁺) buffer. Concurrent high-intensity interval training (HIIT) and β-alanine supplementation may result in greater adaptations than HIIT alone. The purpose of the current study was to evaluate the effects of combining β-alanine supplementation with high-intensity interval training (HIIT) on endurance performance and aerobic metabolism in recreationally active college-aged men.

Methods

Forty-six men (Age: 22.2 ± 2.7 yrs; Ht: 178.1 ± 7.4 cm; Wt: 78.7 ± 11.9; VO₂peak: 3.3 ± 0.59 l·min^-1) were assessed for peak O₂ utilization (VO₂peak), time to fatigue (VO_2TTE), ventilatory threshold (VT), and total work done at 110% of pre-training VO₂peak (TWD). In a double-blind fashion, all subjects were randomly assigned into one either a placebo (PL – 16.5 g dextrose powder per packet; n = 18) or β-alanine (BA – 1.5 g β-alanine plus 15 g dextrose powder per packet; n = 18) group. All subjects supplemented four times per day (total of 6 g/day) for the first 21-days, followed by two times per day (3 g/day) for the subsequent 21 days, and engaged in a total of six weeks of HIIT training consisting of 5–6 bouts of a 2:1 minute cycling work to rest ratio.

Results

Significant improvements in VO₂peak, VO_2TTE, and TWD after three weeks of training were displayed (p < 0.05). Increases in VO₂peak, VO_2TTE, TWD and lean body mass were only significant for the BA group after the second three weeks of training.

Conclusion

The use of HIIT to induce significant aerobic improvements is effective and efficient. Chronic BA supplementation may further enhance HIIT, improving endurance performance and lean body mass.

Sport-specific assessment of lactate threshold and aerobic capacity throughout a collegiate hockey season

The purpose of this study was to examine lactate threshold (LT) and maximal aerobic capacity with a sport-specific skating protocol throughout a competitive season in collegiate hockey players. We hypothesized that maximal aerobic capacity and skating velocity at LT would increase as the season progressed. Sixteen Division I college hockey players performed a graded exercise skating protocol to fatigue at 3 different times (pre-, mid-, and postseason). Subjects skated for 80 s during each stage, followed by 40 s of rest to allow for blood lactate sampling. Velocity at LT was similar during preseason (4.44 ± 0.08 m·s–1) and postseason (4.52 ± 0.05 m·s–1) testing, but was significantly elevated at midseason (4.70 ± 0.08 m·s–1; p < 0.01), compared with preseason. In contrast, LT as a percentage of maximal heart rate (HRmax) was unchanged throughout the season. HRmax remained constant throughout the season, at approximately 190 beats·min–1. Preseason maximal aerobic capacity (48.7 ± 0.8 mL·kg–1·min–1) was significantly higher than that at postseason (45.0 ± 1.1 mL·kg–1·min–1; p < 0.01). In conclusion, skating velocity at LT improved from pre- to midseason, but this adaptation was not maintained at postseason. Additionally, maximal aerobic capacity was reduced from pre- to postseason. These findings suggest a need for aerobic training throughout the college hockey season.

Influence of exercise intensity on time spent at high percentage of maximal oxygen uptake during an intermittent session in young endurance-trained athletes

The purpose of this study was to compare, during a 30s intermittent exercise (IE), the effects of exercise intensity on time spent above 90% VO2max(t90VO2max) and time spent above 95% VO2max(t95VO2max) in young endurance trained athletes. We hypothesized that during a 30sIE, an increase in exercise intensity would allow an increase in t90VO2max and t95VO2max due to a decrease in time to achieve 90% or 95% of VO2max. Nine endurance-trained male adolescents took part in three field tests. After determination of their VO2max and maximal aerobic velocity (MAV), they performed, until exhaustion, two intermittent exercise sessions alternating 30s at 100% of MAV (IE(100)) or 110% of MAV (IE(110)) and 30s at 50% of MAV. Mean time to exhaustion (t (lim)) values obtained during IE(100) were significantly longer than during IE(110) (p < 0.01). Moreover, no significant difference was found in t90VO2max or t95VO2max) expressed in absolute or relative (%t (lim)) values between IE(100) and IE(110). In conclusion, an increased of 10% of exercise intensity during a 30s intermittent exercise model (with active recovery), does not seem to be the most efficient exercise to solicit oxygen uptake to its highest level in young endurance-trained athletes.

The impact of exercise training intensity on change in physiological function in patients with chronic obstructive pulmonary disease

Pulmonary rehabilitation incorporating exercise training is an effective method of enhancing physiological function and quality of life for patients with chronic obstructive pulmonary disease (COPD). Despite the traditional belief that exercise is primarily limited by the inability to adequately increase ventilation to meet increased metabolic demands in these patients, significant deficiencies in muscle function, oxygen delivery and cardiac function are observed that contribute to exercise limitation. Because of this multifactorial exercise limitation, defining appropriate exercise training intensities is difficult. The lack of a pure cardiovascular limitation to exercise prohibits the use of training guidelines that are based on cardiovascular factors such as oxygen consumption or heart rate. Current recommendations for exercise training intensity for patients with COPD include exercising at a 'maximally tolerable level', at an intensity corresponding with 50% of peak oxygen consumption (V-O2peak), or at 60-80% of peak power output obtained on a symptom-limited exercise tolerance test. In general, it appears that higher intensity training elicits greater physiological change than lower intensity training; however, there is no consensus as to the exercise training intensity that elicits the greatest physiological benefit while remaining tolerable to patients. The 'optimal' intensity of training likely depends upon the individual goals of each patient. If the goal is to increase the ability to sustain tasks that are currently able to be performed, lower to moderate-intensity training is likely to be sufficient. If the goal of training, however, is to increase the ability to perform tasks that are above the current level of tolerance, higher intensity training is likely to elicit greater performance increases. In order to perform higher intensity exercise, an interval training model is likely required. High-intensity interval training involves significant anaerobic energy utilisation and, therefore, may better mimic the physiological requirements of activities of daily living. Also, high-intensity interval training is tolerable to patients and may, in fact, reduce the degree of dyspnoea and dynamic hyperinflation through a reduced ventilatory demand. Another factor that will determine the optimal intensity of training is the relative contribution of ventilatory limitation to exercise tolerance. If peak exercise tolerance is limited by a patient's ability to increase ventilation, it is possible that interval training at an intensity higher than peak will elicit greater muscular adaptation than an intensity at or below peak power on an incremental exercise test. More research is required to determine the optimal training intensity for pulmonary rehabilitation patients.

Training content and potential impact on performance: a comparison of young male and female endurance-trained runners

The purpose of the present investigation was to compare the content of 8 weeks of training in young endurance-trained male and female runners and study the potential impact of this training content on performance. Fourteen men and 11 women performed two criterion exercises until exhaustion on an outdoor track before and after the 8-week training period. The first test was a graded exercise to determine maximal aerobic velocity (Mav), the velocity at the lactate concentration threshold (v-Tlac), and the velocity at delta 50 (v delta50: the velocity halfway between Mav and v-Tlac). The second test was a constant run at v delta50 to determine the time to exhaustion at this velocity (tlimv delta50). Training logs were used to monitor the self-directed training sessions. The results showed that the women had a lower training volume but trained at higher exercise velocities than the men. However they presented similar values as the men for expected temporary performance capacity and did not improve their performance (Mav and tlimv delta50) over the 8-week period. After the training period, only v-Tlac (absolute and relative values) was slightly but significantly increased by training. These results could be due to the fact that both men and women did not train more than 10% of the total distance run at exercise velocities equal to or higher than their Mav and did not increase their training load during the 8-week training period. We suggest that changes in training content during the season, such as severe (long-duration or high-intensity) training sessions, may have improved their performance capacity.

Predictive validity of ventilatory and lactate thresholds for cycling time trial performance

PURPOSE

To determine which laboratory measurement best predicts 40 km cycling time-trial (TT) performance.

METHODS

Fifteen male cyclists performed lactate-threshold (LT), ventilatory-threshold (VT), 5 km and 40 km TT. Key variables of interest were Watts at thresholds. For VT determination we used: breakpoint of ventilatory equivalent of oxygen (VE/VO2); breakpoint of ventilatory equivalent of carbon dioxide (VE/VCO2); V-slope; respiratory exchange ratio (RER)=1 and 0.95. For LT we used Stegmann's individual anaerobic threshold; the stage preceding the second 0.5 mmol L(-1) increase (Baldari); 4 mmol L(-1); 1 mmol L(-1) increase in 3 min; the stage preceding the first 1 mmol L(-1) increase as criterion methods (<1 mmol). Analyses also included peak power during the incremental threshold tests (MaxVT(watts), MaxLT(watts)) and 5 km performance (5K(avgwatts)).

RESULTS

Regression analyses between VT variables and 40K(avgwatts) were significant for V-slope (r2=0.63), VE/VO2 (r2=0.64), RER(0.95) (r2=0.53), RER1 (r2=0.57), and MaxVT(watts) (r2=0.65). Regressions between LT variables and 40K(avgwatts) were significant for Baldari (r2=0.52), 4 mmol L(-1) (r2=0.36), <1 mmol (r2=0.35), Keul (r2=0.34), and MaxLT(watts) (r2=0.51). Regressions between 5K variables and 40K(avgwatts) were significant for 5K(avgwatts) (r2=0.58). Paired t-tests between these variables and the 40K(avgwatts) indicated that absolute power outputs at VE/VO2 (P=0.33), RER(0.95) (P=0.93), and 4 mmol L(-1) (P=0.39) were not significantly different from 40K(avgwatts).

CONCLUSION

We conclude that VT-based variables are generally superior to LT variables relative to predicting 40K(avgwatts), the simplest of several valid measures appears to be VE/VO2.

Assessment of ventilatory thresholds during graded and maximal exercise test using time varying analysis of respiratory sinus arrhythmia

OBJECTIVE

To test whether ventilatory thresholds, measured during an exercise test, could be assessed using time varying analysis of respiratory sinus arrhythmia frequency (f(RSA)).

METHODS

Fourteen sedentary subjects and 12 endurance athletes performed a graded and maximal exercise test on a cycle ergometer: initial load 75 W (sedentary subjects) and 150 W (athletes), increments 37.5 W/2 min. f(RSA) was extracted from heart period series using an evolutive model. First (T(V1)) and second (T(V2)) ventilatory thresholds were determined from the time course curves of ventilation and ventilatory equivalents for O(2) and CO(2).

RESULTS

f(RSA) was accurately extracted from all recordings and positively correlated to respiratory frequency (r = 0.96 (0.03), p<0.01). In 21 of the 26 subjects, two successive non-linear increases were determined in f(RSA), defining the first (T(RSA1)) and second (T(RSA2)) f(RSA) thresholds. When expressed as a function of power, T(RSA1) and T(RSA2) were not significantly different from and closely linked to T(V1) (r = 0.99, p<0.001) and T(V2) (r = 0.99, p<0.001), respectively. In the five remaining subjects, only one non-linear increase was observed close to T(V2). Significant differences (p<0.04) were found between athlete and sedentary groups when T(RSA1) and T(RSA2) were expressed in terms of absolute and relative power and percentage of maximal aerobic power. In the sedentary group, T(RSA1) and T(RSA2) were 150.3 (18.7) W and 198.3 (28.8) W, respectively, whereas in the athlete group T(RSA1) and T(RSA2) were 247.3 (32.8) W and 316.0 (28.8) W, respectively.

CONCLUSIONS

Dynamic analysis of f(RSA) provides a useful tool for identifying ventilatory thresholds during graded and maximal exercise test in sedentary subjects and athletes.

Anaerobic threshold: its concept and role in endurance sport

aerobic to anaerobic transition intensity is one of the most significant physiological variable in endurance sports. Scientists have explained the term in various ways, like, Lactate Threshold, Ventilatory Anaerobic Threshold, Onset of Blood Lactate Accumulation, Onset of Plasma Lactate Accumulation, Heart Rate Deflection Point and Maximum Lactate Steady State. But all of these have great role both in monitoring training schedule and in determining sports performance. Individuals endowed with the possibility to obtain a high oxygen uptake need to complement with rigorous training program in order to achieve maximal performance. If they engage in endurance events, they must also develop the ability to sustain a high fractional utilization of their maximal oxygen uptake (%VO(2) max) and become physiologically efficient in performing their activity. Anaerobic threshold is highly correlated to the distance running performance as compared to maximum aerobic capacity or VO(2) max, because sustaining a high fractional utilization of the VO(2) max for a long time delays the metabolic acidosis. Training at or little above the anaerobic threshold intensity improves both the aerobic capacity and anaerobic threshold level. Anaerobic Threshold can also be determined from the speed-heart rate relationship in the field situation, without undergoing sophisticated laboratory techniques. However, controversies also exist among scientists regarding its role in high performance sports.

Effect of time of day on the relationship between lactate and ventilatory thresholds: a brief report

The purpose of this investigation was to study the effect of time of day on the relationship between lactate (LT) and ventilatory thresholds (VT) of pulmonary oxygen uptake (VO2). Seven moderately active male volunteers (26.3 ± 3.0 years, 1.74 ± 0.08 m, 76 ± 5 kg) performed a maximal incremental test (increases of 30 W every 2 min) on a cycle ergometer on consecutive days at 0900 h, 1400h and 1900 h in a randomized fashion. The anaerobic threshold was determined using both ventilatory gas analysis and blood lactate measures. Each of the following variables was recorded both at VT and the LT; heart rate (HR, beats.min(-1)), minute ventilation (VE, L.min(-1)), respiratory exchange ratio (RER), time to threshold (Time, sec), oxygen uptake (VO2, ml·kg(-1).min(-1)) and VO2 as a percentage of maximal oxygen uptake (%VO2max). The correlations between VT and LT variables analyzed by Pearson product moment correlations for each time of day. ANOVA was used to compare the data obtained at different times of the day. There were no significant differences for the data related to time of day either for ventilatory gas analysis or lactate measurements. The correlation coefficients between VT and LT variables were moderate to high (r=0.56-0.94) for time of day. However, the correlations for HR, VO2, and %VO2max (r=0.81-0.94) were slightly stronger compared with Time, VE and RER (r=0.56-0.88). It was concluded that, the data at VT and LT were not influenced by time of day.

Methods to determine aerobic endurance

Physiological testing of elite athletes requires the correct identification and assessment of sports-specific underlying factors. It is now recognised that performance in long-distance events is determined by maximal oxygen uptake (V(2 max)), energy cost of exercise and the maximal fractional utilisation of V(2 max) in any realised performance or as a corollary a set percentage of V(2 max) that could be endured as long as possible. This later ability is defined as endurance, and more precisely aerobic endurance, since V(2 max) sets the upper limit of aerobic pathway. It should be distinguished from endurance ability or endurance performance, which are synonymous with performance in long-distance events. The present review examines methods available in the literature to assess aerobic endurance. They are numerous and can be classified into two categories, namely direct and indirect methods. Direct methods bring together all indices that allow either a complete or a partial representation of the power-duration relationship, while indirect methods revolve around the determination of the so-called anaerobic threshold (AT). With regard to direct methods, performance in a series of tests provides a more complete and presumably more valid description of the power-duration relationship than performance in a single test, even if both approaches are well correlated with each other. However, the question remains open to determine which systems model should be employed among the several available in the literature, and how to use them in the prescription of training intensities. As for indirect methods, there is quantitative accumulation of data supporting the utilisation of the AT to assess aerobic endurance and to prescribe training intensities. However, it appears that: there is no unique intensity corresponding to the AT, since criteria available in the literature provide inconsistent results; and the non-invasive determination of the AT using ventilatory and heart rate data instead of blood lactate concentration ([La(-)](b)) is not valid. Added to the fact that the AT may not represent the optimal training intensity for elite athletes, it raises doubt on the usefulness of this theory without questioning, however, the usefulness of the whole [La(-)](b)-power curve to assess aerobic endurance and predict performance in long-distance events.

Major gene effects on exercise ventilatory threshold: the HERITAGE Family Study

This study investigates whether there are major gene effects on oxygen uptake at the ventilatory threshold (VO(2VT)) and the VO(2VT) maximal oxygen uptake (VT%VO(2 max)), at baseline and in response to 20 wk of exercise training by using data on 336 whites and 160 blacks. Segregation analysis was performed on the residuals of VO(2VT) and VT%VO(2 max). In whites, there was strong evidence of a major gene, with 3 and 2% of the sample in the upper distribution, that accounted for 52 and 43% of the variance in baseline VO(2VT) and VT%VO(2 max), respectively. There were no genotype-specific covariate effects (sex, age, weight, fat mass, and fat-free mass). The segregation results were inconclusive for the training response in whites, and for the baseline and training response in blacks, probably due to insufficient power because of reduced sample sizes or smaller gene effect or both. The strength of the genetic evidence for VO(2VT) and VT%VO(2 max) suggests that these traits should be further investigated for potential relations with specific candidate genes, if they can be identified, and explored through a genome-wide scan.

The scientific basis for high-intensity interval training: optimising training programmes and maximising performance in highly trained endurance athletes

While the physiological adaptations that occur following endurance training in previously sedentary and recreationally active individuals are relatively well understood, the adaptations to training in already highly trained endurance athletes remain unclear. While significant improvements in endurance performance and corresponding physiological markers are evident following submaximal endurance training in sedentary and recreationally active groups, an additional increase in submaximal training (i.e. volume) in highly trained individuals does not appear to further enhance either endurance performance or associated physiological variables [e.g. peak oxygen uptake (VO2peak), oxidative enzyme activity]. It seems that, for athletes who are already trained, improvements in endurance performance can be achieved only through high-intensity interval training (HIT). The limited research which has examined changes in muscle enzyme activity in highly trained athletes, following HIT, has revealed no change in oxidative or glycolytic enzyme activity, despite significant improvements in endurance performance (p < 0.05). Instead, an increase in skeletal muscle buffering capacity may be one mechanism responsible for an improvement in endurance performance. Changes in plasma volume, stroke volume, as well as muscle cation pumps, myoglobin, capillary density and fibre type characteristics have yet to be investigated in response to HIT with the highly trained athlete. Information relating to HIT programme optimisation in endurance athletes is also very sparse. Preliminary work using the velocity at which VO2max is achieved (V(max)) as the interval intensity, and fractions (50 to 75%) of the time to exhaustion at V(max) (T(max)) as the interval duration has been successful in eliciting improvements in performance in long-distance runners. However, V(max) and T(max) have not been used with cyclists. Instead, HIT programme optimisation research in cyclists has revealed that repeated supramaximal sprinting may be equally effective as more traditional HIT programmes for eliciting improvements in endurance performance. Further examination of the biochemical and physiological adaptations which accompany different HIT programmes, as well as investigation into the optimal HIT programme for eliciting performance enhancements in highly trained athletes is required.

Interval training for performance: a scientific and empirical practice. Special recommendations for middle- and long-distance running. Part I: aerobic interval training

This article traces the history of scientific and empirical interval training. Scientific research has shed some light on the choice of intensity, work duration and rest periods in so-called 'interval training'. Interval training involves repeated short to long bouts of rather high intensity exercise (equal or superior to maximal lactate steady-state velocity) interspersed with recovery periods (light exercise or rest). Interval training was first described by Reindell and Roskamm and was popularised in the 1950s by the Olympic champion, Emil Zatopek. Since then middle- and long- distance runners have used this technique to train at velocities close to their own specific competition velocity. In fact, trainers have used specific velocities from 800 to 5000m to calibrate interval training without taking into account physiological markers. However, outside of the competition season it seems better to refer to the velocities associated with particular physiological responses in the range from maximal lactate steady state to the absolute maximal velocity. The range of velocities used in a race must be taken into consideration, since even world records are not run at a constant pace.